Constraints on the expanse of Greater India in the Early Cretaceous from radiolarians
Constraints on the expanse of Greater India in the Early Cretaceous from radiolarians
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DOI：
10.1016/j.epsl.2023.118413
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发表时间：
2023-11
影响因子：
5.3
通讯作者：
Xin Li;Noritoshi Suzuki;J. Meng;Atsushi Matsuoka;Peter O. Baumgartner;Chengshan Wang
中科院分区：
文献类型：
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作者：
Xin Li;Noritoshi Suzuki;J. Meng;Atsushi Matsuoka;Peter O. Baumgartner;Chengshan Wang
定义大印度的原始大小是重建印度-亚洲碰撞的运动学和时间的关键参数。早白垩世时期基于古生物学的东冈瓦纳北岸古海洋学和古地理重建为大印度的范围提供了独立的约束。在这项研究中，使用 Hayashi 定量方法 III，对来自特提斯喜马拉雅山新发现的早白垩世放射虫动物群与来自阿尔戈深渊平原 (AAP) 的非特提斯南方动物群和来自意大利的典型特提斯动物群进行了客观比较。我们发现：（1）澳大利亚西海岸和大印度北海岸南半球冷水放射虫物种的出现归因于约136 Ma东冈瓦纳大陆分裂期间，环南极冷水通过新开通的海道向北侵入； （2）江孜一直处于浅层暖水条件下，有典型的特提斯放射虫动物群（集群3），直到凡兰吉阶晚期，冷水物种（集群1）从南方到来。江孜地区水体边界从特提斯物种占主导地位转变为南方冷水物种占主导地位，这表明其古纬度低于AAP中大洋钻探计划（ODP）第123段，站点765； (3) 晚贝里亚世至凡兰吉阶的南南冷水放射虫分布区间相同，表明藏南康玛距离ODP 765站点较近； (4)意大利不同的放射虫动物群——中巴、康马和AAP揭示了巴雷姆期至阿普第期不同水深的特提斯暖水和南方冷水不同程度影响下的复杂水体条件。这种放射虫生物地理学与古地磁重建高度一致，表明大印度东部在早白垩世期间延伸至埃克斯茅斯高原（>2400公里）。
Defining the original size of Greater India is a critical parameter for reconstructing the kinematics and timing of the India–Asia collision. Early Cretaceous paleontology-based paleoceanographic and paleogeographic reconstruction for the northern coast of East Gondwanaland provides independent constraint for the extent of Greater India. In this study, newly discovered Early Cretaceous radiolarian faunas from the Tethys Himalaya were objectively compared with non-Tethyan austral faunas from the Argo Abyssal Plain (AAP) and the typical Tethyan fauna from Italy using the Hayashi's Quantification Method Type III. We found that (1) The occurrence of austral cold-water radiolarian species at the western coast of Australia and northern coast of Greater India is attributable to northward intrusion of circumantarctic cold water via a seaway newly opened during the breakup of East Gondwanaland from ∼136 Ma; (2) Gyangze was under shallow warm-water conditions with typical Tethyan radiolarian fauna (Cluster 3) until the late Valanginian when cold-water species (Cluster 1) arrived from the south. A water mass boundary shift from Tethyan species dominant to austral cold-water species dominant in Gyangze indicates its lower paleolatitude than Ocean Drilling Program (ODP) Leg 123, Site 765 in the AAP; (3) The same austral cold-water radiolarian-bearing intervals from the late Berriasian to Valanginian indicate that Kangma in southern Tibet was proximal to ODP Site 765; (4) Different radiolarian faunas in Italy–Zhongba, Kangma, and the AAP reveal complex water conditions under different degrees of effect by Tethyan warm water and austral cold water at different water depths during the Barremian to Aptian. This radiolarian biogeography is highly consistent with the paleomagnetic reconstruction and indicates that eastern Greater India extended to the Exmouth Plateau (>2400 km) during the Early Cretaceous.