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1.
The stream profiles of rivers of northern Chile reveal two graded segments separated by 20‐km‐long knickzones. Their formation was initiated in the Late Miocene in response to surface uplift of the western flank of the Altiplano. This phase of uplift that was coeval with the shift of deformation from the Altiplano to the sub‐Andean zone caused relief to grow at the scale of the whole drainage basin. Above and beneath these knickzones, the presence of braided channels and the absence of erosion on adjacent pediplains suggest no substantial modification in the local relief. The knickzones, however, show bedrock channels, and fluvial dissection rates have exceeded erosion rates on adjacent pediplains by two orders of magnitudes. Hence, the data imply that the only geomorphic recorders of relief growth are the knickzones that currently transpose the effects of the Late Miocene phase of surface uplift from the coast to the Altiplano.  相似文献   

2.
裂变径迹测年技术用于确定伸展山脉的隆升时间, 进而可以研究伸展构造的演化规律。 对采自鲁西隆起中部莲花山的 9 个样品进行了磷灰石/锆石裂变径迹分析, 结合已有数据分析鲁西隆起的抬升史。 结果表明莲花山晚白垩世以来经历了两期抬升剥露过程, 一次是在晚白垩世—古新世初期 86~60 Ma, 抬升速率为 0.019 mm/yr, 另一次是在中始新世 44~38 Ma, 抬升速率为 0.10 mm/yr。 因此, 莲花山晚白垩世以来经历了加速抬升剥露过程。 综合研究认为, 鲁西隆起山脉晚白垩世以来具有自南而北、由东向西的差异抬升规律, 且最早可能始于早白垩世。 这种迁移规律受控于早白垩世以来太平洋板块俯冲方向和速度, 以及郯庐断裂带的走滑性质和强度的变化。  相似文献   

3.
郭超  张志勇  吴林  项敦峰  王楠  肖文交 《地球科学》2022,47(9):3417-3430
天山造山带中新生代快速剥露对于了解天山构造演化过程意义重大.然而,人们对于中新生代精确的冷却时间还一直存在争议.本文报道了塔里木盆地北缘库车河剖面中生界砂岩中碎屑磷灰石裂变径迹数据和早二叠世流纹岩热史演化模拟结果. 热年代学年龄趋势显示碎屑磷灰石裂变径迹的主要年龄组分为143.0~148.9 Ma和35.7~38.1 Ma,其中较年轻的组分已经完全重置,揭示了库车坳陷的剥露信息. 热史模拟结果显示了160~140 Ma的快速冷却事件. 结合库车河剖面前人的碎屑锆石U-Pb和重矿物数据,笔者认为欧亚南缘拉萨地体的拼贴是通过刚性的塔里木将挤压应力传递至天山,导致其在晚侏罗世?早白垩世强烈隆升剥蚀,大量碎屑被搬运沉积在塔里木盆地北缘,造成库车坳陷中广泛发育的早白垩世亚格列木组砾岩及其与晚侏罗世地层之间的角度不整合. 在欧亚板块南缘多块体持续拼贴的远程效应下,天山经历始新世快速隆升变形,变形持续向南扩展,导致库车坳陷在晚始新世遭受变形和抬升.   相似文献   

4.
中新生代天山隆升及其南北盆地分异与沉积环境演化   总被引:5,自引:2,他引:3  
明确中生代以来天山隆升的时间顺序、隆升范围,及其与南北两侧盆地的沉积环境演化之间的关系,是天山两侧准噶尔盆地、吐哈盆地与塔里木等盆地原型恢复研究的重要需求。通过分析天山南北主要盆地类型、沉积充填、古气候变化,物源属性、边缘相带迁移反映的物源区远近变化与古水流特征,以及大量磷灰石裂变径迹测年数据认为,中新生代天山主要存在晚三叠世-早侏罗世、晚侏罗世-早白垩世、晚白垩世-始新世、中新世-第四纪的四期阶段隆升。在此基础上,编制了早侏罗世早期-第四纪的天山隆升范围及其南北盆地的沉积环境演化图,表明天山的四阶段隆升控制了北疆与南疆盆地由早、中侏罗世统一泛湖盆至晚侏罗-早白垩世盆地开始分异,再到新近纪以来彻底分割成独立盆地的沉积演化过程。同时,明确了天山南北两侧各盆地储层、烃源岩及盖层的重要形成期与天山隆升的关系,对有效拓展油气勘探范围有所启示。  相似文献   

5.
Apatite fission track thermochronology (AFT) is used to investigate the low-temperature thermal evolution of the Crimean Mountains and provide new insights into the geodynamic and geomorphic evolution of the westernmost tip of the Caucasus–Crimean fold-and-thrust belt. The vast majority of the samples taken from Jurassic sedimentary and magmatic rocks revealed AFT ages in the range of 51–32 Ma. These ages, together with modelled cooling paths, show that the mountain range experienced a thermal overprint after the Late Cimmerian orogeny. We interpret the overprint in terms of the burial of Cimmerian structures by a thick pile (>4 km) of platform sediments during Early Cretaceous–Late Eocene times. This scenario implies that highly elevated palaeosurfaces of Early Cretaceous age survived in large part because of the protection provided by thick accumulations of platform deposits. Since final uplift in the middle Pliocene, the palaeosurfaces have been significantly degraded and dissected by fluvial incision and large-scale landslides.  相似文献   

6.
Although Jurassic-Early Cretaceous sedimentary systems were extensively developed on northeastern Gondwana, deciphering their paleogeography has been complicated by poor exposure and the lack of a robust chronostratigraphic framework. The southeastern margin of the Carpentaria Basin, northeastern Australia is one of the few regions where these sedimentary systems are extensively exposed. Employing a combination of facies analysis and new data from paleontology and detrital zircon geochronology, we present a temporally and environmentally refined paleogeographic framework for this region. A Late Jurassic, southeasterly directed marine incursion invaded northeastern Gondwana, extending inland across the Carpentaria Basin, as demonstrated by a thin (~30 m), marine influenced (fluvio-estuarine) stratigraphic succession capped by a sequence bounding ~30 myr paraconformity. The depositional hiatus marked the Late Jurassic-Early Cretaceous uplift of the Euroka Arch, with loss of sedimentary and fluvial connectivity between the Carpentaria Basin and adjoining Eromanga Basin. Subsequent deposition by low-accommodation fluvial systems resulted in a thin, fluviatile depositional package developing during the Early Cretaceous. Paleocurrent and provenance data indicate that the Middle to Late Jurassic (c. 170–160 Ma) fluvial systems predating the paraconformity extended from the Eromanga Basin to the south across the southeastern Carpentaria Basin, transporting sediment from distal sources in the Lachlan Orogen of southeastern Australia. Fluvial systems of the southeastern Carpentaria Basin post-dating the paraconformity and Euroka Arch uplift show a provenance shift to easterly sources in the Mossman Orogen and Kennedy Igneous Association. Previously unrecognised Jurassic-Early Cretaceous igneous activity provided a persistent source of sediment to the southeastern Carpentaria Basin succession due to reworking of air fall tuff from an active magmatic arc located on the continental margin of northeastern Gondwana.  相似文献   

7.
This study documents sediment infill features and their responses to the tectonic evolution of the Sichuan Basin and adjacent areas. The data include a comparison of field outcrops, well drillings, inter-well correlations, seismic data, isopach maps, and the spatial evolution of sedimentary facies. We divided the evolutionary history of the Sichuan Cretaceous Basin into three stages based on the following tectonic subsidence curves: the early Early Cretaceous (145–125 Ma), late Early Cretaceous to early Late Cretaceous (125–89.8 Ma), and late Late Cretaceous (89.8–66 Ma). The basin underwent NW–SE compression with northwestward shortening in the early Early Cretaceous and was dominated by alluvial fans and fluviolacustrine sedimentary systems. The central and northern areas of the Sichuan Basin were rapidly uplifted during the late Early Cretaceous to early Late Cretaceous with southwestward tilting, which resulted in the formation of a depression, exhibited southwestward compression, and was characterized by aeolian desert and fluviolacustrine deposits. The tectonic framework is controlled by the inherited basement structure and the formation of NE mountains, which not only affected the clastic supply of the sedimentary basin but also blocked warm-wet currents from the southeast, which changed the climatic conditions in the late Late Cretaceous. The formation and evolution of Cretaceous sedimentary basins are closely related to synchronous subtle far-field tectonism and changes in climate and drainage systems. According to the analysis of the migration of the Cretaceous sedimentation centers, different basin structures formed during different periods, including periods of peripheral mountain asynchronous thrusting and regional differential uplift. Thus, the Sichuan Cretaceous sedimentary basin is recognized as a superimposed foreland basin.  相似文献   

8.
青藏高原东北缘的祁连山,在早白垩世期间发生明显隆升,受区域性构造运动和白垩纪特殊行星风系的影响,在山前盆地中沉积了一套特殊的碎屑岩序列。兰州盆地下白垩统发育完整,虽然局部被第四系覆盖,但总体出露良好,其特殊的相序单元构成的非常规体系域概念框架下的陆相层序地层学模式,对研究祁连山隆升的沉积学响应及环境效应具有重要意义。兰州盆地下白垩统为河口群,可以识别出5个三级层序(S.1—S.5),包括LAST和HAST两个非常规体系域,冲积扇和河流相粗碎屑沉积构成三级层序的LAST单元,HAST单元由湖泊相细碎屑地层组成。河口群上部地层发育的风成砂岩序列,在一定程度上可以解释为祁连山隆升造成的"焚风效应"产物,对研究祁连山的阶段性隆升特征具有重要的意义。早、晚白垩世之交,祁连山开始快速强烈隆升,兰州盆地整体抬升为剥蚀区,导致研究区缺失上白垩统。因此,兰州盆地下白垩统特殊的层序地层序列,不仅是早白垩世祁连山隆升的物质记录,还为研究早白垩世东亚大气环流格局变化提供了物质基础。  相似文献   

9.
滇西哀牢山-点苍山形成的构造和地貌过程*   总被引:3,自引:4,他引:3       下载免费PDF全文
青藏高原东南边缘规模最大的一条新生代走滑剪切带沿云南滇西的哀牢山-点苍山山脉分布。构造和地貌证据表明,该山脉的形成可能经历了4个阶段:第1阶段发生在中新世早中期(22~17百万年),以差异性大规模的隆升为特征,同时伴随着剥蚀,成因是剪切带的左行走滑运动;第2 阶段发生在20~10百万年,以区域性侵蚀为特征,山体的大部分与周边地体同时被夷平;第3阶段发生在中新世中晚期(13~9百万年),以区域性隆升和河流快速下切为特征,差异性的侵蚀导致山体雏形的形成;第4阶段始于晚新生代(5百万年),以差异性隆升为特征,其中, 点苍山的隆升是构造成因, 而哀牢山山体的形成可能与红河的下切相辅相成,有限的隆升是地壳发生均衡反弹造成的。  相似文献   

10.
王瑞  姜宝玉 《古地理学报》2021,23(3):581-599
晚白垩世河道和冲积平原等河流相沉积广泛分布于中国大部分地区,保存了大量以鸭嘴龙超科为主的恐龙骨骼化石和遗迹化石。这些河流是否存在水系上的联系以及其对陆地生态系统分布的影响程度,目前研究较少。笔者收集了中国9个晚白垩世陆相盆地共2357个碎屑锆石的U-Pb年龄资料,通过对已收集的碎屑锆石的物源分析,探讨了中国晚白垩世的水系展布模式和物源方向。研究结果表明:晚白垩世中国南方地区可能存在北东—南西向的大型水系,其与现代水系展布模式相反,整体流向可能起源于晚中生代东部高原,向西和西南方向流经中国南方大部分地区,并形成了彼此相互交错、宽阔的河岸和冲积平原带;而北方地区的盆地则显示出被古隆起分隔的山间盆地特征,除共享来自晚中生代东部高原的少量物源外,各个盆地的物源主要来自于周围的古隆起,并形成了较为独立的复杂水系。以鸭嘴龙超科为代表的恐龙主要繁盛于北方地区相对独立的水系所形成的流域,演化出独特的东亚鸭嘴龙超科动物群。南方大型水系所形成的流域虽然保存了大量恐龙蛋和足迹化石,但仅发现少量骨骼化石,推测这可能是因为以鸭嘴龙为主的恐龙不适宜在南方炎热干旱的气候条件下常年生活,而只是在适宜的季节沿南方大型水系迁徙或繁殖。  相似文献   

11.
12.
晋东北地区燕山期地壳活动剧烈而频繁, 经历了3次由伸展→挤压转换→隆升和岩浆活动过程。燕山运动早期形成早侏罗世断陷盆地和中侏罗世挤压坳陷型聚煤构造盆地; 中期中晚侏罗世形成被NW、NE向深大断裂围限的火山断陷盆地, 中基性-酸性火山喷发和浅成、超浅成中酸性岩浆侵入, 晚侏罗世末形成了一系列NNE向褶皱和逆冲推覆构造带; 晚期早白垩世再次形成断陷盆地和开阔平缓褶皱, 义县组不整合在火山岩之上, 晚白垩世处于挤压造山后的山体隆升阶段, 左云组不整合在义县组之上, 伴随有壳源型花岗岩侵入, NW、NE向断裂复活, 形成地堑、地垒式断裂组合, 导致山体隆升。   相似文献   

13.
In this paper, fluvial deposits of Middle Pleistocene age in the mountain‐foreland area of southern Poland (Eastern Sudetes and Western Carpathians) are studied in order to document the evolution of fluvial systems during the coldest stages of glacial periods when the Scandinavian Ice Sheet advanced far to the south. The focus is on fluvial response to climate change and glacial impact on river system behaviour. Also considered is the tectonic uplift of the mountain part of river catchments and its potential influence on the style of fluvial sedimentation in the fore‐mountain area. Three drainage basins that were active during the Elsterian and Saalian glaciations are investigated. Facies analyses are carried out on thick successions of braided river deposits covered with till or glaciolacustrine sediments, which result in a reconstruction of the fluvial activity synchronous with the ice‐sheet advance. The results suggest that fluvial activity declined prior to ice‐sheet advance into the fore‐mountain area. This climatically induced change is directly recorded in alluvial successions by upward‐decreasing bed thicknesses and grain sizes. River longitudinal profiles were shortened in front of the advancing ice sheet. The base level of the studied rivers, created by the ice‐sheet margin, rose in parallel with glacial advance. As a result, the successive reaches of rivers (degradational, transitional, aggradational) underwent shortening and moved upstream within the catchments. Moreover, tectonically induced local increases of river slopes may have influenced the depositional processes.  相似文献   

14.
The mainly continental deposits of northwest Sudan and south-west Egypt have been correlated with coeval shallow marine and marine deposits in northern Egypt along a north-south running cross-section, based on surface and subsurface data. The palaeodepth curve of northern Egypt illustrates the gradual seal-level rise, reaching its maximum during the Late Cretaceous with conspicuous advances during the Aptian and late Cenomanian. A general highstand is also recorded during the Campanian-Maastrichtian in north-west Sudan. A detailed facies correlation is given for the Aptian and late Cenomanian highstand in western Egypt. The correlation of the Cenomanian Bahariya and Maghrabi formations displays short-term relative sealevel fluctuations. The interpretation illustrates the extensiveness of related erosional processes in the hinterland, partly intensified by temporarily uplift of the Uweinat-Aswan High in the south. Regional uplift and constant erosion took place in south-west Egypt during Coniacian and Santonian times. The regional stratigraphic gaps and uncertain interpretation of the Bahariya Uplift are induced by the influence of the Trans-African Lineament, especially during the Late Cretaceous. Low-stand fluvial sheet sandstones characterized by non-cyclic sequence development and high facies stability occur, especially in the Neocomian and early Turonian. During the Barremian and Albian, fluvial architecture changes to more cyclic fluvial sequences and increasing soil formation, due to increasing subsidence, more humid climatic conditions and the generally rising sea level, culminating in the extensive shallow marine Abu Ballas and Maghrabi formations.  相似文献   

15.
早白垩世期间,青藏高原东北缘的祁连山隆升明显,在区域性构造运动和气候变化的综合影响下,在祁连山山前盆地中堆积了一套特殊的碎屑岩序列。甘肃张掖鹦鸽嘴白垩系发育完整,虽局部被第四系覆盖,但总体出露良好,其特殊相序单元构成的非常规体系域概念框架下的陆相层序地层模式,对研究祁连山隆升的沉积学响应及环境效应具有重要意义。鹦鸽嘴剖面下白垩统包括赤金堡组、下沟组和中沟组,可以识别出10个三级层序(S.1-S.10),LAST单元由冲积扇和河流相粗碎屑岩地层组成,湖泊相细碎屑岩沉积物构成三级层序的HAST单元。鹦鸽嘴剖面赤金堡组中下部的4个三级层序和下沟组中普遍发育的风成砂岩,是祁连山隆升造成的"焚风效应"的产物,对研究祁连山阶段性隆升特征具有重要的指示意义。早白垩世,研究区经历了从半干旱气候-干旱气候-潮湿气候的演变,在一定程度上反映了祁连山隆升过程从幕式隆升-快速隆升-均衡稳定隆升的阶段性特征。早白垩世末期,祁连山进入快速强烈隆升阶段,研究区区域性抬升为剥蚀区,整体缺失上白垩统。因此,鹦鸽嘴剖面下白垩统层序地层序列,不仅是早白垩世祁连山隆升过程的物质记录,还为早白垩世东亚大气环流格局变化的研究提供了物质基础。  相似文献   

16.
循化-化隆盆地新生代沉积及盆地基底和周缘山系磷灰石裂变径迹年代学分析揭示了青藏高原东北缘晚白垩世以来经历过3期隆升剥露事件: (1)盆地基底及拉脊山和西秦岭北缘构造带磷灰石裂变径迹年龄分析普遍记录了晚白垩世-始新世中期相对快速的区域性的隆升剥露事件, 西秦岭北缘快速抬升的起始时间为84Ma, 受控于向北的逆冲抬升; 向北到循化-化隆盆地中部的拉目峡抬升的起始时间为69Ma; 更北的拉脊山一带快速抬升期主要为40~50Ma, 从而反映晚白垩世-始新世中期的快速抬升由南向北逐渐扩展.这一期构造隆升事件导致循化-化隆盆地和临夏盆地缺失了北部西宁-民和盆地古近纪所具有的西宁群沉积.隆升剥露结束于31Ma左右, 此时化隆-循化盆地向东与同时期的临夏盆地相连为一个统一的大型西秦岭山前盆地, 两者具有相同的构造、沉积演化史, 因此循化-化隆盆地他拉组底部地层年龄最老不会超过临夏盆地最老地层的古地磁年龄, 即29Ma.(2)渐新世晚期约26Ma拉脊山开始双向逆冲隆升, 并可能延续到中新世早期约21Ma, 隆升作用使循化-化隆盆地成为挟持于拉脊山逆冲带和西秦岭构造带之间的山前挤压型前陆盆地, 循化-化隆盆地开始大规模沉积巨厚的他拉组冲积扇相粗碎屑岩.(3)通过循化-化隆盆地咸水河组和临夏组的沉积相分析、古流方向和砾石成分分析, 揭示出拉脊山构造带在中新世8Ma左右发生的最大规模的双向逆冲隆升事件, 这次事件直接导致循化-化隆盆地由前陆挤压盆地转变为山间盆地, 形成现今青藏高原东北缘的盆山地貌基本格局.   相似文献   

17.
The Magallanes‐Austral Basin of Patagonian Chile and Argentina is a retroforeland basin associated with Late Cretaceous–Neogene uplift of the southern Andes. The Upper Cretaceous Dorotea Formation records the final phase of deposition in the Late Cretaceous foredeep, marked by southward progradation of a shelf‐edge delta and slope. In the Ultima Esperanza district of Chile, laterally extensive, depositional dip‐oriented exposures of the Dorotea Formation contain upper slope, delta‐front and delta plain facies. Marginal and shallow marine deposits include abundant indicators of tidal activity including inclined heterolithic stratification, heterolithic to sandy tidal bundles, bidirectional palaeocurrent indicators, flaser/wavy/lenticular bedding, heterolithic tidal flat deposits and a relatively low‐diversity Skolithos ichnofacies assemblage in delta plain facies. This work documents the stratigraphic architecture and evolution of the shelf‐edge delta that was significantly influenced by strong tidal activity. Sediment was delivered to a large slump scar on the shelf‐edge by a basin‐axial fluvial system, where it was significantly reworked and redistributed by tides. A network of tidally modified mouth bars and tidal channels comprised the outermost reaches of the delta complex, which constituted the staging area and initiation point for gravity flows that dominated the slope and deeper basin. The extent of tidal influence on the Dorotea delta also has important implications for Magallanes‐Austral Basin palaeogeography. Prior studies establish axial foreland palaeodrainage, long‐term southward palaeotransport directions and large‐scale topographic confinement within the foredeep throughout Late Cretaceous time. Abundant tidal features in Dorotea Formation strata further suggest that the Magallanes‐Austral Basin was significantly embayed. This ‘Magallanes embayment’ was formed by an impinging fold–thrust belt to the west and a broad forebulge region to the east.  相似文献   

18.
Analysing the provenance changes of synorogenic sediments in the Turpan‐Hami basin by detrital zircon geochronology is an efficient tool to examine the uplift and erosion history of the easternmost Tian Shan. We present detrital zircon U‐Pb analysis from nine samples that were collected within marginal lacustrine Middle‐Late Jurassic and aeolian‐fluvial Early Cretaceous strata in the basin. Middle‐Early Jurassic (159–172 Ma) zircons deriving from the southern Junggar dominated the Middle Jurassic sample from the western Turpan‐Hami basin, whereas Permian‐Carboniferous (270–330 Ma) zircons from the Bogda mountains were dominant in the Late Jurassic to Early Cretaceous samples. Devonian‐Silurian (400–420 Ma) and Triassic (235–259 Ma) zircons from the Jueluotage and Harlik mountains constituted the subordinate age groups in the Late Jurassic and Early Cretaceous samples from the eastern basin respectively. These provenance transitions provide evidence for uplift of the Bogda mountains in the Late Jurassic and the Harlik mountains since the Early Cretaceous.  相似文献   

19.
南黄海中部隆起自印支期以来经历显著的构造隆升及剥蚀过程.基于大陆架科学钻探CSDP-2井的钻井岩心,应用磷灰石裂变径迹技术研究了南黄海中部隆起晚白垩世以来的剥蚀过程及响应特征.所获得的8个磷灰石样品的裂变径迹年龄显示出两个年龄组,除单个样品为38±3 Ma外,其余样品都集中在(52±4)~(65±5)Ma范围内,基本反映了同一期构造热事件年龄,并且均远小于样品所处的二叠纪年龄,表明样品完全退火并记录了晚白垩世以来的热历史.样品热史模拟结果表明,基于泥岩镜质体反射率计算的最高古地温处于样品退火带温区范围内,各样品从晚白垩世早期(约100 Ma)以来经历持续的降温过程,在约80~75 Ma开始进入部分退火带.南黄海中部隆起第一期快速冷却降温过程出现在晚白垩世末期,并持续至古新世早期,随后进入古近纪表现为持续相对缓慢的降温过程,降温幅度约30 ℃,渐新世末期到中新世早期存在另一期快速冷却过程.热史模拟结果较好地指示了南黄海中部隆起晚白垩世以来的地层剥蚀响应特征.   相似文献   

20.
C.D. Ollier 《地学学报》1992,4(3):312-319
Landscape evolution is on the same time-scale as global tectonics, biological evolution, and major climatic change. Some features of global change reflected in landscape evolution result from the breakup of Pangaea. Others relate to major climatic changes, and yet others to a major change from a dominantly plains landscape of the Mesozoic to an increasingly mountainous landscape in the Tertiary. Worldwide deep weathering profiles of Cretaceous and early Tertiary age suggest widespread planation and warm, moist climates. Erosion of deeply weathered regolith following the formation of new continental margins and tectonic uplift led to the deposition of unusual mature sediments. Many river patterns can be traced to early Tertiary or older antecedents.
Some climatic changes are due to orbital forcing, but others may be related to changing positions of continents, creation of new seaways, or to mountain building. The timing of mountain uplift, climatic changes and biological changes must be resolved to test models of their mutual interaction. Geomorphic input on tectonics, drainage evolution, and deep weathering will be an essential component in dealing with these problems.  相似文献   

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