【作者】 李传涛；

【导师】 张贵宾；

【作者基本信息】 中国地质大学(北京) ， 地球物理学， 2012， 博士

【摘要】 中国大陆及其邻近区域是晚古生代（约200～300 Ma）由多个板块或地块汇聚形成的。在晚中生代到古新世印度次大陆与欧亚大陆碰撞，引起地壳大规模缩短及地表急剧隆升，形成了现今地球上最高的青藏及帕米尔高原和喜马拉雅、兴都库什造山带，从印度半岛至青藏高原、新疆、蒙古、贝加尔一带，成为全球最有代表性的岩石圈汇聚场所。因此，建立包括中国及其邻域在内的亚洲岩石圈的三维结构图像，对了解亚洲地区的地表构造与深部结构关系有着重大意义。本文研究的目的是根据已有的重力异常数据反演亚洲岩石圈的三维密度分布。研究区域的范围是东经60°～150°，北纬15°～60°N。岩石圈三维密度分布的计算经过以下步骤。第一，正演计算沉积层底界和莫霍界面产生的重力异常。第二，利用卫星重力资料计算岩石圈以下物质密度不均匀产生的重力异常。第三，从总的布格重力异常中减去沉积层底界重力异常、莫霍界面重力异常以及岩石圈以下物质密度不均匀产生的重力异常，从而获得了消除了主要密度界面影响的亚洲岩石圈的重力异常。该剩余布格重力异常是由岩石圈内部密度不均匀引起。第四，结合研究区P波速度资料，利用剩余布格重力异常反演计算亚洲岩石圈三维密度结构。为了反演计算研究区域岩石圈三维密度分布，首先将研究区域剖分成由一系列块体构成的离散的密度柱体，并假定每个柱状块体的密度是单一的，模型的长、宽为1°×1°。针对观测数据和剖分体数量大的特点，在反演中利用了代数重建法（ART）。反演结果表明：亚洲的异常密度分布与大地构造格局有着明显的相关性，不同的构造单元密度存在着显著的差异。大洋板块对应高密度区,大陆地块和岛弧区对应密度低区，板块的交接部位和各断裂带不同程度地表现为密度异常梯级陡变带。研究区域东部的太平洋板块、菲律宾海板块和日本海地区呈现高密度异常。最小的低密度异常在菲律宾北部—台湾—冲绳海槽—日本东南海域一线，在其两侧有一个急剧的密度异常转换陡变带。中国—俄罗斯西伯利亚地区呈现北东向的带状低密度异常特征，青藏高原显示低密度异常特征，喜马拉雅造山带显示了强烈的高密度异常特征。更多还原

【Abstract】 The continent of Asian formed by a series of plates and blocks converged rapidly in the latePaleozoic(about 200~300Ma).The Indian subcontinent collided with Eurasian continent, whichis causing the crust shorted and uplifted and forming the highest plateau of Qinghai-Tibet,Pamir, and the orogens of Himalayan and Hindu Kush in the late Mesozoic to Paleocene epoch.Asian lithosphere from Indian subcontinent to Tibet, Xinjiang, Mongolia and Baikal regions, isthe most representative place in the world. The research of three-dimensional densitydistributions in Asia including China and its adjacent regions is great significant to realize theinner structure of the earth.The goal of this paper is to construct a three-dimensional (3-D) density model of the Asianlithosphere and relate this model to geologic structure by using gravity data. The study area isAsian region (60°~150°E and 15°~60°N). Firstly, the gravity anomaly, which is caused byMoho discontinuity and sedimentary layer discontinuity, is calculated by Parker formula.Secondly, the gravity anomaly of the spherical harmonics with the 2-40 order for the lowermantle is calculated, which is based on the model of EGM96. Thirdly, The residual gravityanomaly, which eliminated the gravity effect of Moho discontinuity, the sedimentary layerdiscontinuity and the spherical harmonics with the 2-40 order from the Bouguer gravityanomaly, is considered to be caused by density anomaly in lithosphere. Finally, on the basic ofvelocity data, the three-dimensional crustal density distribution of Asian lithosphere isdetermined by using Algebra Reconstruction Techniques（ART）inversion method. Based onthe theoretical studies above, we have a further research about the three-dimensional densitydistribution of the Asian lithosphere with the newly gravity and terrain data in this paper.A series of the discrete density models were set up in order to invert the three-dimensionaldensity distribution of the Asian lithosphere. The partition of the model grid should be inaccord with the velocity model grid.The density anomalies of the lithosphere show that the density distribution of the Asianlithosphere has some connection with the tectonic structure. There is a significant difference indifferent tectonic units. Oceanic plate corresponds to the high-density areas, and continentalplate and island arcs correspond to low density areas, the fault zone are the densityanomaly suddenchange belt. The minimum value of density lies in the North of Philippines, Hainan province and line follows the southeast coast of China , Okinawa Trough and the Eastsea. China -Russia’s Siberia region showing the north-east to the ribbon low-density anomalycharacteristics, Qinghai-Tibet Plateau shows low-density anomaly characteristics, HimalayanOrogen show a strong high-density anomaly characteristics.更多还原