Rock Damage Structure of the South Longmen-Shan Fault in the 2008 M8 Wenchuan Earthquake Viewed with Fault-Zone Trapped Waves and Scientific Drilling

This article is to review results from scientific drilling and fault-zone trapped waves （FZTWs） at the south Longman-Shan fault （LSF） zone that ruptured in the 2008 May 12 M8 Wenchuan earthquake in Sichuan,China.Immediately after the mainshock,two Wenchuan Fault Scientific Drilling （WFSD） boreholes were drilled at WFSD-1 and WFSD-2 sites approximately 400 m and 1 km west of the surface rupture along the Yinxiu-Beichuan fault （YBF）,the middle fault strand of the south LSF zone.Two boreholes met the principal slip of Wenchuan earthquake along the YBF at depths of 589-m and 1230-m,respectively.The slip is accompanied with a 100-200-m-wide zone consisting of fault gouge,breccia,cataclasite and fractures.Close to WFSD-1 site,the nearly-vertical slip of ～4.3-m with a 190-m wide zone of highly fractured rocks restricted to the hanging wall of the YBF was found at the ground surface after the Wenchuan earthquake.A dense linear seismic array was deployed across the surface rupture at this venue to record FZTWs generated by aftershocks.Observations and 3-D finite-difference simulations of FZTWs recorded at this cross-fault array and network stations close to the YBF show a distinct low-velocity zone composed by severely damaged rocks along the south LSF at seismogenic depths.The zone is several hundred meters wide along the principal slip,within which seismic velocities are reduced by ～30-55％ from wall-rock velocities and with the maximum velocity reduction in the ～200-m-wide rupture core zone at shallow depth.The FZTW-inferred geometry and physical properties of the south LSF rupture zone at shallow depth are in general consistent with the results from petrological and structural analyses of cores and well log at WFSD boreholes.We interpret this remarkable low-velocity zone as being a break-down zone during dynamic rupture in the 2008 M8 earthquake.We examined the FZTWS generated by similar earthquakes before and after the 2008 mainshock and observed that seismic velocities within fault core zone was reduced by ～10％ due to severe damage of fault rocks during the M8 mainshock.Scientific drilling and locations of aftershocks generating prominent FZTWs also indicate rupture bifurcation along the YBF and the Anxian-Guangxian fault （AGF）,two strands of the south LSF at shallow depth.A combination of seismic,petrologic and geologic study at the south LSF leads to further understand the relationship between the fault-zone structure and rupture dynamics,and the amplification of ground shaking strength along the low-velocity fault zone due to its waveguide effect.

Late Quaternary Activity of the Central-North Segment of the Taihang Mountains Piedmont Fault Zone

The location and late Quaternary activity of the Central-North Segment of the Taihang Mountains Piedmont fault zone have been studied by shallow seismic survey and combined drill exploration.Our results show that the Baoding-Shijiazhuang fault and the Xushui fault were active in the late Pleistocene,but the south Xushui fault has been inactive since the late Pleistocene.The maximum magnitude of potential earthquake of the faults is 6.0.

DEFORMATIONAL AND METAMORPHIC HISTORY OF THE CENTRAL LONGMEN MOUNTAINS, SICHUAN CHINA

The Longmen Mountains and adjacent regions on the eastern margin of the Tibetan plateau can be divided into three tectonic units: the eastern Songpan—Garzê fold belt, the Longmen Mountains (Longmen Shan) Thrust—Nappe belt and the Western Sichuan foreland basin that occupies the western part of the Sichuan basin. The Longmen Shan Thrust—Nappe belt is subdivided by six northwest\|dipping major listric thrusts, with accompanying duplexes and imbricate fans, into five large\|scale nappes (Chen & Wilson, 1996). In the inner Longmen Shan, the nappe units have incorporated both Mesoproterozoic basement and Sinian (Neoproterozoic) to Triassic cover sequences as “thick\|skinned" horses. Whereas, in the frontal Longmen Shan, Sinian to Cretaceous cover sediments have been stripped from the basement as “thin\|skinned" fold and thrust sheets, including extensively distributed klippen structures. Pre\|thrusting extension during Devonian to middle Late Triassic times resulted in syndepositional normal faults. Structural inversion of these faults initiated the “Peng Xian—Guan Xian basement complex", Jiuding Shan and Tangwangzhai nappes, during an early episode of the Indosinian Orogeny (Norian to Rhaetian). This was followed by episodic thrusting during latest Triassic to Early Cretaceous times to develop the Guan Xian—An Xian and Southeastern Marginal nappes that have incorporated sediments from the neighbouring foreland basin into the frontal part of the Thrust—Nappe belt. Differential thrusting occurred across the Thrust—Nappe belt during a Late Miocene reactivation of the pre\|existing faults.

Tectonic implication of geomorphometric analyses along the Saravan Fault: evidence of a difference in tectonic movements between the Sistan Suture Zone and Makran Mountain Belt

In this paper, remote sensing techniques,as well as field studies, have been used to investigate the geomorphological processes and landscape evolution along the Saravan Fault, SE Iran to highlight how topographic features were influenced by active tectonics. Quantitative geomorphic analysis was carried out using mountain-front sinuosity(Smf),valley floor width-valley height ratio(Vf), drainage basin asymmetry factor(Af), Hypsometric integral(Hi), drainage basin shape index(Bs), mean axial slope of channel(MASC), standard deviation of topography(STD) and index of active tectonic(Iat).Remote sensing techniques, as well as field studies revealed that the Saravan Fault have three parts trending N-S, NW-SE, and E-W. Obtained results show that basins with high Iat index are located at where the strike of the Saravan Faults changes and where several strike-slip faults are crossed the Saravan fault.

RELATIONSHIP BETWEEN P-T CONTITIONS OF TWO PHASES OF TAN-LU STRIKE-SLIP SHEAR ZONES AND DELAMINATION OF OROGENIC BELTS ON THE EASTERN MARGIN OF THE DABIE MOUNTAINS

The Tan-Lu fault zone joins the Dabie Mountains on its eastern margin, and offsets the Dabie and Sulu orogenic belts sinistrally for about 500 km. On the basis of calculation of temperature and pressure experienced by the two phases of the fault zone as well as the thermo-chronological information on mylonite from the earlier and later Tan-Lu fault zones on the eastern margin of the Dabie Mountains, this paper discusses the delamination history and uplifting magnitudes of the Dabie Mountains from earlier Jurassic to earlier Cretaceous. From mineral assemblages, mineral deformation and muscovite-chlorite geothermometry calculation, it is known that the temperature experienced by the two phases of Tan-Lu fault zones are between 400℃ and 450℃, and the confining pressures are between 0.25Gpa and 0.36GPa for the earlier shear zones and 0.24-0.39GPa for the late shear zones. According to the geobarometry of Si-in-phengite and by considering shear heating and tectonic over-pressure, it is concluded that the maximum formation depths for the two phases of the ductile shear zones are not more than 12 km. Differential formation depths for the two phases of shear zones are 1-2 km at most. At about 190 Ma and 128 Ma, the Tan-Lu fault zone experienced two phases of cooling events. During this period, the eastern margin of the Dabie Mountains experienced a tectonic calm period and no uplifting. According to information from the Tan-Lu fault zone, the uplifting magnitudes of the Dabie orogenic belts are not more than 12 km during the earlier Cretaceous.

Study on rupture zone of the M=8.1 Kunlun Mountain earthquake using fault-zone trapped waves

The observation of the fault-zone trapped waves was conducted using a seismic line with dense receivers across surface rupture zone of the M=8.1 Kunlun Mountain earthquake. The fault zone trapped waves were separated from seismograms by numerical filtering and spectral analyzing. The results show that: a) Both explosion and earthquake sources can excite fault-zone trapped waves, as long as they locate in or near the fault zone; b) Most energy of the fault-zone trapped waves concentrates in the fault zone and the amplitudes strongly decay with the distance from observation point to the fault zone; c) Dominant frequencies of the fault-zone trapped waves are related to the width of the fault zone and the velocity of the media in it. The wider the fault zone or the lower the velocity is, the lower the dominant frequencies are; d) For fault zone trapped waves, there exist dispersions; e) Based on the fault zone trapped waves observed in Kunlun Mountain Pass region, the width of the rupture plane is deduced to be about 300 m and is greater than that on the surface.

Analysis on the Observation Data of Three Profiles across the Qilian Mountain-Haiyuan Fault Zone

由分析 GPS，铺平并且从 Minle， Huazangsi 和 Shagouhe 的严肃观察数据在 2005 期间介绍 Qilian Mountain-Haiyuan 差错到对面 - 2009，这些数据的变化和在不同时间的主要差错的活动特征被获得。Changma-Erbo， Maomaoshan， Zhunglanghe 和 Haiyuan 指责的结果表演在最近的年里是活跃的。在垂直排水量和活动严肃数据之间的关系被分析，并且结果表明严肃变化主要由于集体转移。水平运动速度的方向几乎沿着差错的 GPS 观察表演的结果在 2006 罢工 - 2007 当水平速度在 2007 从差错方向背离了时 - 2008，由增加的东方排水量描绘了。在连续观察的 N 和 E 坐标值的时间系列上的线性趋势的移动之上的进一步的分析在三侧面附近中国的外壳的运动观察网络驻扎表明 Wenchuan 地震在 2007 在观察上有效果 - 2008。在 2008 比较重力的变化 - 2009 与 Bouguer 严肃异例背景，我们发现 Minle 侧面附近的区域在调整和恢复的阶段，当异例完全没在 Huazangsi 和 Shagouhe 侧面附近被恢复时。

Differential Tectonic Deformation of the Longmen Mountain Thrust Belt,Western Sichuan Basin,China

Field investigation and seismic section explanation showed that the Longmen Mountain Thrust Belt has obvious differential deformation： zonation, segmentation and stratification. Zonation means that, from NW to NE, the Longmen Mountain Thrust Belt can be divided into the Songpan- Garz~ Tectonic Belt, ductile deformation belt, base involved thrust belt, frontal fold-thrust belt, and foreland depression. Segmentation means that it can be divided into five segments from north to south： the northern segment, the Anxian Transfer Zone, the center segment, the Guanxian Transfer Zone and the southern segment. Stratification means that the detachment layers partition the structural styles in profile. The detachment layers in the Longmen Mountain Thrust Belt can be classified into three categories： the deep-level detachment layers, including the crust-mantle system detachment layer, intracrustal detachment layer, and Presinian system basal detachment layer; the middle-level detachment layers, including Cambrian-Ordovician detachment layer, Silurian detachment layer, etc.; and shallow-level detachment layers, including Upper Triassic Xujiahe Formation detachment layer and the Jurassic detachment layers. The multi-level detachment layers have a very important effect on the shaping and evolution of Longmen Mountain Thrust Belt.

An Experimental Study on the Observation Method of Hydrogen Concentration in Fault Gas

In order to explore the new technology and methods for seismic underground fluid observation,a test study on measurement of hydrogen concentration in fault gas is carried out at the piedmont fault zone of Zhongtiao Mountain. Through the experiment on observation positions,gas collection devices and sampling depths,the paper presents the observation method for fault gas hydrogen concentration by using an online automatic trace hydrogen analyzer. Comparative tests are conducted on the stability and optimum conditions of this type of instrument in the field environment, and the hydrogen concentrations at different measuring points of the same fault are observed. The results show that it is technically feasible to carry out continuous hydrogen concentration on a fault zone. The method proposed in this study could be a useful tool for setting the observation points,choosing a reasonable observation depth and scientific analysis of the observed data.

Seismogenic Structure around the Epicenter of the May 12,2008 Wenchuan Earthquake from Micro-seismic Tomography

A three-dimensional local-scale P-velocity model down to 25 km depth around the main shock epicenter region was constructed using 83821 event-to-receiver seismic rays from 5856 aftershocks recorded by a newly deployed temporary seismic network. Checkerboard tests show that our tomographic model has lateral and vertical resolution of -2 km. The high-resolution P-velocity model revealed interesting structures in the seismogenic layer： （1） The Guanxian-Anxian fault, Yingxiu-Beichuan fault and Wenchuan-Maoxian fault of the Longmen Shan fault zone are well delineated by sharp upper crustal velocity changes; （2） The Pengguan massif has generally higher velocity than its surrounding areas, and may extend down to at least -10 km from the surface; （3） A sharp lateral velocity variation beneath the Wenchuan-Maoxian fault may indicate that the Pengguan massif＇s western boundary and/or the Wenchuan-Maoxian fault is vertical, and the hypocenter of the Wenchuan earthquake possibly located at the conjunction point of the NW dipping Yingxiu-Beichuan and Guanxian-Anxian faults, and vertical Wenchuan-Maoxian fault; （4） Vicinity along the Yingxiu- Beichuan fault is characterized by very low velocity and low seismicity at shallow depths, possibly due to high content of porosity and fractures; （5） Two blocks of low-velocity anomaly are respectively imaged in the hanging wall and foot wall of the Guanxian-Anxian fault with a -7 km offset with -5 km vertical component.

The Seismogenic Structure of the 2010 Suining Ms 5.0 Earthquake and its Geometry,Kinematics and Dynamics Analysis

In January 2010, the Suining Ms5.0 earthquake occurred in central Sichuan Basin, with the epicenter in Moxi-Longnvsi structural belt and a focal depth of 10 km. Based on structural interpretations of seismic profiles in this area, we recognized a regional detachment fault located at a depth of 9-10 km in the Presinian basement of the Suining area, transferring its slipping from NW to SE orientation. This detachment fault slipped from NW to SE, and underwent several shears and bends, which caused the basement to be rolled in and the overlaying strata fold deformation. It formed a fault-bend fold in the Moxi area with an approximate slip of 4 km. Correspondingly, the formation of the Moxi anticline is related to the detachment fault. With the earthquake＇s epicenter on the ramp of the detachment fault, there is a new point of view that the Suining earthquake was caused by re-activation of this basement detachment fault. Since the Late Jurassic period, under the influence of regional tectonic stress, the detachment fault transfered its slip from the Longmen Mountains （LMS） thrust belt to the hinterland of the Sichuan Basin, and finally to the piedmont zone of southwest Huayingshan （HYS）, which indicates that HYS might be the final front area of the LMS thrust belt.

Sedimentary characteristics and main controlling factors of the Middle-Upper Permian and Middle-Upper Triassic around Bogda Mountain of Xinjiang,NW China

Based on field geological survey,interpretation of seismic data and analysis of drilling and logging data,the evolution of geological structures,stratigraphic sedimentary filling sequence and sedimentary system around the Bogda Mountain were analyzed according to the idea of"structure controlling basin,basin controlling facies and facies controlling assemblages".The tectonic evolution of the basin around the Bogda Mountain can be divided into nine stages.The Middle-Late Permian–Middle-Late Triassic was the development stage of intracontinental rift,foreland basin and inland depression basin when lake,fan delta and braided river delta sedimentary facies developed.Early intracontinental rifting,late Permian tectonic uplift,and middle-late Triassic tectonic subsidence controlled the shape,type,subsidence rate and sedimentary system evolution of the basin.The Bogda Mountain area was the subsidence center and deposition center of the deep water lake basin in the Middle Permian with mainly deep-water deposition and local gravity flow deposition.This area had tectonic inversion in the Late Permian,when the Bogda Mountain uplifted to form a low bulge and a series of fan delta sand bodies.In the Middle-Late Triassic,subsidence occurred in the Bogda low uplift,characterized by extensive development of braided river delta deposits.

Regional fault deformation characteristics before and after the Menyuan Ms6.4 earthquake

This study analyzes data regarding cross-fault deformations within the seismogenic zone of the 2016 Qinghai Menyuan Ms6.4 earthquake and its surrounding area. The results showed that the tendency anomaly sites near the epicenter had relatively long anomaly durations prior to the earthquake, while sudden-jumping anomaly sites started to increase in the middle eastern Qilian Mountains approximately a year before the earthquake and continued to increase and migrate towards the vicinity of the epicenter two to six months before the earthquake. Intensive observations a few days after the earthquake indicated that abnormal returns and turns before the earthquake were significant, but all had small amplitudes, and the coseismic effect was generally minor. In addition, the post-seismic tendency analysis of individual cross faults in the Qilian Mountain fault zone revealed an accelerating thrust tendency at all cross-fault sites in the middle Qilian Mountains after the 2008 Wenchuan Ms8.0 earthquake. This indicates that the Wenchuan mega-earthquake exerted a great impact on the dynamic environment of the northeastern margin of the Qinghai-Tibet plate and significantly enhanced the extrusion effect of the Indian plate on the middle Qilian Mountains, generating favorable conditions for the occurrence of Menyuan thrust earthquakes.

龙门山山前带中段分层差异变形特征及成因

龙门山构造带是研究陆内构造变形活动的理想场所之一。龙门山山前带的构造变形整体具有纵向分段、横向分带、垂向分层的特点。为了明确龙门山山前带中段分层变形特征,并进一步探讨分层差异变形成因。本文应用浅表地质露头、数字高程与三维地震数据等资料,开展龙门山山前带中段构造样式的识别及分层差异解析,绘制典型剖面构造演化图,计算关键层位缩短量。研究表明:龙门山山前带发育多种类型的断层相关褶皱,其中,上三叠统叠瓦逆冲构造以及深部逆冲楔在龙门山山前带中段广泛发育。总体来看,龙门山山前带中段大致以嘉陵江组为界,呈叠瓦逆冲构造系统与深部中小尺度冲断构造系统垂向叠置的构造特征,滑脱层对分层变形起着控制作用。此外,岩性也影响着分层变形,嘉陵江组膏盐岩等区域性分布的软弱层在变形中发挥着传递应变的滑脱层作用;多期次变形的叠加也是导致龙门山山前带中段分层差异变形的重要原因。

2022—2023年四川泸定M_(S)6.8、M_(S)5.0和M_(S)5.6地震序列的发震构造及成因

四川泸定2022年9月5日发生M_(S)6.8强震,随后10月22日和2023年1月26日又分别发生M_(S)5.0和M_(S)5.6强余震,主震和两次强余震的震中相距仅几公里却有着截然不同的震源机制解,因此,探究三者的发震构造、联系及成因至关重要.本研究利用国家地震台网记录到的这三次地震序列的连续波形数据及震相资料进行双差重定位,并进一步采取CAP波形反演方法和P波初动极性反演方法获得研究区M_(L)2.5+的79个余震震源机制解.结果显示,主破裂沿鲜水河断裂磨西段,破裂彻底,余震活动性不高.沿主断裂分布的余震具有明显的分段特征,断层近直立且西北浅东南深.主震及磨西段大部分余震均为走滑机制,是典型的印度—欧亚板块挤压旋转造成鲜水河走滑断裂带应力失稳触发的强震活动.发生在贡嘎山地区的余震是M_(S)6.8主震触发的震群活动,震级水平不高,分布弥散,并没有触发与主断裂共轭的燕子沟、海螺沟和磨子沟次级断裂,而是触发了与主断裂近平行的次级隐伏断裂——贡嘎山断裂.M_(S)5.0和M_(S)5.6两次强余震均发生在该次级隐伏断裂上,断层倾角40°~50°且震源深度较浅.贡嘎山地区拉张型地震活动明显不同于走滑型为主的鲜水河断裂带,可能是印度—欧亚板块挤压旋转作用下贡嘎山快速隆升而地表快速剥离导致局部因重力卸载而垮塌造成的,M_(S)6.8主震有明显的触发作用.三次泸定强震的发生,释放了磨西段及西侧贡嘎山地区部分应力,但并未改变"Y"字形交汇区强震发生的可能性.

川西鲜水河、安宁河和龙门山断裂带地热水的水文地球化学特征及成因模式的讨论

[研究目的]研究川西鲜水河断裂带、安宁河断裂带和龙门山断裂带地热水的水化学特征及成因模式,可为川西地热水资源的合理开发利用提供重要参考依据。[研究方法]本文运用水文地球化学、热储温度计算、氢氧同位素等方法分析了分布在3条断裂带上的48处典型温泉(地热井)的水化学组分、水化学过程、热储温度和深度、热水补给来源等特征,并探讨了其形成模式。[研究结果]结果显示:(1)鲜水河断裂带热水水化学类型以HCO_(3)-Na型为主;龙门山断裂带主要为SO_(4)-Na和Cl-Na型;安宁河断裂带包括HCO_(3)·Cl-Na、HCO_(3)·SO_(4)-Ca·Mg和Cl·SO_(4)-Na型等。(2)3条断裂带地热水组分主要受硅酸盐矿物溶解和离子交换作用控制。(3)鲜水河断裂带热储温度为129.6~210.6℃,深度为2532~4184 m,冷水混入比为66%~82%;安宁河断裂带热储温度为81~121.9℃,深度为2155~3519 m,冷水混入比为52%~95%;龙门山断裂带热储温度为108.2~153℃,深度为3573~5654 m,冷水混入比为68%~89%。(4)3条断裂带的地热水接受大气降雨补给,补给高程分别为鲜水河断裂带2493~5034 m、安宁河断裂带3235~3839 m和龙门山断裂带1628~4574 m。(5)鲜水河断裂带地热水的“δ^(18)O漂移”程度强于安宁河断裂带,龙门山断裂带部分地热水出现“δ^(18)O漂移”和“负向漂移”特征。[结论]基于本次研究得到的3条断裂带地热水成因模式,鲜水河断裂带地热水的开发潜力优于安宁河断裂带、龙门山断裂带,是四川省中高温地热资源开发利用的优势靶区。

龙门山复杂构造带红星1井天然气勘探突破及其油气地质意义

龙门山复杂构造带位于四川盆地西部,是该盆地油气勘探的重点区带,近期风险探井——红星1井首次钻穿龙门山推覆构造体,揭示推覆带下盘存在原地构造,并且在中二叠统栖霞组测试获得12.66×10^(4)m^(3)/d高产工业气流。为了探究该风险探井天然气勘探突破所蕴含的油气地质意义,基于该井所获丰富的钻探资料,重建了推覆体地质模型,并在此基础上对线束三维地震资料进行精细处理解释,恢复了龙门山前山带构造模式,进而剖析了川西龙门山复杂构造带深层碳酸盐岩沉积、储层特征及油气成藏地质条件。研究结果表明:(1)龙门山推覆构造带具有“逆掩推覆、直立倒转、原地系统”3段叠加式地质结构,前山带推覆冲断带二叠系、三叠系地层受断层控制,具有重复倒转的特征;(2)推覆体下盘栖霞组钻遇地层和岩性组合与山前带双鱼石地区特征相同,均为台缘滩相沉积,白云岩储层大面积分布,进一步证实了该区原地构造带台缘相带滩相孔隙型白云岩储层连片大面积分布;(3)龙门山复杂构造带具备“多源供烃—断裂输导—侧向对接—隐伏保存”的油气成藏条件,红星1井测试结果证实,该复杂构造带前山带和山前带均具有良好的油气成藏条件,区带油气勘探前景广阔。

川西龙门山北段中生代差异构造隆升特征

川西龙门山冲断带内部发育多条大型断裂并经历了多期且复杂的构造演化。为探讨龙门山北段中生代以来主要断裂带之间的差异构造隆升,本文开展了锆石裂变径迹年龄测定工作,并计算了冷却速率等构造隆升参数。结果表明,锆石裂变径迹年龄主要集中在238~122 Ma之间,唐王寨向斜和仰天窝向斜核部冷却速率为1.211~1.438℃/Myr,剥蚀速率为0.038~0.048 mm/yr。向斜西北翼冷却速率和剥蚀速率相对稍高,分别为1.150~1.586℃/Myr和0.038~0.053 mm/yr,总体上,锆石裂变径迹年龄、冷却速率和岩石隆升幅度等参数在平面呈带状,且与主干断裂近于平行。各构造隆升参数在青川断裂、北川断裂和江油断裂所夹持的不同区域具有不同的变化范围,自北西至南东方向,构造变形兼具“前展式”和“后展式”特征。由前展式变形转变为后展式变形的时期为139~122 Ma。

山区带状交通工程物探技术研究及应用

山区带状交通工程物探通常面临崎岖地形、高山峡谷、飞水暗河、植被茂盛、陡倾地层等复杂地理环境和地质构造影响。当前,针对山区的物探方法手段单一、技术思路不开阔、数据信息严重不足,存在勘察盲区,尚未形成技术体系,难以有效提导钻探,存在重大地质风险,严重影响后续勘察设计和工程造价。以崎岖山岭DGT深埋长隧道紧邻断裂带和高山峡谷BFSH深埋特长隧道穿越地热发育区勘察项目为依托,运用大数据思维,对近几年涌现出来的航空物探、广域频电磁法、地震微动以及井中物探等新技术进行系统研究,试验攻关综合物探技术在山区勘察的有效性,揭示复杂地形地质条件下工程物探面临的问题并提出针对性措施,综合利用遥感、地质、钻探、试验等勘察技术,建立了“空天地”+“工可-初勘-详勘”多场源一体化勘察模式,形成了数据量大、属性要素全面、动态的勘察大数据,准确识别了断裂带、地热性质、围岩质量和岩土分界面,为优化线路和钻探选位打下良好的基础。通过案例研究,认为运用大数据思维可以提高山区工程勘察设计水平,采用综合技术可以提高地质参数的准确性。

郯庐断裂带江苏段山左口−泗洪断裂活动特征变化及成因分析

山左口−泗洪断裂经历了郯庐断裂带整个演化阶段,该断裂的最新活动时代具有分段性。确定该断裂的活动性分段位置及原因对研究郯庐断裂带内各分支断裂的活动性变化具有重要的参考价值。因此,利用野外地质调查、浅层地震勘探以及钻孔联合地质剖面等深浅部相结合的立体式研究方法,对山左口−泗洪断裂的活动性进行了研究。结果表明:山左口−泗洪断裂在北马陵山东侧为晚更新世活动断裂,在新沂市为中更新世断裂。新沂市嶂仓村小学新发现一条晚更新世−全新世早期活动断裂,该断裂可将山左口−泗洪断裂分为南北两段,北段为晚更新世活动断裂,南段为早中更新世断裂,北段晚更新世以来活动量向南调整至嶂仓村小学断裂带。北马陵山为郯庐断裂带内部沿断裂走向展布的基岩山体,其第四纪以来的持续抬升与山左口−泗洪断裂的活动性变化有一定的耦合关系。该研究对认识郯庐断裂带其他分支断裂的活动性变化和丘陵山脉的形成机制具有重要的参考价值。