Discovery of the Paleocene-Eocene Thermal Maximum in shallow-marine sediments of the Xigaze forearc basin, Tibet: A record of enhanced extreme precipitation and siliciclastic sediment flux
Discovery of the Paleocene-Eocene Thermal Maximum in shallow-marine sediments of the Xigaze forearc basin, Tibet: A record of enhanced extreme precipitation and siliciclastic sediment flux
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西藏日喀则弧前盆地浅海沉积物中古新世-始新世热最大值的发现：极端降水和硅质碎屑沉积物通量增强的记录
DOI：
10.1016/j.palaeo.2020.110095
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发表时间：
2021-01-15
影响因子：
3
通讯作者：
Garzanti, Eduardo
中科院分区：
文献类型：
--
作者：
Jiang, Jingxin;Hu, Xiumian;Garzanti, Eduardo
古新世 - 新世热最大值（PETM，类似于56 Ma）是过去主要的全球深度热热事件之一。浅海洋PETM记录的研究对于了解当前全球变暖的大陆水文反应至关重要。这项研究介绍了位于东部特提斯海洋北部活跃的大陆边缘的Xigaze前臂盆地中PETM的第一个详细文件，并说明了相关的环境和水文变化。基于碳 - 同位素地层，有孔虫生物地层学和锆石U-PB年级地层学，PETM事件是在很大程度上在钙质的jialazi形成中的硅质碎屑单元中鉴定的。浅底栖区4的有孔虫组合位于硅质碎屑单元下方，但被硅质碎屑单元上方的浅底栖区6组合所取代。高分辨率的小额方面分析表明，petm沉积物由碳酸盐 - 刺激性沉积物组成，然后突然改变对Syn-PETM硅质碎屑岩石，然后又是较新的碳酸盐后碳酸盐 - 碳酸盐 - 碳酸盐 - 碳酸盐岩沉积。在PETM期间，硅质碎屑供应显着增加，如砂岩和页岩间隔的厚度所示，导致碳酸盐坡道的暂时灭亡。出处分析并未表明通过早期古近纪的陆原碎屑源区域发生任何重大变化。因此，硅质碎屑供应的增加主要归因于季节性降水的强化，因此在PETM事件中增加了Gangdese Arc的水文循环。
The Paleocene-Eocene Thermal Maximum (PETM, similar to 56 Ma) was one of the major global deep-time hyperthermal events of the past. Studies of shallow-marine PETM records are crucial to understand the continental hydrological response to current global warming. This study presents the first detailed documentation of the PETM in the Xigaze forearc basin located along the northern active continental margin of the eastern Tethys Ocean, and illustrates the associated environmental and hydrological changes. Based on carbon-isotope stratigraphy, foraminiferal biostratigraphy, and zircon U-Pb chronostratigraphy, the PETM event was identified within a siliciclastic unit in the largely calcareous Jialazi Formation. Foraminiferal assemblages of Shallow Benthic Zone 4 are present below the siliciclastic unit, but are replaced by Shallow Benthic Zone 6 assemblages above the siliciclastic unit. High-resolution microfacies analysis indicates that the pre-PETM deposits consist of carbonate-ramp sediments followed by a sudden change to syn-PETM siliciclastic rocks, followed in turn by renewed post-PETM carbonate-ramp deposition. The siliciclastic supply increased notably during the PETM, as indicated by the thickness of both sandstone and shale intervals, resulting in a temporary demise of the carbonate ramp. Provenance analysis does not indicate any major change in the source areas of terrigenous detritus through the early Paleogene. Increasing siliciclastic supply is thus chiefly ascribed to the intensification of seasonal precipitation and consequently increased hydrological circulation in the Gangdese arc during the PETM event.