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The Isparta Angle (IA) is a reverse Λ-shaped morphotectonic structure located to the north of Antalya Gulf in the Eastern Mediterranean Sea. It resulted from the northward curvature of the originally E–W-trending Tauride orogenic belt owing to the nappe emplacements and related clockwise and anti-clockwise rotations in a time period of Early Paleocene to Early Pliocene. The IA is included in the southwest Anatolian tensional neotectonic domain and characterized by a series of grabens and horsts bounded by active normal faults of dissimilar length and trend. The evolutionary history of the graben-horst system is episodic. It is evidenced by two graben fills. These are older and modern (younger) graben fills separated by an intervening angular unconformity. The modern graben fill is nearly flat-lying (non-deformed) whereas older graben fill was deformed into a series of anticlines and synclines with ENE-trending curvi-linear axes by a short-term compressive tectonic regime operated in NNW–SSE direction during Late Pliocene. The diagnostic structures taking a part in the development of grabens and shaping the northern section of the IA are the margin-boundary normal faults. They occur in numerous single and several fault zones displaying a basin ward facing step-like land shape. Most of fault segments, particularly the master faults, are active and have a capacity of creating destructive earthquakes with a magnitude (up to Mw?=?7.0). This is evidenced by both the historical and instrumental period earthquakes. Both the focal mechanism solution of earthquakes and the stereographic plots of slip-plane data, measured on the active margin-boundary faults of various grabens comprising the IA, on the Schmidt lower hemisphere net obviously reveal that the IA is under the influence of the tensional neotectonic regime, not a compressive tectonic regime, i.e. the sinistral strike-slip shearing along the Pliny arc has not propagated yet onshore, and its commencement age is Early Quaternary. 相似文献
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INVERSION RESEARCH OF PALEOSTRESS FIELD IN TENGCHONG AREA BASED ON VENT ALIGNMENT SURVEY METHOD 
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下载免费PDF全文 The acquisition of paleostress data has always been a key and difficult problem in the field of tectonics and crustal dynamics. Previous findings show that the distribution of dykes and the alignment of volcano vents can indicate the direction of major principal stresses during the volcanic eruption period. The extension direction of underground dyke is generally parallel to the linear arrangement direction of vent and both of them give the direction of maximum horizontal principal stress in this period. This law has similar mechanical principle to hydraulic fracturing. Vent alignment survey method is a kind of geostress inversion method based on volcanic linear mode. In this paper theoretical basis of vent alignment survey method and the linear model of volcanic array are introduced. Based on the panchromatic high-resolution remote sensing image and digital elevation model(DEM)data in the Tengchong area, combining the geological exploration data about lithologic distribution of igneous rocks and the past research results of volcanic activities in the area, the research divides the volcanoes in this area, according to the age of volcanic eruption, into Holocene, late Pleistocene, early Pleistocene and Pliocene. Nakamura model was established based on the morphological characteristics and spatial distribution of the crater, and volcanic eruption period to evaluate the linear degree of the volcano in different age, and to carry out inversion of the paleostress field of the four volcanic eruption periods in Tengchong area. The reliability of the inversion results is evaluated according to Paulsen's data reliability assessment system. The data from inverting the paleostress of each show that maximum horizontal principal stress directions in the early Pleistocene period and late Pleistocene period are 39° and 37° respectively and reliability grades of inverted paleostress results in the two eras all belong to grade B; Inverted paleostress results in Holocene and Pliocene are not reliable because of the poor linearity of volcanic arrangement. The geostress direction determined by the vent alignment survey method is fairly consistent with the current geostress field obtained by the focal mechanism solution and the anelastic strain recovery(ASR method)and matches the tectonic history of Tengchong area since Neogene. The research findings demonstrate that the vent alignment survey method is an effective paleostress inversion method. The application of this method in the paleostress inversion of the Tengchong volcanic area is of important reference significance for the study of paleostress field in other volcanic areas in China. 相似文献
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《International Geology Review》2012,54(14):1803-1821
ABSTRACTIn the Central Anatolia, the style of neotectonic regime governing the region has been a controversial issue. A tectonic study was carried out in order to contribute to this issue and better understand the neotectonic stress distribution and style of deformation in the west-southwest of the Konya region. From Middle Miocene to Recent time, Konya region was part of the Central Anatolia extensional province. The present-day topography in the west-southwestern part of Konya is characterized by alternating elongate grabens and horsts trending E-W and NW-SE. The grabens were developed upon low-grade metamorphic rocks of Palaeozoic and Mesozoic ages and ophiolite slabs of possibly Late Cretaceous age. The evolutionary history of grabens is episodic as evidenced by two graben infills; older and younger graben infills separated by an angular unconformity. The older infill consists of fluviolacustrine sequence intercalated with calc-alkaline lavas and pyroclastic rocks. This infill is folded; thrust faulted and Middle Miocene-Early Pliocene in age. The younger and undeformed basin fill comprises mainly of Plio-Quaternary conglomerates, sandstone-mudstone alternations of alluvial fan and recent basin floor deposits. Three major tectonic phases were differentiated based on the detailed mapping, morphological features and kinematic analysis. Approximately N-S trending extension began in the Middle Miocene-Early Pliocene in the region with the formation of E-W and NW-SE-trending grabens. Following NE-SW-directed compression which deformed the older basin fill deposits by folding and thrusting, a second period of ENE-WSW-trending extension began in the late Pliocene and continued to the present. The west-southwestern margin of the Konya depression is bounded by the Konya Fault Zone. It is an oblique-slip normal fault with a minor dextral strike-slip component and exhibits well-preserved fault slickensides and slickenlines. Recent seismicity and fault-related morphological features reveal that the Konya Fault Zone is an active neotectonic structure. 相似文献
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Opening of the Japan Sea back arc basin was accompanied by extensional tectonics in the drifting southwest Japan arc. Various trends of Early Miocene grabens in the arc suggest multi-directional rifting, which necessarily involved strike-slip components of some of basin-margin faults. However, such components are not well understood. In this work we conducted a field survey in the Early Miocene Ichishi basin on the northern side of the Median Tectonic Line, central southwest Japan. We found that the basin was a compound of grabens that were formed along normal and sinistral strike-slip faults, the latter of which had northeast–southwest trends. The block faulting in this phase produced basement highs between sub-basins, which were filled with the lower part of the Ichishi Group. We found a low-angle angular unconformity at a middle horizon in the group, with which we define the upper and lower part of the group. The upper part onlapped both the basement highs and the lower part. It means that the transtensional basin formation ceased sometime between 18 and 17.5 Ma in the Ichishi area. The Ichishi basin turned subsequently into a sag basin subsided due to normal faulting probably along the Nunobiki-sanchi-toen fault zone. The transtension and the basin sag were driven by ENE–WSW extensional stress. This arc-parallel extension produced grabens various areas including Ichishi in the Early Miocene. The extensional deformation was eventually localized to the deep rift along the Fossa Magna to make the lithosphere under southwest Japan decoupled from that under northeast Japan. The decoupling allowed the rapid rotation of southwest Japan from ~17.5 Ma. The cluster of those grabens around the Ise bay probably determined the southeastern margin of the Kinki triangle. 相似文献
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在燕山中西段晚中生代岩体中的116个观测点中共采集到2 321组断层和破裂面滑动数据,利用Tensor软件进行古构造应力状态反演。将反演结果与区域构造变形及构造演化过程研究结果相结合,发现研究区在侏罗纪末-白垩纪初以来存在5期可识别的构造应力场:(1)晚侏罗世末-早白垩世初近N-S向挤压应力场(D1,148~127 Ma);(2)早白垩世NW-SE向挤压应力场(D2,143~127 Ma);(3)垂向挤压主导的多向水平伸展应力场(D3,120~110 Ma);(4)NE-SW向挤压(D4);(5)E-W向挤压的应力场(D5)。D1和D2可能分别与蒙古-鄂霍茨克洋消减关闭作用的远程构造效应,以及古太平洋板块向欧亚大陆板块下的俯冲作用有关,且这两大构造系统在该时期可能同时作用于燕山地区。D3期应力场可能反映源自壳下深部地幔活动引起的垂向挤压动力作用。D4、D5期应力场相对较弱,其动力学背景尚待今后研究进一步分析。本区古构造应力场研究结果表明,华北克拉通破坏峰期期间,主要的伸展作用并不完全符合西太平洋板块后撤主导的被动伸展裂谷模型,而是表现为深部地幔活动引起的垂向挤压作用主导的水平方向多向伸展。 相似文献
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黄骅坳陷中北区和歧口凹陷断裂构造特征及古应力分析 总被引：12，自引：4，他引：12
主要分析了黄骅坳陷中北区和歧口凹陷断裂构造特征。根据三维地震资料编制的Ｔ４和Ｔ０断裂纲要图表明，研究区断裂为伸展正断层，以ＮＥ向、ＮＮＥ向和ＥＷ向断裂为主。在不同时期，歧口凹陷断层走向发生明显变化，由沙一下段ＮＥ向变为上第三系的近ＥＷ向。在不同地段，伸展断裂具有不同的优势方向。横向变换带上发育的断裂也为伸展断裂，具有与主断层垂直相交的方向。通过对断裂古应力分析，黄骅盆地是伸展型盆地，推测其伸展作用为三维放射状，横向变换带也具有三维伸展特征，不存在横向挤压和走滑剪切作用。 相似文献
28.
郯庐断裂带的形成与演化：综述 总被引：81，自引：0，他引：81
从历史的与整体的观点出发，综合了地质、地貌、地球化学与地球物理的资料，系统地研究了郯庐断裂带各阶段的形态学、运动学以及动力学机制。认为此断裂带开始形成于中、晚三叠世，其长度小于１５００ｋｍ，切割深度小于１５～２０ｋｍ，此时最大左行走滑断距为４３０ｋｍ左右。侏罗纪（２０８～１３５Ｍａ）与中始新世－渐新世（５２～２３．３Ｍａ），此断裂带表现为逆断层活动，断层面受挤压较紧闭。白垩纪－早始新世（１３５～５２Ｍａ），郯庐断裂呈现为略带右行走滑的正断层（走滑断距不超过１００ｋｍ），郯庐断裂带与其北部切割深度约为３０～４０ｋｍ。中新世－更新世（２３．３～０．７３Ｍａ）断裂带表现为带有左行走滑的正断层，走滑断距约５０ｋｍ，断裂带切割深度在５０～８０ｋｍ之间。中更新世（０．７３Ｍａ以来）断裂带又变成略带右行走滑的逆断层，走滑断距不足１００ｍ。由于断裂带形成以来的剥蚀深度不大，地表的断层岩都是碎裂岩与断层泥。沿此断裂带在早白垩世构成了中国东部重要的内生金属成矿带。 相似文献
29.
????????κ?????????????????????μ?????????????????????????????????????????????????????????????????????????????????????????γ???????????4?????????????????????????????????????NW-SE???????????????????????????????NE-SW????????????????????????????????E-W????????????????????????????????S-N??4???????????м??????????δ??2??)???????????????????,?????????????????????????????????????????? 相似文献
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燕山板内造山带中段承德一带地层记录齐全且构造变形复杂。该区域主要构造形迹及其运动学特征已经得到了比较系统的研究,但有关形成这些构造形迹的古构造应力场及其演变过程的研究鲜有报道。本文根据断层滑动矢量应力反演理论和方法,通过露头与区域尺度断层运动学数据的搜集与处理,结合研究区域构造层划分特征及主要岩石地层单位的年代学资料,对研究区中侏罗世–早白垩世的构造应力场演变过程进行了研究。经过对擦痕数据进行应力反演并综合分析,共划分出3期5阶段应力场:中侏罗世下花园组沉积之后–髫髻山组火山活动之前的NNW向挤压(D1)(约173~165 Ma);晚侏罗世土城子组沉积中–晚期N-S向挤压(D2-1)(约152~139 Ma);早白垩世初土城子组沉积期末NNE-NE向挤压(D2-2)(约139~135 Ma);以及早白垩世张家口组火山喷发之后垂向挤压主导的多向伸展(D3-1)和NW-NNW向弱挤压(D3-2)(约125 Ma之后)。其中,中–晚侏罗世至早白垩世初以挤压为主,最大主压应力方向发生了大约60°的顺时针旋转,且土城子组沉积作用发生于此挤压作用为主的构造背景之下。早白垩世以伸展为主,并有弱挤压作用出现。同时,研究区内未发现与中侏罗世以来古太平洋板块或伊佐奈岐(Izanagi)板块俯冲作用相关的近W-E向或NW-SE向挤压应力场的存在,可能与克拉通内部变形不均匀有关。 相似文献