2018年帕卢MW7.6地震震源及苏拉威西地区构造应力场特征          下载免费PDF全文

崔华伟  万永革  王晓山  黄骥超  靳志同 《地球科学》2021,46(7):2657-2674

为分析帕卢地震的发震构造及构造应力场特征,基于1976年1月至2018年4月全球CMT目录的震源机制解,反演了2018年9月28日印度尼西亚帕卢地震震源区及苏拉威西地区构造应力场,得到以下初步认识:赤道0°两侧南、北区域的应力场呈现出整体的一致性和局部的不均匀性,北部是以向北倾伏的低倾伏角挤压和向南倾伏的高倾伏角拉张作用为主;南部是近水平的NNW-EW向挤压及低倾伏角的近N-S向拉张的应力状态.摆堆易逆冲推挤及西里伯斯海阻挡导致北部地区的应力场显示俯冲带的特征,也导致北苏拉和马纳都块体的应力场出现差异性.在班达海自东向西的挤压及西部马卡萨盆地的阻挡作用下,南部地区呈现出近E-W向的挤压状态,并沿着NNE-SSW向呈现出地壳物质的构造逃逸现象.深部地幔物质上涌致使苏拉威西中部的R值偏小,形成活火山.受到桑吉双俯冲带和麦纳哈撒海沟的推挤及火山喷发作用,东部交汇区的应力场呈较大倾伏角的拉张为主及R值复杂突变.西部交汇地区的应力场是走滑为主兼有正断应力机制,该应力场有益于此次地震的触发及超剪切波破裂现象的出现.   相似文献   

Carbon isotope and rare earth element composition of Late Quaternary sediment gravity flow deposits on the mid shelf of East China Sea: Implications for provenance and origin of hybrid event beds     

Xin Shan  Xuefa Shi  Peter D. Clift  Shuqing Qiao  Lina Jin  Jianxing Liu  Xisheng Fang  Taoyu Xu  Shunli Li  Selvaraj Kandasamy  Mengwei Zhao  Ying Zhu  Hui Zhang  Dan Zhang  Huawei Wang  Yalong Li  Zhengquan Yao  Sai Wang  Jun Xu 《Sedimentology》2019,66(5):1861-1895

The East China Sea Shelf has an unusually wide and low gradient shelf, supplied from sediment‐charged rivers and large river delta systems, with bottom currents sweeping the sea floor and located in the path of strong typhoons. Sediment gravity flow deposits, including four hybrid event beds and a high density turbidite, are identified in a core from the mid‐shelf of the East China Sea. The hybrid event beds typically comprise three or two internal divisions from the base to the top: (i) H1, H3 and H5; or (ii) H3 and H5. Radiocarbon ages of the hybrid event beds were in the range of 3821 to 8526 yr bp . Based on correlation with surrounding cores, the hybrid events may have happened at any time between 1930 yr bp and 3890 yr bp . The δ¹³C values in hybrid event beds together with bathymetry data suggest local erosion on the shelf. The average δ¹³C value for the H1 division is similar to the H3 division in the hybrid event beds, implying that the organic matter in the H1 and H3 divisions may come from the same source area. Cross‐plots of upper continental crust normalized rare earth elements in the five units reveal that the sediment source of the four hybrid event beds and the turbidite was ultimately primarily from Korean rivers. Partial transformation from a moderate‐strength debris flow with the additional role of erosional bulking can explain occurrences of hybrid event beds on the East China Sea Shelf. The data indicate that hybrid sediment gravity flow deposits were sourced from intra‐shelf failures and subsequently transformed and deposited as hybrid event beds. The study shows that hybrid sediment gravity flows and turbidity currents may not necessarily indicate proximity to a major fluvial or deltaic system and that intra‐shelf sedimentation can be a sediment source. It is unlikely that the debris flows and turbidity currents were triggered by a hyperpycnal flow or tsunami, because both can carry continental and/or coastal signals which have not been recognized in the core. Typhoons are the probable triggering mechanism.  相似文献   

云南中甸地苏嘎印支期斑岩地球化学特征及其成矿标识     

潘彦宁  董国臣  李雪峰  王鹏  孙转荣  董朋生  李华伟 《现代地质》2019,33(6):1275-1285

地苏嘎印支期斑岩体位于中甸岛弧东斑岩带的北端,岩性为石英闪长玢岩,与普朗超大型斑岩铜矿的成矿岩体同属于甘孜—理塘洋壳俯冲作用晚期岩浆活动的产物。全岩地球化学特征显示,地苏嘎石英闪长玢岩具有中等的SiO₂含量,较高的Al₂O₃及全碱(K₂O+Na₂O)含量。全岩亏损高场强元素,富集大离子亲石元素,稀土元素配分曲线呈典型的右倾状,显示出轻稀土富集、重稀土相对亏损的特点。主量元素和微量元素成矿指示方面的研究结果表明:与普朗38个与成矿有关的石英闪长玢岩的全岩数据相比,地苏嘎石英闪长玢岩具有相对较低的SiO₂和Y含量、较高的∑REE和(La/Yb)_N比值,但二者的Al₂O₃/(CaO+Na₂O+K₂O)比值及MnO含量差别不大。在成矿与非成矿斑岩的SiO₂- Al₂O₃/(CaO+Na₂O+K₂O)和Y-MnO图解中,地苏嘎石英闪长玢岩与普朗石英闪长玢岩数据投图结果类似。此外,地苏嘎斑岩体在物探异常、化探异常及遥感影像特征上具有明显的矿化标志,同时岩体的剥蚀深度小于侵位深度,有利于矿床的保存。以上研究结果表明地苏嘎斑岩体具有成为斑岩型铜矿床的潜力。  相似文献   

云南个旧似长石正长岩类及其岩石成因     

王宇菲  董国臣  陈薇  苏麟  殷国栋  朱红运  李华伟 《地学前缘》2019,26(4):209-220

云南个旧碱性岩体主要的岩石类型有碱性正长岩和似长石正长岩,其中,似长石正长岩中出现大量似长石矿物霞石、方钠石和碱性暗色矿物。本文根据矿物成分及特征,将这些似长石正长岩进一步划分为黑榴霞石方钠正长岩、霞石方钠正长岩、霞石正长岩及方钠霞石正长岩4类。岩石地球化学结果表明,4类岩石的地球化学行为整体表现出过碱质岩的特征,K2O+Na2O含量很高,为钾玄岩系列,同时表现出钾质的特点。分异指数高,呈现高度分异演化特点。稀土元素变化大,轻重稀土元素分异明显,富集轻稀土元素,亏损重稀土元素。微量元素富集大离子亲石元素Th、U及Zr、Hf等高场强元素,亏损Ba、Sr大离子亲石元素,而P和高场强元素Ta、Ti亏损,同时Cr、Co、Ni含量非常低,具有中等的负Eu异常和微弱的负Ce异常。研究表明,似长石正长岩在岩浆演化过程中表现出明显的分离结晶作用特征,且岩浆起源温度较高,约为835℃,起源较深。个旧似长石正长岩为A型岩套A1亚型,结合构造判别图解,认为其可能来自角闪石或者金云母相矿物存在的富集地幔,形成于燕山晚期伸展的构造背景,岩浆在较高温度下高度结晶分异,并在侵位过程中伴随陆壳成分的混染。  相似文献   

Co-seismic fault geometry and slip distribution of the 26 December 2004, giant Sumatra–Andaman earthquake constrained by GPS,coral reef,and remote sensing data     

Yongge Wan  Zheng-kang Shen  Min Wang  Yuehua Zeng  Jichao Huang  Xiang Li  Huawei Cui  Xiwei Gao 《地震科学（英文版）》2015,28(3):187-195

We analyze co-seismic displacement field of the 26 December 2004, giant Sumatra–Andaman earthquake derived from Global Position System observations,geological vertical measurement of coral head, and pivot line observed through remote sensing. Using the co-seismic displacement field and AK135 spherical layered Earth model, we invert co-seismic slip distribution along the seismic fault. We also search the best fault geometry model to fit the observed data. Assuming that the dip angle linearly increases in downward direction, the postfit residual variation of the inversed geometry model with dip angles linearly changing along fault strike are plotted. The geometry model with local minimum misfits is the one with dip angle linearly increasing along strike from 4.3oin top southernmost patch to 4.5oin top northernmost path and dip angle linearly increased. By using the fault shape and geodetic co-seismic data, we estimate the slip distribution on the curved fault. Our result shows that the earthquake ruptured *200-km width down to a depth of about 60 km.0.5–12.5 m of thrust slip is resolved with the largest slip centered around the central section of the rupture zone78N–108N in latitude. The estimated seismic moment is8.2 9 1022 N m, which is larger than estimation from the centroid moment magnitude(4.0 9 1022 N m), and smaller than estimation from normal-mode oscillation data modeling(1.0 9 1023 N m).  相似文献   

川滇菱形块体中部现今构造应力场精确求解     

王金泽  万永革  侯江飞  崔华伟 《中国地震》2018,34(4):632-641

自Global CMT和前人文献中搜索了1973～2015年间的34条中小地震震源机制解并进行分析,根据震级对每个地震震源机制解进行加权处理,采用网格搜索法反演了川滇菱形块体中部区域现今构造应力场。结果表明,川滇菱形块体中部区域整体以走滑断层类型为主,而西部呈现正断层类型;整个区域应力场受到近NW向挤压,NE向拉张,应力形因子为0.1。该区域应力场主张应力轴方向近水平,表明有横向的拉张作用。较低的应力形因子表明几乎处于NW-SE向和垂直向的双轴挤压及NE-SW向拉张的应力状态。这种应力状态来源于2种动力作用:(1)在青藏高原物质东流和华南块体阻挡作用下呈现NW-SE向挤压和NE-SW向拉张的走滑应力状态;(2)印度板块缅甸弧对该地区深部的NEE向低角度俯冲作用导致浅部地壳物质具有NEE-SWW向的拉张分量。这2种动力的共同作用导致该地区既出现走滑型地震,又出现正断型地震。  相似文献   

岩石损伤模量分析   总被引：2，自引：0，他引：2       下载免费PDF全文

李博  肖威  王华伟 《地震工程学报》2018,40(2):384-388

从能量的角度出发定义损伤变量,通过应力-应变曲线卸载段有效应力与总应力之间的假定关系,确定损伤模量的计算方法。在单轴和三轴条件下,对岩石损伤相关参数进行统计研究,重点对损伤模量进行计算和对比分析。结果表明,单轴及低围压下损伤模量基本呈逐渐减小的趋势,而随着围压的增大,损伤模量呈先减小后保持动态稳定的趋势。损伤变量的计算充分考虑到围压的影响,可进一步增进对岩石损伤的认识。  相似文献   

湖南常德及其周边地区的地震重定位与应力场分析     

崔华伟  郑建常  侯志刚  赵金花  郑旭 《华南地震》2020,40(4):35-41

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Wind erosion and dust emissions in central Asia: Spatiotemporal simulations in a typical dust year     

Huawei Pi  Brenton Sharratt  Jiaqiang Lei 《地球表面变化过程与地形》2019,44(2):521-534

The prediction of wind erosion and dust emissions is important for controlling erosion and identifying dust sources in arid and semiarid regions of the world. This study predicts quantitatively wind erosion and dust emissions in Xinjiang Province, central Asia. The wind erosion prediction system (WEPS) was used to simulate annual soil and PM10 (particulate matter ≤10 μm in aerodynamic diameter) loss at 64 meteorological stations across the province. Soil and PM10 loss were simulated from bare surfaces at all 64 stations and from cotton and wheat fields at 11 stations. Simulated annual bare soil and PM10 loss were lowest in the Junggar (soil and PM10 loss were, respectively, 121.7 and 7.6 kg m^-2) and Tarim basins (soil loss was 78.2 kg ha^-1 and PM10 loss was 6.5 kg m^-2) and highest in the Tu-ha Basin (soil and PM10 loss were, respectively, 638.2 and 37.7 kg m^-2). Stations with the highest annual soil loss in the Tarim and Tu-ha basins also had the highest number of days with wind speeds >8 m s^-1. This indicated wind influenced erosion, but other factors such as soil type also affect wind erosion. The maximum monthly bare soil and PM10 loss occurred in May in the three basins, substantiating that dust storms occur most frequently during spring in the region. Simulated soil and PM10 loss were lower for cotton and wheat than bare soil, thus suggesting that maintaining vegetative cover during a portion of the year provided some protection to the soil surface from wind erosion. © 2018 John Wiley & Sons, Ltd.  相似文献   

洋中脊热液羽状流的分布特征及其在多金属硫化物找矿中的指示作用     

陈升  陶春辉  周建平  张国堙  秦华伟  王渊  陈栋 《海洋学报》2019,41(8):1-12

热液羽状流是海底热液活动的重要标志,海底多金属硫化物是热液活动的产物。现阶段洋中脊多金属硫化物勘探工作的第一步是开展热液羽状流的近底探测;综合各类异常信息,实现从发现热液活动喷口到发现矿床的突破。本文以热液羽状流为研究对象,从羽状流的近底探测、扩散机制和分布特征3个方面,概述了最新的研究进展和有待完善的方面,阐述了羽状流在洋中脊多金属硫化物找矿中的指示作用,最后总结性地指出时空连续性、参数多元化将是热液探测的发展趋势,有助于提升对热液羽状流分布特征的认识,将为热液区分布模式的研究提供更加精细的探测资料。  相似文献