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1.
潮汕坳陷中生代沉积的折射波2D速度结构和密度 总被引：9，自引：0，他引：9
2006年秋,国家海洋局第二海洋研究所在东沙隆起和潮汕（潮南）坳陷完成了OBS2006-3剖面。在整条剖面速度模型的基础上,采用2D层析成像方法,对潮汕（潮南）坳陷区7个站位的中生界折射震相进行了精细的反演成像。结果表明,坳陷内可分3个沉积层,前两层是新生代沉积,速度分别为2.2 km/s和3.6 km/s,厚度较小,不超过2 km。中生代沉积地层的速度从顶部的4.4 km/s向下逐渐增加到底部的5.4 km/s,厚度较大,最厚处为8 km左右。坳陷内速度是比较均匀地随深度增加的,成水平层状分布。重力反演表明,潮汕坳陷中生代沉积的平均密度为2.45 g/cm3,地壳密度为2.86 g/cm3,下地壳高速层密度为3.05 g/cm3,莫霍面下面的上地幔密度为3.32 g/cm3。 相似文献
2.
塔里木盆地西南部位于昆仑造山带东北方,地壳构造特殊,是中国天然气勘探的重要区域。在地面重力调查的基础上,笔者等对2~15 km的盆地西南部的密度扰动结构进行成像计算,并结合电阻率三维结构对地壳构造进行分析。本文根据重力场小波变换的尺度—源深度转换律,进行地面重力异常场多尺度分解,取得了反映中国地壳不同埋藏深度的小波细节,揭示了研究区地壳的密度结构。结果表明,网度足够密的区域高精度重力场测量可以获得关于沉积盆地深部构造的丰富信息,应用小波多尺度分析和三维反演方法可以把与深层构造有关的地质信息提取出来,客观地为沉积盆地内部构造演化和油气勘探提供依据。塔里木盆地西南部上地壳三维密度扰动成像揭示了昆仑山脉向北仰冲推覆构造楔和山前坳陷带的立体结构,为盆山耦合动力学研究和深层油气勘探提供了新的认识。大地电磁数据三维反演取得的盆地三维电阻率模型,从电性结构角度得到了盆地的三维构造,和盆地西南部的密度结构有很好的相关性,支持了密度扰动成像的有关结论。 相似文献
3.
已有钻井以及地震资料揭示南海南部海域广泛发育中生代地层。为了进一步了解南海南部中生代地层的分布特征及油气地质意义,本文利用最新的卫星重力数据反演中生界的深度和厚度。首先,采用重力场正演技术消除海水的影响,获得南海南部布格重力异常。其次,为了消除新生代沉积层的影响,将新生代沉积层划分为0～3、3～6、6～10 km 3层,并根据前人在南海获得的密度与深度的关系,采用变密度Parker正演方法计算新生代沉积层产生的重力影响,并将其从布格重力异常中减去,从而获得前新生代重力异常。在此基础上,采用小波多尺度分解技术,消除深部莫霍面以及局部岩体重力的影响,从而计算得到反映中生界的重力异常。最后采用三维Parker变密度界面快速反演技术获得南海南部中生界深度和厚度。反演结果与已知中生界钻井具有较好的对应。南海南部地区中生界主要分布在礼乐滩、巴拉望岛北部和万安地区,厚度分布小于9 km,其他大部分地区中生界厚度小于1 km或者不存在中生界。其中中生界在礼乐滩地区最为发育,其次在巴拉望岛北部也广泛发育。结合前人在该区域的油气地质条件研究成果,认为南海南部海域礼乐滩地区中生界具有较好的油气勘探前景。 相似文献
4.
在多层沉积盆地上观测得到的重力异常与对具有相同形状和深度的盆地计算所得到的结果密切相关。后者盆地由同一类沉积物充填!且其密度与前者的等效(加权平均)密度相等。因此,盆地至少有一个已知深度点的话,根据剩余重力异常就可算出其相对等效密度。假定密度是深度的函数,用无限大平板(布格)公式可推出重力与深度的关系式,该关系式结合重力数据可算出盆地深度或绘出其等厚线图。本文将分析密度与深度、重力与深度的指数及新型双曲线函数关系,并结合重力数据用来确定加利福尼亚州San Jacinto地堑、南部的亚利桑那州Tucson盆地的深度。双曲线函数比指数函数更可靠、更接近实际。根据Tucson盆地中最深的一个钻孔上的剩余重力异常,用无限大平板公式算出该盆地沉积物的相对等效密度以及密度与深度的关系。上述钻孔打到了深度为3.66km的前始新世基岩。Tucson盆地中密度与深度的双曲线关系,假定它对于南部的亚利桑那州和西南部的新墨西哥州的其它所有盆地和山脉地区也适用。用无限大平板公式很容易将密度与深度的函数关系转换成重力与深度的函数关系。利用重力与深度的双曲线函数关系,可将该地区的每个盆地的剩余重力异常图转换成盆地深度等值线图。用重力数据算出的盆地深度与搜集到的钻孔资料(19口井)比较可以看出,本文提出的这种简单快速方法,其计算结果与真实深度的误差范围大约为13％。 相似文献
5.
用快速准确重力三维正演算法计算白垩系顶面及以上各密度界面的重力异常,采用“剥皮法”从实测重力异常中减去自垩系顶面及以上各密度界面的重力效应后得到剩余异常,由此反演研究区内白垩系底面深度。由于采用快速三维反演算法并顾及地质及航磁异常信息,求得了白垩系厚度,计算出的底板埋深等更为合理、精细,为洞庭地区油气资源基础性研究及评价提供了重要的信息。 相似文献
6.
《物探化探计算技术》2018,(5)
为了探测渭河新生代盆地的基底组成和结构构造,调查渭河盆地主要地层厚度、埋深和构造特征,在渭河盆地开展二维地震勘探测量,在全面收集渭河盆地以往物探和钻孔资料的基础上,通过实测地震剖面,划分渭河盆地新生界地层,得到固市凹陷基底深约8 100km,西安凹陷基底深约6 600km,固市凹陷明显比西安凹陷基底深,这是本次工作最大的成果之一。再结合收集的重力数据,经过消除莫霍面影响后,分析渭河盆地西安凹陷和固市凹陷整体重力场变化特征,结果表明造成西安凹陷重力低,但基底浅;固市凹陷重力高,但基底深。这种实际地质情况是由于西安凹陷新近系沉积地层比固市凹陷沉积地层厚且深,而古近系地层却较之薄而浅,这种"跷跷板"式的地层分布特征能够引起重力异常"非常规"现象出现。通过此次工作实践,对渭河新生代盆地的基底组成和结构构造有清楚认识,对评价重点勘查区的成藏条件,为渭河盆地氦气资源远景调查提供借鉴。 相似文献
7.
准噶尔盆地油气资源丰富,位于准噶尔盆地与北天山结合部位的准噶尔盆地南缘,构造复杂,地震方法应用效果不理想,因此利用综合地球物理方法圈定研究区页岩气产出层位二叠系芦草沟组的分布深度与范围。通过200块岩石标本物性测量,获得了研究区主要地层密度、磁化率、极化率及电阻率等物性参数：研究区主要为沉积岩系,磁性普遍较弱,其中二叠系地层较三叠系地层磁性小;各地层密度差异不大,其中砂岩密度常见值2.61×10 3 kg/m 3 、泥岩密度常见值2.56×10 3 kg/m 3 、页岩密度常见值2.54×10 3 kg/m 3 ;各地层电性特征差异较大,电阻率特征呈现如下关系：砂岩>泥岩>页岩。对实测重力、磁法、大地电磁测深等地球物理数据进行处理及反演,得到了研究区布格重力异常平面等值线图、磁异常平面等值线图及大地电磁三维反演电阻率结构模型图。研究区东南部主要表现为高布格重力异常、负磁异常特征,布格重力异常峰值为9.5×10 -5 m/s 2 ,磁异常峰值为-100 nT;西北部主要表现为低布格重力异常、正磁异常特征,布格重力异常峰值为-12×10 -5 m/s 2 ,磁异常峰值280 nT。MT三维反演结果显示芦草沟组a、b段分别为较高阻和中低阻。芦草沟组总体表现为中低重力、中低电阻、低磁异常特征。结合地质资料,建立了重磁电综合解释地质剖面。根据断裂破碎带表现为低重力、低电阻、低磁异常特征,新推断出研究区8条逆断层,并进一步推断了研究区芦草沟组地层空间展布特征,为下一步勘探井位论证提供了地球物理依据。 相似文献
8.
青藏高原中部古近纪发育伦坡拉盆地、色林错盆地、尼玛盆地,组成伦坡拉-色林错-尼玛沉积凹陷,总体呈近东西走向,长超过250km,宽30~50km;凹陷中心古近系河湖相沉积地层厚度达5~6km,下部为古新统-始新统牛堡组砾岩、砂岩、泥岩、泥灰岩,上部为渐新统丁青湖组泥岩、页岩、粉砂岩夹油页岩,顶部被新近系河湖相沉积不整合覆盖。凹陷南部发育尼玛-色林错逆冲推覆构造,凹陷北侧发育赛布错-扎加藏布逆冲推覆构造,伦坡拉盆地北部发育薄皮推覆构造,伴有不同规模的褶皱变形。地壳深部不同深度发育多重逆冲推覆构造,羌塘地块南部自北向南逆冲推覆,拉萨地块北部自南向北逆冲推覆;两者对冲部位地壳厚度发生显著变化,地表形成古近纪沉积凹陷。根据深地震反射及构造解释,结合Airy均衡分析,表明不同深度逆冲推覆及对冲构造运动导致地壳缩短增厚,增厚地壳均衡隆升及密度差异对古近纪沉积凹陷及盆地演化具有重要控制作用。色林错凹陷及邻区古近纪沉积记录对青藏高原地壳增厚与隆升过程具有重要指示意义。 相似文献
9.
通过对库车前陆盆地的2条MT测线和3条地震剖面的重力二维模拟与综合解释,提高了在复杂变形带进行的构造建模的可靠性。模拟结果表明,库车前陆盆地是以断层相关褶皱作为滑动机制的前陆冲断带。沿下第三系膏盐岩和膏泥岩、侏罗系一三叠系煤系地层发育的滑脱层控制了断层相关褶皱的变形模式,并导致浅层背斜与深部圈闭的位置不一致。在盆地北面,南天山古生界楔入了北部单斜带的中生代地层,导致剩余重力异常值升高;盆地南面,新生界沉积厚度的增加使剩余重力值逐渐降低,局部盐体的堆积可形成重力异常低谷。此外,拜城凹陷基底的密度较高,可能是凹陷形成初期岩浆底侵的结果。推覆变形自天山向塔里木盆地推移,反映了中新世以来逐渐增强的南北向挤压应力和地壳缩短,是印度板块与欧亚板块碰撞的远距离效应。 相似文献
10.
研究不同地质体之间的密度差异是开展重力勘探研究的地球物理前提。密度界面的划分与构造层的划分具有密切关系,测定地层(岩石)密度并分析测定结果是重力勘探工作的重要内容。依据苏北盆地及相邻地区出露岩石的实测密度数据,将该区岩石按照地层、侵入岩进行系统整理和归纳,将地层纵向划分为新生界、侏罗系—白垩系和太古宇—三叠系3个超密度层,2个Ⅰ级密度界面和3个Ⅱ级密度界面; 通过综合分析地层界际密度和系际密度特征,阐述地层及侵入岩的密度特征及其与重力异常的关系,为该盆地重力资料解释和石油勘探提供可靠的地球物理依据。密度界面的划分与区域构造及储油构造具有密切关系,计算密度分界面起伏或深度变化在区域构造研究和石油勘探中具有重要意义。 相似文献
11.
The gravity and magnetic data along three profiles across the northern part of the K-G basin have been collected and the data is interpreted for basement depths. The first profile is taken from Gadarada to Yanam covering a distance of 60 km and the second starts from Zangareddiguddem to Samathkur covering a distance of 110 km and the third is from Kotturu to Biyyapuppa covering a distance of 100 km. The gravity lows and highs have clearly indicated various sub-basins and ridges. The density logs from ONGC, Chennai, show that the density contrast decreases with depth in the sedimentary basin, and hence, the gravity profiles are interpreted using variable density contrast with depth. From the Bouguer gravity anomaly, the residual anomaly is constructed by graphical method correlating with well data, sub-surface geology and seismic information. The residual anomaly profiles are interpreted using polygon model. The maximum depths to the khondalitic basement are obtained as 5.61km, 6.46 km and 7.45 km for the first, second and third profiles respectively. The regional anomaly is interpreted as Moho rise towards coast. The aeromagnetic anomaly profiles are also interpreted for charnockite basement below the khondalitic group of rocks using prismatic models. 相似文献
12.
利用重力梯度反演南海西南海盆深部构造 总被引：2，自引：0，他引：2
重力梯度异常反映的是重力异常的变化,其分辨率比重力异常高。重力梯度空间参量图能给出构造倾角和倾面的信息,结合重力梯度剖面和梯度空间参量图可以构建出地下构造的几何模型,进而对一些复杂构造进行解释。本文利用重力梯度异常对南海西南海盆进行了解释,得到大致以西南海盆北东向扩张轴为对称轴的穹隆状构造面。该构造面在西南海盆下6~15km处形成一个密度界面,此界面可能是西南海盆北西-南东向海底扩张期间地幔上隆所引起的。 相似文献
13.
海拉尔盆地阿拉尔-罕达盖重磁电剖面深部结构特征及其地质意义 总被引：2，自引：0，他引：2
通过电磁场偏移成像处理技术,探索地震屏蔽层以下深部地质构造特征,揭示了海拉尔盆地深部存在似层状的电性异常,具有复式背斜的构造形态。盆地内各凹陷具有重力低、磁力高、电阻率低的重磁电特征;沉积地层为低频低幅度磁异常,岩浆岩为高频高强度的磁异常;剖面中东部电阻率存在低-高-低3层结构,岩浆岩呈高电阻率特征,古生界呈中低电阻率特征。德尔布干断裂与乌奴尔-鄂伦春断裂控制了深部古生界分布,古生界埋深为2～6 km,厚度为2～4 km;古生界与元古宇的接触界面呈复式背斜的构造形态,由3个背斜构造组成,对浅部凹陷分布有一定的控制作用。海拉尔地区晚古生代石炭纪发育泥岩、页岩、灰岩、板岩,推测盆地覆盖区可能具有一定的油气勘探前景。 相似文献
14.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(4):375-380
Silkeborg Gravity High is a dominant positive gravity anomaly in Denmark. It is associated with an igneous intrusion within the crust. A deep refraction seismic profile locates the top of the intrusion in depths between 11 km and 25 km. The present contribution should be read together with two other papers by the author (Strykowski, 1998; Strykowski, 1999) dealing with the modelling problems of the same area.Strykowski (1998) discusses an advanced method of geological stripping. The focus is on coupling various types of piecewise information (depth to the top/base of geological bodies/layers obtained from depth converted seismograms and interpolated to a horizontal grid, surface gravity data, and mass density information from boreholes). The objective is to model the surface gravity response of known sediments to a depth level of 10 km.Illustrated by the practical example (modelling of the source of Silkeborg Gravity High) Strykowski (1999) discusses methodological aspects of extracting information about the geometry of the source body (in 3D) from (geologically stripped) surface gravity data and from a cross-secting deep seismic profile. The average mass density contrast between the source body (the intrusion) and the surroundings is estimated. The used geometrical information from the seismogram is weak (only the depth interval). A remarkable result of this investigation is that the along profile cross section of the obtained (3D-)structure agrees with the geometrical information of the refraction seismic profile.The present paper is an attempt to extend this result to the rest of the sedimentary basin. Of particular interest is another positive gravity anomaly (another intrusion?) located to the north-west of the studied anomaly. A “final model” obtained here estimates the depth to the source body to 14 km.Nevertheless, the focus of the present paper is not on finding a particular “best model” of the subsurface, but on ambiguity considerations. Especially, on how the different assumptions alter the obtained model? The interesting aspect is whether the used assumptions are supported by the available information. 相似文献
15.
Detailed gravity data collected across the Gadwal schist belt in the state of Andhra Pradesh show an 8.4 mgal residual gravity
anomaly associated with meta-sediments/volcanics of the linear NNW-SSE trending schist belt that shows metamorphism from green
schist to amphibolite facies. This schist belt is flanked on either side by the peninsular gneissic complex. The elevation
and slab Bouguer corrected residual gravity profile data were interpreted using 2-D prism models. The results indicate a synformal
structure having a width of 1.8 km at the surface, tapering at a depth of about 2.6 km with a positive density contrast of
0.15 gm/cc with respect to the surrounding peninsular gneissic complex. 相似文献
16.
R. E. Chvez O. Lazaro-Mancilla J. O. Campos-Enríquez E. L. Flores-Mrquez 《Journal of South American Earth Sciences》1999,12(6):415
Source-depth estimations based on analysis of gravity data enabled us to establish the basement topography in the area of the Mexicali Valley (Mexico). Analysis of the radial power spectrum from all the Bouguer gravity anomaly data indicates that the intermediate wave number interval ranging between 0.025 km−1 and 0.112 km−1 with a mean source depth of 3.5 km corresponds to the sedimentary basin. The gravity spectrum was analyzed to estimate the depth to the basement in different square sectors (windows) of the study area. Linear regression analysis was used to calculate the slopes of the respective power spectrums, to subsequently estimate the depths to the basement in each sector. The basement topography obtained in this way ranged from 2.1 to 4.5 km. Our basement topography is consistent with the depths to the basement reported from wells drilled in the study area. The basement is formed by granites to the northeast, dikes to the southwest, and shaped by structural lows and highs, with graben-horst structures at the center of the studied area.An independent estimation of the mean depth to the basement was obtained based on the ideal body theory. In particular trade-off curves relating the lower bound of the density contrast to the depth to the top of the geological interface were computed. If we assume that the sediments outcrop (as is actually the case), the minimum lower bound on the density contrast is 0.0700 g/cm3. This result would imply a maximum thickness of 13.5 km for the sedimentary infill.Seismic velocities of 5.83 and 4.9 km/s for the basement and the sedimentary infill, respectively, indicates densities of 2.86 and 2.56 g/cm3 according to the Nafe and Drake’s relationship between seismic velocities and densities. The corresponding density contrast of 0.3 g/cm3 helped us to constrain the analysis of the trade-off curves accordingly; the sedimentary thickness is of approximately 3.5 km. This result is in agreement with that obtained from our spectral analysis. 相似文献
17.
The Alleppey Platform is an important morphological feature located in the Kerala-Konkan basin off the southwest coast of India. In the present study, seismic reflection data available in the basin were used to understand the sedimentation history and also to carry out integrated gravity interpretation. Detailed seismic reflection data in the basin reveals that:(1) the Alleppey Platform is associated with a basement high in the west of its present-day geometry(as observed in the time-structure map of the Trap Top(K/T boundary)),(2) the platform subsequently started developing during the Eocene period and attained the present geometry by the Miocene and,(3) both the Alleppey platform and the Vishnu fracture zone have had significant impact on the sedimentation patterns(as shown by the time-structure and the isochron maps of the major sedimentary horizons in the region). The 3-D sediment gravity effect computed from the sedimentary layer geometry was used to construct the crustal Bouguer anomaly map of the region.The 3-D gravity inversion of crustal Bouguer anomaly exhibits a Moho depression below the western border of the platform and a minor rise towards the east which then deepens again below the Indian shield. The 2-D gravity modelling across the Alleppey platform reveals the geometry of crustal extension,in which there are patches of thin and thick crust. The Vishnu Fracture Zone appears as a crustal-scale feature at the western boundary of the Alleppey platform. Based on the gravity model and the seismic reflection data, we suggest that the basement high to the west of the present day Alleppey platform remained as a piece of continental block very close to the mainland with the intervening depression filling up with sediments during the rifting. In order to place the Alleppey platform in the overall perspective of tectonic evolution of the Kerala-Konkan basin, we propose its candidature as a continental fragment. 相似文献
18.
本文按统一比例尺编制了印度-青藏地区1°×1°重力异常图和地形高程图,并用滑动平均方法得到了本区5°×5°重力异常图。用地改后的1°×1°重力异常,采用组合体模型人一机联作选择法,计算了横跨印度-青藏-蒙古长达4680km的岩石圈剖面,还给出了一个楔形体重力正演公式。基本结果有:(1)MBT、MCT的倾角为10°±5°,ITS、NS、KS的倾角为75°±5°;(2)地壳滑脱面的深度在青藏之下约20km,向高喜马拉雅、MCT、MBT抬升至15km;(3)青藏高原南、北边缘均为岩石圈结构的斜坡带,界面倾角由上向下而增大。在大、小喜马拉雅之下,壳内界面(Ⅰ、Ⅱ)的倾角约12°,Moho倾角为18°,岩石圈底面倾角约36°。在祁连山带所有界面倾角都小于喜马拉雅带,其中壳内界面倾角仅约1°,Moho倾角约2°,岩石圈底面倾角约12°;(4)岩石圈厚度由印度、蒙古向高喜马拉雅和祁连山带逐渐增加,与青藏岩石圈的边缘上翘形成主动俯冲和相对逆冲势态。印度岩石圈厚度(或上地幔顶部低密层埋深)不超过50km,蒙古高原(南)厚约70km,到高喜马拉雅和祁连山下分别增加至145和122km,青藏中心地带(怒江两侧)岩石圈厚135km,向南,北边缘各减小到120和90～102km,在高喜马拉雅和祁连山下面形成25和10km的断差;(5)在青藏Moho之下厚5km的高密薄层和软流层之间有一密 相似文献
19.
M. Ravi Kumar D. C. Mishra B. Singh D. Ch. Venkat Raju M. Singh 《Journal of the Geological Society of India》2013,81(1):61-78
Spectral analysis of digital data of the Bouguer anomaly map of NW India suggests maximum depth of causative sources as 134 km that represents the regional field and coincides with the upwarped lithosphere — asthenosphere boundary as inferred from seismic tomography. This upwarping of the Indian plate in this section is related to the lithospheric flexure due to its down thrusting along the Himalayan front. The other causative layers are located at depths of 33, 17, and 6 km indicating depth to the sources along the Moho, lower crust and the basement under Ganga foredeep, the former two also appear to be upwarped as crustal bulge with respect to their depths in adjoining sections. The gravity and the geoid anomaly maps of the NW India provide two specific trends, NW-SE and NE-SW oriented highs due to the lithospheric flexure along the NW Himalayan fold belt in the north and the Western fold belt (Kirthar -Sulaiman ranges, Pakistan) and the Aravalli Delhi Fold Belt (ADFB) in the west, respectively. The lithospheric flexures also manifest them self as crustal bulge and shallow basement ridges such as Delhi — Lahore — Sagodha ridge and Jaisalmer — Ganganagar ridge. There are other NE-SW oriented gravity and geoid highs that may be related to thermal events such as plumes that affected this region. The ADFB and its margin faults extend through Ganga basin and intersect the NW Himalayan front in the Nahan salient and the Dehradun reentrant that are more seismogenic. Similarly, the extension of NE-SW oriented gravity highs associated with Jaisalmer — Ganganagar flexure and ridge towards the Himalayan front meets the gravity highs of the Kangra reentrant that is also seismogenic and experienced a 7.8 magnitude earthquake in 1905. Even parts of the lithospheric flexure and related basement ridge of Delhi — Lahore — Sargodha show more seismic activity in its western part and around Delhi as compared to other parts. The geoid highs over the Jaisalmer — Ganganagar ridge passes through Kachchh rift and connects it to plate boundaries towards the SW (Murray ridge) and NW (Kirthar range) that makes the Kachchh as a part of a diffused plate boundary, which, is one of the most seismogenic regions with large scale mafic intrusive that is supported from 3-D seismic tomography. The modeling of regional gravity field along a profile, Ganganagar — Chandigarh extended beyond the Main Central Thrust (MCT) constrained from the various seismic studies across different parts of the Himalaya suggests crustal thickening from 35-36 km under plains up to ～56 km under the MCT for a density of 3.1 g/cm3 and 3.25 g/cm3 of the lower most crust and the upper mantle, respectively. An upwarping of ～3 km in the Moho, crust and basement south of the Himalayan frontal thrusts is noticed due to the lithospheric flexure. High density for the lower most crust indicates partial eclogitization that releases copious fluid that may cause reduction of density in the upper mantle due to sepentinization (3.25 g/cm3). It has also been reported from some other sections of Himalaya. Modeling of the residual gravity and magnetic fields along the same profile suggest gravity highs and lows of NW India to be caused by basement ridges and depressions, respectively. Basement also shows high susceptibility indicating their association with mafic rocks. High density and high magnetization rocks in the basement north of Chandigarh may represent part of the ADFB extending to the Himalayan front primarily in the Nahan salient. The Nahan salient shows a basement uplift of ～ 2 km that appears to have diverted courses of major rivers on either sides of it. The shallow crustal model has also delineated major Himalayan thrusts that merge subsurface into the Main Himalayan Thrust (MHT), which, is a decollment plane. 相似文献