摘要
地球表层系统是由岩石圈、大气圈、水圈和生物圈相互耦合和变化组成的复杂巨系统。白垩纪是地球表层系统研究的典范,在地球表层各圈层发生了众多重大地质事件。晚白垩世巨大的地幔热异常引起海底扩张速度变快,导致大量海底高原和海山的形成;同时,冈瓦纳大陆裂解,南北大西洋贯通,新的大洋水道形成,可能造成大洋环流格局的大变化。洋壳体积的增加可能使白垩纪海平面比现在高出200～300m,大规模海侵也在晚白垩世中期达到最大范围。在这个过程中,火山作用释放出来的营养物质和火山气体的反馈作用造成的大量陆地营养物质的流入共同促使大洋水体富营养化和普遍缺氧,造成"大洋缺氧事件"。CO2浓度的升高(为现今的4～10倍)是火山排气作用的直接结果,其"温室效应"也被认为可能是促成白垩纪大气和海水高温的重要原因(高于现在10℃)。大洋红层(CORB)是最新提出并被广泛接受的白垩纪重要地质事件,被定义为一套分布在从外陆棚到CCD面之下深水盆地的,在富氧、低生产力和贫营养条件下较低速沉积形成的品红—红色—棕色的细粒远洋沉积物。这些发生于地球表层各圈层的重大地质事件以能量循环的方式(具体表现为C、S、P、H、O等元素循环)相互耦合和变化共同支撑着地球表层系统的运转。但是科学界对这些重大地质事件的成因机制及其所引起的全球变化性质还没有形成一致意见,原因之一就是缺乏对陆相沉积记录的研究。陆相白垩系的广泛发育和"松辽盆地白垩系科学钻探"工程的顺利实施共同构成了中国在白垩纪地球表层系统研究上的地域和材料优势,结合中国在白垩纪地球表层系统重大地质事件研究中已经形成的学术优势,从地球系统科学的角度出发,通过多学科交叉研究将是解决以上问题的关键。
The Earth Surface System is a complicated system which includes geosphere,atmosphere,hydrosphere and biosphere.The Cretaceous is a fantastic research example,when some important events occurred in the Earth Surface System.During the Late Cretaceous,the huge mantle plume brought ocean floor accelerated spreading and it caused the formation of many oceanic plateaus.At the same time,the South and North Atlantic became connected.A new gateway which may take an important role in ocean cycling was formed.The volume increasing elevated the sea level 200-300 m higher than today,and massive transgression reached its maximum during the mid-Late Cretaceous.In this process,volcanic activity and increased land surface eroding provide a large number of nutritious elements for ocean.They made a worldwide alimental and anoxic ocean environment.The releasing carbon dioxide led to a ＂greenhouse climate＂,of which the paleotemperature reached a high level（about 10 ℃ higher than today）.CORB（Cretaceous Ocean Red Beds） is a newly introduced geological event,and it has been accepted by scientists from different countries.After more than twenty years research,it has been defined as a group of red,pink and/or brown fine-grained pelagic marine sedimentary deposits in oxidized,oligotrophic and low production environments.These events in the Earth Surface System coupled each other in the form of energy cycling including element（e.g.C,S,P,H,O etc.） cycling.And they drove the Earth Surface System to change more actively.But a prevalent conclusion of the change mechanism has not been reached yet because of less Cretaceous continental sedimentary research.The wide distributed Cretaceous continental sedimentary record in China and the accomplishment of the project of ＂Cretaceous Scientific Drilling＂ provided the advantage of material for the research.They are the keys to the study of Cretaceous Earth Surface System.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2009年第5期1-14,共14页
Earth Science Frontiers
基金
国家重点基础研究发展计划“973”项目(2006CB701400)
关键词
白垩纪
地球表层系统
地质事件
沉积记录
大洋红层
Cretaceous
Earth Surface System
geological event
sedimentary record
CORBZhou Xin
Guo Zhengtang
