Permian to quaternary magmatism beneath the mt carmel area, israel

Permian to quaternary magmatism beneath the Mt Carmel area, Israel:
Zircons from volcanic rocks and associated alluvial deposits
W.L. Griffin a,
⁎, S.E.M. Gain a
, J.-X. Huang a
, E.A. Belousova a
, V. Toledo b
, S.Y. O'Reilly a
a
ARC Centre of Excellence for Core to Crust Fluid Systems, Dept. Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia
b
Shefa Yamim (A.T.M.) Ltd., Netanya 4210602, Israel
a b s t r a c ta r t i c l e i n f o
Article history:
Received 30 March 2018
Accepted 4 June 2018
Available online 18 June 2018
Xenocrystic zircons from Cretaceous pyroclastic vents on Mt. Carmel, N. Israel, document two major periods of
earlier mafic magmatism: Permo-Triassic (285–220 Ma) and Jurassic (200–160 Ma). Related alluvial deposits
also contain these zircon populations. However, most alluvial zircons are Cretaceous (118–80 Ma) or younger,
derived from Miocene to Pliocene volcanic episodes. The Permo-Triassic-Jurassic zircons are typically large and
glassy; they have irregular shapes and a wide variety of internal zoning patterns. They appear to have grown
in the interstitial spaces of coarse-grained rocks; many show evidence of recrystallization, including brecciation
and rehealing by chemically similar zircon. Grains with relict igneous zoning have mantle-like δ18
O (5.5 ± 1.0‰),
but brecciation leads to lower values (mean 4.8‰, down to 3.1‰). Hf-isotope compositions lie midway between
the Chondritic Uniform Reservoir (CHUR) and Depleted Mantle (DM) reservoirs; Hf model ages suggest that the
source region separated from DM in Neoproterozoic time (1500–1000 Ma). Most Cretaceous zircons have
176
Hf/177
Hf similar to those of the older zircons, suggesting recrystallization and/or Pb loss from older zircons
in the Cretaceous thermal event. The Permo-Jurassic zircons show trace-element characteristics similar to
those crystallized from plume-related magmas (Iceland, Hawaii). Calculated melts in equilibrium with them
are characterized by strong depletion in LREE and P, large positive Ce anomalies, variable Ti anomalies, and
high and variable Nb, Ta, Th and U, consistent with the fractionation of monazite, zircon, apatite and Ti-bearing
phases. We suggest that these coarse-grained zircons crystallized from late differentiates of mafic magmas,
ponded near the crust-mantle boundary (ca 30 km depth), and were reworked repeatedly by successively youn-
ger igneous/metasomatic fluids.
The zircon data support a published model that locates a fossil Neoproterozoic plume head beneath much of the
Arabia-Levant region, which has been intermittently melted to generate the volcanic rocks of the region. The Cre-
taceous magmas carry mantle xenoliths derived from depths up to 90 km, providing a minimum depth for the
possible plume head. Post-Cretaceous magmatism, as recorded in detrital zircons, shows distinct peaks at
30 Ma, 13 Ma, 11.4 ± 0.1 Ma (a major peak; n = 15), 9–10 Ma and 4 Ma, representing the Lower and Cover Ba-
salts in the area. Some of these younger magmas tapped the same mantle source as the Permian-Jurassic
magmatism, but many young zircons have Hf-isotope compositions extending up to DM values, suggesting der-
ivation of magmas from deeper, more juvenile sources.
© 2018 Elsevier B.V. All rights reserved.
1. Introduction
Zircon is an excellent tracer of the timing and nature of magmatic ac-
tivity. It also can be used when magmas remain in the upper mantle or
deep crust, where they can be sampled by later eruptive magmas. This
approach is directly analogous to detrital-zircon analysis in crustal set-
tings, where zircons are used to investigate the magmatic and meta-
morphic history of rocks in the drainage area. As with detrital-zircon
studies, this tool becomes especially effective when UPb dating is
combined with the analysis of HfO isotopes and trace elements.
Several studies of kimberlites (Belousova et al., 2001; Kinny et al.,
1989; Tretiakova et al., 2017) have identified multiple populations of
mantle-derived zircons, demonstrating that zircon can retain crystalli-
zation ages despite high temperatures; it thus can record magmatic ep-
isodes for which surface expression has been lost, or not recognized.
This is less commonly possible with more mafic types of volcanic
rocks, perhaps because xenocrystic zircons have been dissolved or per-
haps because the presence of magmatic zircons is not expected. In gen-
eral, zircon does not crystallize directly from mafic magmas, because of
the high solubility of Zr in such melts. However, if mafic magmas stall
Lithos 314–315 (2018) 307–322
⁎ Corresponding author.
E-mail address: bill.griffin@mq.edu.au (W.L. Griffin).
https://doi.org/10.1016/j.lithos.2018.06.007
0024-4937/© 2018 Elsevier B.V. All rights reserved.
Contents lists available at ScienceDirect
Lithos
journal homepage: www.elsevier.com/locate/lithos

and fractionate during long slow cooling in the upper mantle or lower
crust, zircon can crystallize from late residual melts or fluids. In areas
of continuing magmatic activity, such zircons can be entrained in the
next erupting magma, and their ages may be indistinguishable (within
errors) from the age of the host basalt. Alternatively, the deep-seated
zircons may react with later melts and fluids to give complex age pat-
terns, when they are sampled by still later magmas. The analysis of zir-
con xenocrysts in mafic rocks thus can be used to examine the
magmatic history of the uppermost mantle and lower crust. In this
paper we use this analytical tool to investigate the history of basaltic
magmatism, as sampled by late Cretaceous volcanoes on Mt. Carmel,
northern Israel, with special emphasis on events of crustal underplating
from the breakup of Gondwana to the Pliocene. A secondary aim has
been to constrain the ages of some of the eruptive centers and to under-
stand differences in the sampling patterns of individual centers, as a
guide to exploration.
Late Cretaceous magmatism in the Mt. Carmel area (Fig. 1) involved
repeated pyroclastic eruptions in a shallow marine-shelf setting, build-
ing several km-scale seamounts over the period from ca 97–80 Ma
(Segev and Sass, 2009). Although no older volcanic rocks outcrop within
the region, the Cretaceous vents and tuffs described here contain several
populations of older zircons with distinctive characteristics, revealing a
history of mantle-derived magmatism stretching back to Lower Perm-
ian time (ca 280 Ma). These occurrences offer new insights into
magmatism related to the breakup of Gondwana, and raise questions
surrounding the behaviour of the lithospheric and asthenospheric man-
tle during rifting, and the conditions that would focus repeated mafic
magmatism into this small area (ca 150 km2
) since Permian time.
Here we present UPb dating, OHf isotopic analyses and trace-el-
ement data from N400 zircons, collected both from the Cretaceous pyro-
clastic rocks and from associated alluvial deposits. We use these data to
constrain the ages of some of the Cretaceous eruptive centers, to map
out the mantle distribution of intrusive magmas related to the older vol-
canic episodes, and to discuss the questions flagged above.
1.1. Regional setting
The material described here is derived from Cretaceous volcanic cen-
ters and related alluvial deposits in the Mt. Carmel-Yizre'el Valley area
of northern Israel (Fig. 2). This area lies within a complex system of
minor rifts and other faults, related to the Africa-Arabia plate boundary
that later developed into the Dead Sea Transform, with N100 km move-
ment since the initiation of offset in Miocene time. The NW-SE Carmel
Fault that bounds Mount Carmel on the east (Fig. 1) is part of the Car-
mel-Gilboa system, which forms a 10–20 km wide belt of faulting run-
ning through the Yisre'el Valley, and may extend across the
continental margin (Segev and Rybakov, 2011). The SW side of Mount
Carmel is dissected by multiple N-striking vertical faults with offsets
up to a few hundred meters. The basement rocks, which are not exposed
in this area, are considered to have formed in Pan-African (Cadomian)
time (N620 Ma; Stein and Goldstein, 1996). The Galilee area represents
a zone of thin continental crust, with a Moho depth of 23–32 km (Segev
and Rybakov, 2011). The geophysical data, and estimates of the Creta-
ceous geotherm from mantle-derived xenoliths and xenocrysts (Apter,
2014; our unpublished data) suggest a thin (b100 km), hot lithospheric
mantle. It is not clear whether this is a remnant of a previously thicker
lithosphere that was thinned during rifting and drifting, or has devel-
oped later through magmatic processes (Stein and Hofmann, 1992).
This region experienced considerable mafic and felsic volcanism
during and following the Permo-Triassic Palmyra rifting, related to the
breakup of Gondwana and the opening of the Neo-Tethys ocean refs.
The northern end of Mt. Carmel is the centre of a major NW-SE magnetic
anomaly, which extends well offshore. Modelling by Segev and Rybakov
(2011) indicates that the magnetic source is buried at least 5 km below
the surface, and the authors suggest that it reflects magmatism related
to the Palmyra rifting. This was followed by a major Early Jurassic
(197–193 Ma) event which erupted up to 2.4 km3
of alkali-olivine ba-
salts and pyroclastic rocks with OIB-intraplate geochemical signatures
(Dvorkin and Kohn, 1989). A high positive gravity anomaly centered
Fig. 1. Setting of the Mount Carmel area within the tectonic framework of the Middle East.
After Segev (2009).
308 W.L. Griffin et al. / Lithos 314–315 (2018) 307–322

under the northern end of Mount Carmel has been interpreted to reflect
the existence of a buried shield volcano beneath Mt. Carmel (Ben-
Avraham and Hall, 1977; Gvirtzman et al., 1990). However, a more re-
cent study (Segev and Rybakov, 2011) suggests that the anomaly is
only high relative to deep basins on either side, which are filled with
thick clastic sediments.
The early development of the late Jurassic-Early Cretaceous Levant
magmatic province, extending ca 800 km from central Syria to the
Gulf of Suez, coincided with major rifting across Africa, but no major
rifting events appear to correlate with the relatively sparse distribution
of Early Cretaceous (C1, 137–139 Ma; Segev, 2005; references therein)
continental magmatism within Israel. This magmatism comprises
subalkaline to alkaline basalts, nephelinites, basanites and
microgabbros with hotspot/mantle plume geochemical and isotopic
signatures (Garfunkel, 1989; Laws and Wilson, 1997; Stein and
Hofmann, 1992; Stein and Hofmann, 1994). This type of magmatism
Fig. 2. Geological map of the Yizre'el Valley-Mt Carmel area, showing sampling localities on Mt. Carmel. BO, Beit Oren; HA, Har Alon; MAK, Makhura; MUH, Muhraka, RMC, Rakefet
Magmatic Complex; KM, Kerem Maharal; BS, Bat Shelomo; T, Tavassim; S, Shefaya; O, Ofer.
309W.L. Griffin et al. / Lithos 314–315 (2018) 307–322

continued until ca 125 Ma in Lebanon and possibly into northern Israel
(C2; Segev, 2005).
The Late Cretaceous (98–94 Ma, Turonian-Cenomanian) volcanic ac-
tivity of northern Israel took place in the Mount Carmel-Umm El Fahm
area (Fig. 2), and has been described by Sass (1980). The dominant vol-
canic rocks are pyroclastics of mafic to ultramafic composition; lava
flows played a minor role in this volcanic activity. The volcanism took
place in a shallow marine environment, in intimate contact with marine
sediments containing rich assemblages of fossils. Several outcrops of
black and variegated pyroclastics in isolated areas west of Kerem
Maharal (Fig. 2) overlie the Yagur Formation of Albian (Bein, 1974;
Rosenfeld and Raab, 1984) to earliest Cenomanian age (Lewy, 1991)
and represent the first volcanic eruptions in the area. The black pyro-
clastics appear to represent eruptive vents, while the variegated pyro-
clastics occur as layers of various thickness interbedded with the
carbonates, indicating repeated explosive eruptions and the construc-
tion and levelling of small seamounts. The eruptions continued up to
ca 94 Ma, represented by the Shefaya volcano (Fig. 2).
There is little published information on the composition of the Late
Cretaceous eruptive products, which are variably altered by contact
with sea water. Area-scan EDS analyses of finely-crystalline lapilli
from the Rakefet Magmatic Complex have compositions corresponding
to tholeiitic picrites, but even these apparently fresh samples may have
lost alkali elements during diagenesis. The pyroclastic deposits carry
mantle-derived xenoliths (spinel peridotites, garnet ± spinel pyroxe-
nites, rare garnet websterites), crustal xenoliths ranging from garnet-il-
menite granulites to Triassic limestones, megacrystic Mg-ilmenite,
amphibole and clinopyroxene, and xenocrysts (olivine, orthopyroxene,
diopside, pyrope garnet) derived from mantle peridotites, pyroxenites
and eclogites. P-T estimates on rare garnet websterite xenoliths indicate
they were derived from depths up to ca 90 km (Esperança and
Garfunkel, 1986; Mittlefehldt, 1986; Apter, 2014; Kaminchik et al.,
2014; our unpublished data), giving a minimum depth for generation
of the host magmas.
Abundant Neogene volcanic rocks extend throughout the region
both on the surface and in the subsurface, and are divided into two
main volcanic episodes. The earlier episode (Lower Basalt Fm.) is
assigned to Mid-Late Miocene and was characterized by extension and
faulting across the entire region, coinciding with the initiation of left-
lateral movement on the Dead Sea Transform. This extensional stress re-
gime caused the break-up of the crust, including reactivation of NW-SE
fault systems and graben development, opening paths for volcanic
eruptions focused on the valley margins, adjacent to normal faults.
The younger volcanic period (Cover Basalt Fm.) is assigned to the Plio-
cene and characterized by further faulting of the valleys. Large-scale vol-
canism prevailed across Saudi Arabia, Jordan, Syria and northern Israel
(Segev, 2005), and large areas of central and eastern Galilee as well as
the Golan Heights were covered by basalt flows (Weinstein et al.,
2006), originally totaling ca 300,000 km3
(Shaliv, 1991). Later faulting
and accumulations of the Cover Basalt in the range of 0–150 m, and
minor eruptions between these two episodes, are expressed in out-
crops, mostly in eastern Galilee. In the lower Miocene, between the
eruptive periods of the Lower and Cover basalts, the area was inundated
by a marine transgression, which had important implications for the
distribution of the heavy minerals eroded from the Cretaceous volca-
nics. For example, beach placers (quartzites with carbonate cement)
containing abundant moissanite, garnet and spinel have been sampled
near Migdal-el-Haq during the Shefa Yamim exploration program, far
from known Cretaceous volcanic centres.
1.2. Local setting
The late Cretaceous volcanism on Mount Carmel has been described
in elegant detail by Sass (1980). Despite widespread normal faulting, he
was able to identify 16 volcanic events (Table 1); in 9 cases the corre-
sponding vent was identified, while in three other cases the vents are
buried under younger sediments. Lavas play a minor role in this volca-
nism; four sources were identified but none is correlated with the
known explosion vents. The typical Mount Carmel volcano was a pyro-
clastic cone, erupted in shallow water (b60 m deep), and later eroded to
below the water level. Vents are up to several hundred meters across,
and are characterized by dense black pyroclastics, while the flanks con-
sist of variably altered air-fall and water-laid pyroclastic debris, dipping
away from the cone. Estimated heights of the uneroded cones are from
100 to 350 m, and the ash-fall deposits extend for several kilometers
around some of the vents, where not disrupted by faulting (e.g. Makura,
Fig. 2).
The most complicated volcanoe described by Sass (1980) is the
Rakefet Magmatic Complex, the outcrops of which extend for ca 2.5
km and are bounded by faults on either side. The Complex comprises
three separate eruptive events. The vent of the first Rakefet volcano is
marked by black pyroclastics exposed over at least 60 m vertically.
Our own field investigations suggest that at least three eruptions oc-
curred within the area of the main vent. The bedded pyroclastics of
this vent are overlain by those of the second volcano, from a vent
south of the exposed area. The third volcanic event comprises ca 25 m
of olivine basalt and andesine olivine basalt, some vesicular. Their
source is not located but is presumed to be nearby. The Rakefet Volcanic
Complex is the only example in the area of repeated magmatism within
a small area. The Muhraka volcano to the north, known mainly from
bedded pyroclastics, may be related to this complex (Fig. 2).
Mount Carmel is bounded on the south by the sediments of the
Ramot Menashe syncline (Fig. 1). Drilling (Ein Ha-Shofet #1 deep mon-
itoring drill, Mekorot Ltd) on a magnetic high near the axis of the syn-
cline intersected volcanic rocks at 788–792 m depth, near the base of
the Deir Hanna formation. The rocks at this level are tuffaceous, and
some horizons are marked by abundant large euhedral, zoned crystals
of high-Mg calcite. Several other basalt/tuff horizons were intersected
higher in the Deir Hanna formation (550–750 m). The Uhm-al-Fahm
area, still further south of Mt. Carmel (Fig. 2), exposes a thick section
of basalts, which have not been sampled in this study.
The Shefa Yamim exploration program has sampled many of the
smaller streams and rivers in the drainage basin of the Kishon river,
lying to the east and southeast of Mount Carmel (Fig. 2). Bulk sampling
has been focused on the mid-reach area, where the Kishon River flows
through a narrow gap between Mount Carmel and the adjoining up-
lands, creating a natural trap for transient placers. Most of the samples
labelled “alluvial” in this paper are from this area.
1.3. Sampling
The Shefa Yamim exploration project is aimed at the discovery of
economically viable placer deposits of gemstones (mainly sapphire,
ruby, hibonite, moissanite) and other commodities within the drainage
basin of the Kishon River. The project has sampled the Cretaceous pyro-
clastic centers on Mt. Carmel (Fig. 2; Rakefet, Har Alon, Bat Shelomo,
Muhraka and Beit Oren complexes) and adjacent areas (Ein Ha-Shofet),
and minor and major drainages in the Yaz'rael Valley. Samples range in
size from several kg to N1000 t. All samples were screened through a
static grizzly screen to remove pieces larger than 100 mm in diameter.
Rock samples from the vents were coarsely crushed and then treated
in the same way as alluvial samples. The b100 mm fraction was washed
in a scrubber that breaks up any clods. The b0.5 mm component is
suspended in the wash water and pumped to settling ponds; fractions
larger than 25 mm are used to backfill exploration pits. Samples in the
+8 mm–16 mm and + 16 mm–24 mm size fractions are sorted by
hand on a picking belt. The +0.5 -8 mm component of the sample is
washed and classified into 5 fractions: 0.5–0.7 mm, 0.7-1 mm, 1-
2 mm, 2-4 mm, 4-6 mm, 6-8 mm. These fractions are transferred to a
pulsating jig plant for gravity separation. Samples in the 2 mm–8 mm
size fractions are visually inspected after the jigging process and sorted
in the recovery laboratory. The three smallest size fractions are jigged

separately; most zircons in this study come from these fractions. The
heavy concentrate in the center of the jig pan is collected and dried; ma-
terial on the outer part of the jig pan is discarded. The sorters in the lab-
oratory have demonstrated their efficiency in identifying and
recovering a wide range of mineral species, including garnet (pyrope),
ilmenite, spinel, chrome-diopside, diamond, moissanite, sapphire,
ruby, Carmel Sapphire™ and hibonite, as well as rutile and zircon. The
sample set described here is dominated by zircons from the Rakefet
Magmatic Complex, and the alluvial deposits of the Kishon River mid-
reach, because these localities have been bulk-sampled, providing
abundant material.
The unprocessed heavy mineral concentrates of several samples
were hand-picked under a binocular microscope in the CCFS laborato-
ries; a few rock samples also have been processed by SelFrag (electro-
static disaggregation) techniques at CCFS, sieved and hand-picked
after magnetic and heavy-liquid separation.
1.4. Sample descriptions
Two general groups of zircons in this study can be distinguished by
combinations of external morphology and internal structure, here des-
ignated “Mount Carmel zircon” (MCZ) and “common zircon” (CZ).
MCZ is the most distinctive group. It comprises generally large grains
(0.5–2 mm) with blocky to rounded to irregular shapes, including pro-
nounced rounded knobs and depressions (Fig. 3). Prism or pyramid
faces are visible on some grains but usually show rounding and resorp-
tion. These grains are typically colourless and clear, with a brilliant
luster. Most MCZ have low Cl response, but images of some grains
show patterns that suggest relict, often blurred, igneous or metamor-
phic zoning, including core-rim structures with irregular cores. Many
grains appear to be fractured or even brecciated (see below). Similar ir-
regular zircons have been separated from kimberlite-borne peridotite
xenoliths (A. Guliani, pers. comm. 2016), suggesting that this morphol-
ogy was imposed when the zircons crystallized from melts in the inter-
stitial spaces between other minerals, either in cumulates or in the
peridotitic wall-rock. The outer surfaces of some grains show an un-
usual ‘bubble” texture, suggesting partial melting of the grains, perhaps
during magmatic transport.
For the purposes of this paper, the MCZ zircons can be subdivided
into three classes: igneous, igneous/metamorphic and breccia grains.
“Igneous” grains show oscillatory zoning, or broad lamellar zoning, re-
gardless of external morphology; however, most have more regular
shapes than other MCZ grains. Some grains have distinct cores (usually
metamict, some with contorted zoning) surrounded by thick rims with
or without oscillatory zoning. These are found especially in the Bat
Shelomo vent and the core from the Ein Ha-Shofet locality (Fig. 3a).
“Igneous/metamorphic” grains are mainly homogeneous, but many
contain traces of zoning, or small areas with clear zoning within large
grains that otherwise are homogeneous in CL images. Some of these
grains have relatively homogeneous cores, partially to completely
surrounded by thick homogeneous rims with lighter or darker CL re-
sponse (Fig. 3a). While the grains with homogeneous CL could be
regarded as metamorphic, the continuous transition toward the “igne-
ous” grains, in terms of internal structure and external morphology,
Table 1
Late Cretaceous Volcanic Events in Mt. Carmel, and generalized lithostratigraphic column.
After Sass (1980).
Event no. Rock typesa
Vents with proximal deposits or lavas Isolated pyroclastics (distal flanks) Remarks
1 P,X Kerem Maharal (KM) N. Carmel Lower Tuffs Time equivalent
2 P,X Beit Oren (BO)
3 P,X N. Carmel Intermediate Tuffs Possibly same volcano
4 P,X Tira N. Carmel Upper Tuffs Possible time equivalents
5 P Fureidis Tuffs
6 P,X Tavassim (TA) Possible time equivalents
7 P,X Rakefet 1 (RAK)
8 P,X Rakefet 2 (RAK)
9 P Shefaya (SH) Possible time equivalents
10 P Makura (MA)
11 P Muhraka Tuffs (MU)
12 L Shefaya lavas Probable time equivalents
13 L Ofer lavas (Of)
14 L Rakefet lavas Local or fissure sources
15 L Muhraka lavas
16 P,X Bat Shelomo (BS)
a
P = pyroclastics, L = lavas, X = xenoliths and xenocrysts.

persuades us that most had an igneous heritage. None of these grains
has the low Th/U (b0.1) commonly regarded as indicative of metamor-
phic zircon, though this criterion may not be applicable to zircons in
mafic or ultramafic rocks. These issues are discussed further below in
the light of the isotopic data.
“Breccia” grains generally have low CL response and no traces of
zoning, and are typically irregular in shape. They appear to have been
fractured and rehealed. The differences in CL suggest that the internal
fragments are slightly misaligned, but the fractures are sealed with zir-
con, in optical continuity with the host grain. In some grains brecciated
cores are overgrown by featureless rims (Fig. 3d). Zircons with similar
brecciated/rehealed internal structures have been found in heavy-min-
eral separates from Siberian kimberlites (Tretiakova et al., 2017).
CZ from the vents and the alluvial deposits display a wide range of
morphology, ranging from prismatic to rounded. Oscillatory to lamellar
zoning in CL images indicates that most of the CZ grains are igneous in
origin, but some show evidence of metamorphism. The alluvial deposits
contain a higher proportion of broken and/or rounded grains, as might
be expected. The MCZ population is relatively abundant in the vent
tuffs, but much less common in the alluvial deposits, suggesting that
the brecciated grains, in particular, may not withstand transport as
well as the CZ population.
1.5. Analytical methods
The zircons have been characterized using optical microscopy, scan-
ning electron microscopy (SEM) for CL imaging, electron microprobe
(EMP) for major-element analysis, laser-ablation (LA)-ICPMS for
UPb and trace-element analyses, secondary ion mass spectrometry
(SIMS) for UPb and O-isotope analysis, and LA-multicollector (MC)-
ICPMS for analysis of Hf isotopes. Brief details of these methods are
given in the Appendix. The zircons have been classified in terms of
their primary host rock using their trace-element chemistry and the
classification schemes of Belousova et al. (2001).
2. Results
2.1. UPb ages
The UPb dataset comprises 240 analyses of zircons from the vents
and tuffs, and 190 analyses of detrital zircons. Essentially all analyzed
zircons are concordant (Table A1; Fig. 4). In this paper, ages b1 Ga are
206
Pb/238
U ages; older ones refer to 207
Pb/206
Pb ages.
The zircons from the vents show age peaks in the Permian (ca
285–260 Ma), Triassic (ca 240–220 Ma) and lower Jurassic (ca
210–185 Ma; correlative with the “Asher volcanics” known from deep
wells), which tails off with time to ca 175 Ma (Fig. 5a). There is then
an apparent 40-Myr near hiatus in magmatic activity up to ca 118 Ma,
and then increasing numbers of zircons with decreasing age to a peak
at ca 100 Ma; this tails off to 80 Ma. Bulk sample #479 of the Rakefet
Magmatic Complex yielded five older grains with ages of 3124, 2726,
538 and 420 Ma. The Ein Ha-Shofet sample contains more older grains,
including two Neoarchean grains (2575, 2635 Ma), two mid-Protero-
zoic grains (1829, 1852 Ma) and several Neoproterozoic ones (614,
757, 796, 950, 975 Ma). Most of these are clearly igneous, with well-de-
veloped CL zoning, but many are well-rounded or fragmental. Some
may be detrital zircons, sampled from sediments intercepted at depth
by the basalt during eruption. However, the 2767-Ma grain from
Rakefet is overgrown by zircon dated at 206 Ma, and presumably was
caught up in the Jurassic magmatism.
The individual vents vary widely in their zircon populations (Table
1), although some of this may reflect the volumes sampled from differ-
ent sites. The zircon suite (n = 100) from the Rakefet Magmatic Com-
plex, which was bulk-sampled, covers the entire range of Permian to
Fig. 3. Images of Mount Carmel zircons. Scale bars are 200 μm. a). Cathodoluminescence (CL) and optical-microscope images of zircons showing corroded-prismatic shapes and core-rim
zoning; b). Typical Mt. Carmel-type zircons illustrating irregular shapes and internal structures; c). Optical and CL images of large Mt. Carmel-type zircon showing irregular form and
internal brecciation; d). CL images of zoned Mt. Carmel-type zircons with brecciation.

Jurassic ages, but has only one grain relevant to the age of eruption (93
± 3 Ma). The Bat Shelomo locality is dominated by Permo-Triassic zir-
cons (mean age 253 ± 15 Ma, n = 18). It also includes one old grain
(283 ± 3 Ma) and one grain (99 ± 4 Ma) that may be close to the age
of the vent. However, the sample also contains two Miocene zircons
(13–12 Ma) whose origin is unknown; they may be related to the Mio-
cene marine transgression described above. The Beit Oren complex also
contains zircons with ages ranging from 286 to 190 Ma, but no younger
ones. The Makura complex yielded only 2 grains, with ages of 282 and
281 Ma. The Ein Ha-Shofet sample yielded 76 zircons, of which 50
were dated. Most fall into two clearly separated populations: 190 ±
3 Ma (n = 12) and 273 ± 6 Ma (n = 22). One grain at 99.9 ± 1.4 Ma
constrains the age of the eruption.
The Tavassim vent yielded one Permian grain; the remainder belong
to the Cretaceous suite, ranging from 128 to 84 Ma (n = 4). Similarly,
the Karem Maharal tuffs yielded two Permian zircons (276 and
248 Ma) and three Cretaceous ones (107–90 Ma), providing some con-
straint on the eruption age. Four of the ﬁve zircons from Har Alon are
Fig. 4. Concordia plots of representative UPb data of Mount Carmel zircons. a). 0–30 Ma (inverse Concordia); b-1). 30–98 Ma (inverse Concordia); b-2). 98–120 Ma (inverse Concordia);
c-1). 100–200 Ma (Concordia); c-2). 200–300 Ma (Concordia).

Jurassic (199–193 Ma) but a younger grain (98 Ma) may date the
eruption.
The alluvial deposits (Fig. 5c) contain surprisingly few of the pre-
Cretaceous zircons (MCZ) that dominate the populations from the sam-
pled vents (Fig. 5b); nearly all of the zircon grains fall into the “common
zircon” group described above. However, the zircons from the stream
sediments show a major complex age peak extending from 120 to
75 Ma, indicating that Cretaceous vents have in fact been sampled; the
scarcity of Jurassic-Permian zircons thus may reﬂect a lower survival
rate of these complex zircons during alluvial transport. The presence
of late Cretaceous zircons with ages (75–70 Ma) younger than the sam-
pled vents suggests the (former?) existence of undiscovered vents, and
the continuation of the volcanism into Campanian time. The alluvial
samples also contain zircons with a scattering of ages (Fig. 5d) extend-
ing from the Eocene up into the Pliocene, with peaks at ca 30 Ma, 13 Ma,
11–12 Ma (a major peak; n = 15, 11.4 ± 0.1 Ma, MSWD = 0.79), 9–
10 Ma, and 4 Ma. These appear to represent zircons from the Lower
and Cover Basalts.
Brecciated zircons from the Permian-Jurassic populations can show
spot-to-spot internal variations ranging from a few tens of Myr, up to
190 Myr. In general, the more homogeneous blocks retain the oldest
ages, while boundaries between domains are younger, but several ex-
ceptions were noted. 17 core-rim pairs were analyzed, mostly within
the 250–200 Ma population. However, one Archean (2767 Ma) core
had a distinct 206 Ma rim, suggesting that the Archean grain was picked
up by the host magma emplaced in Triassic time. One Jurassic core (188
Fig. 5. Age histograms and cumulative probability curves for UPb data of Mount Carmel zircons. a). All (0–350 Ma); b). Vent samples (0–350 Ma); c). Alluvial samples (0–350 Ma); d). All
samples (0–20 Ma).

Ma) had a Cretaceous rim (104 Ma), and one late Cretaceous (74 Ma)
core had an Oligocene rim (31 Ma). These pairs are discussed further
below, with the Hf-isotope data.
2.2. Trace-element compositions
Extended chondrite-normalized REE patterns for 90 zircons from the
different vents are gathered in Fig. 6; the analytical data are compiled in
Table A2.
All but one of the analyzed zircons from Bat Shelomo are classified as
igneous. Most of the Permo-Triassic zircons have very similar patterns,
with an overall gently positive slope from Sm to Lu, and strong negative
Eu anomalies coupled with large positive Ce anomalies. One grain with a
metamict core shows disturbance in the form of enrichment in LREE.
One Triassic grain (233 Ma) differs significantly in having lower LREE
and no Eu anomaly, and this pattern is similar to those in both the Cre-
taceous and the Miocene zircons. The Miocene grain has much higher
REE than the other grains.
A similar pattern is seen at Karem Maharal, where the two Permian
grains have high HREE and negative Eu anomalies, while the Cretaceous
grains have flatter patterns with no Eu anomalies. At Tavassim and Beit
Oren, this pattern is repeated; Permian grains show an Eu anomaly
while the Cretaceous grains do not. The metamict cores of two older
grains show an enrichment in LREE. The zircons from Har Alon are Juras-
sic aside from one Cretaceous one. The patterns of the Jurassic zircons
resemble those from the older populations, but with shallower Eu
anomalies; the one Cretaceous grain has a flatter pattern and no Eu
anomaly.
The relatively few obviously igneous zircons from the Rakefet Mag-
matic Complex all have ages in the range 253–175 Ma and have very
similar patterns, with modest Eu anomalies in the oldest grains and
smaller ones in the younger ones. They show a wide range in Th and
U contents, and Th/U b 1. The much larger number of igneous/metamor-
phic grains shows a wider range in absolute REE contents, and especially
a larger spread in the HREE than in the other suites discussed above.
Several of the patterns have flat to slightly negative slopes from Dy to
Lu, combined with very minor Eu anomalies. The spread in Th and U
concentrations covers more than two orders of magnitude. In striking
contrast, the brecciated zircons are more homogeneous, aside from a
range of Eu anomalies.
The variations in REE patterns, UTh relationships and the Eu
anomalies through time are illustrated in Fig. 7. The plot of La/Sm vs
age (Fig. 7a) shows that despite general similarities, especially in the
slope of the HREE, the Permian to Jurassic zircons tend to have more
LREE-enriched patterns than the Cretaceous and younger zircons. The
more strongly negative Eu anomalies, and lower Ce anomalies, of the
Permian to Jurassic zircons, are obvious in Fig. 7b,c. There is no clear re-
lationship between Eu/Eu* and the morphological classifications. There
appears to be an overall decrease in the depth of the Eu anomaly from
the Permian to the Jurassic, but it is not clear if this is significant.
The abundances of Ce, U and Ti have been converted to estimates of
oxygen fugacity (fO2) using the formulation of Loucks and Fiorentini
(2018). The estimates (Table A2; Fig. 7d) cover N4 log units, centered
around the fO2 of the QFM buffer; there is no clear age trend in the
data, but the three 9–12 Ma zircons analyzed record higher fO2 than
most of the older grains.
The Th/U ratios of the zircons show some change with time; Th/UCN
values N0.3 are much more common in the Miocene to Pliocene popula-
tions than in the older ones (Fig. 7e). The Triassic zircons tend to have
lower Th/U than either the Permian or the Jurassic populations. The
lowest U and Th contents are found in brecciated and igneous/meta-
morphic zircons. We interpret this as one effect of the metamorphism
and reworking of these complex zircons.
The analyzed zircons have been classified in terms of their parental
magmas using the trace-element criteria of Belousova et al. (2001).
Nearly all classify as derived from either carbonatite (51/90) or low-Si
granitoids (36/90); three grains classify as kimberlitic zircons. This pat-
tern is typical, in our experience, of mantle-derived zircons in continen-
tal settings, and probably reflects crystallization of zircon from late
differentiates of mafic magmas. In the plot of Y vs U/Yb suggested by
Grimes et al. (2007, 2015) most of the grains fall into the field of “conti-
nental zircon” as distinct from “ocean-crust zircon”, although a signifi-
cant proportion fall outside the suggested fields due to their low U at
low Y contents (Fig. 7f). These anomalous grains largely comprise the
brecciated and igneous/ metamorphic MCZ grains. In the U/Yb-Nb/Yb
plot of Grimes et al. (2015) (Fig. 7g) nearly all of the analyzed zircons,
regardless of age, fall in the field of Ocean-Island zircons, within the
mantle array.
2.3. Hafnium-isotope compositions
Hafnium-isotope data for N350 grains, mainly from the vents, are
given in Table A3.
The pre-Cretaceous zircons show a range of 176
Hf/177
Hf)i from ca
0.2828 to 0.2829 (Fig. 8a), corresponding to εHf values between +5
and + 10 for most grains. A plot of 176
Hf/177
Hf)i vs age (Fig. 8b)
shows a broad trend of increasing 176
Hf/177
Hf)i from Permian through
Jurassic time, with a mean slope corresponding to 176
Lu/177
Hf = ca
0.038, essentially parallel to the Depleted Mantle curve. This trend is in-
dependent of the morphological classification, and is visible in the indi-
vidual populations from the vents of Rakefet and Bat Shelomo, for which
sufficient data are available. It is typical of mantle-derived zircons from
areas such as Siberia and Australia. A similar, but steeper, trend has been
recognized in kimberlitic zircons from southern Africa (Fig. 8b;
Woodhead et al., 2017).
Most of the Cretaceous zircons have 176
Hf/177
Hf)i ratios within the
same narrow range observed in the Permian to Jurassic suites (Fig.
9a), and thus have lower εHf values. Many of the Miocene-Pliocene zir-
cons have 176
Hf/177
Hf)i within the range covered by the main popula-
tions of Cretaceous to Permian zircons (Fig. 9b), but a significant
number have significantly more radiogenic Hf, extending toward the
Depleted Mantle reference line.
A pattern of a decrease in age without a change in Hf isotope compo-
sition may reflect Pb loss due to later thermal disturbance. In the present
case, the situation appears to be more complex. In eight of fourteen
core-rim pairs with clearly-defined rims that are significantly younger
than the core of the grain, the two zones have identical to nearly identi-
cal Hf-isotope compositions (Fig. 9c). Six pairs have rims with signifi-
cantly higher 176
Hf/177
Hf)i than the cores, including one grain with a
Jurassic core and a Cretaceous rim; the tie-lines between core and rim
in these cases mimic the overall very broad trend to more radiogenic
Hf with time (Fig. 9a). There is only one case in which the rim has
lower 176
Hf/177
Hf)i than the core. The microstructures, combined with
the Hf-isotope evidence, suggest that the rims represent growth of
new zircon, remobilized from the existing heterogeneous reservoir,
rather than simple Pb loss.
2.4. Oxygen-isotope compositions
Oxygen-isotope analyses of 45 spots on 15 zircon grains from the
Rakefet volcanic vent (Table A1) cover a range in δ18
O from 3.7 to
5.9‰ relative to Vienna Standard Mean Ocean Water (SMOW), with a
mean of 5.05 ± 0.45‰ (1 s). One grain gives a very high δ18
O, ~12‰,
which is not considered further. Most analyses are within the accepted
“mantle range” of 5.6 ± 0.6‰ (2 s), but the lowest values lie outside of
this range. Intra-grain variation typically is within the 1 s analytical er-
rors (ca 0.3‰), but one brecciated grain shows a range from 4.7 to
5.4‰ (n = 6 spots), and two igneous/metamorphic grains show core-
rim differences of 0.6‰ (n = 2) and 0.8‰ (n = 2), with the rim lighter
in each case. The isotopically heaviest oxygen is found in the grains with
clearly igneous structures (mean δ18
O = 5.5‰; n = 3) and as individual
spots in igneous/metamorphic grains. The brecciated grains have a

0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000Zircon/Chondrite
a) Migdal Ha-Emeq b) Har Alon
Zircon/Chondrite
c) Rakefet100000
10000
1000
100
10
1
0.1
0.01
0.001
100000
10000
1000
100
10
1
0.1
0.01
0.001
d) Beit Oren &
Makura
Beit Oren
Makura
e) Bat Shelomo
Zircon/Chondrite
f) Karem Maharal
h) Tavassimg) Kishon River
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
100000
Zircon/Chondrite
i) Kishon River 20-150 Ma
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
100000
PTiTaNbHfLuYbUErHoYDyThGdEuSmNdPrCeLa
Zircon/Chondrite
<--- Increasing Ionic Radius <---
j) Kishon River 0-20 Ma
PTiTaNbHfLuYbUErHoYDyThGdEuSmNdPrCeLa
<--- Increasing Ionic Radius <---
- 150
- 300 - 150
- 20
- 20
- 0
Fig. 6. Extended trace-element patterns of selected zircons by location, and colour-coded by age. Migdal-Ha-Emeq and Kishon River represent detrital (alluvial) zircons; all others are
sampled from vents and associated pyroclastics as indicated.

Fig. 7. Plots of trace-element parameters vs age of Mount Carmel zircons. a). La/Sm vs age; b). Eu anomaly vs age; c). Ce anomaly vs age; d). fO2 vs age; e). Th/U vs age; f). siscriminant plot
relating zircon chemistry to tectonic setting (Grimes et al., 2007); g). discriminant plot relating zircon chemistry to tectonic setting (Grimes et al., 2015). OI, ocean island volcanics. Sloping
box encloses zircons from mantle-derived rocks.

mean δ18
O = 4.8‰ (n = 7, range 3.7–5.1‰); similar low values are
found in the igneous/metamorphic population, where averages for indi-
vidual grains range from 5.3 to 3.8‰. These patterns suggest that the
process of metamorphic homogenization and brecciation of primary ig-
neous grains involved fluids with oxygen that was isotopically some-
what lighter than the “mantle average”.
3. Discussion
3.1. Younger basalts
The zircon data provide information on the ages and sources of the
Lower Basalts and the Cover Basalts in the drainage of the Kishon
river, mainly the Yizre'el Valley. The youngest population of zircons, as-
sumed to represent the Cover Basalts, has 206
Pb/238
U ages ranging from
3.6 ± 0.2 to 5.5 ± 0.4 Ma (mean 4.2 ± 0.6 Ma (1sd, n = 11)), corre-
sponding to the Lower Pliocene (Fig. 5d). Another major peak at
9–13.5 Ma (mean 11.3 ± 1.2 Ma, n = 22; Mid- to Upper Miocene) is
interpreted as the age of the Lower Basalts in the Yizre'el Valley; ages
back to 17.5 Ma are recognized in the Lower Galilee across the water-
shed at the head of the Yizre'el Valey. These ages correspond well
with the magmatic episodes defined by Shaliv (1991), Weinstein
(2000)and Rozenbaum et al. (2016). The apparent scarcity of magmatic
activity between about 9 and 5 Ma in this area also was previously rec-
ognized by Shaliv (1991). Zircons in each of these age groups show a
large spread in εHf, ranging from low values similar to the Cretaceous-
Permian zircons, up to values closer to the Depleted Mantle (Fig. 9a,b).
This range suggests that the late Miocene to Pliocene magmas were
derived from the asthenosphere, but also interacted with the SCLM
and older underplated basalts (see below) during their ascent.
3.2. Ages of cretaceous volcanic centres
Segev and Rybakov (2011) recognized 5 phases of Cretaceous mag-
matic activity, interpreted as reflecting the impingement of a mantle
plume centered beneath northern Israel, and that caused a major
updoming across Lebanon, Syria and the Sinai. The “Tayasir Volcanics”
are dated between 141 and 134 Ma (Lower Cretaceous), and basalts of
this age have been reported from deep drillings around Mt. Carmel.
This age range is poorly represented in our dataset (Fig. 5b), though
three grains are similar (133 ± 2 Ma) or slightly older (147-146 Ma).
The next episode occurs in lower Aptian time (125–123 Ma; Elije Volca-
nics); it also is reported from drill cores beneath Mt. Carmel; but is ab-
sent in our dataset. The third episode, the late Aptian-Albian Ramon
Fig. 8. Hf-isotope data. a). Hf-isotope data vs age for analyzed zircons, with CHUR and
Depleted Mantle (DM) evolution curves. Dashed lines show estimates of depleted-
mantle model ages; TDM is shown for the least radiogenic compositions; TDM
C
model ages
for the least and most radiogenic Hf from the Permian-Jurassic zircons are calculated
using a mean crustal 176
Lu/177
Hf of 0.015 (Griffin et al., 2000). b). Hf-isotope data vs age,
plotted by vent. Shaded field encloses zircons from off-craton kimberlites in Siberia and
Australia. Inset shows the trend in kimberlitic zircons from southern Africa (Woodhead
et al., 2017).
Fig. 9. Hf-isotope data a). Hf-isotope data vs age, plotted by textural type as seen in CL
images. b). Hf-isotope data vs age for Neogene zircons from alluvial deposits. c). Hf-
isotope data vs age for zoned zircons; lines connect cores and rims.

volcanics, is represented by a group of 7 zircons with ages ranging from
116 ± 6 Ma to 112 ± 10 Ma. The “Carmel Volcanics”, defined as occur-
ring between ca 100–95 Ma (Table 1), are well-represented in our
dataset. The younger Campanian (ca 83–72 Ma) volcanism is repre-
sented by a scatter of zircons from the alluvial samples.
The ages of the youngest zircons from each volcanic center can be
compared with available KAr and ArAr ages (Segev, 2000, 2002,
2009; Segev et al., 2005; Segev and Sass, 2009) (Table 1) to provide fur-
ther constraints on the age of volcanism and the development of the
magmatic system. The Kerem Maharal magmatism, which represents
the earliest known eruptions in the Mount Carmel area, has been
dated to 99.0 ± 1.0 Ma using amphibole megacrysts (Segev, 2009).
Two of the zircon xenocrysts analyzed here give slightly older ages
(107 ± 3, 104 ± 3 Ma), while one is significantly younger (90 ±
2 Ma). The Rakefet basalt, which overlies the tuffs sampled for this zir-
con study (Table 1) has been assigned an average age of 96.7 ±
2.5 Ma (Segev, 2009). Whole-rock ArAr ages on a nearby (E.
Muhraqa) basalt are similar (96.2 ± 2.5 Ma; Segev, 2002). Our large
dataset (n = 100) from Rakefet contains only one Cretaceous zircon,
dated at 93 ± 3 Ma. Two ArAr analyses on an amphibole megacryst
from Tavasim (Segev, 2009) give ages of 99.3 ± 0.6 and 98.0 ±
0.5 Ma; both are only slightly younger than the ages of two zircons
(102 ± 2 and 101 ± 1 Ma), but as at Kerem Maharal one zircon (84
± 8 Ma) is younger than the accepted eruption age. The Bat Shelomo
volcano has been dated by ArAr analysis of amphibole to be 81.6 ±
0.8 Ma (Segev, 2002); our dataset contains one Cretaceous zircon (99
± 4 Ma) but two Miocene zircons (13.1 ± 0.3, 12.0 ± 0.3 Ma).
In several of these cases, the youngest zircons are slightly older than
the accepted KAr and ArAr data. This is consistent with the idea that
the zircons are xenocrysts, rather than phenocrysts, in their host
magma, and thus must be older than the erupted basalt. However, we
see several instances of zircons that are significantly younger than the
accepted eruption ages. These may suggest the existence of unrecog-
nized eruption episodes, either in the same area as the sampling, or
even re-using the same volcanic plumbing system as the earlier, main
eruptions. In some cases, this might be enough to affect KAr or ArAr
ages of amphiboles; this might explain, for example, the anomalously
young age for Bat Shelomo. However, the current datasets from all of
the vents except Rakefet are small, and further work on samples from
the other vents is needed to clarify these questions.
3.3. Source(s) of the zircon xenocrysts
In the samples from the vents, a large proportion of the zircons have
ages corresponding to the Gevim volcanics (Middle Permian to Upper
Triassic, 265–220 Ma), and another large population corresponding to
the Asher volcanics (Upper Triassic to Lower Jurassic, 206–188 Ma).
The Hf and O isotopes of these zircons indicate that their parental
magmas were mantle-derived. As noted above, it is most likely that
such zircons have crystallized from late differentiates of mantle-derived
mafic magmas. Their REE patterns show little obvious evidence of a gar-
net signature, while the presence of negative Eu anomalies in the most
magmatic-looking zircons suggests co-crystallization with plagioclase.
This limits the depth of crystallization to b30 km; we suggest that the
most likely location for these underplated basalts, where they could
cool slowly to produce large grains of cpx, amphibole and zircon,
would be at the density filter represented by the crust-mantle boundary
(25–20 km in this area; Segev and Rybakov, 2011).
The microstructures of the Permian to Jurassic zircons appear to re-
flect a complex history of igneous crystallization, metamorphic recrys-
tallization, resetting and overgrowth. There is a general increase in the
proportion of reworked zircons with time (Fig. 9a), but clearly igneous
grains are present throughout the Permian-Jurassic population. The
Hf-isotope data scatter considerably, but overall define a broad trend
of increasing 176
Hf/177
Hf)i with decreasing age. The slope of this trend
is essentially parallel to that of the Depleted Mantle reference curve;
the trend might therefore reflect internal growth within a volume of ba-
salts+mantle rocks that had 176
Lu/177
Hf similar to the DM. It is perhaps
more likely that it reflects the mixing of older (Permian) materials with
younger magmas, which supplied both heat and the material required
to rework the pre-existing rocks and their zircons.
Stein and Hofmann (1992) surveyed all available data on the Phan-
erozoic basalts of Israel erupted over the last 200 Ma, and noted that
they have remarkably consistent compositions, “chemically and isotopi-
cally indistinguishable from many ordinary plume basalts”, and incom-
patible with crustal contamination. They suggested that the magmas
originated from a fossil plume head, emplaced beneath the region in
Neoproterozoic time, which periodically was remelted to produce ba-
salts when extended, or when influenced by other weak plumes that
failed to penetrate this carapace. Stein and Goldstein (1996) expanded
on this idea, suggesting that such stalled plume heads may be wide-
spread, and that they could be “overprinted with continent-like charac-
teristics by plate convergence and associated magmatism”, becoming an
integral part of the continental lithospheric mantle. Weinstein et al.
(2006) showed that these characteristics are shared by the Neogene ba-
salts of the region.
This model can offer a reasonable explanation for the Hf-isotope
evolution recorded in the Permian-Jurassic zircon xenocrysts in the
Mount Carmel volcanics. Their overall Hf-isotope values are similar to
those of HIMU lavas, commonly attributed to plumes with a significant
contribution of subducted oceanic crust. Interestingly, the Hf-isotope ra-
tios of the Permian-Jurassic zircons also partly overlap the field defined
by zircon megacrysts in kimberlites from on- and off-craton situations
in Siberia and Australia, where Archean lithosphere has undergone
modification by Proterozoic (plume-related?) magmatism and defor-
mation (Fig. 8b; Figs. 2 and 3 in Griffin et al., 2000). Woodhead et al.
(2017) have shown that zircon megacrysts from Cretaceous kimberlites
in South Africa, both on- and off-craton, require a widespread source
with high Lu/Hf (Fig. 8b), which they attribute to plume heads stalled
beneath the lithosphere. The plume-head model is also consistent
with the xenolith suites in the Cretaceous volcanic rocks of Mount Car-
mel, which contain both fertile spinel lherzolites and abundant
pyroxenites.
The zircons derived from the proposed Permian-Jurassic underplate
have Hf model ages (Fig. 8a) ranging from ca 700 Ma (TDM) to 1500 Ma
(TDM
C
). These could be interpreted as reflecting the age of the proposed
fossil plume head, which would be consistent with the Neoproterozoic
age suggested by Stein and Hofmann (1992). However, this may not
be a valid approach; it assumes that the plume head originally had the
Hf-isotope composition of the Depleted Mantle, whereas a HIMU-type
plume could have a significantly less radiogenic Hf-isotope composition.
This also is a period of major crustal activity in the Arabian shield
(Morag et al., 2012), which involved island-arc magmatism, post-colli-
sional granitoid magmatism and at least two volcanic cycles. The Hf-iso-
tope data from the older zircons therefore may reflect the derivation of
basalts from reworked and refertilized mantle, rather than a plume
head, although the two models are not mutually incompatible.
3.4. Compositions of parental melts
The trace-element patterns of the melts from which the zircons crys-
tallized were calculated using the empirical (their geometric mean) dis-
tribution coefficients Dmelt
zircon
of Nardi et al. (2013), on the assumption
that the zircons crystallized not directly from mafic magmas, but from
their late, more SiO2-rich differentiates. The oxygen-isotope data
(Table A1) show no evidence of crustal contamination or assimilation.
The patterns are grouped by age in Fig. 10.
The patterns of the oldest melts (270–230 Ma; mid-Permian to mid-
Triassic) show flat MREE-HREE, but strong depletion in the LREE; they
have marked positive Ce anomalies, and most show moderate negative
Eu anomalies. They also show high [Nb] and [Ta], a large spread in [Th],
[U] and Th/U, and a range of positive and negative Ti anomalies. Several

of these patterns represent zircons that have been disturbed during re-
crystallization, leading to high and irregular REE patterns, and especially
high LREE/MREE.
The mid-Triassic melts (230–210 Ma) are similar to most of the older
ones, but show less scatter in the REE patterns and smaller Ti anomalies.
[Th] and [U] are generally lower than in the older melts, but the range in
these contents is similar. The Triassic-Jurassic (210–175 Ma) melts, on
the other hand, show considerable diversity relative to the older ones.
Some show depletion in HREE, leading to humped patterns; others
show either greater or lesser depletion in LREE. [Th], [U], [Nb] and [Ta]
are higher overall, and the range in Th/U is greater; Ti anomalies, both
positive and negative, also show a greater range.
The flat MREE-HREE patterns with LREE depletion are reminiscent of
the REE patterns seen in e.g. N-MORB, but the anomalies in Ce and Ti,
and the high contents of Nb, Ta, Th and U are not typical of MORB. It
is, in fact, difficult to find primary mantle melts with similar patterns.
However, such patterns might develop through extended fractional
crystallization of magmas with less pronounced REE patterns. The ba-
salts of N. Israel and adjacent areas, from Jurassic through lower Creta-
ceous and Neogene time, are alkali basalts with remarkably constant
trace-element patterns and SrNd isotopes (Stein and Hofmann,
1992; Weinstein et al., 2006). Their trace-element patterns (Fig. 10a)
have mildly negative slopes from Yb to La, with [Th], [U], [Nb] and [Ta]
at ca 100 times chondrites. They have no anomalies in Eu, Ce or Ti;
CN-normalized P/Yb is ca 0.5.
Compared to these probable primary basalts, the strong depletion of
LREE in the calculated melts may reflect crystallization of late phases
such as apatite and monazite, and the HREE depletion could reflect crys-
tallization of both zircon and xenotime. Removal of apatite also can pro-
duce positive Eu anomalies, counteracting the influence of plagioclase
crystallization. The depletion of P relative to the HREE (P/Yb ca 0.1)
seen in all of the melts, and the wide variation in Th and U, also may
be tied to the crystallization of monazite and xenotime, as well as apa-
tite. These comparisons suggest that the calculated melts, and the zir-
cons crystallized from them, represent late-stage differentiates of
basaltic melts cooling slowly in deep-seated magma chambers.
The zircons erupted from Upper Cretaceous to Neogene time are
broadly similar to the Permo-Jurassic ones in having strong LREE deple-
tion, and high ThTa (Fig. 10). However, they show generally more en-
hanced Ce anomalies, smaller Eu anomalies (Fig. 7b,c), and
progressively develop mild HREE depletion relative to the MREE,
producing concave-downward REE patterns. There is also a tendency
toward deeper negative Ti anomalies, especially in the youngest zircons,
and toward Th/UCN values b1.
3.5. Sampling patterns in the cretaceous volcanism
The group of zircons with ages in the Upper Cretaceous (116–95 Ma)
may give an indication of the duration of this episode at depth, even
though the range of eruption ages is shorter. As noted above, it is likely
that none of the Cretaceous zircons truly date their respective eruption,
but rather represent xenocrysts derived from roughly coeval, more dif-
ferentiated, magmatism at depth. The range of 176
Hf/177
Hf values in the
Cretaceous zircons corresponds closely to that of the Permian-Jurassic
populations (Fig. 8), suggesting the Cretaceous magmas were derived
from the same reservoir.
The distribution pattern of the older populations in the different Cre-
taceous vents gives a picture of this reservoir (Fig. 11). The Permian-Tri-
assic (280–220 Ma) zircons are most abundant in the main vents
(Rakefet, Bat Shelomo, Makura and the Ein Hashofet centre in the
Ramot Menashe syncline). The Triassic-Jurassic (Asher) zircons are
found mixed with Permian-Triassic ones in Ein Hashofet and Rakefet,
but make up the bulk of the sample in the northern bodies (Beit Oren,
Karem Maharal and Har Alon); the younger zircons are found mainly
in Karem Maharal, Tavassim and Migdal Ha-Emeq on the western side
of Mt. Carmel. This pattern suggests that the Permo-Triassic magmatism
built up a “pillow” beneath the core of the Mt. Carmel-Menashe area, so
that the magmas of the younger episodes tended to intrude toward the
margins of this central area (Fig. 12).
Segev and Rybakov (2011) used data from deep drillings and geo-
physical surveys (primarily magnetics and gravity) to outline areas
showing ‘significant influence of magmatic bodies”. In this synthesis,
the Late Triassic-Jurassic magmatism is shown extending along the cur-
rent coastline both NE and SW of the Mt. Carmel area, while Permo-Tri-
assic magmatism is isolated farther south. However, the data presented
in this paper indicate that the Permo-Triassic magmatism also was sig-
nificant beneath the Mt. Carmel area and probably contributes to the
complex geophysical signature of the area.
The Permian-Jurassic volcanic rocks reflect the formation of the Le-
vant continental margin by rifting during the breakup of Gondwana,
which produced the Neotethys and Mesotethys oceans. Segev (2000)
listed 17 globally synchronous short-term volcanic cycles (200 to 5
Rakefet 270-230 Ma
1000
100
10
1
0.1
0.01
0.001
Weinstein
Neogene
Rakefet 230-210 Ma Rakefet 210-175 Ma
0.01
0.1
1
10
100
1000
Th U Nb Ta La Ce Pr Nd Sm Eu Ti Gd Dy Y Ho Er Yb Lu P
Kishon R. 115-80 Ma Kishon R. 80-20 Ma
Kishon R. 20-3 Ma
a) b) c)
d) e) f)
Fig. 10. Parental-melt compositions for selected zircon populations, calculated using the distribution coefficients of Nardi et al. (2013). Colour scales relate to age as in Fig. 6. a). Rakefet
magmatic complex, 270–230 Ma. Red line shows mean pattern of Neogene basalts of N. Israel, after Weinstein (2000); this is indistinguishable from the patterns of the Jurassic-Cretaceous
basalts (Stein and Hofmann, 1992); b). Rakefet magmatic complex, 230–210 Ma; c). Rakefet magmatic complex, 210–175 Ma; d). Kishon River Mid-reach placers, 115–80 Ma; e). Kishon
River Mid-reach placers, 80–50 Ma; f). Kishon River Mid-reach placers, 30–3 Ma.

Ma) that are expressed in this wider region, and proposed that they rep-
resent pulses of plume activity. An alternative interpretation would be
that they reflect periods of tectonic re-adjustment during which thin-
ning and mantle upwelling led to the production of new melts from
the proposed fossil plume head of Stein and Hofmann (1992), while co-
eval rifting along old fracture systems allowed the magmas access to the
upper lithosphere and the surface.
In this framework, the concentration of the Cenomanian volcanism
(97–80 Ma) into the Mount Carmel area may reflect its extensive net-
work of translithospheric and crustal-scale high-angle faults, most of
which were reactivated in Miocene time. We cannot know the real ex-
tent of the Permian-Jurassic underplating beneath this area; it may ex-
tend far beyond the 150–300 km2
sampled by the known Cretaceous
vents, and connect with the area identified by Segev and Rybakov
(2011). However, it seems likely that the same set of translithospheric
structures, dating back to the initial rifting from Gondwana, has local-
ized magmatism beneath this area for at least 250–300 million years.
4. Conclusions
Zircon xenocrysts from Cretaceous pyroclastic deposits on Mt. Carmel
and associated alluvial deposits document extensive magmatic activity
beneath the area during Permo-Triassic and Late Triassic-Jurassic time.
The morphology and internal structures of the grains suggest a magmatic
origin, followed by recrystallization, overgrowth and brecciation. Trace-
element data indicate that the parental magmas were alkaline to
carbonatitic, and probably represent residual differentiates of basaltic
melts. Hf-isotope ratios indicate derivation of these melts from an
enriched mantle (OIB-like) source, probably mid- to Neoproterozoic in
age. This may represent the plume head postulated by Stein and co-
workers as the source of basalts across the region. The distribution of
the different age populations across Mt. Carmel and neighbouring areas
suggests that the earliest intrusions built up an underplated “pillow”,
probably near the crust-mantle boundary, and that the emplacement of
the later intrusions occurred primarily around the edges of the pillow.
Fig. 11. Map with distribution of zircon age populations in vents in Yizre'el Valley-Mt Carmel area. Lines A-A', B-B′, C-C′ mark corresponding sections 1-3 in Fig. 12.
Fig. 12. Cartoon showing the relative abundance of three zircon age populations in
different vents, to illustrate the general structure of the proposed gabbroic underplate at
the crust-mantle boundary beneath the Mt. Carmel area. Not to scale.

The Permian to Jurassic zircons record the repeated intrusion of magmas
derived from a common source, and the (repeated?) recrystallization of
older zircons in the presence of fluids with relatively light O-isotopes.
The Cretaceous zircons have Hf-isotope ratios within the range of the
older ones, suggesting that most of the Cretaceous zircon ages represent
Pb-loss, or recrystallization and remobilization of older zircons, during
the Cretaceous thermal event. This may indicate that relatively little Cre-
taceous magma ponded at the crust-mantle boundary and evolved to the
point where they could crystallize zircons. This appears to be consistent
with their more explosive nature. In contrast, many of the younger (Eo-
cene to Miocene) zircons have more juvenile Hf-isotope characteristics,
suggesting the derivation of magmas both from the older “plume-re-
lated” source and from a more primitive convecting mantle.
Acknowledgements
We thank Dr. E. Sass and Prof. Oded Navon for useful discussions on
the geology of Mt. Carmel and the volcanism of Israel in general. Prof.
Xian-Hua Li (IGG-CAS, Beijing) kindly facilitated O-isotope analyses by
SIMS. We are also grateful to Dr. Joseph Guttman, Chief Hydrologist of
Mekorot, for providing the core from the Ein Ha-Shofet drilling. The pro-
ject benefitted greatly from the skill and dedication of the Shefa Yamim
operational staff at Akko and especially the mineral sorters. Michel
Gregoire and an anonymous referee provided helpful suggestions to im-
prove the MS. This study used instrumentation funded by ARC LIEF and
DEST Systemic Infrastructure Grants, Macquarie University and indus-
try. This is contribution 1174 from the ARC Centre of Excellence for Core
to Crust Fluid Systems (http://www.ccfs.mq.edu.au) and 1235 in the
GEMOC Key Centre (http://www.gemoc.mq.edu.au).
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.lithos.2018.06.007.
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