中文摘要：

海相碳酸盐的碳同位素组成记录了地球发展与演化过程中的若干重大事件,作为古生代—中新生代转折时期的石炭纪—三叠纪初具有非常高的δ^13值,以此作为主线,综合研究了相应时间段的氧、锶同位素组成与变化、碳酸盐沉积盆地面积与变化,以此探讨海相碳酸盐碳同位素组成与海平面变化、有机碳库和碳酸盐碳库碳存量的变化、大气和海洋系统中CO_2含量的变化,以及地球生态系统的长周期变化之间的联系。研究表明：①显生宙的碳同位素演化趋势中,δ^13值大于3‰的时间基本上都集中在石炭纪—三叠纪初,但三叠纪初表现为δ^13值的高频率大幅度波动,石炭纪—二叠纪则表现为长时间持续稳定的高δ^13值,显示该时间段有机碳库存量的大幅度增加,相应时间段较高的δ18O值显示有机碳高速埋藏时间间隔中地球系统经历了长时间的变冷和冰室气候条件,说明有机碳高速埋藏、气候变冷、大气p CO_2的降低和p O2升高之间存在有机的联系;②δ^13高值时间间隔中大气CO_2被绿色植物过度消耗,海水被迫不断向大气输送CO_2以达到平衡,但全球气候变冷导致海水数量减少和水柱压力降低又使得海水对CO_2的溶解能力降低以及海相碳酸盐碳库碳存量的减少,从泥盆纪、石炭纪到二叠纪,碳酸盐沉积速度显著降低,全球碳酸盐沉积盆地面积显著减小,到中、晚二叠世,一些碳酸盐沉积被硅质沉积取代,甚至包括一些浅水台地,这可能会导致一些钙质无脊椎动物数量的减少,这也说明二叠纪广泛的硅质沉积是一种全球事件;③显生宙碳酸盐锶同位素演化趋势表明,晚二叠世海水87Sr/86Sr急剧降低,并在二叠纪—三叠纪界线附近达到极小值,显示晚古生代结束时幔源锶的迅速加入,并伴随深部CO_2对大气和海洋系统的补充,但与该过程有关的广泛的火山活动和地球表面温度的升高进一步加

英文摘要：

Carbon isotopic composition of marine carbonates is a record for various important geological events in the process of earth development and evolution. The carbonates of Carboniferous,Permian and Triassic,as the transition from Paleozoic to Mesozoic-Cenozoic have very high δ^13 value. Taking this as the main point,and combined with the oxygen,strontium isotopic composition in carbonates,distribution of carbonate basin area through geologic time,the correlation of carbon isotopic composition of marine carbonates to sea level change,organic carbon burial flux,exchange of CO_2 content in atmosphere and ocean,and long cycle evolution of the earth ecosystems were approached. The results are shown as follows： ①The interval of δ^13 〉3‰ during Phanerozoic was concentrated in Carboniferous,Permian and the beginning of Triassic,but the beginning of Triassic was characterized by higher frequency and larger fluctuations in δ^13 value during a short time,whereas the Carboniferous-Permian presented a continuously stable high δ^13 value,indicating a larger amount of organic carbon accumulation in this time interval. Relatively high δ18O values during this time was also observed,showing a long time of glaciations and cold climate,which suggest a connection among rapid organic carbon burial,cold climate,as well as p CO_2 and p O2 states of atmosphere. ②The over consumption of atmosphere CO_2 by green plants during the time with high δ^13 of seawater forced CO_2 being transferred from ocean to atmosphere for the balance,but the decrease in the seawater amount and water column pressure caused by the global cooling could weaken dissolution capacity of CO_2 in seawater and carbon storage of marine carbonates,and also reduce the carbonate sedimentary rate and decrease the carbonate basin area globally from Devonian to Carboniferous and Permian. During the middle-late Permian carbonate was widely replaced by siliceous sediments even though in shallow carbonate platform,which resulted in the decrease of marine invertebra