Boundary problems between :-
Precambrian/Cambrian
Permian/Triassic
Cretaceous/Tertiary
Neogene/Quaternary
Stratigraphic boundaries are determined by one or more of geological events such as volcanic activity, sedimentation, tectonism, paleo-environments & evolution of life.
Faunal records have played major role in determining the boundaries of the Phanerozoic units.
The other geological events are dated on the evidence of fossil records.
Metallogenic Epoch and Province
Metallogenetic Epochs
Metallogenetic epochs, as defined above, are specific periods characterised by formation of large number of mineral deposits. It does not mean that all the mineral deposits formed during a definite metallogenetic epochs. In India the chief metallogenetic epochs were:
1. Precambrian
2. Late Palaeozoic
3. Late Mesozoic to Early Tertiary
Sedimentary basins are the depressions in the earth's crust where loose particles accumulate and finally lithified to form sedimentary rocks. Basins are particularly attractive to geoscientists from time immemorial due to the wealth hidden here in the form of oil, gas, coal etc. In this document you will find the types of basins, basin-fill types, methods of basin analysis and so on.
Metallogenic Epoch and Province
Metallogenetic Epochs
Metallogenetic epochs, as defined above, are specific periods characterised by formation of large number of mineral deposits. It does not mean that all the mineral deposits formed during a definite metallogenetic epochs. In India the chief metallogenetic epochs were:
1. Precambrian
2. Late Palaeozoic
3. Late Mesozoic to Early Tertiary
Sedimentary basins are the depressions in the earth's crust where loose particles accumulate and finally lithified to form sedimentary rocks. Basins are particularly attractive to geoscientists from time immemorial due to the wealth hidden here in the form of oil, gas, coal etc. In this document you will find the types of basins, basin-fill types, methods of basin analysis and so on.
Karai badland topography and Geo-Heritage site, Take A Geotourism around Grav...sutikshandwivedi
The Karai Badlands national geological monument is located in the Karai area along the Karai-Kulakkalnattam road of Perambalur District, Tamil Nadu. A four km. the stretch of badlands with natural conical mounds and typical fossils of the Cretaceous age is exposed as badlands with a series of conical mounds separated by gulleys.
Badland topography, on either side of Alattur-Ariyalur road, spread within 40-70 km. radius marks the lower part of marine Cretaceous rocks that mainly consists of clay & sandstone of the Karai Formation. Like the Grand Canyon in Colorado, US, Ariyalur is considered a Cretaceous Park of South India by Geo-scientist.
The Geological Survey of India (GSI), has declared Karai Badland as a National Geological monument for its maintenance, protection, promotion, and enhancement of geo-tourism.
Stratigraphy
The Rock formation is here exposed to the Cretaceous of Trichinopoly, Which dates back to the Late Cretaceous. The Succession in the area is broadly divided into 4 Groups -Uttathur, Trichinopoly, Ariyalur, and Ninniyur, Where Uttathur is the oldest. After comparing the age and color of the rock formations here with those of the Himalayas, we have found that they are of the same age. The Karai Formation of Uttatur Group at the Karai-Kulakkalnattam section in the Perambalur district forms the lower part of the Cretaceous sedimentary succession of the Cauvery Basin.
The Karai Badlands area is the type area for Karai Formation. The Karai Formation is exposed as badlands with a series of conical mounds separated by gulleys. It is a wasteland with scanty vegetation and without any topsoil on either side of Karai-Kulakkalnattam road.
The Karai Badlands Formation consists of grey-brown, gypsiferous, glauconitic mudstone, and marl with sporadic thin interbeds of siltstone and calcareous sandstone, particularly in its upper part- sporadic calcareous, siderites and phosphatic concretions/nodules and concretionary horizons occur in some intervals. A variety of marine fossils like ammonites, nautiloids, belemnites, worm tubes, pelecypods, gastropods, and oysters occur in abundance.
The importance of this “Geoheritage Site” lies in the fact that it provides one of the best-exposed sections of Cretaceous rocks with its unique lithology and diversity of extinct marine life. The region is a magnet for cement companies because of the purity of Ariyalur’s limestone. The factories burn a mixture of powdered limestone, gypsum, coal, and other chemicals to produce cement and clinker. But unchecked mining has led to air pollution and large quantities of overburdened soil being heaped up randomly.
How Badland is a form
The Cretaceous Period (135- 65 Million Years) witnessed a series of major geological events in the history of the Earth. Of these, the most significant is the worldwide marine transgression, which has left its mark in many parts of the world including South India.
The term "trap" has been used in geology since 1785–95 for rock formations. It is derived from the Swedish word for stairs (trapp , trappa) and refers to the step-like hills forming the landscape of the region.
The plateau: also called a high plain or tableland, is an area of highland, usually consisting of relatively flat terrain. A plateau is an elevated land. It is a flat-topped table standing above the surrounding area. A plateau may have one or more sides with steep slopes.
LIP – Large Igneous provinces. (Province = Area / Region)
DVP - The Deccan Volcanic Province is one of the Earth’s giant continental flood basalts and has a total exposed area of about half a million square kilometers in Maharashtra, Madhya Pradesh, Gujrat and some part of Andhra Pradesh. Deccan trap has maximum thickness 3400m in western ghat and its thickness goes decrease toward east side. At Amrakantat on east its thickness is just 160m. Geographical distribution is between latitudes 16° - 24° N and longitudes 70° - 77° E.
Petroleum system, facies analysis and sedimentology of jurassic - cretaceous ...FatimaNasirQureshi
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4. ¢ Stratigraphic boundaries are determined by one or
more of geological events such as volcanic activity,
sedimentation, tectonism, paleo-environments &
evolution of life.
¢ Faunal records have played major role in determining
the boundaries of the Phanerozoic units.
¢ The other geological events are dated on the evidence
of fossil records.
BOUNDARY PROBLEMS IN INDIA 4
5. PRECAMBRIAN-CAMBRIAN BOUNDARY
Paleozoic rock formation contain abundant fossil records which
are in contrast to largely unfossiliferous nature of Precambrian
rocks.
BOUNDARY PROBLEMS IN INDIA 5
7. In salt Range :-
The oldest rocks exposed at the base of the southern cliffs
are known as “SALINE SERIES” Consisting of gypsum, marls &
rock salt.
This succession is conformably overlain by Purple Sandstone,
Neobolus Shales, Magnesian Sandstone & Salt pseudomorph
Beds in that order of succession.
Lower Cambrian trilobits fauna and well preserved trails and
burrows are known from Neobolus shales.
The Magnesian Sandstone, a succession of dolo-arenites,
contains a horizon of shales in the middle of the succession
which has yielded fossils trails & burrows resembling those of
Neobolus Shales.
BOUNDARY PROBLEMS IN INDIA 7
8. The nature of contact between the Lower Cambrian fossiliferous
succession & the underlying “saline Series” of Salt Range is very
often characterized by tectonic disturbance that was explained in
terms of disharmonic folding of competent rocks of Purple
Sandstone resting over highly incompetent salt & gypsum beds of
the “Saline Series” of Precambrian age.
Continuous successions of Precambrian-Cambrian rocks are
exposed in various parts of the tethyan Himalayan zone.
In many sections, however the Lower Cambrian rocks are
unfossiliferous. Even in the fossiliferous section, the fauna is
poorly preserverd for specific & generic identification.
BOUNDARY PROBLEMS IN INDIA 8
9. In Kashmir :-
A rich assemblage of microbiota cryptarchs & algae of Late
Precambrian (Late Riphean-Vendian) age have been reported
from the Lower part of the Lolab formation.
The upper parts of this formation has yielded trilobites &
brachiopods of upper Lower Cambrian affinity.
The Precambrian-Cambrian boundary is, thus situated
somewhere in the middle of the Lolab formation which has so
far not yielded any fossils record.
In Spiti, the boundary is located in thee middle part of the
Kunzam la Formation.
The fossil record of the Kunzam la formation is similar to that
of the Lolab Formation.
BOUNDARY PROBLEMS IN INDIA 9
10. In Nandadevi, the fossiliferous Palaeozoic succession rests
over about a 4 km thick unfossiliferous sequesnce of
argillaceous & calcareous fine grained rocks know as Martoli
Formation.
This formation is overlain by about 100m thick Ralam
Conglomerate that constitutes the base of the fossiliferous
Cambrian succession.
The Martoli Formation has been assigned a Late Precambrian
age and the Ralam Conglomerate presumably represents an
unconformity demarcating the Precambrian-Cambrian
boundary.
BOUNDARY PROBLEMS IN INDIA 10
13. • Fossil faunal of the lowermost Triassic rocks is markedly
different from those of the uppermost Permian.
• Extinction of the brachiopod fauna of the Productus Shales is
as abrupt as the appearance & predominance of Triassic
cephalopods.
• The Guruyul ravine of Vihi district in Kashmir provideds one of
the best known sections where the Permian-Triassic boundary is
defined both on faunal & lithological characteristics.
• Palaeontological data from SPITI were regarded to suggest
that the first appearance of Otoceras woodwardi marks the
beginning of the Triassic strata.
• The Triassic succession of Spiti begins with massive limestones
(Otoceras Bed) overlain by flaggy limestone (Ophiceras Bed).
• The carbonate rocks rest over Productus Shale with
intervening thin layes of limonitised pebbly rocks.
BOUNDARY PROBLEMS IN INDIA 13
14. • Similar observation have been recorded from Zanskar Range in
the northwest & Kumaun region in the southeast.
• An almost uninterrupted succession of terrestrial sediments of
Permian-Triassic age is recorded in the Gondwana Sequence of
the Indian Peninsula.
• The Permian rocks of the Damuda Group (Lower Gondwana) are
conformably overlain by the Panchat Formation.
• The lower parts of the Panchat Formation consisting of fine
grained inter-channel deposits are genetically closer to the
underlying rocks of the Damuda Group.
• The Upper Panchets are lithologically akin to coarse sediments
of the Mahadeva Formation of the Triassic age.
• The Panchet rocks contain fossil records of particularly two
reptiles, viz., Lystosaurus and Proterosuchus (Chasmatosaurus).
BOUNDARY PROBLEMS IN INDIA 14
15. The macro-floral record of the Gondwana Sequence of India
shows a major change towards the end of the Permian Period
that expressed by the withdrawal of a large number of leaf
genera.
Spores & pollens have been regarded as the most reliable aid
for dating the Permian-Triassic boundary in the Gondwana
Sequence of India. Thus, the Permian-Triassic boundary in the
Gondwana Sequence of India lies somewhere in the middle of
the Panchet Formation.
BOUNDARY PROBLEMS IN INDIA 15
16. CRETACEOUS-TERTIARY BOUNDARY
• The problem of demarcating the boundary line between the
Cretaceous & Tertiary successions has two aspects.
• The one pertains to locating this boundary in a particular region
on the evidence of some fossil record & the other concern with
the “fixing” of this boundary in the internationally accepted
“Standard Stratigraphic Scale”.
• Boundary between the Phanerozoic units are determined on the
faunal evidence with the presumption that the organic forms
have periodically undergone profound changes at certain periods
of the earth history.
• In general, this assumption has been substained by the fossil
records.
BOUNDARY PROBLEMS IN INDIA 16
17. • In many parts of the world, stratigraphic breaks have been
observed between the Maastichtian & Montian beds.
• The post-Maastichtian &pre-Montian time interval is
represented in other parts of the world by “passage beds”
which is known as Danian Stage.
• Rocks above the “passage beds” contain fauna that have a
definite Tertiary aspects while the rocks underlying them have
a definite Cretaceous affinity.
• There are three regions in the Indian subcontinent which have
exposed such “passage beds”.
The Sind area in Pakistan.
The Tiruchchirappalli area in south India.
The Assam region in the north-eastern India.
BOUNDARY PROBLEMS IN INDIA 17
19. The Pab Sandstone which in mainly unfossiliferous contain
Maastrichtian fossils in some thin beds at the base & the top of
the sandstone succession.
Since the Cardita beaumonti beds overlie the uppermost
Maastrichtian succession, they have been assigned a Danian age
& the Cardita Beaumonti has been recognized as an index fossil
of the Danian on the Indian subcontinent.
Of the three sub-division of the Ranikot Formation, the basal &
lower sub-division are composed of practically unfossiliferous
sandstone of fluviatile origin.
The upper sub-division of the Ranikot Formation contain
abundant marine Palaeocene fauna which indicates that the
marine regression was short lived.
BOUNDARY PROBLEMS IN INDIA 19
20. The upper Cretaceous rocks of the Tiruchchirappalli area have
been classified into Uttatur, trichinapoly & Ariyalur formation.
Blanford divided the Ariyalur succession into lower, middle &
upper units.
The upper unit was later recognized as forming a distinct
stratigraphic unit named as Niniyur Formation. Each yielded a
rich assemblage of lamelobranchs, corals & gastropods.
The underlying Ariyalur Foramtion has yielded a foraminiferal
assemblage of Maastrichtian age. The assemblage consists
mainly the species of Lepidoobitoides, Siderolites & Rotalia.
BOUNDARY PROBLEMS IN INDIA 20
21. • The Upper Cretaceous rocks of Assam region comprising the
Mahadek Formation is conformably overlain by a marina
succession known as langpar Formation.
• The Langpar Formation has yielded a Danian foraminiferal
assemblage. The marine rocks are overlain by a thick
continental sequence of coal bearing sandstone known as
Therria Formation.
• Biswas (1962) has suggested that both the Langpar & the
Therria formation were deposited at the same timem the
former being a marine facies equivalent of the continental
Therria Formation.
• Rama Rao grouped both the formation into the “passage beds”
representind the Cretaceous-Tertiary transition.
• Sah & Singh have recorded the presence of a mic-floral break
between the Mahadek & Langpar formations representing the
Cretaceous-Tertiary boundary in Assam.
BOUNDARY PROBLEMS IN INDIA 21
23. • The Boundary in India has been investigated in the Continental
deposits of the Outer Himalayas & the Kashmir Valley & the
marine deposits of Andaman-Nicobar islands.
• The basic criteria for the recognition of this boundary in the
continental deposits are the first appearance of certain group
of mammals sach as Elephus, Equus & disappearance of
Hipparion.
• The continental succession contains evidence for the first
climate deterioration leading to the glacial phases at the
commencement of the Quaternary deposits.
• The boundary in the marine succession has been demarcated on
the basis of the appearance & extinction of certain planktonic
foraminifera.
BOUNDARY PROBLEMS IN INDIA 23
24. REFERENCES
• FUNDAMENTALS OF HISTORICAL GEOLOGY AND
STRATIGRAPHY OF INDIA BY RAVINDRA KUMAR
BOUNDARY PROBLEMS IN INDIA 24
