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1.
Nanang T. Puspito Yoshiko Yamanaka Takashi Miyatake Kunihiko Shimazaki Kazuro Hirahara 《Tectonophysics》1993,220(1-4):175-192
We present the P-wave seismic tomography image of the mantle to a depth of 1200 km beneath the Indonesian region. The
inversion method is applied to a dataset of 118,203 P-wave travel times of local and teleseismic events taken from ISC bulletins. Although the resolution is sufficient for detailed discussion in only a limited part of the study region, the results clarify the general tectonic framework in this region and indicate a possible remnant seismic slab in the lower mantle.
Structures beneath the Philippine Islands and the Molucca Sea region are well resolved and high-velocity zones corresponding to the slabs of the Molucca Sea and Philippine Sea plates are well delineated. Seismic zones beneath the Manila, Negros and Cotabato trenches are characterized by high-velocity anomalies, although shallow structures were not resolved. The Molucca Sea collision zone and volcanic zones of the Sangihe and Philippine arcs are dominated by low-velocity anomalies. The Philippine Sea slab subducts beneath the Philippine Islands at least to a depth of 200 km and may reach depths of 450 km. The southern end of the slab extends at least to about 6°N near southern Mindanao. In the south, the two opposing subducting slabs of the Molucca Sea plate are clearly defined by the two opposing high-velocity zones. The eastward dipping slab can be traced about 400 km beneath the Halmahera arc and may extend as far north as about 5°N. Unfortunately, resolution is not sufficient to reveal detailed structures at the boundary region between the Halmahera and Philippine Sea slabs. The westward dipping slab may subduct to the lower mantle although its extent at depth is not well resolved. This slab trends N-S from about 10°N in the Philippine Islands to northern Sulawesi. A NE-SW-trending high-velocity zone is found in the lower mantle beneath the Molucca Sea region. This high-velocity zone may represent a remnant of the former subduction zone which formed the Sulawesi arc during the Miocene.
The blocks along the Sunda and Banda arcs are less well resolved than those in the Philippine Islands and the Molucca Sea region. Nevertheless, overall structures can be inferred. The bowl-shaped distribution of the seismicity of the Banda arc is clearly defined by a horseshoe-shaped high-velocity zone. The tomographic image shows that the Indian oceanic slab subducts to a depth deeper than 300 km i.e., deeper than its seismicity, beneath Andaman Islands and Sumatra and may be discontinuous in northern Sumatra. Along southern Sumatra, Java and the islands to the east, the slab appears to be continuous and can be traced down to at least a depth of the deepest seismicity, where it appears to penetrate into the lower mantle. 相似文献
2.
西太平洋边缘构造带是地球上规模最大最复杂的板块边界,以台湾和马鲁古海为界,自北往南大致可以分为3段。北段是典型的沟-弧-盆体系,千岛海盆、日本海盆及冲绳海槽均为典型的弧后扩张盆地。中段菲律宾岛弧构造带为双向俯冲带,构造复杂,新生代经历大的位移和重组,使得欧亚大陆边缘的南海、苏禄海和苏拉威西海成因存在很大的争议。南段新几内亚—所罗门构造带是太平洋板块、印度—澳大利亚及欧亚板块共同作用的结果,既有不同阶段的俯冲、碰撞,也有大规模的走滑与弧后的扩张,其间既有新扩张的海盆,又有正在俯冲消亡的海盆。台湾岛处于枢纽部位,欧亚板块在此被撕裂,南部欧亚大陆边缘南海洋壳沿马尼拉海沟俯冲于菲律宾岛弧之下,而北部菲律宾海洋壳沿琉球海沟俯冲欧亚大陆之下。马鲁古海是西太平洋板块边界又一转折点,马鲁古海板块往东下插于哈马黑拉之下,往西下插于桑义赫弧,形成反U形双向俯冲汇聚带,其洋壳板块已基本全部消失,致使哈马黑拉弧与桑义赫弧形成弧-弧碰撞。 相似文献
3.
Evidence of Cenozoic magmatism is found along the length of New Guinea. However, the petrogenetic and tectonic setting for this magmatism is poorly understood. This study presents new field, petrographic, U–Pb zircon, and geochemical data from NW New Guinea. These data have been used to identify six units of Cenozoic igneous rocks which record episodes of magmatism during the Oligocene, Miocene, and Pliocene. These episodes occurred in response to the ongoing interaction between the Australian and Philippine Sea plates. During the Eocene, the Australian Plate began to obliquely subduct beneath the Philippine Sea Plate forming the Philippine–Caroline Arc. Magmatism in this arc is recorded in the Dore, Mandi, and Arfak volcanics of NW New Guinea where calc-alkaline and tholeiitic rocks formed within subduction-related fore-arc and extension-related back-arc settings from 32 to 27 Ma. Collision along this plate boundary in the Oligocene–Miocene jammed the subduction zone and caused a reversal in subduction polarity from north-dipping to south-dipping. Following this, subduction of the Philippine Sea Plate beneath the Australian Plate produced magmatism throughout western New Guinea. In NW New Guinea this is recorded by the middle Miocene (18–12 Ma) Moon Volcanics, which include an early period of high-K to shoshonitic igneous activity. These earlier magmatic rocks are associated with the subduction zone polarity reversal and an initially steeply dipping slab. The magmatic products later changed to more calc-alkaline compositions and were emplaced as volcanic rocks in the fore-arc section of a primitive continental arc. Finally, following terminal arc–continent collision in the late Miocene–Pliocene, mantle derived magmas (including the Berangan Andesite) migrated up large strike-slip faults becoming crustally contaminated prior to their eruption during the Plio–Pleistocene. This study of the Cenozoic magmatic history of NW New Guinea provides new data and insights into the tectonic evolution of the northern margin of the Australian Plate. 相似文献
4.
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
5.
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
6.
Volcanoes were created, grew, uplifted, became dormant or extinct, and were accreted as part of continents during continuous arc–continent collision. Volcanic rocks in Eastern Taiwan’s Coastal Range (CR) are part of the northern Luzon Arc, an oceanic island arc produced by the subduction of the South China Sea Plate beneath the Philippine Sea Plate. Igneous rocks are characterized by intrusive bodies, lava and pyroclastic flows, and volcaniclastic rocks with minor tephra deposits. Based on volcanic facies associations, Sr–Nd isotopic geochemistry, and the geography of the region, four volcanoes were identified in the CR: Yuemei, Chimei, Chengkuangao, and Tuluanshan. Near-vent facies associations show different degrees of erosion in the volcanic edifices for Chimei, Chengkuangao, and Tuluanshan. Yuemei lacks near-vent rocks, implying that Yuemei’s main volcanic body may have been subducted at the Ryukyu Trench with the northward motion of the Philippine Sea Plate. These data suggest a hypothesis for the evolution of volcanism and geomorphology during arc growth and ensuing arc–continent collision in the northern Luzon Arc, which suggests that these volcanoes were formed from the seafloor, emerging as islands during arc volcanism. They then became dormant or extinct during collision, and finally, were uplifted and accreted by additional collision. The oldest volcano, Yuemei, may have already been subducted into the Ryukyu Trench. 相似文献
7.
Yasushi Watanabe 《Mineralium Deposita》2005,40(3):307-323
Kyushu Island, Japan, is located at the junction of the Southwest Japan arc and the Ryukyu arc. There are two major late Cenozoic
epithermal gold-silver provinces in Kyushu, which are termed the Northern and Southern provinces. The provinces are characterized
by: 1) Pliocene volcanism dominated by calc-alkaline andesite, followed by Quaternary volcanism including extrusion of both
calc-alkaline and tholeiitic magmas; 2) formation of extensional grabens; 3) Pliocene to Pleistocene mineralization, which
was dominated by abundant low sulfidation (LS) epithermal deposits with a few high sulfidation (HS) examples. The two epithermal
gold-silver provinces have evolved differently since about 5 Ma; the Northern province has exhibited diminished hydrothermal
activity from the Pliocene to Pleistocene, whereas the Southern province has witnessed increased hydrothermal activity mainly
in easterly and northerly directions. Changes of tectonic setting from the Pliocene to Pleistocene account for the variable
trends in epithermal gold deposit formation. Westward oblique subduction of the Philippine Sea plate beneath the Southwest
Japan arc caused development of the Hohi graben and arc-related volcanism at about 6 Ma. This was associated with widespread
LS mineralization in and surrounding the Hohi graben, as is represented by the Bajo and Taio deposits. The subduction of the
relatively buoyant Kyushu-Palau ridge during the early Pliocene strengthened the coupling between the slab and overriding
Ryukyu arc, leading to polygenetic andesite volcanism with associated HS (Kasuga, Iwato, and Akeshi) and LS (Kushikino) mineral
deposits forming in the Southern province. A change of the subduction direction of the Philippine Sea plate, from west to
north-northwest in the early Pliocene, increased the orthogonal convergence rate between the Southwest Japan arc and the Philippine
Sea plate, resulting in a decrease of volcanic and hydrothermal activity in the Hohi graben of the Northern province. The
more northerly subduction of the Philippine Sea plate shifted the locus of the Kyushu-Palau ridge subduction northward, resulting
in underplating of the older (85–60 Ma), negatively buoyant Amami basin oceanic slab in the Southern province, rather than
continued subduction of the young (27–15 Ma), buoyant Shikoku basin slab. This replacement caused steepening of the slab angle
and slab-rollback in the Southern province, which was associated with regional extension, an eastward shift of the Ryukyu
volcanic front, and development of the Kagoshima and Shimabara grabens, as well as the Okinawa trough. Rhyolite and basalt
volcanism, in addition to andesite volcanism, have occurred since 2 Ma in the area of the Ryukyu back arc; coincident LS mineralization
at Hishikari and Ohkuchi was affiliated with the rhyolite volcanism. Another change of the subduction direction of the Philippine
Sea plate to the northwest occurred at 2–1 Ma. The forearc sliver of the Southwest Japan arc shifted westward, in association
with right-lateral strike-slip faulting along the Median tectonic line, due to the increase of the westward convergence rate.
This shift resulted in shortening and cessation of graben development in the Hohi area, restricting the subsequent volcanism
and related hydrothermal activity to the central part of the graben. 相似文献
8.
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
9.
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
10.
A synthesis of the geologic evolution of Taiwan 总被引：2，自引：0，他引：2
C.S. Ho 《Tectonophysics》1986,125(1-3)
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
11.
Christina Widiwijayanti Christel Tiberi Christine Deplus Michel Diament Valentin Mikhailov Rmy Louat 《Tectonophysics》2004,386(3-4):203-222
In order to better understand the tectonic framework of the Northern Molucca Sea area, we inverted satellite and sea-surface gravity data into an iterative scheme including a priori seismological and geological data. The resulting 3-D density model images the various tectonic units from the surface down to 40 km. We proceed to various tests to assess the stability and robustness of our inversion. In particular, we performed an offset and average smoothing method to properly refine our results. The resulting model shows a striking vertical regularity of the structures through the different layers, whereas the density contrasts appear strongly uneven in the horizontal direction.The density model emphasizes the complexity of the upper lithospheric structure in the northern Molucca Sea, which is clearly dominated by the interaction between ophiolitic ridges, sedimentary wedges and rigid blocks of the Philippine Sea Plate. It also provides new, hard information that can be used in discussion of the evolution of the region.Large density variations are concentrated in the central part of northern Molucca Sea and dominate the upper lithospheric. North–south trending density structures along the Central Ridge and west dipping thrust faults on the western side of the region are clearly imaged. In the eastern part of the region, we distinguish several blocks, especially the Snellius Plateau which seems to be split into two parts. We interpret this as an oceanic plateau associated with thicker crust that previously belonged to the Philippine Sea Plate. This crust is now trapped between the Molucca Sea complex collision zone and the Philippine Trench, due to the development of a new subduction zone in its eastern side. 相似文献
12.
W.P. Schellart 《地学学报》2007,19(3):211-218
Oligocene–Miocene models for northern New Zealand, involving south‐westward subduction to explain Early Miocene Northland volcanism, do not fit within the regional Southwest Pacific tectonic framework. A new model is proposed, which comprises a north‐east‐dipping South Loyalty basin slab that retreated south‐westward in the Eocene–earliest Miocene and was continuous with the north‐east‐dipping subduction zone of New Caledonia. In the latest Oligocene, the trench reached the Northland passive margin, which was pulled it into the mantle by the slab, resulting in obduction of the Northland allochthon. During and after obduction, the slab detached from the unsubductable continental lithosphere, inducing widespread calc‐alkaline volcanism in Northland. The new model further explains contemporaneous arc volcanism along the Northland Plateau Seamount Chain and sinking of the Northland basement, followed by uplift and extension in Northland. 相似文献
13.
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.
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
15.
《Journal of Asian Earth Sciences》2000,18(5):603-631
Eastern Indonesia is the zone of interaction between three converging megaplates: Eurasia, the Pacific and Indo-Australia. The geological basis for interpretations of the Tertiary tectonic evolution of Eastern Indonesia is reviewed, and a series of plate tectonic reconstructions for this region at 5 million year intervals covering the last 35 million years is presented.The oldest reconstruction predates the onset of regional collisional deformation. At this time a simple plate configuration is interpreted, consisting of the northward-moving Australian continent approaching an approximately E–W oriented, southward-facing subduction zone extending from the southern margin of the Eurasian continent eastwards into the Pacific oceanic domain. Beginning at about 30 Ma the Australian continental margin commenced collision with the subduction zone along its entire palinspastically-restored northern margin, from Sulawesi in the west to Papua New Guinea in the east. From this time until ca 24 Ma, the Australian continent indented the former arc trend, with the northward convergence of Australia absorbed at the palaeo-northern boundary of the Philippine Sea Plate (the present-day Palau-Kyushu Ridge).At ca 24 Ma the present-day pattern of oblique convergence between the northern margin of Australia and the Philippine Sea Plate began to develop. At about this time a large portion of the Palaeogene colliding volcanic arc (the future eastern Philippines) began to detach from the northern continental margin by left-lateral strike slip. From ca 18 Ma oblique southward-directed subduction commenced at the Maramuni Arc in northern New Guinea. At ca 12 Ma the Sorong Fault Zone strike-slip system developed, effectively separating the Philippines from the Indonesian tectonic domain. The Sorong Fault Zone became inactive at ca 6 Ma, since which time the tectonics of eastern Indonesia has been dominated by the anticlockwise rotation of the Bird’s Head structural block by some 30–40°.Contemporaneously with post-18 Ma tectonism, the Banda Arc subduction–collision system developed off the northwestern margin of the Australian continent. Convergence between Indo-Australia and Eurasia was accommodated initially by northward subduction of the Indian Ocean, and subsequently, since ca 8 Ma, by the development of a second phase of arc-continent collision around the former passive continental margin of NW Australia. 相似文献
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How was Taiwan created? 总被引：4，自引：0，他引：4
Since the beginning of formation of proto-Taiwan during late Miocene (9 Ma), the subducting Philippine (PH) Sea plate moved continuously through time in the N307° direction at a 5.6 cm/year velocity with respect to Eurasia (EU), tearing the Eurasian plate. Strain states within the EU crust are different on each side of the western PH Sea plate boundary (extensional in the Okinawa Trough and northeastern Taiwan versus contractional for the rest of Taiwan Island). The B feature corresponds to the boundary between the continental and oceanic parts of the subducting Eurasian plate and lies in the prolongation of the ocean–continent boundary of the northern South China Sea. Strain rates in the Philippines to northern Taiwan accretionary prism are similar on each side of B (contractional), though with different strain directions, perhaps in relation with the change of nature of the EU slab across B. Consequently, in the process of Taiwan mountain building, the deformation style was probably not changing continuously from the Manila to the Ryukyu subduction zones. The Luzon intra-oceanic arc only formed south of B, above the subducting Eurasian oceanic lithosphere. North of B, the Luzon arc collided with EU simultaneously with the eastward subduction of a portion of EU continental lithosphere beneath the Luzon arc. In its northern portion, the lower part of the Luzon arc was subducting beneath Eurasia while the upper part accreted against the Ryukyu forearc. Among the consequences of such a simple geodynamic model: (i) The notion of continuum from subduction to collision might be questioned. (ii) Traces of the Miocene volcanic arc were never found in the southwestern Ryukyu arc. We suggest that the portion of EU continental lithosphere, which has subducted beneath the Coastal Range, might include the Miocene Ryukyu arc volcanoes formed west of 126°E longitude and which are missing today. (iii) The 150-km-wide oceanic domain located south of B between the Luzon arc and the Manila trench, above the subducting oceanic EU plate (South China Sea) was progressively incorporated into the EU plate north of B. 相似文献
19.
John A. Katili 《Tectonophysics》1978,45(4):289-322
Sulawesi with its peculiar K-shaped pattern is situated in an area where the Eurasian, Indian—Australian and Pacific plates interact and collide.Complex geological processess in this area resulted in the transformation of a normal island-arc structure into an inverted one, deformation of an already tectonized belt, sweeping of fragments against unrelated terrain, thrusting of oceanic and mantle material over the island arc, closing of deep-sea basins behind the arc, trapping of old oceanic crust caused by the rolling up of an island arc, formation of a marginal basin by the spreading of the sea floor behind the arc, development of small subduction zones with reverse polarities etc.Small deep-sea basins surrounding Sulawesi such as the Gulf of Bone and the Gulf of Gorontalo originally formed the arc—trench gap of the Sulawesi island arc.The Banda Sea is considered as an oceanic crust trapped by the bending of the east—west trending Banda arc due to the northward drift of Australia combined with the westward movement of the Pacific plate. Similarly the Sulawesi Sea consists of an old Pacific crust trapped by the westward bending of the Sulawesi island arc, caused by the spearheading westward thrust along the Sorong transform-fault system, in which later a minor spreading center became active in its central part. The Molucca Sea comprises tectonic mélange in which presumably a small spreading center developed between the two colliding arcs of northern Sulawesi and western Halmahera. While the Benioff zones dip under the northern Sulawesi and Halmahera arcs in normal fashion, the mélange thrusts over them. The Strait of Makassar is a marginal basin which was brought into existence by the spreading of the sea floor between Kalimantan and Sulawesi.The evolution of Sulawesi started in Miocene time or even earlier when 800 km east of Kalimantan a north—south trending east-facing island arc came into existence, originating from a spreading center located in the Pacific Ocean. Volcanism and plutonism accompanied this subduction process.Collision between Sulawesi and the Australian—New Guinea plate which occurred in early Pliocene time severely transformed Sulawesi into an island with its convex side turned towards the continent, at the same time causing obduction of ophiolite in the eastern arc of this island.The movement of the Pacific plate continued and gradually pushed Sulawesi towards the Asian continent, resulting in the closing of the sea between Kalimantan and Sulawesi islands separated by small straits and deep seas resembling the complicated pattern of the Philippine Archipelago, in which the original double island-arc structure can no longer be recognized. 相似文献
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俯冲带地幔演化与岩浆作用是地球各固体圈层之间发生物质和能量交换的重要地质过程.西太平洋雅浦海沟因其极短的沟-弧距离和洋脊碰撞等独特的地质构造特征成为研究复杂条件下俯冲带演化的理想场所.为了探究雅浦海沟地幔演化与岩浆作用,本文将前人对雅浦海沟火成岩的研究数据进行整合,分析了雅浦海沟火成岩的成因,并根据火成岩形成的制约条件,对卡罗琳板块俯冲到菲律宾海板块的地幔演化与岩浆作用过程进行了讨论.结果显示雅浦海沟火成岩均具有与俯冲相关火成岩的典型特征.橄榄岩地球化学特征指示雅浦海沟地幔熔融程度为20%~25%,地幔在部分熔融过程中受到了流体与熔体的双重交代作用.Re-Os同位素特征指示雅浦海沟地幔中存在约1.16 Ga非常古老的残余地幔,表明地幔可能经历过多期熔融事件,从而导致雅浦海沟地幔非常亏损.雅浦岛弧成因至今仍存争议,主要包括:(1)现今雅浦岛弧为帕里希维拉海盆洋壳的一部分,在中新世因卡罗琳洋脊的碰撞导致帕里希维拉海盆洋壳逆冲到原雅浦岛弧之上.(2)雅浦岛弧在不同构造时期经历过多期岛弧岩浆作用,包括俯冲初始阶段(~52 Ma)的弧前玄武岩、俯冲开始后的岛弧玄武岩(~25 Ma)、与卡罗琳洋脊碰撞(21 Ma)后的岛弧拉斑玄武岩(7~11 Ma).其中7~11 Ma的岛弧拉斑玄武岩指示雅浦岛弧岩浆活动并未因卡罗琳洋脊的碰撞完全停止,很有可能在晚中新世短暂恢复活动. 相似文献