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1.
西南天山造山带与前陆盆地系统 总被引：8，自引：0，他引：8
对比了前陆盆地与前陆盆地系统两个概念, 阐述了前陆盆地系统的基本含义, 引用这一概念分析和对比了库车前陆盆地与西南天山造山带及造山带内“卫星式”盆地的沉积、构造等特征。认为前陆盆地、造山带及造山带内“卫星式”沉积盆地三者之间是相关联的,造山带内的“卫星式”沉积盆地是前陆盆地系统楔顶的延伸部分, 受造山带的影响, 造山楔内不同部位沉积的楔顶存在明显的差异, 针对南天山“卫星式”沉积盆地而言, 尤尔都斯盆地的构造、沉积特征明显不同于焉耆盆地 相似文献
2.
西准噶尔吾尔喀什尔山与额敏盆地间的"盆"–"山"耦合关系清楚,盆地边界平行于造山带呈狭长带状展布。"山"区为志留系–石炭系海相陆源碎屑岩-火山岩沉积组合,"盆"区为二叠系陆相磨拉石与新近系红色砂砾岩及第四系河流阶地堆积,具有典型的海相-陆相双层结构。盆缘被巴尔雷克前陆冲断带围限,"山"区发育铲式逆冲断层与蛇头构造、叠瓦扇构造等逆冲推覆构造。表明该"盆"–"山"组合为一典型的前陆盆地系统。额敏前陆盆地形成于早二叠世,属后期冲断变形影响较弱、早期前陆盆地结构特征较明显的"早衰型"前陆盆地。这一成果为额敏盆地乃至西准噶尔盆地分析、构造演化、沉积作用、"盆"–"山"耦合等研究提供了重要信息。 相似文献
3.
库车前陆盆地前渊带层序地层分析--以白垩系卡普沙良群为例 总被引：9，自引：4，他引：5
库车前陆盆地的白垩系由卡普沙良群(自下而上包括亚格列木组、舒善河组、巴西盖组)和巴什基奇克组组成.盆地北部克孜勒努尔沟的白垩系亚格列木组和巴什基奇克组底部均发育一大套泥石流沉积,表明白垩系卡普沙良群为一期构造活动幕的产物,为一个完整的二级层序,根据沉积演化特征可将其细分为7个三级层序.亚格列木组与舒善河组之间,扇三角洲平原相突变为滨浅湖相沉积,且舒善河组滨岸沙坝微相持续稳定发育,反映前陆盆地楔顶带的发育抑制了构造活动期源于造山带的粗碎屑的供给,使前渊带的沉积物供给速率趋于稳定.此外,克孜勒努尔沟卡普沙良群地层厚度远大于前缘隆起带,与上、下地层呈整合或平行不整合接触.研究表明,克孜勒努尔沟卡普沙良群为一套临近造山带的前渊带沉积. 相似文献
4.
三叠纪充填的一套碳酸盐岩—碎屑岩地层,被划分为两个超层序和5个层序单元。超层序Ⅰ以复理石建造为特征,是金沙江缝合带初始碰撞作用的产物,是唐古拉山地区三叠纪前陆盆地早期挠曲沉降构造活动的沉积响应,标志着晚三叠世诺利期前陆盆地业已形成;超层序Ⅱ以磨拉石与酸性火山岩建造为特征,是前陆盆地晚期冲断抬升构造演化的沉积响应,表明晚三叠世瑞替期来自造山带的沉积物开始越过前陆隆起向隆后盆地迁移。 相似文献
5.
龙门山前陆盆地底部不整合面: 被动大陆边缘到前陆盆地的转换 总被引：4，自引：3，他引：1
晚三叠世龙门山前陆盆地是在扬子板块西缘被动大陆边缘的基础上由印支造山运动而形成的,盆地中地层充填厚度巨大,包括晚三叠世卡尼期至瑞提期的马鞍塘组、小塘子组和须家河组,持续时间达20Myr,显示为1个以不整合面为界的构造层序。位于晚三叠世龙门山前陆盆地构造层序与下伏古生代-中三叠世被动大陆边缘构造层序之间的不整合面属于龙门山前陆盆地的底部不整合面,标志了扬子板块西缘从被动大陆边缘盆地到前陆盆地的转换。该底部不整合面位于晚三叠世马鞍塘组与中三叠世雷口坡组之间,显示为平行不整合面或角度不整合面,在接触面上发育冲蚀坑、古喀斯特溶沟、溶洞、溶岩角砾、古风化壳的褐铁矿、黏土层及石英、燧石细砾岩等底砾岩。该不整合面向南东方向不断地切削下伏地层,且均发育岩溶风化面,上覆的晚三叠世地层沿不整合面向南东超覆,显示了从整合面到不整合面的变化过程,并随着逆冲楔的推进向南东方向迁移,其超覆线、侵蚀带和相带的走向线与龙门山冲断带的走向大致平行。底部不整合面显示为典型的前陆挠曲不整合面,标志着龙门山前陆盆地的形成和扬子板块西缘挠曲下降和淹没过程,底部为古喀斯特作用面,下部为碳酸盐缓坡和海绵礁建造,上部为进积过程中形成的三角洲沉积物,具有向上变粗的垂向结构,表明底部不整合面和前缘隆起的抬升是扬子板块西缘构造负载的挠曲变形的产物,显示了在卡尼期松潘-甘孜残留洋盆的迅速闭合和逆冲构造负载向扬子板块的推进过程。本次在对晚三叠世龙门山前陆盆地底部不整合面的风化壳、残留厚度、地层缺失、剥蚀厚度、地层超覆等研究的基础上,计算了底部不整合面迁移速率、前缘隆起迁移速率、地层上超速率和前缘隆起的剥蚀速率,并与逆冲楔推进速率进行了对比,结果表明,底部不整合面迁移速率、前缘隆起的迁移速率、地层上超速率均介于3~18mm·a-1之间,其与逆冲楔推进速率(5~15mm·a-1)相似,因此,可用底部不整合面迁移速率、前缘隆起的迁移速率和地层上超速率代表逆冲楔推进速率。但是前缘隆起的剥蚀速率很小,介于0.02~0.08mm·a-1之间,仅为逆冲楔推进速率的1/100。 相似文献
6.
Late Cretaceous to early Miocene deposits of the Carpathian foreland basin in southern Moravia 总被引：1，自引：1，他引：0
The Late Cretaceous to Early Miocene strata of the Carpathian foreland basin in southern Moravia (Czech Republic) are represented
by a variety of facies which reflects the evolution of the foreland depositional system. However, because of the intensive
deformation and tectonic displacement and the lack of diagnostic fossils the stratigraphic correlation and paleogeographic
interpretation of these strata are difficult and often controversial. In order to better correlate and to integrate them into
a broader Alpine–Carpathian foreland depositional system, these discontinuous and fragmentary strata have been related to
four major tectonic and depositional events: (a) formation of the Carpathian foreland basin in Late Cretaceous which followed
the subduction of Tethys and subsequent deformation of the Inner Alps-Carpathians; (b) Middle to Late Eocene transgression
over the European foreland and the Carpathian fold belt accompanied by deepening of the foreland basin and deposition of organic-rich
Menilitic Formation; (c) Late Oligocene to Early Miocene (Egerian) uplifting and deformation of inner zones of the Carpathian
flysch belt and deposition of Krosno-type flysch in the foreland basin; and (d) Early Miocene (Eggenburgian) marine transgression
and formation of late orogenic and postorogenic molasse-type foreland basin in the foreland. These four principal events and
corresponding depositional sequences are recognized throughout the region and can be used as a framework for regional correlation
within the Alpine–Carpathian foreland basin.
Received: 18 August 1998 / Accepted: 9 June 1999 相似文献
7.
The Late Triassic Sequence-Stratigraphic Framework of the Upper Yangtze Region, South China 总被引：1，自引：0，他引：1
In the transitional period between the Middle and the Late Triassic, the Indochina orogeny caused two tectonic events in South China: (1) the formation and uplift of the Qinling-Dabie orogenic belt along the northern margin of the South China Plate, due to its collision with the North China Plate; and 2) the development of a 1300-km-wide intra-continental orogen in the southeastern part of the South China Plate, which led to a northwestward movement of the foreland thrust-fold zone. These tectonic events resulted in the ending of the Yangtze Platform, and were a stable paleogeographic factor from the Eidacaran to the end of the Middle Triassic. This platform was characterized by the widespread development of shallow-water carbonates. After the end of the Yangtze Platform, the upper Yangtze foreland basin (or Sichuan foreland basin) was formed during the Late Triassic and became a accumulation site of fluvial deposits that are composed of related strata of the Xujiahe Formation. In western Sichuan Province, the Xujiahe Formation overlies the Maantang Formation shallow-water carbonate rocks of the Xiaotangzi Formation siliciclastic rocks (from shelf shales to littoral facies). The sequence-stratigraphic framework of the Upper Triassic in the upper Yangtze foreland basin indicates a particular alluvial architecture, characterized by sequences composed of (1) successions of low-energy fluvial deposits of high-accommodation phases, including coal seams, and (2) high-energy fluvial deposits of low-accommodation phases, including amalgamated river-channel sandstones. The spatial distribution of these fluvial deposits belonging to the Xujiahe Formation and its relative strata is characterized by gradual thinning-out, overlapping, and pinching-out toward both the east and south. This sedimentary record therefore expresses a particular sequence-stratigraphic succession of fluvial deposits within the filling succession of the foreland basin. The sequence-stratigraphic framework for the Upper Triassic in the Upper Yangtze region provides a record of the end of the Yangtze Platform and the formation of the upper Yangtze foreland basin. 相似文献
8.
宁夏中南部中新世构造活动的地质证据及其意义 总被引：3，自引：0，他引：3
通过区域性新生界的对比及不整合面分布的研究,发现宁夏地区中新世曾发生过两次构造运动,一次发生于早中新世,另一次发生于中中新世晚期,但以后者明显,分布也最广。其中前者集中在六盘山以西地区,后者分布在查汗布拉格—三关口—青铜峡—固原(查-固)断裂沿线。宁夏中北部大部分红柳沟组是在受中新世构造运动影响的环境下沉积的。发生于早中新世的构造运动集中体现在六盘山以西的地区和甘肃部分地区,该期运动使渐新统清水营组变形,由于这些现象多发生于海原断裂附近,因此推测在早中新世海原断裂就可能已活动了。而发生于中中新世晚期的运动体现在如下几个方面,在贺兰山中南段西侧发现了中中新世晚期的逆冲推覆活动,堆积了厚度较大的同构造沉积(红柳沟组);在查-固断裂沿线发现了由于中中新世晚期的构造活动而形成的红柳沟组与清水营组之间的角度不整合面,这些说明在该期青藏高原的变形前锋已到达查-固断裂,也就是鄂尔多斯西缘地区,早新生代盆地因此解体;与此同时盆地内部红柳沟组向上逐渐变粗,也说明中中新世晚期较强烈的构造运动已影响到了该区,香山地区开始隆起并分割了早先的盆地,使之成为背驮盆地。宁夏中南部并入到青藏高原东北缘逆冲构造楔之中,该逆冲构造楔中新世向北东扩展的原因可能是由于高原北部在同期显著的隆升运动使得逆冲楔顶角超过临界值,而向前扩展的,查-固断裂是早期类似于目前海原断裂的青藏高原变形前缘,整个高原东北部的扩展并不是前展式,而是一种没有特定顺序的变形。上述这些现象否定了前人认为宁夏地区第三系的变形发生在上新世末期—更新世以后的观点。 相似文献
9.
中国中西部中、新生代前陆盆地与挤压造山带耦合分析 总被引：69，自引：8，他引：61
中国中西部主要由中、新生代造山带与中、新生代盆地构成盆山格局 :秦岭造山带与南北两侧四川盆地与鄂尔多斯盆地 ;天山造山带与南北两侧塔里木盆地与准噶尔盆地 ;哀牢山造山带与东西两侧楚雄盆地与兰坪思茅盆地等 ,总体上构成盆山耦合。根据挤压造山带类型与前陆盆地类型 ,可以划分出 3种耦合类型 ,即 ( 1)碰撞造山带与周缘前陆盆地 ,( 2 )俯冲造山带与弧后前陆盆地及 ( 3)再生造山带与再生前陆盆地。因此前陆盆地是伴随着造山带的形成与演化而发育 ,造山带断滑系统直接控制前陆盆地结构、沉积层序及构造样式等 ,从而制约前陆盆地油气分布的有序性 相似文献
10.
新生代龙门山前盆地和盐源盆地是青藏高原东缘龙门山－锦屏山冲断带内及前缘地区发育和保存最好的新生代沉积盆地，本次以地层不整合面和ESR测年资料为主要依据，将该区新生代构造地层序列划分为5个构造层序，即TS1（65－55Ma)、TS2(40-50Ma)、TS3（23－16Ma)、TS4(4．7-1.6Ma)和TS5（0．74－0Ma)，据此将青藏高原东缘新生代构造变形和隆升事件划分为5期，其中TS1与喜马拉雅地体和拉萨地体拼合事件相关，TS2与印亚碰撞事件相关，TS3与青藏高原第一次隆升事件相关，TS4与青藏高原第二次隆升事件相关，TS5与青藏高原第三次隆升事件相关。 相似文献
11.
侏罗纪是大别造山带与周缘盆地盆山关系研究的一个重要时期,分布在大别造山带周缘的侏罗纪地层为大别山的造山过程以及深俯冲岩石的折返、剥蚀提供了很好的约束。本文选取大别造山带东南缘安庆月山地区侏罗系磨山组为研究对象,对磨山组碎屑岩进行了详细的粒度分析、碎屑组分分析、重矿物分析和碎屑锆石年代学分析。碎屑岩岩石、沉积特征和粒度分析都指示早侏罗世磨山组为三角洲前缘水下分流河道沉积。碎屑组分分析、重矿物分析结合碎屑锆石年代学分析指示磨山组碎屑岩物源主要来自南侧的华南板块,大别造山带宿松杂岩可能为其提供了少量物源,但碎屑物源中未见石榴子石和典型的三叠纪变质锆石,说明此时大别高压-超高压榴辉岩可能仍未折返至地表。 相似文献
12.
湘西地区志留纪沉积体系及典型前陆盆地的形成模式研究 总被引：5，自引：0，他引：5
湘西地区发育志留系中、下志留统碎屑岩地层,缺失上志留统。经沉积学综合研究,可以划分出滞留盆地、浊积扇、三角洲、潮坪滨岸等沉积体系,从下向上海平面逐渐下降,其物源来自于东南部雪峰隆起。湘西地区志留纪沉积盆地构造演化经历了前陆盆地的形成期、发展期及萎缩期、消亡期几个阶段。其沉积构造演化规律为：前陆盆地初始形成期发育深水滞留盆地沉积体系;前陆盆地发展期发育海相浊积扇沉积体系;前陆盆地萎缩期发育三角洲沉积体系,前陆盆地消亡期发育潮坪沙坝滨岸沉积体系。 相似文献
13.
THE MESOZOIC QIANGTANG FORELAND BASIN IN QINGHAI—XIZANG PLATEAU,CHINANationalKeyFundamentalResearchProjects(973) (G1990 40 80 15 ) ;NSFCGeneralProjects(4980 2 0 13) 相似文献
14.
Along the Caledonian front in central Scandinavia, the expected peripheral or pro-foreland basin is neither physically present nor are there any significant traces in the sedimentary record. In order to explain and quantify this situation, the authors assess the major geometric and mechanical constraints on the Caledonian orogenic wedge and model the orogenic load and its influence on the foreland lithosphere of Baltica. Geologic and geophysical data show a strong foreland lithosphere with a flexural parameter (α) of approximately 100 km. The shape of the orogenic wedge and its critical taper angle are dependent mainly on basal friction and wedge strength. In the external part organic-rich black shales provide a low-friction horizon both at the basal detachment surface and within the wedge itself. The more internal part of the wedge is composed of metamorphic and crystalline rocks, which cooled and strengthened prior to thrusting. As a result, the external part of the wedge had a lower strength and a smaller critical taper angle than its internal part, so the orogenic load is upward concave. Modelling of the effect of such a load on the Baltica lithosphere shows a very small depression in front of the load (2 km). The flexural depression produced by the main part of the orogenic load is filled up by the thickening thrust-and-fold belt, so that there is little space left for a foreland basin. These results imply that the missing foreland basin in front of the central Scandinavian Caledonides is not due to subsequent erosion, but is a primary feature. 相似文献
15.
《地学前缘(英文版)》2023,14(3):101527
Songliao Basin, the largest Mesozoic intracontinental nonmarine basin in eastern China, initiated during the latest Jurassic as a backarc extensional basin; rifting failed and thermal cooling controlled subsidence through the early Late Cretaceous. Integrating 2-D and 3D reflection seismic and borehole data with regional geological studies, we interpret sedimentary sequence and structural patterns of the Coniacian-Maastrichtian fill of Songliao Basin as defining a retroforeland basin system developed after 88 Ma (marked by the T11 unconformity in the basin), including (1) significant increase in the thickness of the Nenjiang Formation eastward towards orogenic highlands of the Zhangguangcai Range and the convergent continental margin; (2) a shift of detrital provenance in the basin from north to southeast; and (3) propagation of E-W shortened structures, increasing eastward in amplitude, frequency, and degree of inversion toward the orogen. During latest Cretaceous, foreland basin fill progressively deformed, as the foredeep evolved to a wedge-top tectonic setting, marked by the basin-wide T04 unconformity within the upper Nenjiang Formation at 81.6 Ma. Much of the basin was brought into the orogenic wedge and eroded by the end of the Cretaceous. Late Jurassic/Early Cretaceous backarc rifting of uncratonized basement comprised of accreted terranes likely facilitated and localized the foreland. Synrift normal faults reactivated and extensively inverted as thrust faults are prominent in the eastern 1/3 of the basin, whereas folds developed above detachments in shaley early post-rift strata dominate the western 2/3 of the basin. Songliao foreland development likely was driven by changing plate dynamics and collision along the Pacific margin after 88 Ma. 相似文献
16.
内蒙古苏尼特左旗晚泥盆世弧背前陆盆地的发现及构造意义 总被引：2，自引：2，他引：0
兴蒙造山带位于中亚造山带东段,是研究地壳生长与古亚洲洋演化的热点区域。内蒙古中部苏尼特左旗地区位于兴蒙造山带中段,区内分布的上泥盆统色日巴彦敖包组磨拉石建造是古亚洲洋闭合的重要证据之一,前人对其岩石组合、地层层序与沉积环境进行了报道,并指出其属于晚泥盆世的前陆盆地,但未就前陆盆地的属性、分类及其与造山带的空间关系展开详细研究。因此,本研究选择该区东北部的昌特敖包剖面,利用野外实测、锆石U-Pb同位素定年、沉积相分析等方法查明该碎屑沉积的地层层序、形成时代与物质来源,在此基础上补充完善了兴蒙造山带北造山带二级构造单元的划分方案。研究结果表明,昌特敖包剖面碎屑沉积属上泥盆统色日巴彦敖包组,而非前人认为的二叠纪大石寨组地层,其碎屑物质主要来自南部的宝力道岛弧与北部兴安-爱力格庙地块。沉积环境分析表明昌特敖包剖面色日巴彦敖包组主要为冲积扇相沉积,上部过渡到干旱气候火山活动背景下的滨浅海相沉积。综合昌特敖包剖面的沉积、年代、物源及大地构造位置特征,可以推断其代表晚泥盆世造山带的弧背前陆盆地。由此,苏尼特左旗地区北造山带的构造单元在前人划定的前陆变形带、混杂带、周缘前陆盆地、岛弧岩浆岩、同碰撞花岗岩以北,还存在弧背前陆盆地。本研究结果为恢复中亚造山带的构造演化过程提供了关键沉积学证据。 相似文献
17.
ZHOU Xiaohu HU Xiumian JIANG Ren GAO Tianshan MA Xue XING Guangfu SUN Gaoyuan SHU Xujie ZHAO Xilin 《《地质学报》英文版》2020,94(4):1138-1158
The Neoproterozoic Jiangnan orogen plays an important role in the study of the Precambrian tectonic evolution of South China. The tectonic nature of the Neoproterozoic sedimentary basins is still controversial, due to poor understanding of the sedimentary sequences and the lack of geochronological data. Here, we present sedimentological, provenance and geochronological data from the Heshangzhen Group in the eastern Jiangnan orogen. Sedimentological analysis shows that the Luojiamen Formation was deposited in a submarine fan, and the overlying Hongchicun Formation was deposited in front of a fan delta. The youngest detrital zircons constrain the lower Luojiamen and Hongchicun formations with ages of 827.3 ± 8.4 Ma and 825 ± 12 Ma, respectively. The sandstones of the Luojiamen Formation are characterized by a large number of intermediate to felsic volcanic grains, suggesting a volcanic arc source. In contrast, quartz and sedimentary lithic grains increase in the Hongchicun Formation, showing a new input from a collisional orogenic source. Detrital zircon from six sandstone samples in the Luojiamen and Hongchicun formations yield similar age spectra of 930–820 Ma with a peak at ca. 845–860 Ma, with one main cluster at 930–820 Ma. Detrital zircons of 930–845 Ma show a positive value of εHf(t)(+2.4 to +11, mean +7.6), which is similar to the volcanic arc of the nearby Shuangxiwu Group. There are a minor group of zircons with U-Pb ages ranging from 820 Ma to 845 Ma from the middle part of the Luojiamen Formation and Hongchicun Formation, with εHf(t) values between-20 to +2.4, which are consistent with the characteristics of the Shuangqiaoshan Group. within light of the bidirectional paleocurrents in the Luojiamen Formation, it is speculated that the zircons of 820–845 Ma were recycled from the Shuangqiaoshan Group, which is derived from a continental arc to the northwest. Our data suggests that the Luojiamen Formation was formed in an inter-arc basin, while the Hongchicun Formation was formed in an accretionary wedge-top basin. When juxtaposed with the conglomeratic characteristics at the bottom of the Luojiamen Formation, it is believed that the unconformity represented by the ‘Shen Gong Movement' reflects the rapid erosion and accumulation process of island arc volcanic material. The disconformity between the Luojiamen and Hongchicun formations is the imprint of transition from inter-arc basin to accretionary wedge-top basin,which represents the collision between the Shuangxiwu arc and the Yangtze Plate. 相似文献
18.
前陆克拉通与造山带增生楔在地壳结构、力学性质等方面有明显的差异。挤压作用使盆山地壳横向变化通过构造变形表现出来。本文设计了具有深浅两个滑脱层"克拉通"与不同能干性的"造山楔"接触砂箱模型,通过模拟实验分析了盆山地壳横向差异变化对挤压构造变形的影响。实验结果表明,端部的挤压收缩位移由刚性的"克拉通"推挤相对软弱的"造山楔"使之形成挤压"冲起构造",而"造山楔"发生收缩变形的同时也斜向推挤刚性的"克拉通",并通过克拉通内部的滑脱层将收缩应变向克拉通内部传递。受不同深度滑脱层发育的影响,"克拉通"发育分层不协调收缩变形。在挤压作用下,随着"造山楔"与"克拉通"地壳在横向上能干性差异的增加,"造山楔"收缩形成的"冲起构造"幅度减小,而向"克拉通"侧向(斜向)挤压形成的"反冲构造"幅度增加,"造山楔"通过深层滑脱层向"克拉通"传递收缩应变的调节能力减弱,通过浅层滑脱层向"克拉通"传递收缩应变的调节能力增强。"造山楔"由深层过渡至浅层形成强变形带,由"克拉通"边缘至内部形成的深层冲断褶皱与浅层褶皱冲断组合过渡为深层褶皱与浅层的褶皱冲断组合,"克拉通"边缘的冲断带由深层的前展式楔状逆冲叠瓦扇构造向"克拉通"内部的浅层褶皱组合过渡。实验结果为理解中国西北部复杂山前冲断带构造的形成机制具有启示作用。 相似文献
19.
下扬子地区从晚奥陶世开始沉积特征发生了明显转变,从浅海相转变为三角洲相沉积.这一沉积特征转变与早古生代晚期经历的强烈造山事件密切相关.通过下扬子地区晚奥陶世到志留纪沉积序列的沉积学和碎屑锆石年代学研究,揭示沉积盆地的性质及其时空演化过程,探讨沉积盆地发育与造山带隆升剥蚀之间的关系.下扬子地区早古生代晚期沉积学特征从东南向西北岩性由岩屑砂岩变为石英砂岩,粒度由粗粒变为细粒;沉积厚度等值线具有明显的不对称性,靠近东南等值线密,且沉积厚度大;往西北等值线稀疏,且沉积厚度小;沉积中心呈狭长带状分布,并从东南向西北方向迁移;具有前陆盆地的沉积特征.上奥陶统到中志留统的碎屑锆石以900～720Ma的年龄为主,指示物源以下伏新元古代晚期裂谷层序为主;从早志留世高家边组开始,450～420Ma碎屑锆石年龄出现并逐渐增多,表明同造山岩浆岩被剥露地表并开始提供物源;碎屑锆石中没有出现明显的代表华夏地块基底1.9～1.7Ga的特征年龄峰值,表明华夏地块不是下扬子地区早古生代晚期前陆盆地的主要物源区.下扬子地区前陆盆地从晚奥陶世开始沉降,晚奥陶世的构造沉降速率超过了沉积物的供给速率,前渊沉积了巨厚的浅海相泥岩夹粉砂岩和砂岩;晚奥陶世末造山带持续隆升并向西北方向扩展,沉积速率加快,沉积物粒度明显变粗,沉积相也由浅海相转变成三角洲前缘相;早志留世开始埋深较大的同造山岩浆岩开始遭受剥蚀,导致前陆盆地中450～420 Ma的碎屑锆石含量明显增加. 相似文献
20.
前陆盆地由于其独特的构造和沉积背景形成不同的层序地层格架样式.以准噶尔盆地车排子地区为例,详细分析了造山带前缘隆起斜坡带层序样式.在准西车排子地区中新生界主要目的层段(下白垩统吐谷鲁群、古近系安集海河组、新近系沙湾组和塔西河组)充填沉积中识别出5条主要等时界面,据界面的性质和级别划分出一级层序2个,二级层序组3个,三级层序4个.受前陆盆地造山带前缘隆起斜坡带独特的沉积背景及多幕逆冲构造活动作用过程的控制,准西车排子地区中新界各三级层序具有二元沉积结构特征,仅发育低位和湖扩体系域.逆冲挤压期发育低位粗碎屑沉积,应力松弛期发育湖扩细碎屑沉积.低位下切谷、大型扇三角洲和湖扩滩坝砂是准西车排子地区的有利储集砂体及勘探目标. 相似文献