Trade space for time for inspecting an earthquake cycle by modern seismological observation: The central-southern part of the Sichuan-Yunnan rhombic block

The central-southern part of the eastern border of the Sichuan-Yunnan rhombic block provides the research strategy of ‘trade space for time' with an interesting fault system, where the segments have similar focal mechanisms and cover almost continuous spectra of elapse rates. We experiment to study the seismological characteristics of different segments with different elapse rates. We employed the de-clustered earthquake catalog for the calculation of b values for each segment. The analysis revealed that different segments have similar b values,which implies that, although different segments have different periods of earthquake recurrence, the 'natural time' for the whole fault system elapses with a homogeneous pace. We extended the earthquake potential score(EPS)for nowcasting earthquakes to a quasi-EPS(q EPS). It is found that q EPS increases with the increase of elapse rates,albeit for those fault segments whose elapse rates have exceeded 1, q EPS may better reflect the seismic hazard.

Precise Location of Earthquakes at the Eastern Boundaries of the Sichuan-Yunnan Rhombic Block

Based on the seismic station data sets from Sichuan and Yunnan provinces,we employed a multi-step seismic location method( Hypo2000 + Velest + HypoDD) to precisely locate the 7,787 earthquakes that occurred during 2010-2015 along the eastern boundaries of the Sichuan-Yunnan rhombic block,namely from southern Dawu to the Qiaojia segment.The final results show that location precision is greatly advanced and epicenter distribution exhibits good consistency with the linear distribution of the seismic faults. Earthquake distribution is quite intensive at the intersection region in the southern segment of the Xianshuihe fault,the Anninghe fault zone,the Xiaojinhe fault zone and the Daliangshan fault zone to the east. The depth profile of seismicity shows a clear stepwise activity along the active seismic fault zones. The profile crossing the faults of the Xianshuihe,Anninghe,and Daliangshan presents a complex interaction among faults near the multiple faults intersection region,Shimian,where the earthquakes are obviously divided into two groups in depth. Earthquakes are very rare at the depth of 15km-20 km,which is consistent with the region of the plastic rheology between 14km-19 km calculated by Zhu Ailan et al.,( 2005).

Present-day Block Movement and Fault Activity on the Eastern Margin of the Tibetan Plateau

The geology and tectonics in the eastern margin of Tibetan Plateau are complex. The main tectonic framework is composed of blocks and faults. Using discontinuous global positioning system survey data for 2008–2014, the velocity field for the Eurasia reference framework was obtained. Based on the velocity field, the present-day velocities of the blocks and boundary faults were estimated. The results reveal that the movement rates of the Chuan-Qing, South China, Chuan-Dian and Indo-China blocks are（17.02±0.60） mm/a,（8.77±1.51） mm/a,（13.85±1.31） mm/a and（6.84 ± 0.74） mm/a, respectively, and their movement directions are 99.5°, 120.3°, 142.9° and 153.3°, respectively. All blocks exhibit clockwise rotation. The displacement rates of the Xianshuihe, Longmenshan, Anninghe, Zemuhe, Xiaojiang and Red River faults are（7.30±1.25–8.30±1.26） mm/a,（10.07±0.97–11.79±0.89） mm/a,（0.96±0.74–2.98±1.73） mm/a,（2.03±0.49–3.20±0.73） mm/a,（3.45±0.40–6.02±0.50） mm/a and（6.23±0.56） mm/a, respectively. The Xianshuihe, Anninghe, Zemuhe and Xiaojiang faults show leftlateral strike-slip movement, while the Longmenshan and Red River faults show right-lateral strikeslip. These characteristics of the blocks and faults are related to the particular tectonic location and dynamic mechanism.

Geochronology and geochemistry of Cretaceous-Eocene granites,Tengchong Block(SW China):Petrogenesis and implications for Mesozoic-Cenozoic tectonic evolution of Eastern Tethys

The Early Cretaceous-Early Eocene granitoids in the Tengchong Block record the evolutionary history of the Mesozoic-Cenozoic tectono-magmatic evolution of Eastern Tethys.(a)The Early Cretaceous granitoids with relatively low(^(87)Sr/^(86)Sr)iratios of 0.7090-0.7169 andε_(Nd)(t)values of-9.8 to-7.8 display metaluminous,calc-alkaline dominated by I-type granite affinity and hybrid mantle-crust geochemical signatures.They may have been derived from melting of the subducted Meso-Tethyan BangongNujiang oceanic crust with terrigenous sediments in an arc-continent collisional setting.(b)The Late Cretaceous-Paleocene granitoids with relatively high(^(87)Sr/^(86)Sr)iratios of 0.7109-0.7627,andε_(Nd)(t)values of-12.1 to-7.9 exhibit metaluminous to peraluminous,calc-alkaline dominated by S-type granite affinity and hybrid Lower-Upper crust geochemical signatures,which may be originated from partial melting of the Meso-Proterozoic continental crust in the collision setting between the Tengchong Block and Baoshan Block.(c)The Early Eocene granitoids have metaluminous,calc-alkaline I-type and S-type granites dual affinity,with relatively high(^(87)Sr/^(86)Sr)iratios of 0.711-0.736,ε_(Nd)(t)values of-9.4 to-4.7,showing crust-mantle mixing geochemical signatures.They may have been originated from partial melting of the late Meso-Proterozoic upper crustal components mixed with some upper mantle material during the ascent process of mantle magma caused by the subduction of the Neo-Tethyan Putao-Myitkyian oceanic crust,and collision between the Western Burma Block and the Tengchong Block.It is these multi-stage subductions and collisions that caused the spatial and temporal distribution of the granitic rocks in the Tengchong Block.

Triassic magmatism in the eastern part of the South China Block： Geochronological and petrogenetic constraints from Indosinian granites

The granitic dykes in the Badu Group, Zhejiang Province, South China provide important insights on tectonic setting and crustal evolution of the South China Block （SCB） and the Indochina Block during Triassic. Here we report LA-ICP-MS U-Pb data of granitic rocks from the Hucun and Kengkou which show early Triassic ages of 242 ± 2 and 232 ± 3 Ma, respectively, representing their timing of emplacement. The dyke rocks are enriched in K, AI, LREE, Rb, Th, U, and Pb, and are depleted in Nb, Ta, St, and Ti. The rocks are characterized by highly fractionated REE patterns with （La/Yb）N ratios of 28.46 -38.07 with strong negative Eu anomalies （Eu/Eu＊ = 0,65-0.73）. In situ Hf isotopic analyses of zircons from the Hucun granite yielded CHf（t） values of -13.9 to -6.4 and two-stage depleted mantle Hf model ages of 1.68-2.15 Ga, which indicate that the magma was formed by partial melting of the Paleo- proterozoic metasedimentary protoliths in the Cathaysia Block. The zircons from the Kengkou granite have eHf（t） values ranging from -40.7 to 31.5 and yield two-stage depleted mantle Hf model ages of 0.99 -2.49 Ga, indicating magma origin from a mixed source. The Hucun and Kengkou dykes, together with the Triassic A-type granites in SE China were probably generated during magmatism associated with crust-mantle decoupling along the convergent plate boundary between SCB and the Indochina Block.

Fault plane solutions in Sichuan-Yunnan rhombic block and their dynamic implica-tions

Harvard Centroid Moment Tensor （CMT） solutions for earthquakes from 1977 to 2004 showed that the stress fields are obviously different in northwestern Sichuan sub-block （NWSSB）, western parts of Central Yunnan sub-block （CYSB） and eastern part of CYSB. The characteristics of the mean stress fields in these three regions are obtained by fitting to CMT solutions. The stress state in NWSSB is characterized by its sub-horizontal tensile principal axis of stress （T axis） in roughly N-S direction and west dipping compressive principal axis of stress （P axis）; the one in western part of CYSB is characterized by its ENE dipping T axis and sub-horizontal medium principal axis of stress （B axis） in roughly N-S direction; the one in eastern part of CYSB is characterized by its sub-horizontal P axis in roughly NNW-SSE direction and sub-horizontal T axis in roughly WSW-ENE direction. Finite element method simulation clearly shows that the Indian Plate imposes great extrusion on Sichuan-Yunnan rhombic block （SYRB） near Assam massif. The value of the simulated compressive principal stress decreases with the distance from Assam massif. The simulated directions of the T axes in SYRB form annular distribution encir cling Assam. For a homogeneous elastic medium with free boundary conditions on the top and bottom surfaces as well as the displacement boundary conditions derived from the GPS observations on the lateral boundaries, the computation results are consistent with the Harvard CMT solutions in NWSSB and western part of CYSB, while inconsistent with the Harvard CMT solutions in eastern part of CYSB. The inconsistency in eastern part of CYSB can be reduced when it includes inhomogeneous elastic media. The stress states in NWSSB and western part of CYSB revealed by the Harvard CMT solutions are not local, which are mainly controlled by the boundary force on the whole region. On the other hand, the stress state in eastern part of CYSB given by the Harvard CMT solutions is local, which may be affected by local topography, material inhomogeneity, and the drag force underneath.

Advances in the deep tectonics and seismic anisotropy of the Lijiang-Xiaojinhe fault zone in the Sichuan-Yunnan Block,Southwestern China

The Sichuan-Yunnan Block(SYB)is located at the SE margin of the Qinghai-Tibetan Plateau(TP).Under the influence of the southeastward movement of material originated from the TP,intense crustal deformation,frequent seismic activity,and complex geological structures are observed in the SYB.The Lijiang-Xiaojinhe fault(LXF)goes through the central part of the SYB,dividing it into two blocks from north to south,and forming an intersecting fault system with the surrounding faults.This paper firstly introduces the morphology and the nature of the LXF,the distribution of the regional surface displacements and the focal mechanisms,and then analyzes the medium deformation and the effects of faults.Moreover,according to the regional tectonics and geophysical patterns,the paper discusses the characteristics of the north-south blocks of the SYB and the abrupt change of deep structure along the LXF zone.Since seismic anisotropy is an essential property for detecting crustal stress,deep structures and dynamical mechanisms,this paper is dedicated to the advances in seismic anisotropy at different depths and different scales in the study area.There are noteworthy differences in the anisotropic features between the north part and the south part of the SYB,possibly associated with a clear boundary adjacent to the LXF.Such phenomenon suggests some close correlation between anisotropic zoning boundary and the LXF,although this boundary is not consistent with the LXF in strike.The results from the deformation of the crust and the upper mantle elucidate the distribution patterns of the crust-mantle coupling in the north part and the crustmantle decoupling in the south part,even though this conclusion needs to be further verified by more studies.Presently,the scientific understanding of the deep tectonics and the media deformation around the“generalized”LXF i.e.the LXF with the Jinpingshan fault on its eastern side,is still insufficient,and related equivocal topics deserve more in-depth studies.

Geochemistry and Petrogenesis of Cretaceous Adakitic Dykes from Eastern Cathaysia Block

An intrusive dyke is linear in regional scale,tectonic stresses play an important role in controlling the orientation of fractures that form for the dyke when magma rises buoyantly into the lithosphere

The Recent Crustal Deformation on the Sichuan-Yunnan Rhombic Block Boundaries

Based on data from an across-fault survey along the Sichuan-Yunnan rhombic block boundaries, the recent deformation characteristics on each fault have been analyzed. It was found that the rate of crustal deformation is slowing down along the northern segment and increasing along the southern segment. Each fault has different features of deformation. The horizontal deformation is mainly characterized by left-lateral strike-slip. The rate of vertical deformation is less than that of the horizontal deformation. The faults have the feature of upper wall uplifting alternated with descending. The anomaly changes of crustal deformation at some sites are closely related to the seismicities near the sites.

Neoarchaean-Palaeoproterozoic Mafic Dyke Swarms from the Singhbhum Granite Complex,Singhbhum Craton,Eastern India:Implications for Identification of Large Igneous Provinces and Their Possible Continuation on Other Formerly Adjacent Crustal Blocks

The Singhbhum craton of the eastern India consists of the Singhbhum Granite Complex(SGC)and the Chotanagpur Gneissic Complex(CGC)separated by the Singhbhum Mobile Belt(SMB).The CGC is intruded by Mesoproterozoic as well as Cretaceous mafic dykes;in

鄂尔多斯盆地神木–佳县区块深部煤层气地质特征及勘探开发潜力

我国深部(以下均指埋深大于2000 m)煤层气资源丰富,勘探开发潜力巨大。与中浅部相比,深部煤层气在富集成藏规律与开发方式方面均具有显著的差异性,急需针对重点区块开展解剖性分析研究。神木–佳县区块位于鄂尔多斯盆地东北部,目前尚处于深部煤层气勘探的起步阶段,深部煤层气富集特征及开发潜力等尚不明确。基于研究区近期实施的地震资料、300余口井的测井资料和4口取心井的参数资料等,系统分析煤储层基础地质特征,总结煤层气富集主控因素与富集规律,类比剖析研究区深部煤层气勘探开发潜力。研究区深8号煤的镜质体反射率介于0.7%~1.8%,大部分区域煤层演化已处于热解生气高峰,区域上煤层净煤厚度高达7~8 m,煤层发育稳定,构造相对简单、水动力封闭性较强、顶底板封盖条件较好,为煤层气大面积连续成藏提供了优越条件,其中佳县南区的煤层气资源条件最好。与鄂尔多斯盆地东部其他区块深部煤层相比,研究区煤层中游离气占比明显更高(15.21%~46.47%),煤层中吸附气主要受吸附压力封存控制,而游离气受毛管力封闭与浮力重力分异双重控制,两种封存机制共同决定了深部煤层含气量的垂向分带与平面分区,以佳县南部为例总结了吸附气吸附压力主控、游离气毛管压力封闭与重力分异耦合控制的典型深部煤层气富集模式。与临兴区块和大宁–吉县区块类比分析结果表明,神木–佳县区块具有较好的煤层气资源基础、储层改造条件和高产潜力,预示了此区块深部煤层气规模化开发的美好前景。此外,大宁–吉县区块深部属典型的高煤阶煤,而神木–佳县深部为中煤阶煤,因此,该研究认识进一步丰富完善了深部煤层气富集理论,对于全国深部煤层气勘探开发实践有重要指示意义。

川滇菱形块体东边界震源机制与应力场特征

文中利用四川、云南、重庆、青海、甘肃地震台网以及西昌密集台阵和巧家密集台阵的数字地震波形资料,采用CAP全波形反演方法及HASH初动极性和振幅比方法,获得了川滇菱形块体东边界区域3 951组M L≥1.0地震的震源机制。进而基于以上震源机制,采用阻尼区域应力场反演算法(MSTASI)和Vavrycuk的迭代联合反演方法获得了研究区的构造应力场分布特征、主要活动断裂的应力性质和摩擦系数。结果显示,研究区震源机制P轴、T轴以及最大主应力轴σ1和最小主应力轴σ3总体上倾角较小,揭示了近水平的挤压或剪切应力环境。σ1以NW-SE和NWW-SEE向为主,从北到南有顺时针旋转的趋势,应力性质以走滑型为主,局部兼有逆冲型和拉张型,整体分布特征与区内走滑型边界断裂活动性质一致。R值具有明显的空间差异,鲜水河断裂-龙门山断裂-安宁河断裂交会地区R值相对较高,有明显的挤压特征;鲜水河断裂带、安宁河断裂带北段和小江断裂带的R值均在0.25~0.5之间,表现为NE-SW向挤压和NW-SE向拉张,拉张应力可能远小于挤压应力;大凉山断裂带北段和则木河断裂带的R值均在0.5~1之间,表现为NW-SE向压缩和NE-SW向拉张,且挤压应力大于拉张应力。研究区域主要断裂的摩擦系数也有差异:安宁河断裂带和大凉山断裂带北段的摩擦系数相对较低,在0.75以下,鲜水河断裂带、则木河断裂带及大凉山断裂带南段的摩擦系数偏高,在0.80以上。川滇菱形块体东边界活动断裂带上的构造应力相对较高,尤其是鲜水河断裂带和小江断裂带的应力更高,需要关注其地震危险性。

鄂尔多斯盆地东缘深部煤层气开发先导试验效果与启示

鄂尔多斯盆地东缘大宁-吉县区块深部煤层气勘探开发取得突破对煤层气产业带来重大影响,引起业内广泛关注和跟进。前期一些学者对深部煤层气勘探开发理论技术难点与对策开展了研究,但缺乏对典型气田开发先导试验系统总结。通过深入剖析深部煤层气地质特征与效益开发难点,总结大宁-吉县区块开发先导试验项目取得的进展和成效,明确开发规律并提出效益开发对策。结果表明:(1)深部煤层具有广覆式发育、含气性好、游离气含量高、保存条件好、煤体结构好、脆性指数高、顶底板封盖性强等地质特征,但微构造发育、渗透性极差、矿化度高等因素制约了深部煤层气效益开发;(2)不同地质条件下气井生产特征差异较大,通过先导试验落实气井产能和适应性开发技术对策,采用滚动开发模式可有效降低煤层强非均质性带来的开发风险;(3)开展地质-工程一体化井网优化设计,构建井网与缝网高度弥合的人造气藏,可实现资源动用和采收率最大化;(4)“长水平段+多段多簇+大砂量”的大规模、大排量极限体积压裂技术可增大有效改造体积和井控储量,大幅提高单井产量;(5)深部煤层气井具有“见气时间短、上产速度快、初期产量高、递减快”的生产特征,可实现短期快速规模上产,但气田长期稳产需持续新井投入;(6)前期开发成本偏高,实现效益开发需不断提高工程作业效率、降低开发成本。综合认为,深部煤层气资源品质好,可动用性强,具备快速推广复制条件,大宁-吉县区块深部煤层气开发实践可为国内其他区块深部煤层气规模动用提供技术借鉴,对加快深部煤层气规模勘探开发具有重要意义。

川滇地块东部老鹰山的构造地貌特征及其揭示的地块隆升和旋转运动

印−欧大陆板块的碰撞与挤压造成了青藏高原的隆升和陆内变形,同时引起川滇菱形地块的侧向逃逸与旋转,目前针对川滇菱形地块中部和西部地区的旋转量已进行了大量古地磁研究,但对其东部地区的旋转研究相对缺少。由于河流地貌对地块的旋转量十分敏感,因此,研究利用30 m分辨率的数字高程模型(DEM)提取了川滇菱形地块东部老鹰山地区的22个流域盆地,通过分析其局部地形起伏比、河流纵剖面、河流陡峭指数以及流域方位角4个地貌参数来确定老鹰山地区的地块旋转量和隆升量。研究结果显示:老鹰山地区自晚中新世以来,隆升量约为358 m,隆升趋势为北高南低;河流陡峭指数值整体分布趋势由北向南逐渐降低,高值区主要分布在老鹰山地区北部,低值区主要分布在研究区老鹰山顶部以及老鹰山地区南部;同时根据流域方位角结果表明老鹰山地区旋转量为逆时针旋转15°左右。研究表明自晚中新世以来,川滇地块内元谋断裂以西受走滑断裂影响较小,主要为顺时针旋转;元谋断裂以东受走滑断裂等强烈的左行走滑影响,发生了逆时针旋转并伴随着差异隆升。

川滇块体东边界断裂带应力演化特征及地震危险性数值

建立川滇块体东边界及龙门山断裂带区域三维粘弹性有限元模型,以GNSS速度场为约束,计算区域内主要断裂带长期平均构造应力积累速率;并根据历史地震破裂滑动模型,计算其对鲜水河断裂带、龙门山断裂带等造成的同震和震后库仑应力变化,从而得到研究区域主要断裂带总应力演化结果。研究表明,鲜水河断裂带、大凉山断裂带南段以及理塘断裂带的构造应力积累速率较高,达到1.0~1.5 kPa/a。2022年泸定MS6.8地震破裂区在一个地震复发周期内的构造应力积累量约为0.177 MPa,而历史强震产生的库仑应力加载量为0.07 MPa,二者共同导致了泸定地震的发生。此外,安宁河断裂带地震空区在前次地震离逝时间(约487 a)内的总应力积累量约为0.3 MPa,大凉山断裂带南段以及理塘断裂带历史地震离逝时间均为千年左右,总应力积累量>1.0 MPa,可能有较大的地震活动潜力。

临兴区块深部煤层气井生产特征及影响因素

【目的】深部煤层气生产特征与中浅部煤层气生产特征具有明显区别,且同一区块内深部煤层气排采井也存在差异性。相关研究尚处于探索阶段,深入分析深部煤层气生产特征差异的影响因素对后续大规模开发阶段的产能预测与生产管理具有重要意义。【方法】为明确临兴区块深部煤层气生产特征及其影响因素,基于含气性、煤厚、埋深、水化学特征及压裂工艺等地质工程因素开展研究。【结果和结论】结果表明:(1)临兴区块深部煤层气井分为过饱和气藏自喷井、过饱和气藏排采井和欠饱和气藏排采井3类。(2)含气性是3种生产特征的主控因素,工区内1800~2000 m埋深的煤层气井含气量与稳产气量均相对较高。(3)欠饱和气藏排采井储层保存条件较差,水化学特征与其他两类井存在明显差异,导致其生产效果相对较差,且由于高矿化度和高碳酸氢根离子产生的管柱结垢与腐蚀导致排采不连续。(4)大规模压裂是提高气井产量的有效储层改造措施,压裂砂对裂缝的有效支撑是保障深部煤层气井高气量稳产的关键因素。上述成果明确了临兴区块深部煤层气生产特征差异影响因素,对研究区和邻近地区深部煤层气生产具有参考意义。

鄂尔多斯盆地东缘深部煤层气高效开发理论技术体系

针对深部煤储层埋藏深、渗透率低、应力环境复杂等开发难题,总结大宁—吉县区块近5 a勘探开发取得成果,明确了资源富集条件、有效改造体积、水平段长、良好储盖组合条件是气井高产关键因素。在“人造气藏”开发理论指导下,建立了地质-工程一体化背景下的深部煤层气高效开发技术体系:(1)基于储层资源条件、构造保存条件和工程改造条件三大类11项指标,建立深部煤层气地质工程开发甜点评价标准;(2)基于微幅构造刻画、多尺度裂缝预测、三维地质模型构建等技术,形成“地质+工程”全要素定量化、可视化表征的煤储层精细评价技术;(3)按照“地质小尺度、三维地震微尺度、轨迹走靶体、少调快钻”导向思路,形成以钻前轨迹精优设计、精准入靶及靶后微调为核心的三阶段地质工程一体化导向技术;(4)按照实现资源动用和采收率最大化为目标,形成“地应力场、天然裂缝场、人工裂缝场、井型与方位、井网井距”五位一体井网优化设计技术;(5)依据深部煤层气赋存特征、渗流机理和气井生产特征,形成以产量不稳定分析法为主,经验产量递减法、数值模拟法和经验类比等多方法结合的气井产能评价及EUR预测技术;(6)遵循“四位一体”精准选段和“井间交错+段内差异化”设计原则,形成以构建人造气藏为目标的大规模体积压裂技术;(7)根据气井气水变化特征,形成全生命周期不同生产阶段排采优化控制技术;(8)结合当前AI技术进展与深部煤层气开发规律、集输等特征,探索了地质、工程、地面等多专业一体化协同环境下集输和数智化技术。在这一成果指导下,已投产29口水平井生产初期日产量5×10^(4)~16×10^(4) m^(3),平均10.2×10^(4) m^(3),区块日产气量突破300万m^(3),对加快鄂尔多斯盆地东缘深部煤层气规模上产具有重要指导意义,也为同类资源高效开发建立了参考标准。

塔里木盆地东部超深层油气勘探快速实现新突破

塔里木盆地东部蕴藏着丰富的油气资源,是我国陆上油气资源增储上产的重点地区。在国家油气勘查开采体制改革、新一轮找矿突破战略行动等政策背景下,中央-地方-企业紧密融合新机制助推了油气勘探开发快速实现突破的新模式,带来了极大的经济效益和社会效益。创新优化制定了塔东尉犁西1区块勘探部署方案,实现了8000 m以深地质层位设计和实钻对比“零”误差,取得了信源1井、信源2井、信源3井超深层油气重大发现。同时,形成了一系列科技创新成果,提高了超深层地质体识别精度,形成了地质工程一体化技术体系,明确了缝洞型储层发育区,形成了2亿t级规模超深层油气富集新区。新机制新模式开辟了“十四五”油气增储上产新领域,奠定了塔东油气资源接续基地建设基础,推进了新一轮找矿突破战略行动目标的实现。

2022年6月10日四川马尔康M_(S)6.0震群同震地质灾害发育特征及其控制因素分析

为了揭示震群型同震地质灾害的分布规律和特征,理清不同类型地震诱发地质灾害的差异性,进一步认识巴颜喀拉地块周边和内部的地震风险,从而高效指导地震诱发次生地质灾害预测与防治工作,文章以2022年马尔康M_(S)6.0震群同震地质灾害为研究对象,通过对震群序列数据、区域构造环境研究成果、区域地壳形变研究数据、震后短期内的地质灾害数据等进行系统分析研究,揭示马尔康M_(S)6.0震群的区域和深部构造环境、同震地质灾害的主控因素。结果表明:马尔康M_(S)6.0震群是发生在周缘边界活动性极强的巴颜喀拉地块内部次级断裂上强震空区内的深部粘滑型地震,多次震级相近的地震可能是由于松岗断裂的次级断裂破裂和之间的隔堤相继破裂的结果;地震新增地质灾害隐患83处,导致地质灾害隐患点变形加剧106处,并诱发了多处高位滑坡和系列震裂山体,震后震中草登乡地质灾害极高、高、中风险区面积分别占比1.62%、4.80%和12.37%;地震诱发同震地质灾害的控制因素由主到次为发震断裂及其关联断裂、地震震级及能量衰减、地形坡度及高差、岩体结构及结构面密度。此次发震的松岗断裂与龙日坝活动断裂交切区未来强震风险高,发震断裂及与其有联动效应的断裂周边在地震时发生地质灾害风险高。

大湾区块陡坡带沙三中亚段砂砾岩体沉积特征及成因探讨

辽河坳陷东部凹陷大湾区块陡坡带沙三中亚段沉积时期发育了一套砂砾岩体,由于该区勘探程度较低,前人尚未对该区砂砾岩体进行深入的分析和研究,对其成因及分布规律认识不清,制约了该区的勘探进程。利用岩心观察、岩石薄片、粒度分析、重矿物组合特征以及古地貌恢复等技术手段,对研究区砂砾岩体沉积特征、物源及成因进行研究,结果表明:大湾区块陡坡带沙三中亚段砂砾岩体为近岸水下扇沉积体系,物源来自于东部茨榆坨潜山凸起,同时大湾区块位于茨榆坨潜山凸起倾没端,是主物源的优势倾泻方向,有利于形成规模扇体。在此基础上明确了大湾区块陡坡带沙三中亚段砂砾岩体展布特征,从而为大湾区块陡坡带岩性油气藏勘探寻找有利目标提供了指导。