晚三叠世中卡尼期极端气候事件:研究进展及存在问题

作为三叠纪最显著的气候变化事件,全球性的卡尼期气候事件以幕次降雨量增多为特征,在西北特提斯洋地区表现较为明显,主要反映了从碳酸盐岩到黑色页岩的岩性变化,近年来这一地质事件在美国、中国、日本等地的卡尼阶地层中也有识别.其成因一直是学者研究的重点,有人认为是板块构造运动促使大气或大洋循环发生了变化,或是超级大陆聚合碰撞而触发大火成岩省喷发致使全球气候发生了紊乱,也有人认为是地球系统综合因素相互作用的结果.联系到中国西南部地区卡尼阶现状,认为超级季风、构造运动和卡尼期气候变化的关系值得深入研究,此外卡尼期气候事件过程中碳酸盐补偿深度上升问题、卡尼期黑色页岩事件反映的大洋生产力以及多幕卡尼期气候事件反映的气候波动事件等科学问题也是今后的研究中值得重视的.

Mid-Carnian (Late Triassic) Extreme Climate Event: Advances and unsolved problems

As one of the most pronounced climatic cextremes in the geological history, the mid-Carnian (Late Triassic) extreme climate event, also named the Carnian Pluvial Event (CPE), has been widely recognized from the United States, China, Japan, and many places of Europe over past decades. The known evidence shows that the CPE is characterized by a dramatic increase in rainfalls and could last for nearly one million years. The CPE is represented by the sharp replacement of platform facies carbonates with the siliciclastic succession of mid-Carnian age worldwide. Several scenarios have been proposed to account for the CPE: (1) The plate tectonic activities such as collision and aggregation of the Pangea are believed to have prompted the atmosphere and ocean circulation changes; (2) the coeval large igneous province eruptions such as the Wrangellia Volcanic Province may have triggered a dramatic increase in CO₂ contents in atmosphere, which caused a warm, wet climatic condition; (3) Possible global climate disruption such as megamonsoon induced the elevated rainfalls; and integration of all of these factors accounted for the climatic extreme. The strata record from southwestern China suggests that the link among the megamonsoon, tectonic movement and climate changes during the Carnian Stage is worthy studying in detail. In addition, further studies on some critical issues concerning the rise of carbonate compensation depth (CCD), high oceanic productivity reflected by the Carnian black shale, and pulses of humid climate during the mid-Carnian are crucial for better understanding of this deep-time climatic extreme.