科研之友
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摘要
We obtained bulk-sediment delta O-18 and delta C-13 data from biostratigraphically-constrained Tethyan marine sections at Aghia Marina (Greece), Guri Zi (Albania), and Brumano and Italcementi Quarry (Italy), and revised the published chemostratigraphy of the Pizzo Mondello section (Italy). We migrated these records from the depth to the time domain using available chronostratigraphic tie points, generating Ladinian-Rhaetian delta C-13 and delta O-18 records spanning from similar to 242 to similar to 201 Ma. The delta O-18 record seems to be affected by diagenesis, whereas the delta C-13 record appears to preserve a primary signal and shows values increasing by similar to 1 parts per thousand in the Ladinian followed by an similar to 0.6 parts per thousand decrease across the Ladinian-Camian boundary, followed by relatively constant (but oscillatory) Carnian values punctuated by a negative excursion at similar to 233 Ma in the early Carnian, a second negative excursion at similar to 229.5 Ma across the early-late Carnian boundary, and a positive excursion at similar to 227 Ma across the Carnian-Norian boundary. The Norian record is characterized by a long-term decreasing trend and a negative excursion at similar to 216 Ma. Rapid increases and decreases in delta C-13 have been observed in the Rhaetian, but these may be at least in part due to mixing of different sources of carbonate carbon with different delta C-13 values. Our Triassic delta C-13 record has been compared to data from the literature, and a composite delta C-13 record spanning the last similar to 242 Myr of Earth%26apos;s history has been generated. This composite record shows a sequence of dated delta C-13 trends and events that can be used for stratigraphic correlation as well as for a better understanding of the global carbon cycle in the Mesozoic-Cenozoic.
- 出版日期2014-4-1
