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| 华北东部橄榄岩与岩石圈减薄中的地幔伸展和侵蚀置换作用 | |
| 引用本文： | 郑建平,路凤香,W. L. GRIFFIN,余淳梅,张瑞生,袁晓萍,吴秀玲.华北东部橄榄岩与岩石圈减薄中的地幔伸展和侵蚀置换作用[J].地学前缘,2006,13(2):76-85. |
| 作者姓名： | 郑建平 路凤香 W. L. GRIFFIN 余淳梅 张瑞生 袁晓萍 吴秀玲 |
| 作者单位： | 1. 中国地质大学,武汉,地球科学学院,湖北,武汉,430074;中国地质大学,地质过程与矿产资源国家重点实验室,湖北,武汉,430074 2. 中国地质大学,武汉,地球科学学院,湖北,武汉,430074 3. 澳大利亚,GEMOC中心,Macquarie大学地球与行星科学系,NSW,2109 |
| 基金项目： | 国家重点基础研究发展计划(973计划);教育部长江学者和创新团队发展计划 |
| 摘 要： | 对比分析了华北不同时代捕虏体橄榄岩及其南部超高压地质体橄榄岩的矿物化学。具古老难熔岩石圈地幔特征的橄榄岩是古生代金伯利岩捕虏体和早中生代苏鲁变质带地质体的主要岩石类型。具这一性质的橄榄岩也构成了河南鹤壁上新世玄武岩捕虏体的主体部分,并可以在辽宁阜新晚中生代玄武岩中被发现。具饱满岩石圈地幔性质的橄榄岩则是阜新晚中生代火山岩、特别是郯庐断裂带(山旺)及其附近地区(栖霞)中新世玄武岩捕虏体的主要类型。从华北东部已有的捕虏体橄榄岩及地质体橄榄岩所表现出的新生饱满与古老难熔地幔的时、空分布特点,即有些地区捕虏体橄榄岩表现出不同性质地幔共存现象(如阜新、鹤壁)或橄榄石Mg#呈渐变关系看:克拉通岩石圈地幔因扬子板块俯冲所引起的早期(如早中生代)地幔伸展、和晚中生代—渐新世因太平洋俯冲所引起的热扰动的软流圈物质上涌对古老地幔产生强烈的侵蚀作用(引起岩石圈的巨大减薄);中新世以来的软流圈热沉降作用出现新生岩石圈地幔并表现为岩石圈的小幅增厚,从而实现地幔置换过程和华北东部岩石圈的整体减薄过程。岩石圈幔内薄弱带及岩石圈深断裂(如郯庐断裂带)起了软流圈物质侵蚀古老岩石圈地幔的通道作用并导引着深部物质运移和不规则减薄作用等。个别地区(如阜新)强烈的软流圈上涌于晚中生代就已经开始,显示地幔置换作用的强烈不均一性。 |
| 关 键 词： | 橄榄岩 捕虏体 地质体 岩石圈减薄 地幔置换作用 伸展与侵蚀 华北东部 |
| 文章编号： | 1005-2321（2006）02-0076-10 |
| 收稿时间： | 2005-10-23 |
| 修稿时间： | 2005-12-20 |
Lithospheric thinning accompanying mantle lateral spreading, erosion and replacement beneath the eastern part of North China: evidence from peridotites |
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| ZHENG Jian-ping,LU Feng-xiang,W. L. GRIFFIN,YU Chun-mei,ZHANG Rui-sheng,YUAN Xiao-ping,WU Xiu-ling.Lithospheric thinning accompanying mantle lateral spreading, erosion and replacement beneath the eastern part of North China: evidence from peridotites[J].Earth Science Frontiers,2006,13(2):76-85. | |
| Authors: | ZHENG Jian-ping LU Feng-xiang W L GRIFFIN YU Chun-mei ZHANG Rui-sheng YUAN Xiao-ping WU Xiu-ling |
| Institution: | 1. Faculty of Earth Sciences, China University of Geosciences , Wuhan 430074,China ;2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences ,Wuhan 430074,China; 3. GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Sydney, Australia |
| Abstract: | We have compared the mineral chemistry of peridotites from xenoliths in volcanic rocks of different eruptive ages in the North China block to those from the Sulu ultra-high pressure (UHP) metamorphic terrane,south of the block. Refractory peridotites are the major rock types in both the Paleozoic North China kimberlitic xenoliths and the early Mesozoic Sulu UHP terrane. These types of peridotites constitute the majority of Pliocene Hebi basaltic xenoliths, and they are also found in late Mesozoic (~100 Ma) Fuxin basalts. In contrast, fertile peridotites are the major xenoliths in the late Mesozoic Fuxin basalts and,especially,in Miocene basalts from areas within the Tanlu Fault zone (e.g. Shanwang) and its adjacent area (e.g. Qixia). The spatial and temporal distributions of the refractory and fertile lithospheric mantle indicate the co-existences of different nature of mantle in some localities (such as Hebi and Fuxin). This suggests that Mesozoic-Cenozoic lithospheric thinning was accompanied by mantle replacement. The subduction of the Yangtze plate may have caused lateral spreading of the cratonic lithospheric mantle in the early Mesozoic. The thermal disturbance resulting from the subduction of a Pacific Ocean plate gave rise to the strong eroding of the cratonic mantle by asthenospheric materials in the late Mesozoic-Oligocene. Both the earlier lateral spreading and the younger strong erosion of the cratonic mantle brought about major thinning of the lithosphere. These processes collectively accomplished mantle replacement and lithospheric thinning in the eastern part of North China. A mantle weak zone in the lithosphere and the trans-lithospheric Tanlu fault functioned as channels for asthenospheric materials eroding the existed mantle. In addition, slight lithospheric thickening occurred during the Neogene-Quaternary in response to the cooling of upwelling asthenosphere. |
| Keywords: | peridotite xenolith terrane lithospheric thinning mantle replacement lateral spreading and eroding eastern part of North China |
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