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龙门山冲断带北段前锋带新生代构造变形 总被引：3，自引：0，他引：3
龙门山北段前锋构造的地震剖面解释和前缘盆地内沉积地层的磁组构研究表明前锋构造中发育两期构造挤压作用,即整体强烈的晚三叠世变形和由北向南逐渐减弱的弱新生代构造变形。受这两期构造挤压作用的控制,龙门山北段前锋构造中发育上、下两套构造层,地表构造为晚三叠世时期形成,而深部隐伏构造则形成于新生代。北部的矿山梁和天井山构造几何学上表现为一个双重构造,浅层是一个晚三叠世形成的断层转折褶皱;深层是新生代形成的多个逆冲岩片叠置所构成的隐伏堆垛背斜;南部的青林口和中坝构造主体表现为叠瓦状逆冲,前锋构造是断层转折褶皱和断层传播褶皱。新生代构造冲断位移量以及造成早期构造抬升由北向南逐渐减小,反映新生代变形强度由北向南的减弱。磁组构研究表明新生代变形从龙门山冲断带边缘到盆地内部,磁组构从铅笔状磁组构到初始变形磁组构并逐渐过渡到沉积磁组构。由南向北磁组构由初始变形磁组构转变为铅笔状磁组构,说明应变越来越强,从而进一步证明了龙门山前锋新生代构造的弱变形作用和变形强度的北强南弱分布特征。 相似文献
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构造叠加弱应变沉积岩地区的磁组构研究——以川西北盆地为例 总被引：3，自引：1，他引：2
磁组构是一种灵敏的应变指示计。单一方向应力作用下,在平行层缩短的初始阶段,磁线理与地层走向是一致的。然而,在构造叠加背景下弱变形的沉积岩地区,另一个（多个）不同方向的应力使得已经产生定向排列的磁性矿物发生旋转,表现为磁线理和与地层走向斜交。川西北盆地在新生代是一个典型的构造叠加区域,来自龙门山和米仓山的变形在此相互作用。本文在川西北盆地分3条剖面在18个采样点中采集了172个样品进行了磁组构研究。研究区内观察到3种弱变形的磁组构类型：沉积磁组构、初始变形磁组构和铅笔状磁组构。由于应变的叠加,由盆地内部向造山带前缘没有出现应变由弱到强的变化趋势,同时磁线理的方向也不一致。由盆地向造山带,来自米仓山的变形逐渐增强,磁线理从与地层走向一致转变成与地层走向斜交。 相似文献
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龙门山前陆褶皱冲断带构造解析与川西前陆盆地的发育 总被引：57，自引：2，他引：55
通过详细的野外地质调查和精细的地震剖面构造解析。揭示了龙门山前陆褶皱冲断带的基本构造特征。对比分析了龙门山北段与南段构造变形几何学和运动学的差异。提出龙门山北段主要表现为一系列复杂的逆冲推覆构造,晚三叠纪变形强于新生代;龙门山南段则以基底卷入的叠瓦状冲断为特点,晚白垩纪-早第三纪变形尤为突出。与前陆褶皱冲断带相对应的是,川西晚三叠纪时期的周缘前陆盆地主要表现在整个龙门山褶皱冲断带的前渊地区;而晚白垩纪-早第三纪再生前陆盆地却局限在川西盆地的南部,并且印-藏碰撞的持续挤压作用使得晚新生代构造变形不断向东扩展进入川西盆地南部。 相似文献
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龙门山南段邛西断层转折褶皱磁组构及其有限应变 总被引：1，自引：0，他引：1
龙门山南段位于四川盆地以西,其新生代构造变形特征对于认识青藏高原东缘的变形机制具有一定的指示意义。磁组构是一种灵敏的应变指示计,在变形微弱的沉积岩地区尤为适用。在龙门山南段邛西断层转折褶皱不同构造部位选取48个采样点开展磁组构研究,分析断层转折褶皱的有限应变特征及区域构造变形机制。实验结果表明,邛西地区上白垩统中主要载磁矿物为高矫顽力的赤铁矿,背斜整体应变较弱,且存在3种类型的磁组构,以沉积磁组构和初始变形磁组构为主,铅笔状磁组构少见,主要存在于靠近褶皱中段的前翼部位,说明断层转折褶皱前翼较后翼和核部应变强,且中段地层应变较其他部位更为强烈。此外,各采样点磁线理的优势方位为近南北向(N10°E),表明邛西断层转折褶皱的形成与龙门山南段晚新生代近东西向的地壳水平缩短有关,暗示龙门山南段的最大主压应力方向在晚新生代存在转变的可能。 相似文献
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龙门山南段位于四川盆地以西,其新生代构造变形特征对于认识青藏高原东缘的变形机制具有一定的指示意义。磁组构是一种灵敏的应变指示计,在变形微弱的沉积岩地区尤为适用。在龙门山南段邛西断层转折褶皱不同构造部位选取48个采样点开展磁组构研究,分析断层转折褶皱的有限应变特征及区域构造变形机制。实验结果表明,邛西地区上白垩统中主要载磁矿物为高矫顽力的赤铁矿,背斜整体应变较弱,且存在3种类型的磁组构,以沉积磁组构和初始变形磁组构为主,铅笔状磁组构少见,主要存在于靠近褶皱中段的前翼部位,说明断层转折褶皱前翼较后翼和核部应变强,且中段地层应变较其他部位更为强烈。此外,各采样点磁线理的优势方位为近南北向（N10°E）,表明邛西断层转折褶皱的形成与龙门山南段晚新生代近东西向的地壳水平缩短有关,暗示龙门山南段的最大主压应力方向在晚新生代存在转变的可能。 相似文献
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川西前陆盆地中—新生代各构造层的残余厚度展布和沉积特征分析发现,四川克拉通周缘的前陆盆地在晚三叠世时期发育于龙门山山前,明显属于龙门山褶皱逆冲构造载荷所形成的前渊凹陷;侏罗纪早期的沉积地层呈面状分布,没有表现出显著的挠曲沉降,指示了一个构造相对平静的阶段;中侏罗世早期前渊凹陷迁移至龙门山北段和米仓山山前,前渊沉积从晚三叠世的北东向转换为近东西向,广泛的湖泊相沉积预示了前陆盆地的欠充填状态;中侏罗世中晚期,川西盆地沉降中心又迁移到大巴山山前,相应的挠曲变形又从近东西向转化为北西向,构成了大巴山的前渊凹陷;晚侏罗世—早白垩世时期,沉降中心再次回到米仓山山前,巨厚的前渊凹陷沉积指示了米仓山冲断带的主要活动时期;白垩纪末—古近纪的前渊凹陷则跃迁至雅安—名山地区。川西前陆盆地的同造山沉降中心以四川盆地中心为核心在西部和北部呈弧形迁移,沉积序列不断更替和叠加。中生界各构造层底界构造图显示现今的构造低部位位于川西北地区和川西南地区,在川西北地区均有东西走向的等值线分布,而川西南地区等值线走向则为北东-南西向。因此分析认为,晚侏罗世至早白垩世的构造变形可能控制了川西盆地现今的地层变形,形成了川西北地区的南北向构造挤压结构,而晚期的新生代构造变形则主要体现在川西盆地的西南部,形成北东-南西向的地层展布特征。 相似文献
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龙门山飞仙关断层传播褶皱磁组构特征及构造意义 总被引：3，自引：0，他引：3
沿龙门山南段冲断前锋带飞仙关断层传播褶铍剖面钻取了270个磁组构定向岩芯样品,对其进行了磁性矿物与磁组构分析。通过等温剩磁和三轴热退磁实验确定了样品中的主要载磁矿物为赤铁矿。磁组构测试结果显示27个采样点的磁组构为中间组构与构造组构两种类型。通过对各点磁组构特征及各项磁组构参数进行详细分析,再结合断层传播褶皱运动学模型,得出断层传播褶皱形成过程中岩石应变及磁组构演化：断层扩展前的平行层缩短作用把原始的沉积组构改造成为中问组构;在断层扩展过程中,两翼地层的旋转抬升产生的简单剪切作用对地层磁化率各向异性产生影响,使得校正的磁化率各向异性度Pj值局部升高,以及在剪切变形强烈的区域形成构造磁组构。 相似文献
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造山带和盆地是在时空发展和形成机制上具有密切联系的构造系统。青藏高原内部晚三叠世古特提斯造山带的形成,对北缘的塔里木盆地产生了重要的影响,导致了盆地内部西昆仑山前地区发生了强烈的冲断构造变形,而这一冲断构造变形所形成的古构造-古地貌对后期侏罗-白垩纪的沉积具有重要的控制作用,同时也决定了该地区的油气分布。本文基于对西昆仑山前露头区中生代地层分布详细的野外考察和盆地覆盖区钻井资料的整理,结合对盆-山结合带清晰地震剖面的详细解释,开展西昆仑山前的晚三叠世古构造特征及侏罗-白垩纪沉积充填过程研究,以期揭示晚三叠世的古构造-古地貌特征及对沉积的控制作用。通过研究发现,西昆仑山前地区发育晚三叠世前陆褶皱冲断带,冲断带根部发育基底卷入构造,锋带发育叠瓦状构造;古生界受逆冲断裂控制,形成一系列的北陡南缓的背斜隆起,冲断带前锋位置与新生代构造前锋位置相近。三叠纪末古地貌形态由于特提斯造山带的强烈隆升,总体呈南高北低的地貌形态,但是褶皱冲断构造带受地表风化剥蚀作用,背斜核部形成南缓北陡的古隆起,而断层破碎带形成南陡北缓的洼地,是侏罗系发育前的基本地貌格架。早侏罗世受特提斯造山带造山后伸展的影响,西昆仑山前发育4个箕状断陷,控陷断层发育于古造山带一侧;受大型控陷断层的影响,在断陷内部呈北高南低的地形特点,断陷内侏罗系逐渐向北部斜坡超覆。晚三叠世形成的古构造-古地貌与早侏罗世断陷叠加形成的古地理格架一直控制了侏罗纪-早白垩世的沉积,直到晚白垩世沉积时才没有起到控制作用。 相似文献
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塔西南新生代前陆盆地东段盆山结构与冲断带变形特征 总被引：1，自引：0，他引：1
塔西南新生代前陆盆地受西昆仑山造山带南北向挤压和帕米尔弧形构造带向北突进的影响,导致盆山结构与盆地冲断带构造变形在平行造山带方向表现出明显差异。本文通过地震资料解释,系统研究了塔西南新生代前陆盆地东段盆山结构与冲断带的构造变形特征,认为塔西南新生代前陆盆地东段盆山结构表现为西昆仑造山带向北大规模冲断,盆地区挠曲沉降,前陆地区发育宽的褶皱冲断带,冲断带前锋已扩展至捷得背斜一线,褶皱冲断带与前渊坳陷存在大范围重叠。盆地东段的褶皱冲断带在纵向上可以分为基底卷入变形带、滑脱变形带。山前第一排变形带受多期构造叠加影响,产生横向变形的分异:西段柯东段早期为构造楔形体变形形成的背斜构造,后期被甫沙–克里阳右行走滑断裂改造,剖面呈现复杂的变形特征;东段克里阳段构造变形以早期的逆冲推覆为主。结合生长地层与磁性地层分析,冲断带的变形总体表现出前展式的构造变形特征,上新世阿图什组沉积期开始形成柯东构造带;随后变形向北传播,在上新世早中期形成柯克亚构造带;至早中更新世晚期,构造变形扩展至固满–合什塔格构造带。 相似文献
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从川西龙门山前陆盆地上三叠统一侏罗系沉积纪录可以看出,早中侏罗世以后整个盆地地层构型为一个板状特征,但在其近造山带一侧的盆地边缘又有大量的冲积粗碎屑存在,砂砾质粗碎屑楔形体在早中侏罗世主要位于龙门山前缘中北段,而晚侏罗世一早白垩世则明显地向南西方向迁移,盆地在不同时期,不同部位和不同成分的砂砾质粗碎屑楔形体的时空展布显示物源迁移明显,这是龙门山造山带走滑作用沉积的产物。 相似文献
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《International Geology Review》2012,54(8):661-735
The Longmen Shan region includes, from west to east, the northeastern part of the Tibetan Plateau, the Sichuan Basin, and the eastern part of the eastern Sichuan fold-and-thrust belt. In the northeast, it merges with the Micang Shan, a part of the Qinling Mountains. The Longmen Shan region can be divided into two major tectonic elements: (1) an autochthon/parautochthon, which underlies the easternmost part of the Tibetan Plateau, the Sichuan Basin, and the eastern Sichuan fold-and-thrust belt; and (2) a complex allochthon, which underlies the eastern part of the Tibetan Plateau. The allochthon was emplaced toward the southeast during Late Triassic time, and it and the western part of the autochthon/parautochthon were modified by Cenozoic deformation. The autochthon/parautochthon was formed from the western part of the Yangtze platform and consists of a Proterozoic basement covered by a thin, incomplete succession of Late Proterozoic to Middle Triassic shallow-marine and nonmarine sedimentary rocks interrupted by Permian extension and basic magmatism in the southwest. The platform is bounded by continental margins that formed in Silurian time to the west and in Late Proterozoic time to the north. Within the southwestern part of the platform is the narrow N-trending Kungdian high, a paleogeographic unit that was positive during part of Paleozoic time and whose crest is characterized by nonmarine Upper Triassic rocks unconformably overlying Proterozoic basement. In the western part of the Longmen Shan region, the allochthon is composed mainly of a very thick succession of strongly folded Middle and Upper Triassic Songpan Ganzi flysch. Along the eastern side and at the base of the allochthon, pre-Upper Triassic rocks crop out, forming the only exposures of the western margin of the Yangtze platform. Here, Upper Proterozoic to Ordovician, mainly shallow-marine rocks unconformably overlie Yangtze-type Proterozic basement rocks, but in Silurian time a thick section of fine-grained clastic and carbonate rocks were deposited, marking the initial subsidence of the western Yangtze platform and formation of a continental margin. Similar deep-water rocks were deposited throughout Devonian to Middle Triassic time, when Songpan Ganzi flysch deposition began. Permian conglomerate and basic volcanic rocks in the southeastern part of the allochthon indicate a second period of extension along the continental margin. Evidence suggests that the deep-water region along and west of the Yangtze continental margin was underlain mostly by thin continental crust, but its westernmost part may have contained areas underlain by oceanic crust. In the northern part of the Longmen Shan allochthon, thick Devonian to Upper Triassic shallow-water deposits of the Xue Shan platform are flanked by deep-marine rocks and the platform is interpreted to be a fragment of the Qinling continental margin transported westward during early Mesozoic transpressive tectonism. In the Longmen Shan region, the allochthon, carrying the western part of the Yangtze continental margin and Songpan Ganzi flysch, was emplaced to the southeast above rocks of the Yangtze platform autochthon. The eastern margin of the allochthon in the northern Longmen Shan is unconformably overlapped by both Lower and Middle Jurassic strata that are continuous with rocks of the autochthon. Folded rocks of the allochthon are unconformably overlapped by Lower and Middle Jurassic rocks in rare outcrops in the northern part of the region. They also are extensively intruded by a poorly dated, generally undeformed belt, of plutons whose ages (mostly K/Ar ages) range from Late Triassic to early Cenozoic, but most of the reliable ages are early Mesozoic. All evidence indicates that the major deformation within the allochthon is Late Triassic/Early Jurassic in age (Indosinian). The eastern front of the allochthon trends southwest across the present mountain front, so it lies along the mountain front in the northeast, but is located well to the west of the present mountain front on the south. The Late Triassic deformation is characterized by upright to overturned folded and refolded Triassic flysch, with generally NW-trending axial traces in the western part of the region. Folds and thrust faults curve to the north when traced to the east, so that along the eastern front of the allochthon structures trend northeast, involve pre-Triassic rocks, and parallel the eastern boundary of the allochthon. The curvature of structural trends is interpreted as forming part of a left-lateral transpressive boundary developed during emplacement of the allochthon. Regionally, the Longmen Shan lies along a NE-trending transpressive margin of the Yangtze platform within a broad zone of generally N-S shortening. North of the Longmen Shan region, northward subduction led to collision of the South and North China continental fragments along the Qinling Mountains, but northwest of the Longmen Shan region, subduction led to shortening within the Songpan Ganzi flysch basin, forming a detached fold-and-thrust belt. South of the Longmen Shan region, the flysch basin is bounded by the Shaluli Shan/Chola Shan arc—an originally Sfacing arc that reversed polarity in Late Triassic time, leading to shortening along the southern margin of the Songpan Ganzi flysch belt. Shortening within the flysch belt was oblique to the Yangtze continental margin such that the allochthon in the Longmen Shan region was emplaced within a left-lateral transpressive environment. Possible clockwise rotation of the Yangtze platform (part of the South China continental fragment) also may have contributed to left-lateral transpression with SE-directed shortening. During left-lateral transpression, the Xue Shan platform was displaced southwestward from the Qinling orogen and incorporated into the Longmen Shan allochthon. Westward movement of the platform caused complex refolding in the northern part of the Longmen Shan region. Emplacement of the allochthon flexurally loaded the western part of the Yangtze platform autochthon, forming a Late Triassic foredeep. Foredeep deposition, often involving thick conglomerate units derived from the west, continued from Middle Jurassic into Cretaceous time, although evidence for deformation of this age in the allochthon is generally lacking. Folding in the eastern Sichuan fold-and-thrust belt along the eastern side of the Sichuan Basin can be dated as Late Jurassic or Early Cretaceous in age, but only in areas 100 km east of the westernmost folds. Folding and thrusting was related to convergent activity far to the east along the eastern margin of South China. The westernmost folds trend southwest and merge to the south with folds and locally form refolded folds that involve Upper Cretaceous and lower Cenozoic rocks. The boundary between Cenozoic and late Mesozoic folding on the eastern and southern margins of the Sichuan Basin remains poorly determined. The present mountainous eastern margin of the Tibetan Plateau in the Longmen Shan region is a consequence of Cenozoic deformation. It rises within 100 km from 500–600 m in the Sichuan Basin to peaks in the west reaching 5500 m and 7500 m in the north and south, respectively. West of these high peaks is the eastern part of the Tibetan Plateau, an area of low relief at an elevations of about 4000 m. Cenozoic deformation can be demonstrated in the autochthon of the southern Longmen Shan, where the stratigraphic sequence is without an angular unconformity from Paleozoic to Eocene or Oligocene time. During Cenozoic deformation, the western part of the Yangtze platform (part of the autochthon for Late Triassic deformation) was deformed into a N- to NE-trending foldandthrust belt. In its eastern part the fold-thrust belt is detached near the base of the platform succession and affects rocks within and along the western and southern margin of the Sichuan Basin, but to the west and south the detachment is within Proterozoic basement rocks. The westernmost structures of the fold-thrust belt form a belt of exposed basement massifs. During the middle and later part of the Cenozoic deformation, strike-slip faulting became important; the fold-thrust belt became partly right-lateral transpressive in the central and northeastern Longmen Shan. The southern part of the fold-thrust belt has a more complex evolution. Early Nto NE-trending folds and thrust faults are deformed by NW-trending basementinvolved folds and thrust faults that intersect with the NE-trending right-lateral strike-slip faults. Youngest structures in this southern area are dominated by left-lateral transpression related to movement on the Xianshuihe fault system. The extent of Cenozoic deformation within the area underlain by the early Mesozoic allochthon remains unknown, because of the absence of rocks of the appropriate age to date Cenozoic deformation. Klippen of the allochthon were emplaced above the Cenozoic fold-andthrust belt in the central part of the eastern Longmen Shan, indicating that the allochthon was at least partly reactivated during Cenozoic time. Only in the Min Shan in the northern part of the allochthon is Cenozoic deformation demonstrated along two active zones of E-W shortening and associated left-slip. These structures trend obliquely across early Mesozoic structures and are probably related to shortening transferred from a major zone of active left-slip faulting that trends through the western Qinling Mountains. Active deformation is along the left-slip transpressive NW-trending Xianshuihe fault zone in the south, right-slip transpression along several major NE-trending faults in the central and northeastern Longmen Shan, and E-W shortening with minor left-slip movement along the Min Jiang and Huya fault zones in the north. Our estimates of Cenozoic shortening along the eastern margin of the Tibetan Plateau appear to be inadequate to account for the thick crust and high elevation of the plateau. We suggest here that the thick crust and high elevation is caused by lateral flow of the middle and lower crust eastward from the central part of the plateau and only minor crustal shortening in the upper crust. Upper crustal structure is largely controlled in the Longmen Shan region by older crustal anisotropics; thus shortening and eastward movement of upper crustal material is characterized by irregular deformation localized along older structural boundaries. 相似文献
13.
Ruth Soto Antonio M. Casas-Sainz Juan J. Villalaín Beln Oliva-Urcia 《Tectonophysics》2007,445(3-4):373-394
In this work we analyse and check the results of anisotropy of magnetic susceptibility (AMS) by means of a comparison with palaeostress orientations obtained from the analysis of brittle mesostructures in the Cabuérniga Cretaceous basin, located in the western end of the Basque–Cantabrian basin, North Spain. The AMS data refer to 23 sites including Triassic red beds, Jurassic and Lower Cretaceous limestones, sandstones and shales. These deposits are weakly deformed, and represent the syn-rift sequence linked to basins formed during the Mesozoic and later inverted during the Pyrenean compression. The observed magnetic fabrics are typical of early stages of deformation, and show oblate, triaxial and prolate magnetic ellipsoids. The magnetic fabric seems to be related to a tectonic overprint of an original, compaction, sedimentary fabric. Most sites display a NE–SW magnetic lineation that is interpreted to represent the stretching direction of the Early Cretaceous extensional stage of the basin, without recording of the Tertiary compressional events, except for sites with compression-related cleavage.Brittle mesostructures include normal faults, calcite and quartz tension gashes and joints, related to the extensional stage. The results obtained from joints and tension gashes show a dominant N–S to NE–SW, and secondary NW–SE, extension direction. Paleostresses obtained from fault analysis (Right Dihedra and stress inversion methods) indicate NW–SE to E–W, and N–S extension direction. The results obtained from brittle mesostructures show a complex pattern resulting from the superposition of several tectonic processes during the Mesozoic, linked to the tectonic activity related to the opening of the Bay of Biscay during the Early Cretaceous. This work shows the potential in using AMS analysis in inverted basins to unravel its previous extensional history when the magnetic fabric is not expected to be modified by subsequent deformational events. Brittle mesostructure analysis seems to be more sensitive to far-field stress conditions and record longer time spans, whereas AMS records deformation on the near distance, during shorter intervals of time. 相似文献
14.
龙门山造山带早期断裂活动的古地震制约——来自汶川科钻(WFSD)岩心的证据 总被引：2，自引：0，他引：2
强地震是断裂活动的表现形式,可以诱发地表沉积层序顶部未固结的软沉积物发生变形,形成新的变形层(即震积岩***)。因此,在连续沉积剖面中赋存的多层震积岩应是断裂活动的直接证据。川西前陆盆地中的软沉积物变形记载了龙门山断裂带的活动信息,对认识龙门山造山带演化历史具有重要意义。本文通过"汶川地震断裂带科学钻探"一号孔(WFSD-1)和三号孔(WFSD-3)连续岩心剖面的岩性分析和构造研究,识别出11段不同深度的液化角砾岩层,它们是地震触发成因的软沉积物变形岩层。11个液化角砾岩段厚度从~20m至102m不等,分布在晚三叠世须家河组二-五段。这些液化角砾岩层记录了龙门山前陆盆地形成过程中晚三叠世断裂活动特征及趋势。这些厚度不等的震积岩粗略指示约2~20万年的地震活动长周期(地震幕),以及约4至70万年的间震期(地震幕的间隔时间),反映了龙门山断裂早期脉动式(幕式)活动特征。从不同段液化角砾岩层分布间隔规律来看,地震活跃期间隔(即间震期)越来越短,显示龙门山造山带断裂活动越来越强的趋势。结合前人地表软沉积物变形研究,我们认为龙门山造山带在晚三叠世经历了多期次的正断-逆冲活动的造山作用(至少经历14个地震活跃期),形成龙门山雏形及前陆盆地。 相似文献
15.
上扬子克拉通北部晚古生代-中三叠世的沉积盆地是在勉-略洋盆南侧发展起来的被动大陆边缘盆地, 在泥盆纪-中二叠世以稳定沉降为主, 向北以碳酸盐岩缓坡与台地向勉略洋盆过渡; 中二叠世末期受峨眉地裂运动影响形成隆坳相间的格局; 早-中三叠世构造体制由伸展变为挤压, 沉积建造由开阔海碳酸盐岩台地逐渐向半局限台地、半封闭海湾膏盐湖相以及陆相碎屑岩含煤岩系过渡.该陆缘盆地经历了晚三叠世上扬子北缘前陆盆地、中侏罗世-早白垩世川西、川北前陆盆地, 以及晚白垩世至今构造残留盆地的改造.其中, 晚三叠世须三-须六期上扬子北缘前陆盆地的前缘隆起大致沿汶川、剑阁和万源一线分布.热年代学分析结果表明, 汶川、剑阁和万源一线以南的上二叠统烃源岩在早中生代始终处于埋藏增温状态, 只是自晚白垩世才进入抬升降温阶段, 呈"同代"烃源岩的特征; 而汶川、剑阁和万源一线以北的龙门山、米仓山和大巴山山前冲断地区, 上二叠统烃源岩则围绕生烃窗经历了多次增温和降温过程, 热演化历史复杂, 呈"隔代"烃源岩的特征.因此, 对于上扬子克拉通北部晚古生代-中三叠世陆缘盆地的勘探, 汶川、剑阁和万源一线以南比其北侧更有利. 相似文献