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1.
The Greater Caucasus is Europe's largest mountain belt. Significant uncertainties remain over the evolution of the range, largely due to a lack of primary field data. This work demonstrates that depositional systems within the Oligocene–Early Miocene Maykop Series on either side of the Western Greater Caucasus (WGC) display a similar provenance and divergent palaeocurrents away from the range, constraining a minimum age for the subaerial uplift of the range as early Early Oligocene. An Eocene–Oligocene hiatus, basal Oligocene olistostromes and a marked increase in nannofossil reworking also point to initial deformation in the earliest Oligocene. The initial uplift of the WGC occurred during the final assembly of the Tethysides to its south. Uplift commenced after the Late Eocene final suturing of northern Neotethys and during the initial collision of Arabia with the southern accreted margin of Eurasia. This suggests that compressional deformation was rapidly transferred across the collision zone from the indenting Arabian plate to its northern margin.  相似文献   

2.
位于青藏高原东北缘的西宁、贵德盆地的新生代沉积序列较完整的记录了盆地周围物源区构造变形过程。重矿物是碎屑物质的重要组成部分,是最直观、有效揭示源区母岩、构造-沉积过程的重要手段。通过重矿物的系统分析,结合沉积-构造变形,揭示出始新世-上新世末西宁-贵得盆地及其源区经历了几个构造活动阶段:古新世-始新世早期的隆升阶段、始新世中期-渐新世晚期的构造稳定阶段、渐新世末-中新世初的构造隆升阶段、中中新世构造稳定阶段和晚中新世以来的强烈隆升阶段。并结合特征矿物（绿泥石）及古水流分析,推断古近纪西宁-贵德盆地是东昆仑山前一个统一盆地。中新世早期青藏高原的扩张导致了拉脊山开始隆起,使原型盆地解体;约8.5 Ma以来拉脊山强烈隆升,两侧盆地逐渐转变为山间盆地。这为正确理解青藏高原东北缘盆山格局的形成和演化提供了重要依据。  相似文献   

3.
滇西新生代兰坪盆地和剑川盆地分别位于哀牢山–红河断裂带两侧,青藏高原东构造结内,其沉积过程和构造变形对青藏高原东南缘的构造演化有重要的启示意义。通过对这两个盆地古近纪沉积和构造过程的研究,我们发现兰坪盆地和剑川盆地及邻区的构造变形分为三期:始新世早期的强烈挤压变形、始新世中晚期的伸展变形、渐新世的走滑变形。始新世早期的挤压变形主要表现为兰坪地区的褶皱–冲断系统、哀牢山-红河断裂的逆冲活动和剑川盆地的宽缓褶皱。沉积方面,古新统勐野井组(E_1m)较为稳定的细粒滨湖相沉积转变为始新统宝相寺组(E_2b)较粗的具有前陆盆地性质的河流相沉积,特别是宝相寺组底部发育的一套快速堆积的磨拉石建造,可能是对始新世强烈挤压环境下的沉积响应。始新世中晚期伸展变形体现在盆地的构造环境由早期的挤压环境变为伸展环境和该时期大量富钾岩体和岩脉的侵入,沉积学上,下始新统宝相寺组的河流相转变为中始新统金丝厂组(E_2j)具有快速堆积磨拉石特征的曲流河沉积,极可能是对构造体制变革的沉积响应。渐新世的走滑变形则体现在渐新统的缺失和哀牢山–红河断裂的早期左行走滑。因此,我们认为剑川–兰坪地区在始新世中期和渐新世均发生了显著的运动学转换,这一认识也得到了始新世中期兰坪和剑川盆地物源明显变化的支持。结合青藏高原东南部始新世中晚期岩浆的活动,渐新世大型剪切带(崇山剪切带、高黎贡剪切带)的强烈走滑和保山块体的旋转,我们推测青藏高原东南缘古近纪的构造演化为古新世-始新世早期的挤压、始新世中晚期的伸展、渐新世的转换压缩。  相似文献   

4.
The lateral termination of the Alpine-Pyrenean Orogen relief onshore is located in the NW Iberian Peninsula. It overlies a Variscan basement (Iberian Massif), where the sedimentary record of the Alpine tectonic is very scarce. Thus, the characterisation of the tectonic evolution of the lateral termination is difficult and timing and geometries of the main tectonic structures remain unclear. Combining the tectonothermal histories obtained by modelling of the apatite fission-track data (AFT) with structural mapping allows for a comparative study of the different tectonic scenarios and deformation transfer in the lateral termination of an orogen. AFT ages for the studied area vary from 53.5?±?12.9 and 222?±?12?Ma (from Late Triassic to Early Eocene). The beginning of the Cenozoic cooling episodes is in agreement with the infilling of the Tertiary basins (Late Eocene or Oligocene). Calculated uplift for the Alpine Orogeny is around 2,400?m. The Cantabrian Mountains were uplifted and emplaced southwards and the main period of exhumation began in the Palaeogene at rates of ~0.02?mm/a and continued during the Neogene at rates of ~0.06?mm/a. However, the Galaico-Leoneses Mountains, located to the south of the studied area, were uplifted and emplaced northwards during the Neogene, showing more rapid uplift rates of ~0.08?mm/a, suggesting that the western termination of the Alpine-Pyrenean Orogen relief is the result of the successive interaction of two Alpine deformation fronts.  相似文献   

5.
In Alpine Corsica, the Jurassic ophiolites represent remnants of oceanic lithosphere belonging to the Ligure‐Piemontese Basin located between the Europe/Corsica and Adria continental margins. In the Balagne area, a Jurassic ophiolitic sequence topped by a Late Jurassic–Late Cretaceous sedimentary cover crops out at the top of the nappe pile. The whole ophiolitic succession is affected by polyphase deformation developed under very low‐grade orogenic metamorphic conditions. The original palaeogeographic location and the emplacement mechanisms for the Balagne ophiolites are still a matter of debate and different interpretations for its history have been proposed. The deformation features of the Balagne ophiolites are outlined in order to provide constraints on their history in the framework of the geodynamic evolution of Alpine Corsica. The deformation history reconstructed for the Balagne Nappe includes five different deformation phases, from D1 to D5. The D1 phase was connected with the latest Cretaceous/Palaeocene accretion into the accretionary wedge related to an east‐dipping subduction zone followed by a Late Eocene D2 phase related to emplacement onto the Europe/Corsica continental margin. The subsequent D3 phase was characterized by sinistral strike‐slip faults and related deformations of Late Eocene–Early Oligocene age. The D4 and D5 phases were developed during the Early Oligocene–Late Miocene extensional processes connected with the collapse of the Alpine belt. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

6.
《Geodinamica Acta》2013,26(2):87-101
The Paleogene Alicante Trough of the South-Iberian Margin (External Betic Zone) consists of a narrow sedimentary basin that has active margins located to the north-northwest (active mainly during the Eocene) and to the south-southeast (active during the Oligocene). Both margins, consisting of shallow unstable platforms, were the source areas for the external-platform slope (in the opposite margins) and deepbasin (in the middle) depositional realms. The southern margin, lost under the Mediterranean Sea, is recognized only by the reconstructed Oligocene slope sediments.

The eight successions studied, on opposites external-platform-slope margins and the deep within the central part of the basin, lead us to divide the basin into two depositional realms: the subsident Western Depositional Area (WDA) and the not subsident Eastern Depositional Area (EDA). This study has also enabled us to divide the infilling of the basin into two depositional sequences: Eocene p.p. (EDS) and Oligocene p.p. (ODS) in age, respectively, bound by two sequence boundaries (unconformities) at the Early Eocene (P6 zone) and Early Oligocene (P19 zone). The EDS and ODS are comprised of turbiditic and olisthostromic deposits and frequently slumps, evidencing an active tectonic in the margin-basin system.

The correlation of the Paleogene sedimentary reconstructed in the Alicante Trough with other four synthetic successions throughout the External (three in the Subbetic Domain) and one in the Internal Betic Zone indicate a Paleogene generalised deformational framework. In addition, this evolution is contemporaneous to the Pyrenean, Iberian and the Nevado-Filabride Alpine deformation. The Paleogene tectonic recognised in the External Betic Zone is younger since the main orogenic deformation took place in the late Burdigalian to early Tortonian. The origin of these early tectonics is discussed in relation to the Nevado-Filabride Alpine deformation.  相似文献   

7.
The Jurassic through Oligocene stratigraphies of Trinidad and the Serrania del Interior of eastern Venezuela exhibit many similarities because of their proximity on the passive continental margin of northeastern South America. A slightly later subsidence in eastern Venezuela, and the generally deeper-water sedimentation in Trinidad, is interpreted to be the result of a serration of the original rift margin, producing an eastern Venezuelan promontory and Trinidadian reentrant. We interpret these serrations to be the result of oblique (NW-SE) spreading of North and South America during Middle and Late Jurassic time. The stratigraphies of northeastern Venezuela and Trinidad contrast in the Hauterivian-Albian interval, with dynamic shallow shelf environments prevailing in the Serrania del Interior and deeper marine submarine-fan deposition in Trinidad. Both areas develop middle to Upper Cretaceous source rocks during a time of eustatic sea level high and widespread oceanic anoxia. A slight lowering of eustatic sea level may have been responsible for the clastic influx represented by the sandstones of the Maastrichtian San Juan and Galera formations, disturbing the previous pelagic and hemipelagic sedimentation. The seaward transport of these sandstones may have been responsible for the localized erosion of the Maastrichtian section in central and southern Trinidad. Sedimentation stabilized with slope and outer-shelf turbiditic deposition during the Paleocene and Early Eocene, before diachronous, west-to-east shallowing occurred. Shallowing from the turbidites to shallow-water limestones and sandstones occurred in eastern Venezuela in the late Middle Eocene, and in the Late Eocene/Early Oligocene in Trinidad. Alhough eustasy and sediment progradation could have influenced the shallowing, its magnitude and rate requires that a tectonic uplift have occurred. Margin buckling, caused by the N-S relative convergence of North and South America, and forebulge uplift ahead of the Caribbean plate both are possible mechanisms. Following the shallowing, both areas subsided rapidly into laterally variable Oligocene to Recent flysch-like sedimentation. This is interpreted to represent the onset of direct interaction of the Caribbean plate with the South American depocenters of Trinidad and eastern Venezuela. Miocene to Recent sedimentation has been strongly influenced by these plate interactions.  相似文献   

8.
The common elements and differences of the neighboring Austral (Magallanes), Malvinas and South Malvinas (South Falkland) sedimentary basins are described and analyzed. The tectonic history of these basins involves Triassic to Jurassic crustal stretching, an ensuing Early Cretaceous thermal subsidence in the retroarc, followed by a Late Cretaceous–Paleogene compressional phase, and a Neogene to present-day deactivation of the fold–thrust belt dominated by wrench deformation. A concomitant Late Cretaceous onset of the foreland phase in the three basins and an integrated history during the Late Cretaceous–Cenozoic are proposed. The main lower Paleocene–lower Eocene initial foredeep depocenters were bounding the basement domain and are now deformed into the thin-skinned fold–thrust belts. A few extensional depocenters developed in the Austral and Malvinas basins during late Paleocene–early Eocene times due to a temporary extensional regime resulting from an acceleration in the separation rate between South America and Antarctica preceding the initial opening of the Drake Passage. These extensional depocenters were superimposed to the previous distal foredeep depocenter, postdating the initiation of the foredeep phase and the onset of compressional deformation. Another pervasive set of normal faults of Paleocene to Recent age that can be recognized throughout the basins are interpreted to be a consequence of flexural bending of the lithosphere, in agreement with a previous study from South Malvinas basin. Contractional deformation was replaced by transpressive kinematics during the Oligocene due to a major tectonic plate reorganization. Presently, while the South Malvinas basin is dominated by the transpressive uplift of its active margin with minor sediment supply, the westward basins undergo localized development of pull-apart depocenters and transpressional uplift of previous structures. The effective elastic thickness of the lithosphere for different sections of each basin is calculated using a dynamic finite element numerical model that simulates the lithospheric response to advancing tectonic load with active sedimentation.  相似文献   

9.
梁承华  徐先兵  李启铭  桂林  汤帅 《地球科学》2019,44(5):1761-1772
华南中-新生代构造演化受太平洋构造域和特提斯洋构造域的联合控制.以江南东段NE-SW向景德镇-歙县剪切带和球川-萧山断裂中发育的脆性断层为研究对象,利用野外交切关系和断层滑移矢量反演方法厘定了7期构造变形序列并反演了各期古构造应力场,讨论了断层活动的时代及其动力学.白垩纪至新生代研究区7期古构造应力场分别为:(1)早白垩世早期(136～125Ma)NW-SE向伸展;(2)早白垩世晚期(125～107Ma)N-S向挤压和E-W向伸展;(3)早白垩世末期至晚白垩世早期(105～86Ma)NW-SE向伸展;(4)白垩世中期(86～80Ma)NW-SE向挤压和NE-SW向伸展;(5)晚白垩世晚期至始新世末期(80～36Ma)N-S向伸展;(6)始新世末期至渐新世早期(36～30Ma)NE-SW向挤压和NW-SE向伸展;(7)渐新世早期至中新世中期(30～17Ma)NE-SW向伸展.结合区域地质研究表明,第1期至第4期古构造应力场与古太平洋构造域的板片后撤、俯冲以及微块体(菲律宾地块)间的碰撞作用有关;第5期伸展作用受控于新特提斯构造域俯冲板片后撤,而第6期和第7期古构造应力场主要与印-亚碰撞的远程效应有关.白垩纪至新生代,华南东部受伸展构造体制和走滑构造体制的交替控制.先存断裂的发育可能是导致华南晚中生代走滑构造体制的主要控制因素.  相似文献   

10.
More than 1400 km of two-dimensional seismic data were used to understand the geometries and structural evolution along the western margin of the Girardot Basin in the Upper Magdalena Valley. Horizons are calibrated against 50 wells and surface geological data (450 km of traverses). At the surface, low-angle dipping Miocene strata cover the central and eastern margins. The western margin is dominated by a series of en echelon synclines that expose Cretaceous–Oligocene strata. Most synclines are NNE–NE trending, whereas bounding thrusts are mainly NS oriented. Syncline margins are associated mostly with west-verging fold belts. These thrusts started deformation as early as the Eocene but were moderately to strongly reactivated during the Andean phase. The Girardot Basin fill records at least four stratigraphic sequences limited by unconformities. Several periods of structural deformation and uplifting and subsidence have affected the area. An early Tertiary deformation event is truncated by an Eocene unconformity along the western margin of the Girardot Basin. An Early Oligocene–Early Miocene folding and faulting event underlies the Miocene unconformity along the northern and eastern margin of the Girardot Basin. Finally, the Late Miocene–Pliocene Andean deformation folds and erodes the strata along the margins of the basin against the Central and Eastern Cordilleras.  相似文献   

11.
The compression and attendant deformation of a thick and vast sedimentary prism formed since Early Riphean times on the northern continental margin of the Indian craton gave rise to the Himalaya mountains as a result of convergence and collision of the Indian and Asian plates. The oceanic trench-sediments, tectonically implanted with sea-floor material and intimately associated with calc-al-kaline volcanics in the narrow Sindhu-Tsangpo belt extending from Kohistan through Dras, Leh, Darchen (Mansarovar) to Shigatse and beyond, represent the subduction-island arc complex which developed south of the dynamic southern margin of the Asian continent and was welded to the colliding Indian plate during the late Eocene to Oligocene period. This complex is fringed to the north by a wide zone of Andean-type granitic bodies. The evolution of the Himalayan orogen is closely connected with the development of the present-day Andaman-Nicobar-Indonesia island arc-subduction system in the southeast and the Makran Ranges-Oman Trench in the southwest.The evolution of the Himalaya was accomplished in four major phases of tectonic upheaval during the late Cretaceous to Palaeocene (Karakoram phase), late Eocene to Oligocene (Malla Johar phase), middle Miocene to Pontian (Sirmurian phase), and late Pliocene to middle Pleistocene (Siwalik phase). While the Karakoram phase marks the convergence of continents and the Malla Johar phase represents the collision and subduction, it was during the Sirmurian upheaval that the main tectonic features developed and the Himalaya acquired its distinctive structural complexion  相似文献   

12.
During the Late Jurassic–Early Oligocene interval, widespread hydrothermal copper mineralization events occurred in association with the geological evolution of the southern segment of the central Andes, giving rise to four NS-trending metallogenic belts of eastward-decreasing age: Late Jurassic, Early Cretaceous, Late Paleocene–Early Eocene, and Late Eocene–Early Oligocene. The Antofagasta–Calama Lineament (ACL) consists of an important dextral strike-slip NE-trending fault system. Deformation along the ACL system is evidenced by a right-lateral displacement of the Late Paleocene–Early Eocene metallogenic belts. Furthermore, clockwise rotation of the Early Cretaceous Mantos Blancos copper deposit and the Late Paleocene Lomas Bayas porphyry copper occurred. In the Late Eocene–Early Oligocene metallogenic belt, a sigmoidal deflection and a clockwise rotation is observed in the ACL. The ACL is thought to have controlled the emplacement of Early Oligocene porphyry copper deposits (34–37 Ma; Toki, Genoveva, Quetena, and Opache), whereas it deflected the Late Eocene porphyry copper belt (41–44 Ma; Esperanza, Telégrafo, Centinela, and Polo Sur ore deposits). These observations suggest that right-lateral displacement of the ACL was active during the Early Oligocene. We propose that the described structural features need to be considered in future exploration programs within this extensively gravel-covered region of northern Chile.  相似文献   

13.
赵志刚  王鹏  祁鹏  郭瑞 《地球科学》2016,41(3):546-554
东海盆地处于西太平洋俯冲带前缘,是发育在华南克拉通基底之上的,以晚白垩世-新生代沉积为主的新生代盆地.东海盆地性质是在活动大陆边缘减薄陆壳之上的,由于洋-陆俯冲消减所引起的张裂、拉伸作用而形成的弧后裂谷型盆地,是西太平洋众多“沟-弧-盆”体系的一部分.东海盆地陆架外缘隆起控制着东海盆地的演化过程,该地质单元形成于晚白垩世,是陆缘隆起和增生楔的复合体,中新世后由于菲律宾海板块的活动而解体为现今的钓鱼岛隆褶带和琉球隆起.结合对陆架外缘隆起的研究后认为,东海盆地晚白垩世以来的演化历程具有3大构造阶段,即:第一阶段,古新世-中始新世西部坳陷形成发展期;第二阶段,中始新世-渐新世东部坳陷形成发展期,其中,中晚始新世太平洋板块的转向是东、西部坳陷构造迁移的分界点;第三阶段,中新世-全新世,东海盆地进入到菲律宾板块影响时期,原先的构造格局开始分解.   相似文献   

14.
The present study deals with the lithostratigraphy and planktonic foraminiferal biostratigraphy of the Late Eocene-Middle Miocene sequence in the Al Bardia area, northeast Libya. The lithostratigraphical studies carried out on three stratigraphical surface sections, namely Wade Al Rahib, Wadi Al Hash and Wadi Al Zeitun, led to the recognition of three rock units from base to top: (1) the Al Khowaymat Formation (Late Eocene-Early Oligocene); (2) the Al Faidiyah Formation (Late Oligocene-Early Miocene); and (3) the Al Jaghboub Formation (Early-Middle Miocene). The planktonic foraminiferal biostratigraphical analysis led also to the recognition of nine planktonic foraminiferal zones ranged in age from Late Eocene to Early Miocene with one larger foraminiferal zone of Middle Miocene age. These are, from base to top, as follows: Truncorotaloides rohri Zone (Late-Middle Eocene, Lutetian), Globigerinatheka semiinvoluta and Turborotalia cerroazulensis s.l. Zones (Late Eocene, Priaborian), Cassigerinella chipolensis/Pseudohasitgerina micra Zone (Early Oligocene, Rupelian), Globigerina ciperoensis ciperoensis, Globorotalia kugleri Zones (Late Oligocene, Chattian), Globigerinoides primordius Zone (Early Miocene, Aquitanian), Globigerinoides altiaperturus/Catapsydrax dissimilis and Globigerinoides trilobus Zones (Early Miocene, Burdigalian), and the larger benthonic foraminiferal zone, Borelis melo melo Zone (Middle Miocene, Langhian to Serravallian). The study of planktonic foraminifera proved the existence of a regional unconformity between the Early and Late Oligocene, with the Middle Oligocene deposits being absent (absence of Globigerina ampliapertura and Globorotalia opima opima Zones), and another, smaller unconformity located between the Late Eocene and Early Oligocene, in which the uppermost part of the Late Eocene is missing.  相似文献   

15.
南海北部珠江口—琼东南盆地白垩系—下渐新统记录了华南大陆边缘从主动陆缘向被动陆缘的转换过程。基于盆地构造-地层、单井相、地震相等特征的综合分析,结合南海中南部的沉积环境和区域构造演化,探讨南海北部白垩纪—渐新世早期的沉积环境演变及构造控制背景。研究发现: (1)南海北部白垩系广泛分布,古新统分布极为有限; 始新世早-中期,琼东南盆地只在部分凹陷深部发育了小规模的滨浅湖相和扇三角洲相沉积,珠江口盆地白云凹陷以大规模发育的湖泊相为特征; 始新世晚期—渐新世早期,琼东南盆地和珠江口盆地白云凹陷都受到海侵作用的影响,以海岸平原相和滨浅海相为主。 (2)构造演变包括5期:包括白垩纪安第斯型大陆边缘的“弧—盆”体系发育期,古新世区域隆升剥蚀山间盆地发育期,始新世早-中期裂陷发育,始新世晚期—渐新世早期陆缘破裂期,渐新世晚期东部海盆稳定扩张期。最后,探讨了南海盆地中生代末/新生代初的动力学转换过程及特征。  相似文献   

16.
Linear belts of Gondwana basins developed in the Indian continent since Late Palaeozoic along favoured sites of Precambrian weak zones like cratonic sutures and reactivated mobile belts. The Tibetan and Sibumasu - West Yunnan continental blocks, that were located adjacent to proto-Himalayan part of the Indian continent, rifted and drifted from the northern margin of the East Gondwanic Indo-Australian continent, during Late Palaeozoic, when the said northern margin was under glacial or cool climatic condition and rift-drift tectonic setting. The Indo-Burma-Andaman (IBA), Sikule, Lolotoi blocks were also rifted and drifted from the same northern margin during Late Jurassic. This was followed by the break-up of the Australia-India-Madagascar continental block during the Cretaceous. The activity was associated with hot spot related volcanism and opening up of the Indian Ocean. The Late Cretaceous and Tertiary phases of opening of the Arabian Sea succeeded the Early Cretaceous phase of opening of the Bay of Bengal, part of the Indian Ocean. The Palaeo- and Neo-Tethyan sutures in Tibet, Yunnan, Laos, Thailand and Vietnam reveal the complex opening and closing history of the Tethys. The IBA block rotated clockwise from its initial E-W orientation because of 90°E and adjacent dextral transcurrent fault movements caused due to faster northward movement of the Indian plate relative to that of Australia. The India-Tibet terminal collision during Early-Middle Eocene initiated Himalayan orogenesis and contemporaneously there was foreland basin development that was accompanied with sporadic but laterally extensive continental-flood-basalt (CFB) type and related volcanism. The Paleogene rocks of the Himalayan foreland basin are involved in tectonism and are mostly concealed under older rocks.

The Mesozoic-Early Eocene ophiolite terrane on IBA does not represent the eastern suture of the Indian plate but occurs as klippe on IBA, caused due to oblique collision between Sibumasu and IBA during Late Oligocene. Post-collisional indentation of Y-shaped Indian continent into the Asian collage produced Himalayan syntaxes, clockwise rotation of the Sibumasu block which was then sutured to the Tibetan and SE Asian blocks, and tectonic extrusion of the Indochina block along the Ailao Shan Red River (ASRR) shear zone. Highly potassic magmatic rocks were emplaced during Late Palaeogene at the oroclinally flexed marginal parts of the South China continental lithosphere. These magmatic bodies were dislocated by the ASRR left lateral shear zone soon afterwards. Petrogenetic and tectonic processes that generated the Eocene CFB volcanics at the Himalayan foreland basin may have also produced Late Palaeogene magmatism from outer parts of the Namche-Barwa Syntaxis. Their site-specific location and time sequence suggest them to be genetically related to the India-Asia collision process and Indian continent's indentation-induced syntaxial buckling. Deep mantle-reaching fractures were apparently produced during India-Asia terminal collision at the strongly flexed leading brittle edge of the Indian continental lithosphere, and possibly later in time at the outer oroclinally bent marginal parts of the rigid South China continental lithosphere, generating typical magma.

The subduction zone that developed along the western margin of IBA due to oblique convergence between the IBA and the Indian plate is still active. The northern end of IBA ultimately collided with the NE prolongation of the Indian continent and was accreted to it during Mio-Pliocene. The Shillong massif was uplifted and overthrust over the Bengal Basin located over its passive margin to the south, whereas, the Eocene distal shelf sediments of IBA were overthrust over the Tertiary shelf of the Indian continent.  相似文献   


17.
Recent studies in northwest New Guinea have shown the presence of at least two marginal basins of different age, both of which formed in back-arc settings. The older basin opened between the Middle Jurassic and Early Cretaceous, a remnant of which is now preserved as the New Guinea Ophiolite. Its obduction started at 40 Ma and it was finally emplaced on the Australian margin at 30 Ma. The younger basin was active during the Oligocene to Middle Miocene and was obducted in the Early Pliocene. Studies of the western edge of the Philippine Sea also reveal an important deformation of the Philippine arc in the Oligocene, which hitherto has remained unexplained. Using information from these systems, paleomagnetic results, kinematic reconstructions and geochemistry of the supra-subduction ophiolite, we present a plate model to explain the region's Eo–Oligocene development. We suggest that an extensive portion of oceanic crust extended the Australian Plate a considerable distance north of the Australian Craton. As Australia began its steady 7–8 cm/year northward drift in the Early Eocene, this lithosphere was subducted. Thus, the portion of the Philippine Sea Plate carrying the Taiwan–Philippine Arc to its present site may have actually been in contact with the ophiolite now in New Guinea and obduction led to deformation of the Philippine Sea Plate itself. Neogene Plate kinematics transported the deformed belt in contact with the Sunda block in the Late Miocene and Pliocene. This interpretation has implications for the origin for the Philippine Sea Plate and the potential incorporation of continental fragments against its boundaries.  相似文献   

18.
《Geodinamica Acta》2013,26(1-3):83-100
The Magura Basin domain developed in its initial stage as a Jurassic-Early Cretaceous rifted passive margin that faced the eastern parts of the oceanic Alpine Tethys. In the pre- and syn-orogenic evolution of the Magura Basin the following prominent periods can be distinguished: Middle Jurassic-Early Cretaceous syn-rift opening of basins (1) followed by Early Cretaceous post-rift thermal subsidence (2), latest Cretaceous–Paleocene syn-collisional inversion (3), Late Paleocene to Middle Eocene flexural subsidence (4) and Late Eocene - Early Miocene synorogenic closing of the basin (5). The driving forces of tectonic subsidence of the basin were syn-rift and thermal post-rift processes, as well as tectonic loads related to the emplacement of accretionary wedge. This process was initiated at the end of the Paleocene at the Pieniny Klippen Belt (PKB)/Magura Basin boundary and was completed during Late Oligocene in the northern part of the Magura Basin. During Early Miocene the Magura Basin was finally folded, thrusted and uplifted as the Magura Nappe.  相似文献   

19.
Andean orogenic processes controlled the spatial and temporal distribution of the magmatic and sedimentary record. This contribution integrates new U/Pb zircon ages, heavy mineral analyses and biostratigraphic constraints from the Neogene sedimentary record of the fore‐arc and intra‐arc basins and volcano‐plutonic rocks of southwestern Colombia, to reconstruct these orogenic processes. The results reveal continuous arc magmatism since the Late Oligocene, with a major post‐Middle Miocene magmatic peak and exhumation. When integrated with other geological constraints, the tectonic evolution of the margin includes Eocene‐Oligocene oblique convergence with limited magmatic activity, followed by the initiation of a Late Oligocene‐Early Miocene arc that migrated to the east in the Middle Miocene, when it experienced a major increase in magmatic activity, crustal deformation, exhumation and thickening. This orogenic evolution is related to the shallowing of the slab dip due to the subduction of the Neogene Nazca Plate.  相似文献   

20.
A.C. Ries 《Earth》1978,14(1):35-63
The anticlockwise rotation of the Iberian Peninsula away from south Brittany during the Mesozoic has been demonstrated from palaeomagnetic data. Marine magnetic, seismic and gravity surveys have indicated that there is oceanic crust in the Bay of Biscay. Initial rifting began in the Triassic but the major part of the rotation of the Iberian Peninsula occurred during the Late Cretaceous. Two mechanisms for the opening of the Bay of Biscay have been proposed, firstly a simple anticlockwise rotation of the Iberian plate and secondly, a 350 km sinistral displacement of the Iberian plate along transform faults about a pole of rotation near Paris. Geological data, partly new, favours the first mechanism but with a pole of rotation approximately 100 km east of the west end of the Pyrenees rather than in the southeast corner of the Bay of Biscay. Geophysical data indicates a further small rotation of the Iberian Peninsula during the Late Eocene which resulted in the formation of the Pyrenees.  相似文献   

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