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Similar to Plea for a modern* definition of the Jurassic / Cretaceous boundary (illustrated by the case study of the lowermost Cretaceous in Alicante, SE Spain)
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Plea for a modern* definition of the Jurassic / Cretaceous boundary (illustrated by the case study of the lowermost Cretaceous in Alicante, SE Spain)
- 1. Pleafor a modern* definition of the Jurassic / Cretaceous boundary (illustrated by the case study of the lowermost Cretaceous in Alicante, SE Spain) Bruno R.C. GRANIER
- 2. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us.“ William A.P. Wimbledon (Berriasian WG officer) YELLOW NOTES reflect additions and changes
- 3. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us." Sierra de Fontcalent (Alicante, Spain)
- 4. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us." Tithonian Berriasian Sierra de Fontcalent (Alicante, Spain)
- 5. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us." Tithonian Berriasian Sierra de Fontcalent (Alicante, Spain) T/B not shouting at us!
- 6. An obvious stage (and system) boundary the M/D (K/P) Staryi Krym (Crimea) Finestrat (Spain)
- 7. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us.“ If there is nothing obvious for the T/B as a stage boundary … WHY should it be THE system boundary too?
- 8. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us.“ If there is nothing obvious for the T/B as a stage boundary … May be it is time to think of an alternative, i.e., another stage boundary that could be a MUCH better system boundary !
- 9. "In the marine facies, the reason perhaps that no-one got around to defining the boundary is that there is no obvious boundary (…) and the obvious is not there shouting at us.“ If there is nothing obvious for the T/B as a stage boundary … May be it is time to think of an alternative, i.e., another stage boundary that could be a MUCH better system boundary ! My 1st choice goes the B/V !
- 10. Goban Spur (Montadert et al., 1979) Wilmington (Schlager, 1989) Maroc (Vail et al., 1977) A seismic summary of earliest Cretaceous events
- 11. My playground … mostly carbonate platforms!
- 12. Oman: a basinal section
- 13. Oman: a basinal section radiolarite porcelanite
- 14. B / V boundary ? T / B transition zone The “J / K” of the practical oil geologists Abu Dhabi: a platform section
- 16. Atlantic Ocean
- 17. Now Spain!
- 19. Cabezon de Oro
- 21. 250µm
- 22. Pebbles and cobbles are EXTRAclasts, not INTRAclasts 100µm250µm
- 24. Puig Campana
- 25. Cabezon de Oro 250µm5 mm
- 26. Sierra Helada
- 27. Sierra Helada
- 29. Busot
- 30. Busot
- 32. Major events in the Early Valanginian of Alicante •step 1 (near the beginning): drowning / major transgression that marks the end of the “Jurassic” carbonate PF In basinal settings, siliciclastic wedges connected (ramp) or not (wall) to the surrounding shelves •step 2 (near the end): tectonic extension with correlative starvation, condensation, erosion, fractures (at the crest of blocks)
- 34. 1st stage of the Cretaceous = Neocomian Last stage of the Jurassic = Portlandian
- 35. The Valanginian and the Hauterivian were substages of the Neocomia
- 36. The Berriasian was a substage of the Portlandian
- 37. Modern* stratigraphy of a Jurassic / Cretaceous boundary
- 38. •the historical reason (Kilian) •“In the marine facies, the reason perhaps that no-one got around to defining the” T/B “boundary is that there is no obvious boundary ... ” •in the middle of an overall “regressive” trend Tithonian / Berriasian CONCLUSION: 2 options the “old” and …
- 39. •the historical reason (Desor, 1854; Coquand, 1869; Renevier, 1874) •at the top of an overall “regressive” trend •2 huge eustatic pulses on Vail’s / Haq’s charts •1st SB1 of Vail •1st drowning of Schlager •the huge Valanginian transgression (better correlation: Tethyan and Boreal) •the Weissert event, •the end of “Jurassic” carbonate PF •“Motion III” at the 1973 Symposium •a number of biotic events, ... •“… there is no obvious boundary ... ” •the historical reason (Kilian) •in the middle of an overall “regressive” trend •in the middle of the gradually decreasing δC13 curve (G.P. Price’s talk) Tithonian / Berriasian Berriasian / Valanginian CONCLUSION: 2 options the “old” and the “modern”
- 40. Those who think the “old” Tithonian / Berriasian, i.e., Option 1, should remain a system boundary, PLEASE raise your hand ! OR …
- 41. Thank you for your attention! Merci de votre attention !