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and Cesare (1993) contoured for pressures ranging from 100 to 500 MPa. For
methane at $375 °C, while fluids in rocks of 5 wt.% TOC are miscible at $2
Calculated densities of the fluid(s) at 100 MPa. At this pressure the CH4-domina
while the H2O-dominated phase will have a relatively much higher density of $9
totalKarooBasin
westernKarooBasin
wt%TOC
Area intruded by 100 m thick sill [km2]
GenerationpotentialCH4[Gt]
35 000
30 000
25 000
20 000
15 000
10 000
5 000
50 000 250 000 350 000150 000
10
9
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VøringandMøreBasins
Fig. 9. Calculated total methane potential in gigatons, (Gt) as a
function of area covered by a cumulative intrusion thickness of
100 m continuous sill. The generation potentials are for the western
7017
Gt
150
000
km2
Thermogenic methane from contact metamorphism
(Aarnes et al., 2010)](https://image.slidesharecdn.com/egu-20talk-140310100443-phpapp01/75/The-Boltysh-crater-fill-sediments-a-500-000-year-record-of-the-lower-Danian-28-2048.jpg)
Uploaded byIain Gilmour
The Boltysh crater fill sediments – a 500,000 year record of the lower Danian
The document summarizes research on sediments from the Boltysh impact crater in Ukraine that preserve a 500,000 year record of the early Danian period. The continuous lacustrine sediments within the crater provide an expanded and detailed record of a negative carbon isotope excursion approximately 200,000 years above the Cretaceous-Paleogene boundary, correlating to the Dan-C2 excursion in the marine record. Changes in floral communities through the excursion reflect changing biomes from a rapidly warming climate during an early Danian hyperthermal event, followed by ecosystem recovery, analogous to other major climatic events in the geologic record. The timing of the excursion may correlate with the late stages of
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The Boltysh crater fill sediments – a 500,000 year record of the lower Danian
- 1. The Boltysh craterfill sediments – a 500,000 year record of the lower Danian I. Gilmour1, D.W. Jolley2, R.J. Daly2, S.P. Kelley1, and M.A. Gilmour1 1. Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK 2. Department of Geology & Petroleum Geology, University of Aberdeen, Aberdeen AB9 2UE, UK
- 2. The Boltysh craterlacustrine sediments accumulated in around 600m of accommodation space on the Ukrainian shield. The continuity of this accommodation space post-impact would have ensured a continuous record of deposition without the intervals of non-deposition inherent in fluvio-deltaic depositional settings.
- 3. Boltysh Impact Crater • 25km complex crater • Ukrainian Shield – impact on land • Ar/Ar age 65.17 ± 0.64 Ma (Kelley & Gurov, 2002)
- 4. Boltysh Impact Crater • 25km complex crater • Ukrainian Shield – impact on land • Ar/Ar age 65.17 ± 0.64 Ma (Kelley & Gurov, 2002) • Drilled in the 1960s & 70s • Cores lost
- 5. Boltysh Impact Crater • 25km complex crater • Ukrainian Shield – impact on land • Ar/Ar age 65.17 ± 0.64 Ma (Kelley & Gurov, 2002) • Drilled in the 1960s & 70s • Cores lost • 500m crater-fill sediments central peak Impact melt Cross sec(on reconstructed from Russian data
- 6. Boltysh Impact Crater • 25km complex crater • Ukrainian Shield – impact on land • Ar/Ar age 65.17 ± 0.64 Ma (Kelley & Gurov, 2002) • Drilled in the 1960s & 70s • Cores lost • 500m crater-fill sediments • Paleogeography n the North-Eastern Peri-Tethys during the Cretaceous Baraboshkin et al., 2003
- 9. Drilled ~12m impactbreccia at base of hole
- 11. • 596m cored borehole west of central upliA • >95% recovery • 596 -‐ 582m – allochthonous impact breccia • 390m Cenzoic crater fill • 582 – 490m cyclic, fining upwards, poorly sorted sands and sandy muds > turbidity currents • 490 – 190m finely laminated organic rich shales • Lacustrine, abundant plant macrofossils • ~300m abundant ostracods and gastropods (in life posi(on), interbedded with gypsum lamellae > shallow evapora(ve lake
- 12. Palynology Summary • Palynomorphs– most abundant fossil group • Good preservation – no thermal alteration/degradation • Dominated by pollen and spores but include algae • Early Danian throughout – Consistent with Cavagnetto and Gaudant (2000) based on IGCP pollen stratigraphic scheme of Meyer (1980) • Highly diverse palynoflora – crater marginal – regional vegetation Ferns Swamp cypresses Normapolles
- 13. Relationship between theBoltysh and Chicxulub Impacts • Palynological Succession – Replacement of one floral community with another in a given area • Supported by δ13CTOC record • Recovery successions – Well documented (volcanic) – K-Pg from Western Interior (US) • “Fern spike” – an influx of fern spores in post K-Pg sediments • Phase 1 – warm temperate, subhumid, broadleaved evergreeen • Phase 2 – leaf, rhizome and cuticles of ferns • Phase 3 – early successional, high ppt • Phase 4 – warm temperate, moderately diverse
- 14. Location of K/PgBoundary Jolley, D.W., Gilmour, I., Gurov, E.P., Kelley, S.P., Watson, J., 2010. Geology 38, 835–838.
- 15. Hopane in sediment (biological configura(on) Hopane in sediment (geological configura(on) ββ22R βα22R αβ22R αβ22S x
- 16. ββ ββ + αβ + βα Energy Reac(on progress AAer Seifert and Moldowan, 1980) ββ βα αβ ΔG2 ΔG3 ΔG1 ΔG4 Thermal maturity
- 17. 8.5m No ββ present ββ biological 7.1m ββ transi(on
- 18. Modelling cooling ofimpact hydrothermal systems Figure 3. Results of a numerical simulation of the hydrothermal system at a 30-km crater on early Mars. The central peak of the crater is on the left side of each figure. Surface permeability k0 is 10À2 darcies. Solid arrows and dotted arrows indicate the water and steam fluxes, respectively. The lack of arrows in some regions indicates that fluxes are less than 2 orders of magnitude smaller than the maximum flux. Solid lines are isotherms, labeled in degrees Celsius. The length of the arrows scales logarithmically with the flux magnitude, and the maximum value changes with each plot. (a) 25 years, max. water flux = 6.66 Â E12S09 ABRAMOV AND KRING: HYDROTHERMAL ACTIVITY ON EARLY MARS E12S09 Abramov & Kring, 2005)
- 19. 8.5m No ββ present ββ biological 7.1m ββ transi(on ca. 20ka
- 20. Jolley, D.W., Gilmour, I., Gurov, E.P., Kelley, S.P., Watson, J., 2010. Geology 38, 835–838. <20ka
- 21. Boltysh • Pre-dates Chicxulubimpact – Establishment of an early successional flora post Boltysh impact implies 5-10ka pre-Chicxulub • Cooling hydrothermal system – Timescale for post-Boltysh and Post-Chicxulub recovery • Rest of core – 550 C-isotope measurements – Early Danian climate change
- 22. Carbon Isotopes • algal/higherplant input • Significant CIE 537 – 271m • Lacustrine δ13Corg • Selective preservation • Maturation • Allochthonous inputs • Boltysh OM • Immature sapropellic kerogen • %C not correlated with δ13Corg • Reliable indicator of C cycle change K Pg -38 -36 -34 -32 -30 -28 -26 -24 -22 -20 δ13Corg (‰) Δδ13C ~ -‐3‰ Δδ13C ~ +4‰ Posi(ve excursion
- 23. -38 -36 -34-32 -30 -28 -26 -24 -22 -20 δ13Corg (‰)
- 24. Dan-C2 CIE ! Atlantic(Quillévéré et al. (2008) – Benthic δ13C – 2 excursions ! Tethys (Coccioni et al. (2010) – Similar to Atlantic X Pacific (Westerhold et al. 2011) – No record at Shatsky Rise – Restricted to Atlantic? ! Continental – Boltysh lacustrine record – Global CIE Quillévéré et al. (2008) Fig. 2. Changes in δ13 C and δ18 O of bulk sediments, CaCO3 content, and magnetic susceptibility (χ) in the lowermost Danian at Contessa Highway, plotted with changes in δ13 C and δ18 O of bulk sediments, CaCO3 content, and magnetic susceptibility from the equivalent stratigraphic interval at ODP Hole 1049C (Black Nose, NW Atlantic) and DSDP Holes 527 and 528 (Walvis Ridge, SE Atlantic), where the Dan-C2 event was first recognized by Quillévéré et al. (2008). Reliable 300R.Coccionietal./EarthandPlanetaryScienceLetters297(2010)298–3 Coccioni et al. 2010
- 25. Comparison with Toarcianand PETM CIEs In contrast to the marine Dan-C2 records, the Boltysh record more closely resembles other major CIEs – Isotope stages after Cohen et al. (2007)
- 26. CIE Mass Balance McInerney& Wing (2011)
- 27. regional and evenglobal ecosystems. A rapid larly forced, end Maastrichtian extinctions across the Fig. 1. Present-day Deccan Trap outcrop extent. Major tectonic structures redrawn from Biswas (1991). Main Deccan Province – from Cripps et al. (2005) • Final stages of Deccan – interac(on of basal(c lavas and dykes with con(nental shelf sediments • Evidence of interac(on in the Mumbai area organic-‐rich shales occur as intertrappean sequences • δ13Corg ~ -‐26‰ • Produc(on of thermogenic CH4 from sedimentary organic • isotopic frac(ona(on = -‐1.4‰ and -‐17.5‰ (Clayton et al. 1991)
- 28. in the vitrinit intrusi and M accura tures 900°C An is that into ho as long ganic m sins w emplac (13) sh geothe thickn and Cesare (1993) contoured for pressures ranging from 100 to 500 MPa. For methane at $375 °C, while fluids in rocks of 5 wt.% TOC are miscible at $2 Calculated densities of the fluid(s) at 100 MPa. At this pressure the CH4-domina while the H2O-dominated phase will have a relatively much higher density of $9 totalKarooBasin westernKarooBasin wt%TOC Area intruded by 100 m thick sill [km2] GenerationpotentialCH4[Gt] 35 000 30 000 25 000 20 000 15 000 10 000 5 000 50 000 250 000 350 000150 000 10 9 8 7 6 5 4 3 2 1 VøringandMøreBasins Fig. 9. Calculated total methane potential in gigatons, (Gt) as a function of area covered by a cumulative intrusion thickness of 100 m continuous sill. The generation potentials are for the western 7017 Gt 150 000 km2 Thermogenic methane from contact metamorphism (Aarnes et al., 2010)
- 30. Summary – BoltyshCrater fill sediments • 24km diameter Boltysh Impact Crater in Ukraine – Lacustrine crater fill sequence of fine grained organic carbon-rich sediments – Preserve a uniquely complete and detailed negative carbon isotope excursion (CIE) in an expanded section of several hundred metres. • Position of CIE in the early Danian, ca. 200ka above K/Pg – Correlates with Dan-C2 CIE in marine record – Early Danian Hyperthermal Event • Changes in floral communities through the CIE reflect changing biomes caused by rapidly warming climate, followed by recovery – EDH event had a similar duration to the Toarcian and Paleocene/Eocene events • Temporal correlation EDH event with late stages of Deccan Continental Flood basalt province, and initiation of rifting – Deccan province: cause of global warming and the carbon-isotope excursion • A high resolution record that is potentially resolving the effect of Chicxulub from the effects of Deccan • High resolution/stratigraphically complete records have implications…
Editor's Notes
- #13 Normapolles is an extinct morphogenus of Late Cretaceous/Early Danian pollen grain – defines the normapolles palynofloral province.
- #14 communities in early succession will be dominated by fast-growing, well dispersed species – “early colonisers”
- #24 Note – decrease in humid warm temperate flora at base of section marked by Pteridophyta – fernsWinterwet best characterised by Normapolles group – these continue the pre K/Pg regional ‘Normapolles Province’ flora and are meditteranean type winterwet flora. Note absence of humid taxa like Cupressaceae (swamp cypresses) and fernsRecovers to cool temperate flora. This is most like a pine and myrtle moor.
- #28 Last Deccan stages Ar/Ar dated as early Danian