残余洋盆的大地构造演化及其油气意义  

Tectonic evolution of remnant oceanic basin and its implication for hydrocarbon

作　　者：李江海[1,2] 程海艳[1,2] 赵星[1,2] 贺电[1,2] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]北京大学石油天然气研究中心,北京100871

出　　处：《地学前缘》2009年第4期40-51,共12页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973"项目(2009CB219302)

摘　　要：残余洋盆是板块拼合碰撞过程中残留的、未彻底闭合的洋盆,为碰撞陆块之间最晚闭合的区域。它们在走向上与蛇绿岩缝合带渐变过渡,普遍具有不规则的几何形态(三角形、贝壳形、凹四边形)和复杂的构造边界。盆地内充填大面积的巨厚三角洲-浊流相(海底扇)沉积,物源来自于周边造山带的隆升剥蚀。残余洋盆的构造背景、几何形态、鉴别标志及其最终消亡过程,正成为大陆动力学需要深入研究的重大科学问题。由于欧亚大陆内各个陆块尺度较小和陆块数目较多,拼合的陆块边缘形态不完全匹配,古生代末以来,在古亚洲洋盆及特提斯洋盆聚合边界上广泛发育残余洋盆。已发现的残余洋盆实例有:孟加拉湾、黑海、南里海、南沙海槽、东地中海、准噶尔、松潘—甘孜等盆地。它们普遍具有海相沉积巨厚、盆地深度较大、快速而持续的沉降等特点。陆块几何形态不规则、陆块拼合的随机性、板块远大于陆块尺度,均是形成残余洋盆的重要原因。随着板块碰撞及陆块调整,残余洋盆主要发生被动式的消亡,包括巨厚的沉积充填(弧前增生楔及海底浊积扇)及多期构造变形。残余洋盆普遍具有重要的油气价值和勘探前景。Remnant oceanic basins distributed along the continental collisional belt represent the latest closed oceanic crustal area. Laterally, it is connected with ophiolite suture zone, commonly showing irregular geometries and complicate tectonic boundaries. They have been filled with the thick delta-submarine fan turbidites, derived from erosion of adjacent uplifted orogenic complexes. The regional tectonic framework, geometry, identification, and final closure, present an ongoing challenge to the understanding of continental dynamics. Eurasia is comprised of many blocks of small size, it is difficult for the continental margin to be completely matched and assembled by continental collision. Following the closure of Paleo-Asian and Paleo-to Neo-Tethyan ocean since latest Paleozoic, remnant oceanic basins have been widely developed along the convergent plate boundaries, such as the Bengal basin, Black Sea basin, South Caspian basin, Nansha trough, Eastern Mediterranean basin, Junggar basin, Songpan-Ganzi basin, etc. These basins were characterised with thick marine accumulations, large depth, and rapid and continued subsidence, etc. Tectonic configuration, collage of small continental blocks with large passive margin may have contributed to the formation and development of remnant basin. This summary indicates that remnant oceanic basins were passively closed through thick sedimentary filling, such as forearc accretionary complex and submarine fan complex, and poly-phase structural deforma- tion, due to the plate collision and reorganization of continental blocks. An understanding of remnant ocean is also very important for exploration of hydrocarbons.

关 键 词：残余洋盆 浊积岩系 陆块 造山带 油气勘探 

分 类 号：P542[天文地球—构造地质学]