Gondwana Research ( IF 6.1 ) Pub Date : 2021-02-03 , DOI: 10.1016/j.gr.2021.01.010 Harshita Bhatia , Mahasin Ali Khan , Gaurav Srivastava , Taposhi Hazra , R.A. Spicer , Manoshi Hazra , R.C. Mehrotra , T.E.V. Spicer , Subir Bera , Kaustav Roy
After India separated from Gondwana, its 9000 km northward voyage from the Southern Hemisphere to its modern position joined with Eurasia took 160 million years. During that journey, India experienced a range of climatic conditions due to secular climate variations and its changing latitudinal position. Documenting India's climate during its trans-equatorial journey allows us to sample climate across the low latitudes, at a time when global temperatures were exceptionally high, such as we might experience in the future. Here, we reconstruct, quantitatively, the palaeoclimate of India during its voyage, focussing on the latest Maastrichtian–earliest Danian, late Paleocene, early Eocene and late Oligocene timeslices. We exploit the relationship between fossil leaf form and climate and use the Climate-Leaf Analysis Multivariate Program to reconstruct 24 individual palaeoclimate parameters, while fossil leaf traits also allow us to identify different monsoon types. We find that throughout the Paleogene India persistently experienced a monsoon climate similar to that of modern Indonesia-Australia; a monsoon system that exists today primarily as a function of seasonal trans-equatorial migrations of the Inter-tropical Convergence Zone (ITCZ). The reconstructed near-equatorial thermal regime of India was cooler, and showed a greater seasonal temperature variation than at similar latitudes today, suggesting a wider seasonal latitudinal migration of the ITCZ throughout the Paleogene. Leaf traits showing adaptation to the South Asia Monsoon only developed after the end of the Paleogene.
中文翻译:
白垩纪晚期-古成纪的印度季风气候与印度板块运动的关系以及南亚季风的诞生
印度从冈瓦纳(Gondwana)分离后,其从南半球到现代位置的9000公里北航程与欧亚大陆一起历时1.6亿年。在那段旅程中,印度由于长期的气候变化及其纬度位置的变化而经历了一系列的气候条件。记录印度在跨赤道过程中的气候,使我们能够在全球气温异常高的时候(例如将来可能遇到的情况)对低纬度地区的气候进行采样。在这里,我们定量地重建了印度航行期间的古气候,重点是最新的马斯特里赫特时期-最早的达尼安,古新世晚期,始新世和渐新世晚期。我们利用化石叶片形态与气候之间的关系,并使用“气候叶分析多元方案”来重建24个单独的古气候参数,而化石叶片性状也使我们能够识别不同的季风类型。我们发现,在整个古近纪,印度一直经历着类似于现代印度尼西亚-澳大利亚的季风气候。今天存在的季风系统主要是由于热带辐合带(ITCZ)的季节性跨赤道迁移所致。印度重建的近赤道热区温度较低,并且比今天类似的纬度显示出更大的季节性温度变化,这表明整个古近纪ITCZ的季节性纬度迁移范围更广。