A Preliminary Analysis of the Seismogenic Structure of the Akto MS6.7 Earthquake Sequence on November 25, 2016

In this study,data from the Xinjiang regional network and IRIS shared global stations are used to relocate the Akto M_S6. 7 earthquake sequence on November 25,2016 by using double difference location method. Three earthquakes of M_S4. 8,M_S6. 7 and M_S5. 0 are inverted by using the g CAP method,and the focal mechanism solutions are obtained.According to the results of relocating,the location of the main shock is 39. 22°N,73. 98°E,the distribution of the earthquake sequence is about 70 km in length,and the focal depth is mainly within the range of 5-20 km. The plane and depth profiles of the earthquake sequence show that aftershocks extended in SEE direction after the main shock and the dip angle of fault plane is steep. Focal mechanism results show that the three earthquakes are characterized by strike-slip movement. Based on the results of field geological investigation,it is inferred that the seismogenic fault of the Akto earthquake is Muji fault,which is located at the northernmost end of the Kongur extensional system.The possible cause of this earthquake is that the Indian Plate continues to push northward,and during this compression process,the Indian Plate is affected by the clockwise rotation of the Tarim basin,which causes the accumulation of right-lateral action of the Muji fault,resulting in this earthquake.     

柯树北岩体岩石谱系单位的建立及构造环境分析

柯树北岩体为陆壳改造型（S型）花岗岩，具有结构和成分演化序列，运用岩石结构列序法，将其划分为6个单元，归并为1个超单位，按侵入体空间展布形式，岩体地质学，岩石学，构造地球化学等资料，提出了岩浆侵位是受区域拉张应力控制的认识。     

Early growth fault activity: new evidence for extension in the upper Cambrian Owen Group,Proprietary Peak,western Tasmania,Australia

The coarse-grained, upper Cambrian Owen Group of western and northern Tasmania is a prominent feature of the Tasmanian landscape and regional map series. The group has previously been divided into four informal formations (Lower Owen Conglomerate, Middle Owen Sandstone, Middle Owen Conglomerate and Upper Owen Sandstone) that have been correlated across the state over tens to hundreds of kilometres. The deposition of these sediments is largely believed to have occurred during extensional tectonics, but some authors continue to argue a compressional tectonic regime. Detailed mapping and sedimentological work around Proprietary Peak on the Mount Jukes massif, 10 km south of Queenstown, Tasmania, has identified significant depositional variations controlled by early growth faulting and paleotopography. Discontinuity of stratigraphic units (L6–L13) across two growth faults on the north face of Proprietary Peak shows the strong effect on sediment deposition in the area. Paleotopography is also evident with most stratigraphic units (L8–L13 and U1) gradually onlapping basement during their deposition. Significant paleotopography has also been identified on East Jukes Peak, where lower Owen Group sedimentary units onlap basement volcanics, with no evidence for tectonically controlled deposition. Field evidence strongly supports the deposition of the Owen Group during extensional tectonics, after a period of prolonged erosion of the underlying Mount Read Volcanics. The distinct variation in vertical and lateral extent of stratigraphic units within the Owen Group in the Proprietary Peak area suggests that widespread lithostratigraphic correlation of older Owen Group sedimentary units across Tasmania may not be feasible.     

内蒙古乌斯尼黑蛇绿混杂岩带形成时代的地质新证据

贺根山-乌斯尼黑蛇绿混杂岩带的属性和形成时代存在明显的认识上的分歧.早期认为是二叠纪侵入的超镁铁质岩体.该超镁铁质岩体侵入了下二叠统格根敖包组,并被哲斯组地层不整合覆盖,形成时代为二叠纪.20世纪80年代以来,通过中国北方板块构造研究,在硅质岩中采集到的一系列化石资料表明,贺根山地区蛇绿混杂岩的形成时代应为中-晚泥盆世...     

中国东部中新生代大地构造问题研究

基于"构造体系控油作用研究"项目, 总结中国东部中新生代大地构造的基本特征及其演变的内在规律。研究表明, 中国东部中新生代构造形变史, 以侏罗纪末幕运动为标志划分为前后2个大阶段, 发育2种巨型扭动构造型式, 即华夏系和新华夏系, 其间存在广泛的构造不整合; 显示二元结构, 即新华夏系形变构造层与华夏系形变构造层的叠置, 是本区大地构造的基本特征。     

A conjugate strike-slip fault system within the extensional tectonics of Western Turkey

Three main shocks M-1, M-2 and M-3 (17 October 2005 at 05:45 UTC, M _w 5.4; 17 October at 09:46 UTC, M _w 5.8 and 20 October at 21:40 UTC, M _w 5.9) and their associated aftershocks within the Gulf of S i ğac i k, 50 km southwest of Izmir, Turkey were studied in detail. A temporary seismic network deployed during the activity allowed the hypocentre of M-3 and subsequent aftershocks to be determined with high accuracy. A relative relocation technique was used to improve the epicentres of M-1 and M-2. All three main shocks have strike-slip mechanisms which agree with the linear trends of the aftershock locations. Two distinct zones were illuminated by the aftershock locations. The zones contain clear echelon patterns with slightly different orientations from the trend of the aftershock distribution. M-2 and M-3 ruptured along of the eastern rupture zone which aligns N45°E. However the strike direction of M-1 is not clearly identified. The alignment of the two rupture zones intersect at their southern terminus at an angle of 90°. The fault zones form conjugate pair system and static triggering is considered as a probable mechanism for the sequential west to east occurrence of M-1, M-2 and M-3. This earthquake sequence provides seismological evidence for conjugate strike-slip faulting co-existing within a region dominated by north–south extension and well-developed east–west trending normal faults.     

东准噶尔鲍尔羌吉——带热隆伸展构造的厘定

东准噶尔1：25万造山带填图方法研究过程中，在鲍尔羌吉一带发现较为典型的伸展构造，与许志琴等提出的热隆伸展构造有相似之处，其隆升与晚古生代造山后期抬升侵位的花岗岩有关，重熔花岗岩侵位上隆形成“热穹隆”构造，在岩体顶部垂直主应力作用下导致上部地壳伸展减薄，形成以晚古生代花岩为核心的伸展构造。     

临清坳陷变换构造研究

讨论了临清坳陷内3个规模较大的调节构造带,即封丘左行传递带、马陵横向背斜调节带和夏津—腰站斜向背斜调节带的构造特征及成因机制。临清坳陷内“东西分带、南北分块”的构造特征,是由平行于裂谷轴方向的NNE(NE)向伸展正断层和垂直(或斜交)于裂谷轴方向的NW(NWW)斜向滑移断层及横向构造带等共同作用造成的;区内3个规模较大的调节构造带是造成“南北分块”的构造原因,这些调节构造带垂直或斜交于裂谷方向．通过传递带或调节带的方式调节不同伸展域间的应变,从而使区域应变守恒。     

Palaeosols and palaeokarst beneath subaerial unconformities in an Upper Devonian isolated reef complex (Judy Creek), Swan Hills Formation,west‐central Alberta,Canada

Subaerial unconformities are used widely for palaeoenvironmental and palaeogeographic reconstructions, sequence stratigraphy and petroleum reservoir assessments. Recognition and interpretation of these unconformities, particularly those with associated palaeosols, may be problematic in Lower and Middle Palaeozoic carbonate successions because of the collective effect of limited land plant development, superficial similarities between some pedogenic and marine features, and overprinting by later diagenesis. The isolated Judy Creek reef complex in the Lower Frasnian Swan Hills Formation in west‐central Alberta, Canada, contains two subaerial unconformities, R0.5 and R4, which formed as a consequence of relative sea‐level falls of at least regional scale. Deposits beneath these unconformities have distinctive palaeosol and palaeokarst features. The lower unconformity, R0.5, occurs at the top of a progradational reefal phase of stromatoporoid rudstones–floatstones and peloidal packstones–grainstones and has been recognized in at least one other isolated Swan Hills reef complex (Snipe Lake). Palaeosol–palaeokarst profiles beneath this unconformity extend as deep as ca 2 m below the unconformity. These profiles are characterized by the presence of small rhizoliths, laminar calcretes, ferroan dolomite glaebules, desiccation cracks, breccias, green shale and solution vugs. The upper unconformity, R4, occurs at the top of a backstepping phase of reef growth and has been correlated widely between isolated reefs and carbonate banks on both the western and eastern shelves of the Central Alberta Basin. Palaeosol–palaeokarst profiles, extending as deep as ca 9·5 m beneath the R4 unconformity, are distinguished by abundant, sub‐horizontal desiccation cracks filled with green shale, occurring in peloidal wackestones–packstones. Comparison of the R0.5 and R4 profiles indicates that the major intrinsic controls on the development and modification of the profiles are parent‐material lithology, particularly the prior degree of induration and particle size; the low topographic relief at the top of the reef interior; and limited vegetation of the exposed reef top due to unfavourable growth conditions and geographic isolation. In addition to climate, the major extrinsic controls are the extent of relative sea‐level fall, estimated to be 2·5 to 3 m and 13 to 14 m associated with the R0.5 and R4 unconformities, respectively, and the degree of shoreface erosion during the ensuing marine transgression, estimated to be up to 3 m. This study highlights the complex interplay of mainly physical and chemical processes influencing the formation of subaerial unconformities in carbonate environments during the Devonian, before major evolutionary innovations among vascular land plants led to more intense pedogenesis.     

延吉盆地多期不整合面的形成及其油气地质意义

延吉盆地是一个后期改造较为强烈的断陷盆地。应用地震、地质、测井资料识别出延吉盆地中存在6个较大的不整合面,它们以角度不整合和超覆不整合2种类型为主。分析认为,燕山Ⅰ、Ⅱ幕运动形成了盆地雏形,燕山Ⅳ幕运动则使盆地回返,此期出现大量高岭石（40%）,表明其与大气水淋滤等有关。短暂沉降后（龙井组）,燕山运动晚期（Ⅴ幕）发生的又一次大规模以南北挤压为主的构造运动,导致南北两翼抬起幅度巨大,剥蚀厚度超过700 m,盆地中部剥蚀厚度大约为300 m。不整合面是划分三大构造层（前断陷期、断陷期、坳陷期）的依据。其早白垩世铜佛寺组和大砬子组间的整合关系利于油气的生成。不整合面既可改善储集体的渗透性,又是形成油气二次运移的良好通道。初步预测与不整合有关的油气藏（侵蚀残丘、地层超覆不整合、断层坡折）可作为下一步勘探的目标。