沉积记录对白垩纪中国大陆古气候模拟的约束

Constraints of sedimentary records on Cretaceous paleoclimate simulation in China mainland

古气候模拟已经成为白垩纪古气候研究中不可替代的技术手段。但是目前中国白垩纪陆相古气候模拟的一些关键边界条件尚未完全确定。通过白垩纪沉积记录对中国大陆白垩纪古海陆边界和古地形做出约束。早白垩世,新疆西南部喀喇昆仑地区可能存在喀喇昆仑海湾,在东北松辽盆地东侧有乌苏里湾;晚白垩世,受全球海平面上升的影响,特提斯海向北延伸,新疆西部地区存在塔西南海湾和喀喇昆仑海湾;而受燕山运动的影响,乌苏里湾向东退出松辽盆地,影响变小。在古地形方面,认为东北大兴安岭,西北天山、祁连山、昆仑山等山脉,西南云贵高原、川西高原、横断山,秦岭—大别山在白垩纪时均已形成并隆升到一定高度;指出"东部高原"和"沿岸山脉"的存在与否可能对白垩纪古气候状况产生深远的影响。此外,还讨论了沉积记录与古气候模拟结果的对比、验证对中国大陆白垩纪古气候重建的重要作用。

Simulation has been an important method in research on Cretaceous paleoclimate,but some boundary conditions have not been confirmed yet.In this study,we have constrained the distribution of land and ocean and the paleotopography in the Cretaceous using continental sedimentary records in China.During the Early Cretaceous,the Karakorum Gulf lay in the southwest of Xinjiang and the Wusuli Gulf was located to the east of Songliao Basin,Northeast China.During the Late Cretaceous,the global sea level rose,which made the Tethyan Ocean extend northward;the southwest Tarim Gulf and Karakorum Gulf lay in the west of Xinjiang;and the Wusuli Gulf had retreated from Northeast China.In the aspect of paleotopography,the Da Hinggan Mountains,Tianshan Mountains,Qilian Mountains,Kunlun Mountains,Hengduan Mountains,Qinling-Dabie Mountains,West Sichuan Plateau,and Yungui Plateau had already existed and may have reached some altitude.It is pointed out that the existence of East Plateau and Southeast Ridge would have been of significant influence on Cretaceous climate conditions in China.Furthermore,we have discussed the significance of making validation and comparison between paleoclimate simulation and sedimentary records in reconstruction of Cretaceous paleoclimate.