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1.
The Late Tertiary history of the Mediterranean region exemplifies processes of ocean basin closure and continental collision, as determined from integrated land and marine evidence. During the Mesozoic–Early Tertiary, tectonic settings were dominated by evolution of Neotethys. This ocean generally widened eastwards, with a number of oceanic strands in the Eastern Mediterranean area. Great diversity of tectonic settings and palaeo-environments developed during the Tertiary closure history of these oceanic basins. In the Eastern Mediterranean region, more northerly Neotethyan strands were closed by the Mid Tertiary, while oceanic crust remained in the south in the present Eastern Mediterranean Sea area. Northwards subduction of the remaining southerly Neotethyan strand was probably active by the Early Miocene. Different areas exhibit different stages of convergence and ocean basin closure. In the east, the amalgamated Eurasian plate had collided with the Arabian margin (Africa) by the Late Miocene, while oceanic crust still persisted further west. Steady-state subduction during the Late Tertiary gave rise to the Mediterranean ridge, as a substantial mud-dominated accretionary wedge. In the Aegean area, sufficient northward subduction took place to activate arc volcanism and pervasive back arc extension, short of marginal basin opening. In the easternmost Mediterranean, only limited subduction took place, associated with supra-subduction zone extension (e.g. in Cyprus). Today, steady state-subduction continues only locally, where vestiges of Neotethys remain (e.g. Herodotus abyssal plain). In the Western Mediterranean area, suturing of the African and Eurasian plates initially took place in the Betic region (Early–Mid Tertiary), where the Neotethys had existed only as a narrow connection with the Central North Atlantic. In the Central Mediterranean region, where the Western Neotethys was wider, northward subduction was active, apparently as early as the Late Cretaceous. In a widely accepted interpretation, an Andean-type magmatic arc developed along the southern margin of Europe and was then rifted off in the Late Oligocene-Early Miocene, to form the Corsica-Sardinia Block, opening the North Balearic marginal basin in its wake. The migrating subduction zone and microcontinent then collided diachronously with North Africa-related continental units (North Africa and Apulia) from Late Oligocene-Early Miocene, giving rise to collisional thrust belts in the Northern and Southern Apennines and along the North African continental margin (i.e. the Maghrebian chain) to the Betic-Rif area. From the Early Miocene onwards, a separate subduction system became active, related to removal of Neotethyan oceanic crust to the southeast (Ionian Sea), fueling suprasubduction zone extension and opening of the Tyrrhenian Sea. ‘Orogenic collapse’ is an alternative mechanism of such extension, and is widely believed to have caused divergent thrusting in the Betic and Rif regions of the westernmost Mediterranean, at the same time as crustal extension and subsidence of the Alboran Sea. 相似文献
2.
NIE Rui SONG Hao LI Qi GUO Yuping YAN Wenquan SI Fei YAO Chang LI Wei ZHAO Zichao 《《地质学报》英文版》2019,93(Z2):115-116
In this paper we compare four types of stratigraphic architectures around the continental margins in the South China Sea (SCS) based on a plentiful of seismic profiles. The results indicate that stratigraphic patterns are not only related closely to structure regimes of peripheral of the SCS, but also are restrained by crust structure from continental crust to oceanic crust. In the extensional setting, depositional centres during the syn‐spreading stage are located in the strong extensional area. A wedge‐decrease continental crust represented by the Pearl River Mouth type is characterized by high deposition and subsidence rate during the syn‐rifting and syn‐spreading stages in the distal zone. And in the Zhongjiannan type with a continental ribbon, high deposition and subsidence rate during the syn‐rifting and syn‐spreading stages are present in the proximal zone. However, in the southern and eastern margins with compressional setting, the Liyue and Zengmu microcontinent blocks are separated from the South China with the seafloor spreading of SCS, in which a confined or relative thin syn‐spreading deposits are presence. High deposition and subsidence rate is closely related to the collision or subduction condition during the post‐spreading stage in the Liyue bank type and the Zengmu type, a huge progradational clinoforms are present along the subduction and collision margin. Therefore, this study shows distinct stratigraphic architecture in different continental rifted margins, distinct depositional and subsidence characteristics formed during the process of lithospheric rupture can provide an effective method for the study on the continental marginal sea in the western Pacific. 相似文献
3.
南海是西太平洋海域最大的边缘海,然而南海扩张终结后动力学过程研究仍较为薄弱.通过构造变革界面识别、褶皱冲断带沉积记录等方面的系统研究,揭示南海南部和东部陆缘在南海后扩张期的演化历程.研究表明南海南部和东部边缘经历了多个微板块从俯冲到碰撞的演变历程,形成了陆-陆碰撞、弧-陆碰撞、洋-弧俯冲等多个特征迥异的板块边界.南海南部陆缘属于古南海俯冲拖曳构造区,婆罗洲西北沙捞越-曾母地块率先碰撞,随后经历了婆罗洲东北沙巴-南沙地块碰撞、西南巴拉望-卡加延岛弧碰撞.南部多个微板块碰撞导致古南海呈剪刀式从西向东逐渐关闭和消亡,总体形成了以微地块碰撞、深海槽发育和造山带前缘巨厚沉积充填为特色的碰撞陆缘.东部陆缘属于菲律宾海俯冲-碰撞构造区,南海东部洋壳自中新世开始向菲律宾海板块俯冲,弧-陆碰撞仅局限于东部陆缘南北两端.澳洲-印度板块、菲律宾海板块与欧亚板块相互作用控制了南海边缘海闭合过程,南海正在进行的关闭过程主要集中在东缘和南缘,东缘呈现了以南海洋壳消亡为特征的闭合过程,而南缘则呈现以微陆块碰撞为特征的古南海闭合过程.显然,南部后扩张期陆缘演变可为边缘海闭合过程研究提供极佳的范例,同时对我国海洋权益保护和南海大陆边缘动力学研究具有重要意义. 相似文献
4.
P-wave velocity structure of the margin of the southeastern Tsushima Basin in the Japan Sea using ocean bottom seismometers and airguns 总被引：2，自引：0，他引：2
Takeshi Sato Toshinori Sato Masanao Shinohara Ryota Hino Minoru Nishino Toshihiko Kanazawa 《Tectonophysics》2006,412(3-4):159-171
The Tsushima Basin is located in the southwestern Japan Sea, which is a back-arc basin in the northwestern Pacific. Although some geophysical surveys had been conducted to investigate the formation process of the Tsushima Basin, it remains unclear. In 2000, to clarify the formation process of the Tsushima Basin, the seismic velocity structure survey with ocean bottom seismometers and airguns was carried out at the southeastern Tsushima Basin and its margin, which are presumed to be the transition zone of the crustal structure of the southwestern Japan Island Arc. The crustal thickness under the southeastern Tsushima Basin is about 17 km including a 5 km thick sedimentary layer, and 20 km including a 1.5 km thick sedimentary layer under its margin. The whole crustal thickness and thickness of the upper part of the crust increase towards the southwestern Japan Island Arc. On the other hand, thickness of the lower part of the crust seems more uniform than that of the upper part. The crust in the southeastern Tsushima Basin has about 6 km/s layer with the large velocity gradient. Shallow structures of the continental bank show that the accumulation of the sediments started from lower Miocene in the southeastern Tsushima Basin. The crustal structure in southeastern Tsushima Basin is not the oceanic crust, which is formed ocean floor spreading or affected by mantle plume, but the rifted/extended island arc crust because magnitudes of the whole crustal and the upper part of the crustal thickening are larger than that of the lower part of the crustal thickening towards the southwestern Japan Island Arc. In the margin of the southeastern Tsushima Basin, high velocity material does not exist in the lowermost crust. For that reason, the margin is inferred to be a non-volcanic rifted margin. The asymmetric structure in the both margins of the southeastern and Korean Peninsula of the Tsushima Basin indicates that the formation process of the Tsushima Basin may be simple shear style rather than pure shear style. 相似文献
5.
利用最新多道地震剖面资料,结合重力、磁力、地形等地球物理资料,揭示了中沙地块南部断裂空间展布特征、断裂发育时期、断裂内部构造形变特征及深部地壳结构,并基于认识探讨了断裂的发育机制。研究结果认为,中沙地块南部陆缘构造属性为非火山型被动大陆边缘：地壳性质从西北向东南由减薄陆壳向洋陆过渡壳再向正常洋壳发育变化;Moho面埋深从中沙地块下方的26 km快速抬升到海盆的10~12 km;从中沙地块陡坡至其前缘海域的重力异常明显负异常区为洋陆过渡带,在重力由高值负异常上升到海盆的低值正、负异常的边界为洋陆边界。中沙地块南部发育有4组阶梯状向海倾的深大正断裂,主要发育时期为晚渐新世到中中新世。断裂早期发育与南海东部次海盆近NS向扩张有关,后期遭受挤压变形、与菲律宾海板块向南海的NWW向仰冲有关。该研究有助于更好认识南海海盆的扩张历史和南海被动大陆边缘的类型。 相似文献
6.
南海北部陆缘盆地形成的构造动力学背景 总被引：2，自引：0，他引：2
摘要：南海北部陆缘盆地处于印度板块与太平洋及菲律宾海板块之间,但三大板块对南海北部陆缘盆地的影响是不同的。通过对三大板块及古南海演化的研究,可知南海北部陆缘地区应力环境于晚白垩世发生改变。早白垩世处于挤压环境,晚白垩世以来转变为伸展环境并且不同时期的成因不同。晚白垩世-始新世,华南陆缘早期造山带的应力松弛、古南海向南俯冲及太平洋俯冲板块的滚动后退导致其处于张应力环境。始新世时南海北部陆缘裂陷盆地开始产生,伸展环境没有变,但因其是由太平洋板块向西俯冲速率的持续降低及古南海向南俯冲引起的,南海北部陆缘盆地继续裂陷。渐新世-早中新世,地幔物质向南运动及古南海向南俯冲导致南海北部陆缘地区处于持续的张应力环境;渐新世早期南海海底扩张;中中新世开始,三大板块开始共同影响着南海北部陆缘盆地的发展演化。 相似文献
7.
8.
José Rodriguez-Fernandez Juan-Carlos Balanya Jesús Galindo-Zaldivar Andrés Maldonado 《Geodinamica Acta》2013,26(4):159-174
AbstractThe Powell Basin is one of the few present-day examples of a small isolated ocean basin largely surrounded by blocks of continental crust. The continental blocks in this basin result from the fragmentation of the northern Antarctic Peninsula. This basin was created by the eastward motion of the South Orkney microcontinent relative to the Antarctic Peninsula. The axial rift, identified by multichannel seismic profiles obtained during the HESANT 92/93 cruise, and the gravimetric anomalies of the basin plain, together with the transcurrent faults along the northern and southern margins, indicate a predominant WSW-ENE trend of basin extension. The South Orkney microcontinent was incorporated into the Antarctic Plate during the Miocene as a consequence of the end of basin spreading. The eastern and western margins are conjugate and have an intermediate crust in the region of transition to the basin plain. The differences in the basement structure and the architecture of the depositional units suggest that the extensional process was asymmetrical. The southern transtensive margin and the northern transcurrent margin are rectilinear and steep, without any intermediate crust in the narrow fault zone between the base of the continentalblocks slope and the oceanic crust. The multichannel seismic profiles across the central sector of the basin reveal a spreading axis with a double ridge and a central depression filled with sediments. The geometry of the reflectors in this depression indicates that the ponded deposits belong to the early stages of oceaniccrust accretion. This structure is similar to the overlapping spreading centres observed in fast-spreading oceanic axes, where the spreading axis has relay and overlapping segments.The depositional units of the margins and basin plain have been grouped into four depositional sequences, comprising the classic stages in the formation of an ocean basin: pre-rift (S1), syn-rift (S2), syn-drift (S3), and post-drift (S4). The pre-rift sequence has deformed reflectors and is observed in the southern and eastern margins. The syn-rift sequence, tectonically disrupted, fills depressions bounded by faults and is well-developed in the eastern margin where it is truncated by an erosive surface identified as the break-up unconformity. The syn-drift sequence is wedge-shaped in the basin, thickening towards the margins and having onlap relations on the flanks of the spreading ridge. The post-drift sequence is the thickest unit and is characterised by a cyclic pattern of alternating packages of high-amplitude reflectors, very continuous, and low-amplitude reflectors. Towards the western and eastern margins, the same sequence has channel-levee complexes and channelised, wedged bodies attributed to turbiditic deposits of submarine fans derived from canyons located in the slope and outer shelf. The cyclic nature of this sequence is probably related to advancing and receding grounded ice sheets in the continental shelf since the latest Miocene. 相似文献
9.
RenzoSartori 《《幕》》2003,26(3):217-221
A deep, narrow, and distorted Benioff zone, plunging from the Ionian Sea towards the southern Tyrrhenian basin, is the remnant of a long and eastward migrating subduction of eastern Mediterranean lithosphere. From Oligocene to Recent, subduction generated the Western Mediterranean and the Tyrrhenian back-arc basins, as well as an accretionary wedge constituting the SouthernAoenninic Arc.In the Tyrrhenian Sea, stretching started in late Miocene and eventually produced two small oceanic areas: the Vavilov Plain during Pliocene (in the centralsector) and the Marsili Plain during Quaternary (in the southeastern sector). They are separated by a thicker crustal sector, called the Issel Bridge. Back-arc exten-sion was rapid and discontinuous, and affected a land locked area where continental elements of various sizesoccurred. Discontinuities in extension were mirrored bychanges in nature of the lithosphere scraped off to form the Southern Apenninic Arc. Part of the tectonic units of the southern Apennines, accreted into the wedge from late Miocene to Pliocene, had originally been laid down on thinned conti-nental lithosphere, which should constitute the deep portion of the present slab. After Plio-cene, only Ionian oceanic lithosphere wassubducted, because the large buoyancy of thewide and not thinned continental lithosphere of Apulia and Africa (Sicily) preserved the seelements from roll back of subduction. After Pliocene, the passively retreating oceanic slabhad to adjust and distort according to the geometry of these continental elements.The late onset of arc volcanism in respect to the duration of extension in the Tyrrhenian-Ionian system may find an expla-nation considering an initial stage of subduc-tion of thinned continental lithosphere. The strong Pleistocene vertical movements that occurred in the whole southeastern system(subsidence in the back-arc basin and upliftin the orogenic arc) may instead be related to the distortion of the oceanic slab. 相似文献
10.
Haibo Huang Enyuan He Xuelin Qiu Jianke Fan Xunhua Zhang 《International Geology Review》2020,62(7-8):1070-1080
ABSTRACT We construct a complete density transection based on the velocity structures across the Zhongsha Bank in the South China Sea. Gravity modelling of the lateral density contrasts between tectonic units helps us to determine the structural attributes and boundaries between continental blocks and deep basins. The configuration of the continent–ocean boundary (COB) around the Zhongsha Bank is mapped based on the gravity/magnetic anomaly and crustal structures. A low-density mantle is found beneath the Zhongsha Bank and the oceanic basins, and this mantle is associated with the high heat-flow background. The COB orientation is northeast-east in the north of the bank, with faulted linear structures. In further southeast, where there is a more intact crust, the COB orientation changed to north-northeast. The reconstructed density model and gravity/magnetic map indicate that the Zhongsha Bank is conjugated with the Liyue Bank by a rifted basin, where the crust had experienced localized deformation before the seafloor spreading. Because of the insufficient magmatism in the oceanic basin, the spreading ridge propagates into the weakened continental lithosphere between the two continental blocks, thus completely separating the Zhongsha Bank from the Liyue Bank. Seafloor spreading ridge jumps within the South China Sea may also be affected by the heterogeneous lithosphere beneath the continental blocks and oceanic basins. 相似文献
11.
Han-Joon Kim Hyeong-Tae Jou Hyun-Moo Cho Harmen Bijwaard Takeshi Sato Jong-Kuk Hong Hai-Soo Yoo Chang-Eob Baag 《Tectonophysics》2003,364(1-2):25-42
Despite the various opening models of the southwestern part of the East Sea (Japan Sea) between the Korean Peninsula and the Japan Arc, the continental margin of the Korean Peninsula remains unknown in crustal structure. As a result, continental rifting and subsequent seafloor spreading processes to explain the opening of the East Sea have not been adequately addressed. We investigated crustal and sedimentary velocity structures across the Korean margin into the adjacent Ulleung Basin from multichannel seismic (MCS) reflection and ocean bottom seismometer (OBS) data. The Ulleung Basin shows crustal velocity structure typical of oceanic although its crustal thickness of about 10 km is greater than normal. The continental margin documents rapid transition from continental to oceanic crust, exhibiting a remarkable decrease in crustal thickness accompanied by shallowing of Moho over a distance of about 50 km. The crustal model of the margin is characterized by a high-velocity (up to 7.4 km/s) lower crustal (HVLC) layer that is thicker than 10 km under the slope base and pinches out seawards. The HVLC layer is interpreted as magmatic underplating emplaced during continental rifting in response to high upper mantle temperature. The acoustic basement of the slope base shows an igneous stratigraphy developed by massive volcanic eruption. These features suggest that the evolution of the Korean margin can be explained by the processes occurring at volcanic rifted margins. Global earthquake tomography supports our interpretation by defining the abnormally hot upper mantle across the Korean margin and in the Ulleung Basin. 相似文献
12.
红海是地球上最年轻的大洋,其板块构造活动正处于威尔逊旋回的幼年期。红海南北两端分别连接着威尔逊旋回的胚胎期和终结期,即东非大裂谷和地中海。这一独特的地理位置和构造部位使其成为板块构造理论研究的圣地。本文通过对已有的地质、地球物理和地球化学资料进行综合分析,了解了红海地区的地形、重磁异常和沿脊的玄武岩地球化学组成等地质构造特征,探讨了红海裂谷的洋壳分布、地幔源区不均一性以及扩张演化历史等问题。红海地形中间深、南北两端浅,可以分为北、中北、中南、南等四段。重磁异常的条带主要出现在中南段,其他段不明显,因而限制了以往对红海扩张历史的认识。目前认为红海全段存在洋壳,红海两岸的沿岸悬崖是共轭扩张陆缘,呈向南开口的喇叭型扩张,而非对应红海岸线的梭子型。红海裂谷沿脊的地幔源区具有明显的不均一性,南段玄武岩显示E-MORB特征,表现为阿法尔地幔柱的影响。红海的发育经历了裂谷前火山作用(31~29Ma)、大陆张裂(29~13Ma)和洋底扩张(<13Ma)三个主要阶段。红海裂谷的形成演化与非洲大陆的裂解、阿法尔地幔柱的活动、新特提斯洋的闭合等密切相关,了解红海的地球动力学过程将为揭示区域大地构造演化以及板块运动规律提供依据。 相似文献
13.
Recent geophysical measurements, including multi-channel seismic reflection, on the Svalbard passive margin have revealed that it has undergone a complex geological history which largely reflects the plate tectonic evolution of the Greenland Sea and the Arctic Ocean. The western margin (75–80°N) is of a sheared-rifted type, along which the rifted margin developed subsequent to a change in the pole of plate rotation about 36 m.y. B.P. The north-trending Hornsund Fault on the central shelf and the eastern escarpment of the Knipovich Ridge naturally divide the margin into three structural units. These main marginal structures strike north, paralleling the regional onshore fault trends. This trend also parallels the direction of Early Tertiary plate motion between Svalbard and Greenland. Thus, the western Svalbard margin was initially a zone of shear, and the shear movements have affected the adjacent continental crust. Although, the nature and location of the continent—ocean crustal transition is somewhat uncertain, it is unlikely to lie east of the Hornsund Fault. The northern margin, including the Yermak marginal plateau, is terminated to the west by the Spitsbergen Fracture Zone system. This margin is of a rifted type and the preliminary analysis indicates that the main part of the investigated area is underlain by continental crust. 相似文献
14.
南海大陆边缘盆地构造演化差异性及其与南海扩张耦合关系 总被引：3，自引：0，他引：3
南海大陆边缘盆地由于边界条件的差异,不仅形成了不同类型的陆缘盆地,如离散型、走滑伸展型和伸展挠曲复合型,而且这些盆地构造演化存在明显的非同步性。这些陆缘破裂过程与南海扩张作用过程呈现明显不一致性。研究表明,南海扩张时期南海南、北大陆边缘均形成了一系列裂陷盆地,然而,南海南部、北部大陆边缘盆地裂陷作用结束时间不同,北部大陆边缘盆地裂陷作用结束于23 Ma或21 Ma,而南部大陆边缘盆地裂陷作用结束于15.5 Ma,显然北部大陆边缘盆地裂陷结束时间明显早于南部大陆边缘盆地。南海扩张停止后,南海南、北部陆缘仍表现出明显差异,北部陆缘仍以伸展作用为主,晚中新世以来出现快速沉降幕,而南海南部陆缘则以挤压作用为主,且其挤压时间及强度呈现南早北晚的特点,即南部曾母盆地明显早于南薇西盆地和北康盆地。南海南、北大陆边缘盆地形成演化的差异性,特别是构造转型差异变化,为新生代南海扩张的迁移性提供了有力的佐证,可以推断南海不同期次海盆扩张可能存在向南的突然跃迁。因此,本次研究梳理出的南海不同陆缘盆地张裂伸展的非同步性可为南海洋盆扩张演化过程解释提供新的证据。 相似文献
15.
A traverse through the western Kunlun (Xinjiang,China): tentative geodynamic implications for the Paleozoic and Mesozoic 总被引：13，自引：0，他引：13
The northern part of the western Kunlun (southern margin of the Tarim basin) represents a Sinian rifted margin. To the south of this margin, the Sinian to Paleozoic Proto-Tethys Ocean formed. South-directed subduction of this ocean, beneath the continental southern Kunlun block during the Paleozoic, resulted in the collision between the northern and southern Kunlun blocks during the Devonian. The northern part of the Paleo-Tethys Ocean, located to the south of the southern Kunlun, was subducted to the north beneath the southern Kunlun during the Late Paleozoic to Early Mesozoic. This caused the formation of a subduction-accretion complex, including a sizeable accretionary wedge to the south of the southern Kunlun. A microcontinent (or oceanic plateau?), which we refer to as “Uygur terrane,” collided with the subduction complex during the Late Triassic. Both elements together represent the Kara-Kunlun. Final closure of the Paleo-Tethys Ocean took place during the Early Jurassic when the next southerly located continental block collided with the Kara-Kunlun area. From at least the Late Paleozoic to the Early Jurassic, the Tarim basin must be considered a back-arc region. The Kengxiwar lineament, which “connects” the Karakorum fault in the west and the Ruogiang-Xingxingxia/Altyn-Tagh fault zone in the east, shows signs of a polyphase strike-slip fault along which dextral and sinistral shearing occurred. 相似文献
16.
The orogenic belts encircling the present-day Adriatic Sea are the deformed Mesozoic continental margin of an area known as Adria, the outline of which began to take shape during Middle Triassic continental rifting. Early Jurassic oceanic rifting was usually close to, but not coincident with, sites of earlier continental rifting. The Triassic rifted zones were usually incorporated into the continental margin of Adria, profoundly influencing its subsequent development. The Mesozoic platform/basin morphology of this margin can be correlated along the length of the belt.Palaeomagnetic data from autochthonous outcrops of the foreland of Adria do not indicate relative rotation and moreover suggest that this foreland has moved in coordination with Africa since the Early Mesozoic. Seismic soundings indicate that thick Mesozoic sedimentary sequences which can be correlated with sections on the African platform are continuous beneath the eastern Mediterranean seas. The concept of Adria as having behaved as a promontory of the African plate is tested by correlation of the main tectonic events in the belt with the spreading history of the Atlantic. The simplest model which adequately accounts for available data comprises a continuous Mesozoic continental margin from the Magrebids of Tunisia, through the Apennines, Alps, Dinarides and Hellenides to the alpine belt of Turkey. This margin was the southern margin of the Mesozoic Tethys and its foreland was more or less continuous with the African platform. Some structural and geochemical features of the double ophiolitic belt on the eastern side of Adria may be explained in terms of more external oceanic branches giving a more diversified continental margin of Adria. The present undulations of the Periadriatic belt are mainly a product of Late Cretaceous to recent deformation, which severely modified the shape of this margin by continental collision and by subsequent development of back-arc features. 相似文献
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综合介绍了世界上几个典型蛇绿岩带中伸展变形构造的实例,如何形成辉长质或其它不同层次的糜棱岩,可造成辉绿岩墙群的倾斜旋转,可使得原始洋壳厚度变薄等,蛇绿岩中伸展构造记录了已经消失的洋盆的生成,拆离和消减过程中的关信息,研究蛇绿岩中伸展变形构造,有助于恢复古洋盆的规模的演化过程,也是蛇绿岩研究的新方向这一。 相似文献
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采用"造山带混杂岩区"新理论,首次在贺根山-黑河缝合带中段发现海勒斯台俯冲增生混杂岩,建立由"基质"+"岩块"组成的俯冲增生杂岩体系,其构造样式为整体左行逆冲剪切.基质主要有糜棱岩、千糜岩、超糜棱岩及少量的沉凝灰岩、粉砂岩、细砂岩,构造环境为弧前盆地,时代主要为中寒武世;岩块有洋岛海山岩块、弧后洋盆洋壳残片、火山弧岩块、裂离陆块,岩块的年龄区间主要在中寒武世-中奥陶世,裂离陆块时代为新太古代.结合俯冲增生杂岩基质年龄、岩块的年龄、侵入混杂岩的TTG年龄（449 Ma）和变形程度、接触关系等,将海勒斯台俯冲增生杂岩的形成时代厘定为中晚奥陶世.认为研究区俯冲作用在早寒武世就已经开始,在大陆边缘形成火山岛弧;奥陶纪初期弧后发育弧后盆地,至中奥陶世弧后盆地出现洋壳;此时中寒武世的基质经俯冲下切后在中奥陶世时期折返上升;晚奥陶世时期由于区域的持续汇聚挤压,该弧后洋盆很快夭折;弧陆开始碰撞,导致双向俯冲.在弧陆碰撞过程中,晚期形成的弧后盆地洋壳等新岩块混入早期形成的基质中.海勒斯台俯冲增生混杂岩带的发现填补了贺根山-黑河缝合岩带中段的空白,对区域构造格架厘定具有非常重要的意义,为研究古亚洲构造域演化提供了新的证据. 相似文献