摘要
发生于晚石炭世—中二叠世末期的冰期事件是显生宙史上最剧烈的冰期事件,也是地史上最后一次从冰室期到温室期的转换期。通过薄片鉴定、扫描电镜、主量元素、微量元素、碳氧同位素和锶同位素等地球化学手段,对四川盆地中二叠统茅口组一段古温度及古气候进行恢复,探讨中二叠世重大气候演变过程及驱动机制。研究结果表明,四川盆地中二叠统茅一段灰岩—泥质灰岩韵律层的生物组合类型以有孔虫、腕足和软体动物为主,不发育造礁生物和钙质绿藻;岩石结构以生物碎屑支撑和灰泥支撑为主,无鲕粒等非骨架颗粒,与国际典型的凉水碳酸盐岩类似。通过δ18O与ω(Mg)/ω(Ca)恢复古温度,灰岩沉积期的古海水温度为3.72~12.38℃(平均8.15℃,δ18O标准),13.79~14.28℃(平均13.90℃,ω(Mg)/ω(Ca)标准);泥质灰岩沉积期的古海水温度为7.00~14.24℃(平均10.97℃,δ18O标准),13.82~15.41℃(平均14.27℃,ω(Mg)/ω(Ca)标准)。中二叠统茅一段沉积期古温度变化主要受米兰科维奇短偏心率旋回驱动,短偏心率的旋回性变化是古温度、古气候旋回变化的驱动机制。
From the Late Carboniferous to the end of Middle Permian,the most intense glacial event in history of Phanerozoic occurred and it is also the last transition period from icehouse stage to greenhouse stage in geological history.In this paper,the paleotemperature and paleoclimate in the first member of the Middle Permian Maokou Formation(Mao⁃1)were restored by means of thin section identification,scanning electron microscope,major elements,trace elements,carbon isotopes,oxygen isotopes and strontium isotopes,and the major climate evolu⁃tion process and its driving mechanism in the Middle Permian were discussed.The results show that the biological assemblage type(mainly composed of foraminifera,brachiopods and molluscs,without reef⁃building organisms or calcareous green algae)and rock structure characteristics(supported by bioclastic and plaster,without oolitic or other non⁃skeletal particles)of the limestone⁃marl alternations in the Mao⁃1 member are similar to those of the international typical cool⁃water carbonate.During the limestone sedimentary period,the paleotemperature of seawater was 3.72 to 12.38℃(8.15℃in average,δ18O standard)or 13.79 to 14.28℃(13.90℃in average,ω(Mg)/ω(Ca)standard),while during the marl sedimentary period,the paleotemperature of seawater was 7.00 to 14.24℃(10.97℃in average,δ18O standard)and 13.82 to 15.41℃(14.27℃in average,ω(Mg)/ω(Ca)standard).The paleotemperature changes in the sedimentary period of Mao⁃1 Member was mainly driven by the short eccen⁃tricity cycle of Milankovitch.The cyclical change of the short eccentricity was the driving mechanism of paleotem⁃perature and paleoclimate cycle changes.
作者
范建平
宋金民
刘树根
江青春
李智武
杨迪
金鑫
苏旺
叶玥豪
黄士鹏
王佳蕊
姜华
罗平
FAN Jianping;SONG Jinmin;LIU Shugen;JIANG Qingchun;LI Zhiwu;YANG Di;JIN Xin;SU Wang;YE Yuehao;HUANG Shipeng;WANG Jiarui;JIANG Hua;LUO Ping(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology),Chengdu,Sichuan 610059,China;Xihua University,Chengdu,Sichuan 610039,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)
出处
《石油实验地质》
CAS
CSCD
北大核心
2023年第4期726-738,共13页
Petroleum Geology & Experiment
基金
国家自然科学基金面上项目(41872150)
国家自然科学基金企业创新发展联合基金(U19B6003)联合资助。
关键词
灰岩—泥质灰岩韵律
凉水碳酸盐岩
古温度
茅一段
中二叠统
四川盆地
limestone-marl alternation
cool⁃water carbonate
paleotemperature
first member of Maokou Formation
Middle Permian
Sichuan Basin
