| Popis: |
The Lower Jurassic is composed of the Hettangian, Sinemurian, Pliensbachian and Toarcian, among which the Toarcian oceanic anoxic events (T-OAE) have been widely studied. Depositions of black shales and negative excursions of both δ13Corg and δ13Ccarb at the Sinemuiran-Primbalian boundary, which has been recorded in the United Kingdom, France, Italy, Portugal and China.This event, known as the "S-P boundary event" (SPBE), characterized by significant carbon isotope, environmental and climatic perturbations in global scale. It is considered to be similar to the T-OAE, a well-known oceanic anoxic event, during which light carbon was released into the atmospheric system, although it is still unknown the sources of the carbon inputs. Research has so far dominantly focused on the marine strata in Europe, while few studies have evaluated the Lower Jurassic terrestrial strata. The Lower Jurassic lacustrine deposits are well developed in the Sichuan Basin, China. Similar to the T-OAE in the Daanzhai Member of Ziliujing Formation, the negative excursion of δ13Corg was recorded in the blackshales and shelly limestones of the Dongyuemiao Member, Ziliujing Formation, indicating that the SPBE likewise has an impact on the Early Jurassic ancient lake in the Sichuan Basin. |
