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1.
The Antique Ophiolite Complex exposed along the western side of Panay Island, central Philippines was derived from the Jurassic to Cretaceous proto-South China Sea oceanic leading edge of the Palawan microcontinental block. The subduction and ultimate closure of this ocean basin resulted in the emplacement and exposure of this lithospheric fragment along the collisional boundary of the microcontinental block and the oceanic- to island arc-affiliated Philippine mobile belt. The ophiolite complex has volcanic rocks having normal- to transitional mid-ocean ridge basalt (MORB) to island arc tholeiitic (IAT) geochemistry consistent with the transitional MORB–IAT characteristics of its peridotites. The chromitites manifest subduction signature suggestive of the involvement of water in its generation. All of these would be consistent with generation in a supra-subduction zone environment, specifically in a subduction-related marginal ocean basin. The collision of the Palawan microcontinental block with the Philippine mobile belt along western Panay resulted, aside from ophiolite emplacement, into arc curvature, island rotation, serpentinite diapirism and thrusting along the forearc side. The offshore bathymetric expression of the microcontinental block along the collision zone shows the leading edge of this oceanic bathymetric high to have spread laterally. This is indicative of its being buoyant resulting to non-subduction as supported by available earthquake hypocenter data.  相似文献   

2.
Abstract. The aseismic Palawan microcontinental block is an oceanic bathymetric high that has collided with the seismically-ac-tive Philippine Mobile Belt since the Early Miocene. Consequently, tectonic microblocks immediately north (Luzon) and south (Western Visayas Block) of the collision front rotated in opposite senses. The rotation led the microblocks to onramp adjacent strike-slip faults, and converted these to subduction zones, namely, the current Manila and Negros Trenches. In addition, the collision also initiated the southward propagation of a major left-lateral strike slip fault, the Philippine Fault Zone, and the Philippine Trench, which bounds the Philippine archipelago along its eastern boundary. Based on onshore and offshore data, the Philippine Fault Zone and the East Luzon Trough - Philippine Trench appears to also propagate northward. Furthermore, the opposite direction of propagation is also noted for the Manila and Negros Trenches from the locus of the collision in the Central Philippines to their northern and southern extensions, respectively. The ages of initiation of the Manila Trench (Early Miocene), Philippine Fault Zone (Middle Miocene) and Philippine Trench (Pliocene) as encountered along a west to east transect in the Central Philippines are consistent with the collision and subsequent indentation of Palawan with the rest of the Philippine Mobile Belt.  相似文献   

3.
During the Paleogene the Proto-South China Sea was subducted beneath northern Borneo. Subduction ended with Early Miocene collision of the Dangerous Grounds/Reed Bank/North Palawan block and the Sabah–Cagayan Arc. Much of northern Borneo then became emergent forming the Top Crocker Unconformity. Later in the Early Miocene subsidence resumed. It is proposed that northward subduction of the Celebes Sea initiated formation of the Sulu Sea backarc basin, followed by subduction rollback to the SE. This formed a volcanic arc, which emerged briefly above sea level and collapsed in the Middle Miocene. As rollback continued the Sulu Arc was active during Middle and Late Miocene between Sabah and the Philippines. Rollback drove extension in northern Borneo and Palawan, accompanied by elevation of mountains, crustal melting, and deformation offshore. There were two important extensional episodes. The first at about 16 Ma is marked by the Deep Regional Unconformity, and the second at about 10 Ma produced the Shallow Regional Unconformity. Both episodes caused exhumation of deep crust, probably on low angle detachments, and were followed by granite magmatism. The NW Borneo–Palawan Trough and offshore Sabah fold and thrust belt are often interpreted as features resulting from collision, regional compression or subduction. However, there is no seismicity, dipping slab or volcanicity indicating subduction, nor obvious causes of compression. The trough developed after the Middle Miocene and is not the position of the Paleogene trench nor the site of Neogene subduction. Inboard of the trough is a thick sediment wedge composed of an external fold and thrust belt and internal extensional zone with structures broadly parallel to the trough. The trough is interpreted as a flexural response to gravity-driven deformation of the sediment wedge, caused by uplift on land that resulted from extension, with a contribution of deep crustal flow.  相似文献   

4.
Abstract. High seismic activity in the Philippines originates from tectonic convergence related to surface and subsurface seismotectonic features. Based on earthquake data, the archipelago can be divided into the seismically-active Philippine Mobile Belt and the aseismic North Palawan Block. The latter represents a rifted continental fragment of the Eurasian margin that juxtaposed with the rest of island arc units in central Philippines. Earthquake hypocenter plots on planar and in vertical profiles show that the seismic events are associated with known seismotectonic features. In addition, data suggest that the collision zone between the North Palawan Block and the Philippine Mobile Belt is characterized by a decreased amount of hypocenters at > 100 km depths. Although field evidence favors the presence of a subducted slab or slabs beneath western central Philippines, these are difficult to image using the present seismicity distribution dataset.  相似文献   

5.
解习农  赵帅  任建业  杨允柳  姚永坚 《地球科学》2022,47(10):3524-3542
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   

6.
The crustal gravitational potential energy change (ΔGPE) caused by earthquakes in the Philippine area from January 1976 to November 2011 was estimated in this study. The active convergence between the Philippine Sea Plate and the Sundaland–Eurasian margin is reflected by the greatest gains in GPE along the Philippine, Negros and Cotabato trenches, whereas the Manila Trench is covered by a GPE loss pattern. Although the Philippine Mobile Belt (PMB) itself is actually affected by the ongoing collision and subduction processes, almost the entire Philippine Fault Zone is dominated by GPE loss, revealing a slightly extensional environment along the fault. The time evolution of the cumulated ΔGPE for different segments along the Philippine archipelago shows distinct patterns. Due to the numerous large underthrusting events that have occurred along the Philippine Trench, the cumulated ΔGPE is regularly increasing in its most southern segment. However, in the middle segments, where the Palawan Block enters into collision with the PMB, the increase in cumulated ΔGPE is relatively small. In the most northern segment, where the North Luzon is located, a decrease of cumulated ΔGPE demonstrates that the seismic characteristic of the Manila Trench is dissimilar from other subduction systems in the world. We suggest that the collision of both the Palawan Block and the Benham Rise with the PMB promotes the rotation of the PMB and facilitates the northward escape of the northeastern Luzon, resulting in a decrease of cumulated ΔGPE in the northern Philippines.  相似文献   

7.
The Amnay Ophiolitic Complex in Mindoro, the Philippines, is considered an emplaced Cenozoic South China Sea oceanic lithosphere as a result of the collision between the Palawan microcontinental block and the Philippine mobile belt. Middle Oligocene sedimentary rocks intercalated with dominantly MORB-like pillow lavas and volcanic flows suggest the generation of this ophiolite complex in an intermediate spreading ridge within a back-arc basin setting. The volcanic rock suite geochemistry also manifests a slab component suggesting that it is a supra-subduction zone ophiolite. Petrography of the gabbros shows a plagioclase-clinopyroxene crystallization order consistent with a back-arc basin setting. Spinel and pyroxene geochemistry shows that the lherzolites and aluminous-spinel harzburgites are products of low degrees of partial melting. The chromitites hosted by the harzburgites could have not been associated with the MORB-like volcanic suites, gabbros, lherzolites and aluminous-spinel harzburgites. The chromitites are products of mantle sources that have undergone higher degrees of partial melting that would have involved the presence of water. The study of this ophiolitic complex gives us a glimpse of the characteristics of the South China Sea.  相似文献   

8.
The Philippine mobile belt represents a crustal fragment, wedged between two subduction systems exhibiting opposite polarity. The eastern (Philippine—Quezon) system probably originated in the Eocene during northwest—southeast spreading of the west Philippine basin. Westward subduction is continued, probably as a result of northward motion of the Philippine basin crust. The western (Manila—Bataan) system originated in the Oligocene by spreading and formation of the South China Sea basin. Eastward subduction dominates the tectonics in the northern part of the archipelago and resulted in the formation of the Bataan orogene, a sequence of three parallel volcanic arcs emplaced in obducted oceanic crust. Geochemical and radiometric data indicate that the arcs migrated eastward with time (Miocene to Present) while changing composition from tholeiitic via calc-alkaline to shoshonitic. Centers of the latter two types are presently active. Depocenters behind the arcs also migrated eastward with time, suggesting correction of the isostatic disequilibrium caused by geanticlinal uplift of the orogene. Paleomagnetic evidence suggests that central Luzon is rotating counterclockwise probably due to differential spreading in the South China Sea basin. The west Philippine basin rotates clockwise. This results in significant “Einengung” in the southern part of the archipelago.  相似文献   

9.
日本列岛是晚古生代以来洋、陆沿活动陆缘汇聚及南来地体拼贴的产物，在日本海中新世张开以前曾是亚洲大陆的一部分，因此其历史对于完善东亚显生宙后期的构造演化记录是极为可贵的。本文在有关研究成果的基础上提出：(1)日本列岛主体是中亚造山带沿走向的延伸，记录了从朝鲜半岛向南中生代亚洲大陆的增生历史。中朝克拉通的东界应在它的西面经图们江带弧形转折后沿朝鲜半岛以东南下。(2)从锡霍特阿林到菲律宾，亚洲前沿以侏罗纪为主的消减-增生杂岩也可能在闽粤沿海的大片中生代火山岩下面发现；长乐-南澳变质带可能相当于巴拉望或西菲律宾地块并与日本的黑濑川带有关。(3)日本学者有关飞骅边缘带是秦岭-大别缝合带向东延续的论述，提示该带可能是中亚和秦岭两个造山带向东延续的复合，中朝和扬子陆块在它以西依次尖灭。  相似文献   

10.
The Philippine archipelago resulted from a complex series of geologic events that involved continental rifting, oceanic spreading, subduction, ophiolite obduction, arc-continent collision, intra-arc basin formation and strike-slip faulting. It can be divided into two tectono-stratigraphic blocks, namely; the Palawan–Mindoro Continental Block (PCB) and the Philippine Mobile Belt (PMB). The PCB was originally a part of the Asian mainland that was rifted away during the Mesozoic and drifted in the course of the opening of the South China Sea (SCS) during Late Paleogene. On the other hand, the PMB developed mainly from island arcs and ophiolite terranes that started to form during the Cretaceous. At present, the PMB collides with the PCB in the Visayas in the central-western Philippines. This paper discusses recent updates on Philippine geology and tectonics as contribution to the establishment of the International Geologic Map of Asia at 1:5 M scale (IGMA5000).  相似文献   

11.
《Tectonophysics》1987,144(4):337-352
Halmahera is situated in eastern Indonesia at the southwest corner of the Philippine Sea Plate. Active arc-arc collision is in process in the Molucca Sea to the west of Halmahera. New stratigraphic observations from Halmahera link this island and the east Philippines and record the history of subduction of the Molucca Sea lithosphere. The Halmahera Basement Complex and the basement of east Mindanao were part of an arc and forearc of Late Cretaceous-Early Tertiary age and have formed part of a single plate since the Late Eocene-Early Oligocene. There is no evidence that Halmahera formed part of an Oligo-Miocene arc but arc volcanism, associated with eastwards subduction of the Molucca Sea beneath Halmahera, began in the Pliocene and the Pliocene arc is built on a basement of the early Tertiary arc. Arc volcanism ceased briefly during the Pleistocene and the arc shifted westwards after an episode of deformation. The present active arc is built upon deformed rocks of the Pliocene arc. The combination of new stratigraphic information from the Halmahera islands and models of the present-day tectonic structure of the region deduced from seismic and other geophysical studies is used to constrain the tectonic evolution of the region since the Miocene. Diachronous collision at the western edge of the Philippine Sea Plate which began in Mindanao in the Late Miocene impeded the movement of the Philippine Sea Plate and further motion has been achieved by a combination of strike-slip motion along the Philippine Fault, subduction at the Philippine Trench and subduction of the Molucca Sea lithosphere beneath Halmahera.  相似文献   

12.
The collision between the North Palawan Block (NPB) and Philippine Mobile Belt (PMB) has been the subject of studies considering its significance in help-ing define the tectonic evolution of the Philippine is-land arc system. The geology of the western Panay island reveals the presence of a continent-related block (Buruanga Peninsula) juxtaposed to an oceanic frag-ment (Antique Ophiolite Complex). Our recent work in the Buruanga Peninsula helped us define the terrane boundary between the Peninsula and the Antique Ophiolite Complex. However, considering available published data, the Antique Ophiolite Complex has never been considered to be a part of the NPB and to mark the collision zone between Palawan and the PMB.  相似文献   

13.
A synthesis of the geologic evolution of Taiwan   总被引：2，自引：0，他引：2  
The island arc of Taiwan is composed of Cenozoic geosynclinal sediments more than 10,000 m thick, lying on a pre-Tertiary metamorphic basement. Pleistocene to Miocene andesitic islands surround the main island and are related mostly to arc magmatism. The Penghu Island Group in the Taiwan Strait is covered with Pleistocene flood basalt. Neogene shallow marine clastic sediments are exposed mainly in the western foothills with Pleistocene andesitic extrusives at the northern tip and the northeastern offshore islands. A thick sequence of Paleogene to Miocene argillitic to slaty metaclastic rocks underlies the western Central Range and forms the immediate sedimentary cover on the pre-Tertiary metamorphic complex to the east, which represents an older Mesozoic arc-trench system. The Coastal Range in eastern Taiwan is a Neogene andesitic magmatic arc, including also a large variety of volcaniclastic and turbiditic sediments. Cenozoic Taiwan is the site of arc-continent collision where the Luzon arc on the Philippine Sea plate overrides the Chinese continental margin on the Eurasian plate. East and northeast of Taiwan, the polarity of subduction changes whereby the oceanic Philippine Sea plate is subducting beneath the Ryukyu arc system on the Eurasian plate. Continent-arc collision in Taiwan island is anomalous and may occur in a broad belt of deformation rather than along a well-defined plate boundary or subduction zone.  相似文献   

14.
The Hidaka Collision Zone (HCZ), central Hokkaido, Japan, is a good target for studies of crustal evolution and deformation processes associated with an arc–arc collision. The collision of the Kuril Arc (KA) with the Northeast Japan Arc (NJA), which started in the middle Miocene, is considered to be a controlling factor for the formation of the Hidaka Mountains, the westward obduction of middle/lower crustal rocks of the KA (the Hidaka Metamorphic Belt (HMB)) and the development of the foreland fold-and-thrust belt on the NJA side. The “Hokkaido Transect” project undertaken from 1998 to 2000 was a multidisciplinary effort intended to reveal structural heterogeneity across this collision zone by integrated geophysical/geological research including seismic refraction/reflection surveys and earthquake observations. An E–W trending 227 km-long refraction/wide-angle reflection profile found a complicated structural variation from the KA to the NJA across the HCZ. In the east of the HCZ, the hinterland region is covered with 4–4.5 km thick highly undulated Neogene sedimentary layers, beneath which two eastward dipping reflectors were imaged in a depth range of 10–25 km, probably representing the layer boundaries of the obducting middle/lower crust of the KA. The HMB crops out on the westward extension of these reflectors with relatively high Vp (>6.0 km/s) and Vp/Vs (>1.80) consistent with middle/lower crustal rocks. Beneath these reflectors, more flat and westward dipping reflector sequences are situated at the 25–27 km depth, forming a wedge-like geometry. This distribution pattern indicates that the KA crust has been delaminated into more than two segments under our profile. In the western part of the transect, the structure of the fold-and-thrust belt is characterized by a very thick (5–8 km) sedimentary package with a velocity of 2.5–4.8 km/s. This package exhibits one or two velocity reversals in Paleogene sedimentary layers, probably formed by imbrication associated with the collision process. From the horizontal distribution of these velocity reversals and other geophysical/geological data, the rate of crustal shortening in this area is estimated to be greater than 3–4 mm/year, which corresponds to 40–50% of the total convergence rate between the NJA and the Eurasian Plate. This means that the fold-and-thrust belt west of the HCZ is absorbing a large amount of crustal deformation associated with plate interaction across Hokkaido Island.  相似文献   

15.
The Rosario–Bunawan district is situated about 200 km north of Davao City, the capital of the Mindanao Island, Southern Philippines. Gold is produced from the Co-O mine, containing about 2,034,000 t of ore at 10.9 g/t Au, and in numerous small-scale operations by local miners. Epithermal gold mineralization in the Rosario–Bunawan district and the Co-O mine is confined to narrow (0.2–4 m) low-sulfidation quartz–chalcedony–calcite veins in volcanic and volcaniclastic wall rocks. Three major vein orientations are distinguished: (1) the NNW–SSE-trending set with a sinistral strike-slip sense of deformation (Philippine Fault trend); (2) the ENE–WSW-trending dextral strike-slip set (Palawan trend) and associated veins in the Riedel geometry; and (3) the WNW–ESE-trending conjugate set (Co-O trend). Three structural stages are defined: (1) extensional shear or shear veins formed in the Co-O, the Philippine Fault, and Palawan trends during regional NW–SE compression and near vertical vein opening (D1); (2) reactivation of veins in the Philippine Fault, veins associated with the Palawan, and, to a lesser extent, the Co-O trends during E–W compression and near horizontal N–S-oriented vein opening (D2). New D2 extensional shear or shear veins formed in the Philippine Fault, and structures associated with the Palawan and associated Riedel trends; (3) the D3-stage block faulting subsequently displaced all of the auriferous veins. The auriferous Rosario–Bunawan district is situated between two splays of the Philippine Fault, which acted as a lateral ramp system during the oblique convergence of the Philippine Sea plate and the Eurasian plate. The oblique convergence resulted in a change from a compressional (D1) to a transpressional (D2) regime, which was a prerequisite for the two-stage vein opening and hydrothermal mineralization, leading to an economic gold enrichment. D1 compressional tectonics may have caused an elevated geothermal gradient in shallow crustal levels, forming the heat source for the fluid plumbing system, which is at variance to typical epithermal deposits formed in extensional zones. D2 thrusting of a limestone nappe together with syn-tectonic diorite intrusions may have further increased the geothermal gradient, maintaining the fluid plumbing system. The limestone nappe may, at the same time, have represented an aquitard forcing the hydrothermal fluids into the volcanic and volcaniclastic wall rocks, which is regarded as critical for the two-stage gold mineralization in the Rosario–Bunawan district.  相似文献   

16.
ABSTRACT

The North Palawan Canyon is a large, previously undescribed submarine canyon that incises the continental shelf and slope of the southern South China Sea. Using multibeam bathymetric data and two-dimensional seismic reflection data, we have characterized current canyon morphology and documented lower-canyon migration in cross-section since the middle Miocene. We have also explored possible causes for the ancient migrations. The 175 km modern canyon is flanked by sediment waves outside its northern bank, and depositional lobes fan out from the canyon mouth. Over the past 15 million years, at least 20 cycles of significant canyon incising and infilling have occurred, along with significant canyon migration. This migration, as recorded in the sedimentary (seismic) record near a leftward bend in the canyon’s lower reach, can be divided into three stages: southward migration during the middle Miocene (averaging 1.24 km/m.y.), northward migration during the late Miocene (1.34 km/m.y.), and stationarity since the Pliocene. The overall zigzagging pattern of the canyon thalweg (as seen in cross-section through time) results from lateral and downstream migration in an aggradational environment. The early (middle to late Miocene) rapid zigzagging migration of the lower main channel, first southward and then northward, was probably associated with the strong collision of the North Palawan Block with the Philippine Mobile Belt, which would have triggered submarine instabilities and deformed the seafloor. The more recent (Pliocene and later) slowing or cessation of canyon migration is likely the result of the now quieter tectonic setting and long-term climatic cooling and drying.  相似文献   

17.
A synthesis of crustal thickness estimates was made recently utilizing available field, geochemical, seismicity, shear wave velocity and gravity data in the Philippines. The results show that a significant portion of the Philippine archipelago is generally characterized by crust with a thickness of around 25 to 30 kilometers. However, two zones, which are made up of a thicker crust (from 30 to 65 km) have also been delineated. The Luzon Central Cordillera region is characterized by thick crust. Another belt of thickened crust is observed in the Bicol-Negros-Panay-Central Mindanao region. This paper examines the interplay of tectonic and magmatic processes and their role in modifying Philippine arc crust. The processes, which could account for the observed crustal thicknesses, are presented. The contributions of magmatic arcs as compared to the contribution of the emplacement and accretion of ophiolite complexes to crustal thickness are also discussed.  相似文献   

18.
The South China Sea (SCS) is a region of interaction among three major plates: the Pacific, Indo-Australian and Eurasian. The collision of the Indian subcontinent with the Eurasian plate in the northwest, back-arc spreading at the center, and subduction beneath the Philippine plate along Manila trench in the east and the collision along Palawan trough in the south have produced complex tectonic features within and along the SCS. This investigation examines the satellite-derived gravity anomalies of the SCS and compares them with major tectonic features of the area. A map of Bouguer gravity anomaly is derived in conjunction with available seafloor topography to investigate the crustal structure. The residual isostatic gravity anomaly is calculated assuming that the Cenozoic sedimentary load is isostatically compensated. The features in the gravity anomalies in general correlate remarkably well with the major geological features, including offsets in the seafloor spreading segments, major faults, basins, seamounts and other manifestations of magmatism and volcanism on the seafloor. They also correlate with the presumed location of continental-oceanic crust boundary. The region underlain by oceanic crust in the central part of the SCS is characterized by a large positive Bouguer gravity anomaly (220–330 mgal) as well as large free-air and residual isostatic anomalies. There are, however, important differences among spreading segments. For example, in terms of free-air gravity anomaly, the southwest section of mid-ocean has an approximately 50 km wide belt of gravity low superimposed on a broad high of 45 mgal running NW–SE, whereas there are no similar features in other spreading segments. There are indications that gravity anomalies may represent lateral variation in upper crustal density structure. For instance, free air and isostatic anomalies show large positive anomalies in the east of the Namconson basin, which coincide with areas of dense volcanic material known from seismic surveys. The Red River Fault system are clearly identified in the satellite gravity anomalies, including three major faults, Songchay Fault in the southwest, Songlo Fault in the Northeast and Central Fault in the center of the basin. They are elongated in NW–SE direction between 20±30'N and 17°N and reach to Vietnam Scarp Fault around 16°30'N. It is also defined that the crustal density in the south side of the Central Basin is denser than that in the north side of the Central Basin.  相似文献   

19.
Collision of the Izu arc in Central Japan is discussed with a focus on its tectonic effects to the east of the arc, in the Miura-Boso Peninsulas of Honshu. The tectonics are the combination of the following events: Philippine Sea plate spreading in the Late Oligocene to Early Miocene; opening of the Sea of Japan in the middle Miocene; obduction of ophiolitic rocks in the northeasternmost corner of the Philippine Sea plate, and forearc sedimentation between the Honshu and Izu arcs. Oblique subduction has shifted the plate boundary from northeast to southwest, from the present Mineoka Tectonic Belt through the Miura Fold Belt to the Sagami trough since the Miocene. Remarkable right-lateral transpressional deformation occurred throughout this period of the oblique collision and subduction.  相似文献   

20.
台湾造山带是中新世晚期以来相邻菲律宾海板块往北西方向移动,导致北吕宋岛弧系统及弧前增生楔与欧亚大陆边缘斜碰撞形成的。目前该造山带仍在活动,虽然规模很小,但形成了多数大型碰撞造山带中的所有构造单元,是研究年轻造山系统的理想野外实验室,为理解西太平洋弧-陆碰撞过程和边缘海演化提供了一个独特的窗口。本文总结了二十一世纪以来对台湾造山带的诸多研究进展,讨论了其构造单元划分及演化过程。我们将台湾造山带重新划分为6个构造单元,由西至东分依次为:(1)西部前陆盆地;(2)中央山脉褶皱逆冲带;(3)太鲁阁带;(4)玉里-利吉蛇绿混杂岩带;(5)纵谷磨拉石盆地;(6)海岸山脉岛弧系统。其中,西部前陆盆地为6.5Ma以来伴随台湾造山带的隆升剥蚀形成沉积盆地。中央山脉褶皱逆冲带为新生代(57~5.3Ma)欧亚大陆东缘伸展盆地沉积物由于弧-陆碰撞受褶皱、逆冲及变质作用改造形成的。太鲁阁带是造山带中的古老陆块,主要记录中生代古太平洋俯冲在欧亚大陆活动边缘形成的岩浆、沉积和变质岩作用。玉里-利吉蛇绿混杂岩带和海岸山脉岛弧系统分别为中新世中期(~18Ma)以来南中国海板块向菲律宾海板块之下俯冲形成的岛弧和弧前增生楔,其中玉里混杂岩中有典型低温高压变质作用记录,变质年龄为11~9Ma;岛弧火山作用的主要时限为9.2~4.2Ma。纵谷磨拉石盆地记录1.1Ma以来的山间盆地沉积。台湾造山带的构造演化可划分为4个阶段:(a)古太平洋板块俯冲与欧亚大陆边缘增生阶段(200~60Ma);(b)欧亚大陆东缘伸展和南中国海扩张阶段(60~18Ma);(c)南中国海俯冲阶段(18~4Ma);(d)弧-陆碰撞阶段(<6Ma)。台湾弧-陆碰撞造山带是一个特殊案例,其弧-陆碰撞并不伴随着弧-陆之间的洋盆消亡,而是由于北吕宋岛弧及弧前增生楔伴随菲律宾海板块运动向西北方走滑,仰冲到欧亚大陆边缘,形成现今的台湾造山带。  相似文献   

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