中国大陆壳幔结构研究的进展与展望

对地球壳幔结构的研究是地震学的一个经典课题。在所有研究地球内部结构的地球物理方法中，地震波方法是最有效、最精确的一种工具。文章介绍了中国大陆壳幔结构研究的进展和展望。     

复杂地壳接收函数H-κ叠加——以安纳托利亚板块为例

本文理论分析了具有不同沉积层和壳幔过渡带结构的接收函数及其相关的H-κ叠加结果,然后采用接收函数H-κ叠加和波形反演方法获得了具有复杂构造演化历史的中北安纳托利亚板块的地壳厚度(H)、V_P/V_S(κ)和V_S结构.理论分析表明:厚的沉积层或沉积层和厚的壳幔过渡带共存都会使H-κ叠加失效;渐变型壳幔过渡带导致H-κ叠加的H位于过渡带中间,且随着频率增大逐渐靠近过渡带上方;倒转型壳幔过渡带导致H-κ叠加具有多极值,其结果可能反应过渡带内最大波阻抗界面上的地壳结构;1km·s~(-1)的V_P变化会导致H-κ叠加的H变化7km,而κ变化较小.实际资料分析表明:中北安纳托利亚H,κ和V_S具有强烈的横向不均匀性,大部分区域沉积层厚度0.5km,局部地区壳幔过渡带厚度3km;北安纳托利亚断层切穿地壳,在局部地区可能存在流体;研究区存在残留古老的小陆块体.本文研究表明,仔细分析接收函数波形和其随方位角的变化特征且用其他地震学方法进行约束,有助于采用H-κ叠加方法获取复杂地壳结构信息.     

浙皖地区地壳-上地幔结构和华南与扬子块体边界

基于屯溪－温州剖面宽角反射地震资料,拟合反演了地壳浅层和深部结构,并利用非纵剖面记录构制了上幔顶部结构图象。结果表明,江绍断裂带是本区最明显的构造分界,其西北一侧的扬子块体和东南侧的华南块体地壳和上地幔顶部结构以及地球物理特征明显不同。金（华）衢（州）盆地下方地幔上隆,上地幔岩石层中有低速体,可能是一个复杂的岩浆房构造。地幔岩石层呈现出由ＳＥ至ＮＷ向仰冲的叠瓦式片状构造,提示该区明显受水剂压应力控制。     

Preliminary study on the relationship between the crust-mantle structure and the formation of Laowangzhai superlarge gold deposit

The essential shallow-crust structural factors controlling the formation of Laowangzhai gold deposit include favorable tectonic and regional structural site, the release site of a great deal of the earth energy, favorable orecontrolling structure system, abundant and favorable source rocks for gold, ductile shearing, abundant minerogenetic materials source in extensive crust and mantle. And the essential deep-seated crust-mantle structure factors dominating the formation of the ore deposit include intracrustal low-velocity len, high-velocity bodies in the lower part of middle crust and lower crust, the steps on the slope of Moho, connecting site of mantle rises, the crust-mantle transition layer, upwelling of asthenosphere and the low-velocity plume. It is concluded that the fundamental reason that controls the formation of Laowangzhai superlarge gold deposit lies in the coupling between deep and shallow crust-mantle structure factors controlling the formation of the deposit and their coupling with the lithospheric evolution and geological event. Project supported by the National Climbing Plan Programme A-30.     

Magma underplating and Hannuoba present crust-mantle transitional zone composition: Xenolith petrological and geochemical evidence

Studies on the deep-seated xenoliths from global volcanoes reveal that the present petrological crust-mantle boundary between the lower crust and the upper mantle actually is a transitional layer from mainly mafic granulites to ultramafic spinel lher-zolites[1,2], i.e. a transitional zone distinctive from the seismological Moho[3]. Oceanic lithosphere crust- mantle transitional zone can be established from the study on the exposed ophiolites. However, as for the continental lithosphere, since …     

中国东部地区的壳-幔过渡带结构

莫霍面是地壳和上地幔的边界,但莫霍面并不是一个简单的"面",而是一个反映地壳和地幔物质交换、相互作用等动力学意义的"过渡带".本文综合深地震反射、宽角地震折射和高温高压岩石物理实验结果,确定壳-幔过渡带的地震P波速度变化范围为6.8~7.5 km·s^-1.在克拉通等构造活动稳定地区壳-幔过渡带内的速度梯度强且壳-幔过渡带厚度薄,而在造山带等构造活动区域壳-幔过渡带内的速度梯度弱且壳-幔过渡带厚.中国东部地区的壳-幔过渡带的平均厚度约为5~10 km,在四川盆地下方最薄（<5 km）,而在华北克拉通中部造山带下方的壳-幔过渡带最厚（~30 km）.综合地球化学结果,华北中部巨厚壳-幔过渡带主要是幔源岩浆的底侵作用和堆晶作用而形成.     

青藏高原东北缘祁连山造山带至阿拉善地块壳幔电性结构研究

在青藏高原东北缘祁连山造山带至阿拉善地块之间完成了一条372km的大地电磁剖面,通过二维反演计算,获得了沿剖面180km深的壳幔电性结构模型,结合研究区地质和地球物理资料开展综合分析,研究结果表明:(1)剖面自南向北所经过的祁连山造山带、走廊过渡带和阿拉善地块对应3种壳幔电性结构模型:东祁连壳幔高-低-高阻似层状电性结构、河西走廊壳幔低阻带状电性结构和阿拉善南缘壳幔高-低-高阻层状电性结构.(2)剖面所经过的主要断裂带在电性结构上表现为低阻异常带或电性梯度带,并且止于中上地壳或消失于下地壳低阻层中.除这些分布于中上地壳的断裂系统以外,在下地壳至上地幔顶部还存在两条切割莫霍面的壳幔韧性剪切带:西华山北缘壳幔韧性剪切带和阿拉善南缘壳幔韧性剪切带.其中,西华山北缘壳幔韧性剪切带可能是1920年海原8.6级地震发生的深部背景之一;而阿拉善南缘壳幔剪切带可能是卫宁北山燕山晚期和喜山期幔源岩浆上升到地壳浅部或喷出到地表的通道,为在该区域寻找晚中生代至新生代含矿隐伏岩体提供了深部电性结构依据.(3)由若干形状不规则、彼此不相连的"碎块状"极高阻块体组成的中上地壳与"似层状"的中下地壳低阻层共同构成的地壳电性结构,是引起青藏高原东北缘强烈破坏性地震最佳的地壳电性结构组合之一.印度板块向欧亚板块俯冲碰撞楔入引起青藏高原块体向北东方向运移与阿拉善地块向南的俯冲碰撞楔入,是青藏高原东北缘强震活动带产生的动力学背景.     

Crust-mantle structure feature and the seismic activity of the main tectonic units in the North Tanlu fault zone

IntroductionThe Northern Tanlu fault zone (from Yingkou to Luobei) crosses the northeast mainland ofChina. Because of its large scale, long history activity and controlling earthquakes prominently, itis paid closely attention by geologists, and a imp amount of geological survey has been done inthese years (Bureau of Geology and Mineral Resources of Liaoning Province, 1989; Bureau ofGeology and Mineral Resources of Jinn Province, 1988; Bureau of Geology and Mineral Resources of Heilongi…     

攀枝花古地幔柱壳、幔结构与地球物理边界场特征

攀枝花古地幔柱的形成与演化对这一地域的大地构造格局、金属矿产的聚集和区域大陆动力学研究均有着极为重要的科学意义和应用价值.本文通过穿越攀枝花古地幔柱中心部位的四条人工源深部地震探测剖面和区域地球物理边界场响应研究提出：（1）攀枝花古地幔柱具有特异的壳、幔速度结构;（2）在其中心部位由结晶基底到壳、幔边界均为高速体,且结晶基底和Moho界面局部隆起、地壳内部存在厚达10余千米的低速层,且被数条深、大断裂切割;（3）重力场、磁力场的边界异常场响应组构了攀枝花古地幔柱的地表形态和中心部位的圈闭范围.     

扇形边界条件下的龙门山壳幔电性结构特征

沿甘肃碌曲-四川龙门山-重庆合川布设了长周期大地电磁剖面,对龙门山及邻区进行了壳幔电性结构探测,采用更直观合理的扇形边界条件下的反演算法对长周期大地电磁资料进行二维反演.该剖面电性结果揭示了自北西向南东岩石圈深部的若尔盖壳幔高阻块体、松潘壳幔低阻带、龙门山壳幔高阻块体和川中壳幔高阻块体电性结构特征;龙门山逆冲推覆构造带下方的龙门山壳幔高阻体显示为向北西延伸的楔形构造,推断龙门山及松潘-甘孜地块由于受青藏高原东缘和上扬子地块双向挤压,松潘-甘孜地块地壳物质向龙门山逆冲推覆,中下地壳至上地幔向下向南东俯冲,呈现上扬子地块西缘壳幔高阻楔形体插入青藏高原东缘的态势;初步认为上扬子地块西缘深部以松潘壳幔韧性剪切带作为中新生代以来的边界.     

乐昌—霞葛MT剖面深部电性结构研究

为研究华南地区的壳幔电性结构,完成了华南地区乐昌—霞葛大地电磁测深剖面的探测,获得了该剖面的地电模型,并结合倾子、极化图和感应矢量等信息对地电模型进行了研究,对华南的电性结构、断裂特征和壳幔结构有了新的认识.研究结果表明:剖面上地壳西厚东薄,表面被大量的花岗岩高阻体所覆盖,6条断裂沿剖面展布.剖面两端岩石圈增厚,厚度超过100km,推测剖面西段岩石圈增厚是由于陆内挤压造山或陆内碰撞汇聚造山作用,而剖面东端的岩石圈增厚形成于大洋板块的俯冲;中部岩石圈减薄,厚度在60～80km之间,可能是与软流圈物质上侵有关.     

Preliminary study of the straticulate structure of crust-mantle beneath east Guangdong and south Fujian Provinces of China

Using the 12 deep focus teleseismic P waveforms recorded by 6 short-period seismographs in east Guangdong and Fujian region of China as the observed data, synthetic P waveforms comparable to the observed ones are obtained by gradually adjusting the crust-mantle model and calculating the corresponding synthetic seismograms. The results suggest that the crust-mantle structure in this region is a vertically straticulate media structure consisting of 3 pairs of thin layers with a high- and low-velocity alternation. The crustal thickness tends to increase gradually from south to north, being 31.5 km in the south and 32.4 km in the north. Finally, the suggested model is tested using the explosive data of Yunfu, Guangdong Province. The theoretical travel-time of P waves agrees fairly well with the observed travel-time. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 172–179, 1992.     

新疆天山地区壳幔S波速度结构特征及变形分析

天山地区地质构造复杂,地震活动频繁,其壳幔变形和深部结构一直受到学者们的高度关注.然而,由于天山地区地震台站资料较少,致使壳幔变形研究结果与解释存在诸多争议.本研究利用在天山地区（40°N-46°N,78°E-92°E）新布设的11个流动宽频带地震台站和该地区39个固定台站的观测资料,采用接收函数与面波联合反演方法,获得了研究区地壳厚度及壳幔S波速度结构.反演结果显示天山地区（41.5°N-44°N,78°E-88°E）平均地壳厚度为56 km,塔里木盆地（40°N-41.5°N,79°E-90°E）、准噶尔盆地（44°N-46°N,82°E-90°E）和吐鲁番盆地（42°N-43°N,88°E-90°E）具有较厚的沉积层,地壳平均厚度为43 km、53 km和46 km,整体表现为天山厚、盆地相对较薄的特征;在研究区南天山的最高峰（42°N,80.5°E）及北天山的最高峰（43.5°N,86°E）附近,中下地壳存在较厚的低速层,我们认为在强烈挤压作用下低速、低强度的中下地壳强烈变形可能是导致该区域快速隆升的主要原因.在研究区中部,位于塔里木盆地与准噶尔盆地之间的天山地区,中下地壳及上地幔均存在低速层,且盆地莫霍面向天山倾斜明显.结合前人的研究成果推测,在南北向构造挤压应力作用下,塔里木盆地与准噶尔盆地发生了向天山造山带方向的双向壳幔层间插入俯冲.在研究区东部,塔里木盆地东北缘与天山东部接触带的地壳内没有明显的低速层,推测应处在早期挤压变形状态,该区域的壳幔边界为缓变的速度梯度带,可能与上地幔热物质侵入或渗透有关.     

Crust-mantle transitional zone of Tianshan orogenic belt and Junggar Basin and its geodynamic implication

The traveling time of the reflection waves of each shot point from the crust-mantle transitional zone has been obtained by data processing using wavelet transform to the waves reflected from the crust-mantle transitional zone. The crust-mantle transitional zone of the Xayar-Burjing geoscience transect can be divided into three sections: the northern margin of the Tarim Basin, the Tianshan orogenic belt and Junggar Basin. The crust-mantle transitional zone is composed mainly of first-order discontinuity in the Tarim Basin and the Junggar Basin, but in the Tianshan orogenic belt, it is composed of 7–8 thin layers which are 2-3 km in thickness and high and low alternatively in velocity, with a total thickness of about 20km. The discovery of the crust-mantle transitional zone of the Tianshan orogenic belt and Junggar Basin and their differences in tectonic features provide evidence for the creation of the geodynamic model “lithospheric subduction with intrusion layers in crust” for the Tianshan orogenic belt.     

Velocity structure of the crust and upper mantle in Xingtai earthquake region and its adjacent area

ＶｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅｏｆｔｈｅｃｒｕｓｔａｎｄｕｐｐｅｒｍａｎｔｌｅｉｎＸｉｎｇｔａｉｅａｒｔｈｑｕａｋｅｒｅｇｉｏｎ　ａｎｄ　ｉｔｓａｄｊａｃｅｎｔａｒｅａＺｈｉ－ＰｉｎｇＺＨＵ；（祝治平）Ｘｉａｎ－ＫａｎｇＺＨＡＮＧ；（张称康）Ｙｕ...     

巴颜喀拉块体地壳结构多样性探测

青藏高原内部地壳岩性的改造、岩性随深度变化及形变构造是探索研究地壳增厚、物质运动问题的关键.巴颜喀拉块体位于青藏高原中北部,地域广袤,通过对块体内中、东部不同区域的深地震广角反射/折射震相的综合分析,利用反射率理论地震图方法对不同性质震相走时及振幅特征进行细致的模拟计算,进一步研究巴颜喀拉块体内部不同区域地壳精细结构.结果显示:巴颜喀拉块体地壳厚度50~60 km、整体向西逐渐增厚,结晶地壳平均速度6.07~6.18 km·s~(-1)、岩层速度大幅降低,壳内多强反射界面结构、但不同区域差异明显;东部若尔盖盆地地壳介质速度整体低速、壳幔边界较为清晰;中部玉树一玛多段下部地壳发现约6.8 km·s~(-1)的"高速度"介质结构,壳幔边界不清、被改造为2~4 km厚的高速度梯度层,显示了巴颜喀拉块体内部地壳增厚、介质岩性结构被改造的差异性.地壳内部多组强反射、低视速度走时震相揭示了介质岩性的低速破碎、弱化蠕变以及可能的壳内解耦构造.局部地区下地壳的高视速度震相特征显示了青藏高原地壳改造增厚大背景下可能存在稳定的"原始地壳"结构残留或是与上地幔物质的浸入交流.巴颜喀拉块体内不同区域地壳增厚、岩性结构、结晶基底及壳幔边界性质被改造的多样性为深入认识青藏高原地壳形变及动力学过程带来新的启迪.     

Global Crust-Mantle Density Contrast Estimated from EGM2008, DTM2008, CRUST2.0, and ICE-5G

We compute globally the consolidated crust-stripped gravity disturbances/anomalies. These refined gravity field quantities are obtained from the EGM2008 gravity data after applying the topographic and crust density contrasts stripping corrections computed using the global topography/bathymetry model DTM2006.0, the global continental ice-thickness data ICE-5G, and the global crustal model CRUST2.0. All crust components density contrasts are defined relative to the reference crustal density of 2,670 kg/m³. We demonstrate that the consolidated crust-stripped gravity data have the strongest correlation with the crustal thickness. Therefore, they are the most suitable gravity data type for the recovery of the Moho density interface by means of the gravimetric modelling or inversion. The consolidated crust-stripped gravity data and the CRUST2.0 crust-thickness data are used to estimate the global average value of the crust-mantle density contrast. This is done by minimising the correlation between these refined gravity and crust-thickness data by adding the crust-mantle density contrast to the original reference crustal density of 2,670?kg/m³. The estimated values of 485 kg/m³ (for the refined gravity disturbances) and 481?kg/m³ (for the refined gravity anomalies) very closely agree with the value of the crust-mantle density contrast of 480?kg/m³, which is adopted in the definition of the Preliminary Reference Earth Model (PREM). This agreement is more likely due to the fact that our results of the gravimetric forward modelling are significantly constrained by the CRUST2.0 model density structure and crust-thickness data derived purely based on methods of seismic refraction.     

长江中下游成矿带中段岩石圈电性结构研究

长江中下游成矿带位于大别造山带、长江中下游凹陷、江南隆起带等大地构造单元结合部位,通过在研究区内布设两条首尾相接共计150km长的大地电磁剖面,获得了50km以浅岩石圈尺度的电性分布.长江中下游地区中段地下电性结构显示出在地下10km和30km处分别存在明显的圈层结构,以此认为现今横向稳定的"电莫霍"反映了研究区经历燕山期陆内构造-岩浆活动后已基本上完成壳幔重新平衡;而分隔大地构造单元的郯庐断裂带、长江断裂带以及江南断裂带在电性上具有特征的梯度显现,在印支造山期后的引张背景下,断裂带成为强伸展活动带与控制了燕山期大范围的陆内岩浆活动;高导地幔的局域性存在以及从北向南地幔导电性的变化反映了在经受深部动力学过程中处于不同大地构造部位的地幔所遭受的不同类型的改造以及地幔深部的构造极性.     

川南、滇北地震台网区域壳幔介质分层结构的初步研究

本文利用川南、滇北21个地震台短周期地震仪的深源远地震波形作为观测资料,通过调整地壳和上地幔介质模型并计算相应的综合地震图的方式,直至获得与观测波形可相比拟的综合地震图。据此,推断该地震台网区域的地壳中下部由一组高速和低速相间的薄层所组成,且大部分台站下的地壳厚度达到或超过54km。此外,文中还研究了该区域壳幔介质的吸收特点。     

鄂尔多斯地块北部至阴山造山带深部电性结构特征研究

在SinoProbe-01项目的资助下,完成了一条跨越鄂尔多斯地块北部、河套断陷盆地和阴山造山带的大地电磁剖面,剖面长约440 km,共包括24个宽频测点和4个宽频一长周期联合测点.采用NLCG算法对TE和TM模式数据进行了二维反演,获得了该剖面的二维电性结构模型.结果表明:鄂尔多斯地块北部由浅至深电性结构比较简单,成层性较好,大体可分为低阻沉积盖层-高阻上地壳-低阻下地壳和上地幔顶部三层;河套断陷盆地和阴山造山带电性结构相对复杂,电阻率高低相间.鄂尔多斯地块北缘、河套断陷盆地以及阴山造山带区域的壳幔高导体可能与硫化物和部分熔融作用有关,而鄂尔多斯地块内部大规模的壳幔高导层可能是由高导矿物引起的.河套断陷盆地的沉降、阴山造山带的地势抬升和鄂尔多斯地块北缘东胜一杭锦旗一带的的隆起之间有着紧密的关系,它们的形成可能与区域伸展构造环境条件下的软流圈物质上涌有关.