中国中生代两个古大洋与沉积盆地

TWO PALAEO-OCEANS AND SEDIMENTARY BASINS DURING MESOZOIC ERA IN CHINA

高长林 叶德燎 黄泽光 吉让寿

Gao Changlin Ye Deliao Huang Zeguang Ji Rangshou

中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

Wuxi Research Institute of Petroleum Geology, Research Institute of Petroleum Exploration and Production, SINOPEC, Wuxi, Jiangsu 214151, China

中国西南部特提斯洋由班公湖—怒江小洋盆和雅鲁藏布江主洋盆及其间的拉萨小陆块组成。特提斯演化可划分为以下5个阶段:1)裂谷起始阶段(P);2)扩张阶段(T1—J2-3);3)班公湖—怒江洋敛合阶段(J2-3—K1),拉萨陆块向北漂移,班公湖—怒江洋自东向西封闭,拉萨地块拼合到亚洲大陆块上;4)主洋盆俯冲阶段(K1—E2),主洋盆急剧向北俯冲,形成冈底斯陆缘火山弧和日喀则弧前复理石堆积,喜马拉雅地区由被动边缘沉积(K2-3)向局部残留“台型”浅海沉积过渡(E1—E22);5)碰撞阶段(E23—Q),从始新世晚期起,印度陆块与亚洲大陆碰撞,影响范围波及整个中国中西部,陆内前陆盆地和拉分盆地形成。南海确实存在过一个中生代特提斯海洋。晚侏罗—早白垩世的动物具有太平洋动物群的特色,说明此期的特提斯洋可能和太平洋沟通。南海东北与南部边缘中生代时中特提斯海与西太平洋沟通。中国东南部大陆边缘中生代构造演化有2个重要特点:1)古特提斯俯冲阶段(T2—J2),洋壳向亚洲大陆俯冲和沿南北向转换断层平移活动,亚洲大陆东部外侧增生,该洋盆是古特提斯的直接延伸部分;2)中国东部J2以后发生了根本的变化,185 Ma左右三联点扩张形成的太平洋是这一转变的标志,库拉板块向北移动(J2—K1)和向亚洲东北部俯冲、微地块拼贴,而在中国华南和台湾则沿南北向转换断层斜向俯冲和微地块拼贴,形成从锡霍特阿林—西南日本—琉球群岛—台湾中部的俯冲增生造山带和华南广阔的火山—岩浆带。裂谷盆地和拉分盆地形成。

The Tethys Ocean is composed of the Bangong Lake-Nujiang Small Ocean and Yarlung-Zangbo Main Ocean,as well as the Lhasa small blocks in the West China.The evolution of Tethys can be divided into 5 stages.1)Rifting stage(P);2)Spreading stage(T-J2-3).3)Closing stage of Bangong Lake-Nujiang Ocean(J2-3-K1).The Lhasa blocks drifted to the north.The Bangong Lake-Nujiang Ocean closed from east to west.At the same time, the Lhasa blocks cottaged to the Asian Massif.4)Subduction stage(K1-E2).The Yarlung-Zangbo Main Ocean Basin subducted to the north.The Gangdese continental margin volcanic island and the Xigaze fore-arc flysch were formed.It was changed from passive margin sedimentation(K2-3) to relict platform shallow sea deposition(E1-E22) in the Himalayan area.5) Collision stage(E23-Q).The Indian Massif and the Asian Continent collided,influencing the West China.Intracontinental foreland basin as well as pull-apart basin were formed.There did exist a Mesozoic Tethys Ocean in the South China Sea.The fauna had the same characteristics as the Pacific fauna.It is illustrated that,the Tethys Ocean was connected with the Pacific Ocean.The NE South China Sea was connected with the West Pacific Ocean.Tectonic evolution of the continental margin of SE China in the Mesozoic is stated as follow.1)The subduction stage of the Palaeo-Tethys(T2-J2).The oceanic crust subducted into the Asian Continent and paralleled displacement along transfer fault in N-S direction.The eastern margin of Asian Continent was accreted.It is pointed out that,the oceanic basin was part of the Palaeo-Tethys extending directly.2)Great changes have taken place since the Late Jurassic in the East part of China.The Pacific Ocean was formed by the expansion of three conjunction points in 185 Ma.The Kula Plate(J3-K1) moved to the north and subducted to tie NE Asia.Micro-massifs were collaged.Clino-subduction along the S-N transfer fault and micro-massifs took place in the South China and Taiwan.The subuducted accreting orogenic belt in Sikhote-Alin-SW Japan-Ryukyu Islands-Middle Taiwan and the volcano-magmatic belts in South China were formed.Rifting basins and pull-apart basins were formed.

中国石化科技开发项目(P01025)

https://doi.org/10.11781/sysydz200602095