大洋核杂岩与拆离断层研究进展  

Progress in Researches on Oceanic Core Complexes and Detachment Faults

作　　者：于志腾 李家彪[1] 丁巍伟[1] 张洁[1,2] 梁裕扬 朱磊 

机构地区：[1]国家海洋局第二海洋研究所,浙江杭州310012 [2]浙江大学地球科学系,浙江杭州310027 [3]中国大洋矿产资源研究开发协会,北京100860

出　　处：《海洋科学进展》2014年第3期415-426,共12页Advances in Marine Science

基　　金：国家自然科学基金重点项目--南海西南次海盆中脊3D地震成像及其构造演化(91028006);国家自然科学基金青年科学基金--南海东北部俯冲边界构造演化特征(41206046);中国大洋协会十一五研究课题--西南印度洋中脊热液压OBS深部构造及其动力过程的综合研究(DYXM-15-02-3-01)

摘　　要：大洋核杂岩和拆离断层是洋中脊中发育的重要构造,被广泛关注.拆离断层一般为长期活动的,低角度的,大断距的正断层,绝大多数形成于慢速和超慢速扩张洋中脊的内侧角上,其将地壳深部和上地幔的物质拆离到海底面形成大洋核杂岩.大洋核杂岩因其表面发育了窗棱构造,在多波束图像上更容易识别.大洋核杂岩所处的地壳年龄较年轻,为0～10 Ma.洋中脊半扩张速率约为10 mm/a,具有不对称扩张的特点,有拆离断层的一侧扩张速率更快.在大洋核杂岩取得的岩芯中代表性岩石为辉长岩,地震资料解释认为大洋核杂岩下具有一个大的辉长岩侵入体.发育大洋核杂岩和拆离断层的区域有升高的布格重力异常,高的P波速度和抬升的莫霍面.拆离断层起源于岩浆供给不足的区域,大多在大洋中脊洋脊段（segment）的末端,其演化会受到上地幔辉长岩体侵入的影响,通过旋转铰链的模式进行.总结了全球大洋核杂岩和拆离断层的分布情况,讨论了其岩石特征、地球物理场特征,探讨其成因机制和演化模式,并探讨了未来的研究方向.Oceanic core complexes and detachment faults are important structures on mid-ocean ridges （MORs） and increasingly become a hot in recent decades.Oceanic core complexes have been widely identified from the multibeam bathymetry images due to their megmullion structure.Detachment faults are commonly long-lived low angle normal faults,and mostly occur at the inside corner of the slow or ultra-slow spreading ridges with dominant half-spreading rates of 0～10 mm.The detachment faults,with age range from 0Ma to 10Ma,are associated with asymmetric spreading,representing the spreading is faster and the detachment faults are active.Drilled cores obtained below the domes of oceanic core complexes indicate a giant gabbros incursion.Detachment faults are characterized by elevator residual Bouguer gravity anomaly,high P-wave velocity and uplifted Moho.It has been widely accepted that they would develop at the time when magma supply was limited,and would be controlled by the rolling-hinge model.In this paper,we systematically presented some aspects of oceanic core complexes and detachment faults,including their morphology,global distribution,lithology signatures,geophysical structure,evolutionary mechanism.Finally,we put forward some prospects on the research of oceanic core complexes and detachment faults in Chinese deep-sea geology and their research in the future.

关 键 词：拆离断层 大洋核杂岩 窗棱构造 辉长岩 P波速度 不对称扩张 岩浆供给 起源与演化 

分 类 号：P736[天文地球—海洋地质]