河西—祁连山地区近期形变场演化特征与孕震构造模式   总被引：2，自引：2，他引：2  

王庆良 《地震》1994,(3):64-71

本文通过对河西－祁山地区近２０年形变场演化特征的分析，提出了代表该区区域应力松驰、岩石圈底部软流层对流加速以及地壳中上部应力强化与强震孕育三种应力状态的特征性形变图象，文章还通过典型强震构造组合特征、形变场特征的分析，提出了该区北西西、北东向两组构造的组合孕震模式，并利用上述孕震模式对该区近期强震危险地点进行了初步判定。  相似文献   

Combined analysis of SKS splitting and regional P traveltimes in Siberia   总被引：3，自引：0，他引：3  

S. Oreshin  L. Vinnik  L. Makeyeva  G. Kosarev  R. Kind  F. Wentzel 《Geophysical Journal International》2002,151(2):393-402

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华北板内深部构造   总被引：9，自引：0，他引：9  

邢集善  刘建华  赵晋泉 《山西地震》2002,(4):3-12

华北板块的形成经历了早前寒武纪、燕山期及喜马拉雅期3个主要构造发展期，由于华北板块自身运动及所受应力场的作用，加之上地幔岩石圈的不均一性等因素，在中、新生代形成许多特殊的板内构造块。综合应用地质、地球物理和地球化学的成果，对华北板内深部结构进行了研究。从深部构造角度划分出6个金及金金属成矿带、4个金刚石成矿带，并对华北地区的地震及地热资源与新生事大陆裂谷的关系进行了探讨。  相似文献   

Study on Eogene Basalts: Implication of the Deep Process over the Bohaiwan Basin Evolution     

Ye Delong Lu Fengxiang Zhu Qinwen Zheng JianpingFaculty of Earth Sciences  China University of Geosciences  Wuhan  《中国地质大学学报(英文版)》1997,(1)

ＳｔｕｄｙｏｎＥｏｇｅｎｅＢａｓａｌｔｓ：ＩｍｐｌｉｃａｔｉｏｎｏｆｔｈｅＤｅｅｐＰｒｏｃｅｓｏｖｅｒｔｈｅＢｏｈａｉｗａｎＢａｓｉｎＥｖｏｌｕｔｉｏｎ＊ＹｅＤｅｌｏｎｇＬｕＦｅｎｇｘｉａｎｇＺｈｕＱｉｎｗｅｎＺｈｅｎｇＪｉａｎｐｉｎｇＦａｃｕｌｔｙ...  相似文献   

Deglacial land emergence and lateral upper-mantle heterogeneity in the Svalbard Archipelago—I. First results for simple load models     

Doris Breuer  Detlef Wolf 《Geophysical Journal International》1995,121(3):775-788

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岩石圈—软流圈物质循环促进大陆增生的新方式     

杨文采 《地质论评》2019,65(5):1039-1053

大陆动力学研究地球内能量和物质的运动和伴随的信息传播,上地幔中的软流圈是地球内部的物质运动的关键部位之一。由于观测的技术方法少,人类对软流圈内部的地质作用过程所知甚少。在青藏高原,过去地震波三维层析成像的分辨率不高,难以对地壳上地幔构造进行准确的定位。我们收集和整理了地方地震台的数字化观测数据,使地震体波三维层析成像的准确度大大提高,为解决软流圈的地质构造准确成像提供了新的可能性。根据地震体波三维层析的成像结果,在古特提斯洋和特提斯洋俯冲板块前沿的软流圈底部410 km间断面上方,存在反映古大洋俯冲板块的高速体,它们在青藏高原、苏鲁和伊朗都有出现。清晰和稳定的高波速异常的位置表明,特提斯洋俯冲板块现在已经拆沉在软流圈的底部,古特提斯洋俯冲板块也可能曾经拆沉在软流圈的底部。对比青藏高原和苏鲁的地壳上地幔波速结构推测,拆沉造成软流圈中的轻元素物质上涌,进入大陆岩石圈,造成岩浆活动。上涌还使碰撞造山带地壳厚度减小,而岩石圈厚度增加。大约100 Ma后,俯冲下去的大洋残块会被软流圈物质磨蚀交代,使岩石圈厚度增加, 形成大陆下方的大陆根,造成大陆克拉通化和体积增生。大洋板块俯冲后在软流圈拆沉是岩石圈—软流圈物质循环的一种重要方式,对软流圈中物质均衡和体积稳定也起重要作用。  相似文献   

内蒙古突泉县牤牛海地区超镁铁质岩地球化学及源区特征     

付俊彧  汪岩  钟辉  宋维民  孙巍  那福超  钱程  杨雅军  庞雪娇  江山 《吉林大学学报(地球科学版)》2017,47(4)

内蒙古突泉县牤牛海地区发育超镁铁质岩,主要岩石类型为蛇纹石化橄榄岩、辉石橄榄岩、异剥辉石橄榄岩和蛇纹岩,局部蛇纹岩中可见显微鬣刺假象结构,包括蛇纹石呈假像的柱状中空骸晶结构、鱼骨状或羽状结构。岩石化学具有高镁(w(MgO)为33.63%~39.44%)、铬(2 200×10~(-6)~17 200×10~(-6))、镍(1 900×10~(-6)~3 000×10~(-6)),高CaO/Al_2O_3(0.56~39.01,平均为7.05),低钛(w(TiO_2)为0.01%~0.02%)、低铝(w(Al2O3)为0.03%~0.36%)、低碱(w(K_2O+Na_2O)为0.03%~0.65%)特征,类似科马提岩;Mg#值(平均为87)与纯橄榄岩(86)接近;稀土元素(w(∑REE)为0.32×10~(-6)~2.79×10~(-6))明显低于大洋脊含量,轻稀土富集(LREE/HREE为2.80~16.68),Eu正异常明显(δEu为0.59~4.84);微量元素富集大离子亲石元素(LILE)Rb、Ba、Sr,亏损高场强元素(HFSE)Nb、P等。说明超镁铁质岩石岩浆源自亏损软流圈地幔,并受到俯冲流体交代作用,形成于岛弧环境。牤牛海超镁铁质岩与西部包括突泉围场、好老鹿场、超日海乌拉、梅劳特乌拉、苏尼特左旗二道井一带超镁铁质岩共同构成一条近东西向展布的超镁铁质岩(蛇绿岩)带,通过地质建造分析,认为该构造带可能为华北板块与西伯利亚板块最终缝合带。  相似文献   

Research progress on layered seismic anisotropy - A review     

《地震研究进展（英文）》2021,1(1):100005

Seismic anisotropy is an effective feature to study the inner structure of the Earth. In complex tectonic area, the assumption of single-layer anisotropy is sometimes not well consistent with the observed data; thus, the assumption of multi-layered (i.e. stratified) anisotropy should be considered. At present, the main methods to study anisotropy include receiver functions, shear wave splitting from local and teleseismic events (SKS, SKKS, and PKS, hereafter collectively called XKS), P- and Pn wave travel time inversion, surface wave inversion from far-field earthquakes and ambient noise. Each of the above method has its own advantages and limitations. Thus, one or more of the above methods are often combined to characterize multi-layered anisotropy, of which the depth range of anisotropic layers are different. This paper reviews the research progress of multi-layered anisotropy for the purpose of providing a basis for future seismic anisotropy investigations.  相似文献   

Oxidation state of lithospheric mantle along the northeastern margin of the North China Craton: implications for geodynamic processes     

《International Geology Review》2012,54(11):1418-1444

Quaternary volcanic rocks in the Kuandian (KD), Longgang (LG), Changbaishan (CBS), Wangqing (WQ), and Jilin (JL) volcanic centres in eastern Liaoning and southern Jilin provinces contain mantle xenoliths of spinel-facies lherzolites and minor harzburgites. Among the study sites, the KD, LG, and CBS volcanic fields are located on the northeastern margin of the North China Craton (NCC), whereas the WQ and JL fields lie on the southern margin of the Xing'an–Mongolia Orogenic Belt (XMOB). The (Fo) components of olivine (Ol) and Cr# (=Cr/(Cr + Al)) of spinel, together with trace element abundance of clinopyroxene, suggest that the subcontinental lithospheric mantle (SCLM) in the study area has undergone a low degree (4–6%) of partial melting. The rocks do not show modal metasomatism, but clinopyroxene grains in selected samples show elevated large ion lithophile element compositions, suggesting that the mantle xenoliths underwent minor cryptic metasomatism by exchange with a silicate melt. Two-pyroxene thermometry yielded equilibration temperatures ranging from 740°C to 1210°C. The corresponding oxygen fugacity (fO₂) was calculated to range from FMQ –2.64 to +0.39 with an average of –0.59 (n?=?53). The oxidation state is comparable to that of abyssal peridotites and the asthenospheric mantle. We failed to discover differences in equilibration temperatures and oxidation state between lherzolites and harzburgites, suggesting that partial melting did not affect fO₂ values. In addition, similar fO₂ of non-metasomatized and metasomatized samples suggest that metasomatism in the region did not affect fO₂. Our data suggest that the present SCLM beneath the northeastern margin of the NCC and the southern margin of the XMOB are very similar and likely formed from a fertile asthenosphere after delamination of an old lithospheric keel below the NCC in response to the west-dipping subduction of the Pacific oceanic plate since early to middle Mesozoic time.  相似文献   

长江中下游成矿带三维S波速度结构及对深部过程的约束   总被引：3，自引：1，他引：2       下载免费PDF全文

徐峣  吕庆田  张贵宾  江国明  张昌榕  单希鹏  吴强 《地球物理学报》2015,58(12):4373-4387

利用73个固定台站记录的163个远震事件数据,采用多道互相关技术挑选了5524条S波到时数据,并对S波到时数据进行地壳校正,在此基础上采用天然地震层析成像方法和远震S波到时信息,获得了长江中下游成矿带上地幔的三维S波速度结构模型.研究结果表明:(1)研究区域上地幔存在着明显的低速异常,且走向与成矿带相同,可能为上涌的软流圈热物质;(2)研究区域地幔过渡带和上地幔底部存在着明显的高速异常,可能为俯冲的古太平洋板块和拆沉的岩石圈;(3)成矿带上地幔的低速异常呈现由南向北逐渐变浅的空间分布特征,该特征表明软流圈热物质由南向北上涌.综合分析认为,成矿带中生代大规模岩浆活动和成矿作用的深部过程主要与岩石圈的拆沉密切相关.  相似文献