Rise and fall of the Eastern Great Indonesian arc recorded by the assembly, dispersion and accretion of the Banda Terrane, Timor     

Ron   《Gondwana Research》2006,10(3-4):207-231

New age, petrochemical and structural data indicate that the Banda Terrane is a remnant of a Jurassic to Eocene arc–trench system that formed the eastern part of the Great Indonesian arc. The arc system rifted apart during Eocene to Miocene supra-subduction zone sea floor spreading, which dispersed ridges of Banda Terrane embedded in young oceanic crust as far south as Sumba and Timor. In Timor the Banda Terrane is well exposed as high-level thrust sheets that were detached from the edge of the Banda Sea upper plate and uplifted by collision with the passive margin of NW Australia. The thrust sheets contain a distinctive assemblage of medium grade metamorphic rocks overlain by Cretaceous to Miocene forearc basin deposits. New U/Pb age data presented here indicate igneous zircons are less than 162 Ma with a cluster of ages at 83 Ma and 35 Ma. ⁴⁰Ar/³⁹Ar plateau ages of various mineral phases from metamorphic units all cluster at between 32–38 Ma. These data yield a cooling curve that shows exhumation from around 550 °C to the surface between 36–28 Ma. After this time there is no evidence of metamorphism of the Banda Terrane, including its accretion to the edge of the Australian continental margin during the Pliocene. These data link the Banda Terrane to similar rocks and events documented throughout the eastern edge of the Sunda Shelf and the Banda Sea floor.  相似文献   

对弧后扩张作用的探讨   总被引：5，自引：0，他引：5  

刘池洋 《地质论评》1993,39(3):187-195

俯冲之后的大洋板块继续向陆运动,导致大陆地壳和上地幔内部各圈层在深部发生多层次的水平剪切,引起弧后宽达几千公里地区的裂陷扩张,并形成盆地。其形成的盆地平行于俯冲带。弧后扩张作用的强度和存在与否,取决于仰、俯冲板块双方运动速度矢量的组合类型。离散型产生扩张,聚敛型则以挤压为主。  相似文献   

数字水准仪及其在机场跑道板块高程测量中的应用     

马俊海  冯守良  卢廷军  鲍建宽  周庆礼 《测绘工程》2001,10(2):54-55,58

数字水准仪具有测量速度快、读数客观、能减轻作业劳动强度、精度高、测量数据便于输入计算机和容易实现水准测量内外业一体化的特点，在某国际机场跑道，滑行道、联络道板块高程测量中进行了应用试验，效果良好。  相似文献   

The Grenvillian and Pan-African orogens: World's largest orogenies through geologic time, and their implications on the origin of superplume   总被引：11，自引：11，他引：0  

S. Rino  Y. Kon  W. Sato  S. Maruyama  M. Santosh  D. Zhao 《Gondwana Research》2008,14(1-2):51

The Neoproterozoic Earth was shaped largely by the Grenvillian and Pan-African orogenies. Out of these, the Grenvillian orogeny has long been regarded to be of minor nature in terms of global-scale orogenic episodes, whereas the Pan-African orogeny has been widely recognized in many continental fragments, although not in major parts of Asia. Based on chronological information in zircons from major river mouths across several important terrains of the globe, we show here that the Grenvillian orogeny contributed significantly to the formation of the continental crust. The time period between 0.6 Ga and 0.8 Ga marked the climax at the dawn of the Pan-African orogeny. Continental crust formed in this period is concentrated in the Pan-African orogenic belts widely across the globe. These regions were widespread over the half hemisphere of the globe, and were subsequently reduced in size after they moved to form Laurasia. The normalized frequency distribution of zircon ages from river-mouth sand over the world clearly demonstrates that Neoproterozoic and (0.9–0.6 Ga) and Grenvillian (1.3–1.0 Ga) peaks define the largest population. This means that extensive subduction, and hence active plate tectonics, might have operated through these periods. The zircon study has also brought to light new regions of the Grenvillian orogenic belts, particularly in the continents which are now covered by thick Phanerozoic sedimentary basins. Based on the new locations of Grenvillian orogens identified in this study, and using the distribution patterns as a marker bed, we propose revised paleogeographic configurations of the Rodinia and Gondwana supercontinents.Our results demonstrate that the Neoproterozoic was the most active period of crust formation in the Earth. The cold basins, formed right after the assembly of Rodinia, exhibit a basin chain fringing the northern periphery of Rodinia, which turned into sites of mantle upwellings and led to the rifting and separation of the supercontinental assembly. The continents then moved northwards after the formation of Gondwana at ca. 540 Ma, and enlarged the northern half of the supercontinent Pangea since 250 Ma.Based on the results, we also evaluate the role of supercontinents in the mechanism of generation of superplumes addressing the enigma that the coldest mantle right above the Core–Mantle Boundary turns to the hottest one over a period of several hundreds of million years. Slab graveyard formed by the Pan-African subduction can be imaged through P-wave tomography. We postulate that the high-velocity anomaly in the D” layer underneath Gondwana has now transformed to the low-V regions to generate the African superplume. The tectonic history of solid Earth in the Phanerozoic seems to be controlled by the slab graveyards formed by the Grenvillian orogeny ca. 1.0 Ga.  相似文献   

Petrochemistry of the south Marmara granitoids, northwest Anatolia, Turkey   总被引：1，自引：1，他引：0  

Zekiye Karacık  Yücel Yılmaz  Julian A. Pearce  Ö. Işık. Ece 《International Journal of Earth Sciences》2008,97(6):1181-1200

Post-collision magmatic rocks are common in the southern portion of the Marmara region (Kap?da?, Karabiga, Gönen, Yenice, Çan areas) and also on the small islands (Marmara, Av?a, Pa?aliman?) in the Sea of Marmara. They are represented mainly by granitic plutons, stocks and sills within Triassic basement rocks. The granitoids have ages between Late Cretaceous and Miocene, but mainly belong to two groups: Eocene in the north and Miocene in the south. The Miocene granitoids have associated volcanic rocks; the Eocene granitoids do not display such associations. They are both granodioritic and granitic in composition, and are metaluminous, calc-alkaline, medium to high-K rocks. Their trace elements patterns are similar to both volcanic-arc and calc-alkaline post-collision intrusions, and the granitoids plot into the volcanic arc granite (VAG) and collision related granite areas (COLG) of discrimination diagrams. The have high ⁸⁷Sr/⁸⁶Sr (0.704–0.707) and low ¹⁴³Nd/¹⁴⁴Nd (0.5124–0.5128). During their evolution, the magma was affected by crustal assimilation and fractional crystallization (AFC). Nd and Sr isotopic compositions support an origin of derivation by combined continental crustal AFC from a basaltic parent magma. A slab breakoff model is consistent with the evolution of South Marmara Sea granitoids.  相似文献   

Discussion on initial mechanism of the Tan-Lu fault zone北大核心CSCD     

Zhao T.  Ziiu G.  Xiang B.-W.  Lin S.-Z.  Gu C.-C. 《矿物岩石地球化学通报》2016,(6):1120-1140

The Dabie and Sulu orogens between the North China and the Yangtze cratons were left-laterally offset about 4(H) km along the NE-striking Tan-Lu Fault Zone. The fault zone terminates abruptly at the southeastern corner of the Dabie Orogen, suggesting unique origin of the fault zone which remains controversial. Structures in the Zhangbaling Croup and Feidong Complex in the Zhangbaling Uplift formed in a flat-lying ductile detachment zone with a shear sense of top to the SSW. Whereas, the Tan-Lu shear zone in the l.ujiang area exhibits as a sinistral ductile shear zone. Thus, the Tan-Lu Fault Zone in the east of the Dabie Orogen experienced two phases of deformation. The first phase deformation exhibits as sinistral ductile shear belts, the sinistral ductile shear zone was then involved in the NK-SW trending tightly folds and thrusts deformation. The Susong Complex and Zhangbaling Group in the Dabie Orogens exhibit as exhumation structures. According previous muscovite 4'Ar/,>Ar ages and deformation of syn-collisional folds and thrusts, we propose an indentation-induced continent-Tearing model for the initialization the Tan-Lu Fault Zone.  相似文献   

Post-subdution evolution of the Northern Lhasa Terrane,Tibet: Constraints from geochemical anomalies,chronology and petrogeochemistry     

Shi-mian Yu  Xu-dong Ma  Yan-chun Hu  Wei Chen  Qing-ping Liu  Yang Song  Ju-xing Tang 《China Geology》2022,5(1):84-95

Bangong-Nujiang collisional zone(BNCZ)is an older one in Qinghai-Tibet Plateau and resulted in the famous Bangong-Nujiang metallogenic belt,which plays an important role in evaluating the formation and uplift mechanism of plateau.The northern and central Lhasa Terrane composed the southern part of the BNCZ.Since ore deposits can be used as markers of geodynamic evolution,the authors carried 1∶50000 stream sedimental geochemical exploration in the Xiongmei area in the Northern Lhasa Terrane to manifest the mineralization,and based on this mineralization with geochemical and chronological characteristics of related magmatic rocks to constrain their geodynamics and connection with the evolution of the Lhasa Terrane.The authors find Early Cretaceous magma mainly resulted in Cu,Mo mineralization,Late Cretaceous magma mainly resulted in Cu,Mo,and W mineralization in the studying area.The results suggest a southward subduction,slab rolling back and break-off,and thickened lithosphere delamination successively occurred within the Northern Lhasa Terrane.  相似文献   

Phase Stability and Reactions of Subducting CaCO3 under Upper Mantle Conditions     

GUI Weibin  SHEN Kewei  LIU Jin 《《地质学报》英文版》2023,97(1):309-315

CaCO₃ is an important component of marine sediments and one of the major deep-carbon carriers at subduction zones. Some subducted CaCO₃ can be dissolved in subduction fluids and recycled back to the surface via arc volcanoes degassing. At the same time, there still remain large amounts of CaCO₃ and its reaction products, which could be further transported into Earth’s deep interior. These internal processes link atmosphere, hydrosphere and biosphere with the deep...  相似文献   

大洋俯冲和大陆碰撞沿走向的转换动力学及流体-熔体活动的作用   总被引：2，自引：1，他引：1  

李忠海  许志琴 《岩石学报》2015,31(12):3524-3530

为了深入探讨大洋俯冲和大陆碰撞沿走向的转换及其动力学特征,同时更好的理解俯冲-碰撞带的流体-熔体活动及其效应,我们建立了一系列三维空间的大尺度、高分辨率的动力学数值模型。模拟结果显示,在板块会聚过程中,流体-熔体活动可以降低周围岩石的流变强度及两个板块之间的耦合作用,并能够促进大陆碰撞带俯冲板块的断离。同时,俯冲-碰撞带的空间转换模型揭示其深部结构存在巨大的沿走向的差异性,大陆碰撞带发生俯冲板块断离,而大洋俯冲板块持续下插。并且上覆板块的地壳物质发生从陆-陆碰撞带向洋-陆俯冲带的侧向逃逸。这种三维空间中沿走向的差异性俯冲-碰撞模式与中-东特提斯构造带相吻合,并揭示其动力学机制。  相似文献   

地中海东部地幔演化过程:来自希腊Lesvos岛中新世钾质岩浆作用的启示     

徐雯雯  刘栋  赵志丹  车悦  齐宁远  雷杭山  朱锐 《岩石学报》2021,37(12):3735-3758

希腊Lesvos岛广泛出露的中新世钾质岩浆岩为深入探讨地中海东部地区新生代构造演化和深部过程提供了宝贵机会。本文对Lesvos岛碰撞后钾质岩石开展了系统的矿物电子探针分析、锆石U-Pb定年和Hf同位素分析及全岩地球化学分析。研究结果表明：Lesvos岛出露的碰撞后火山岩主要由玄武粗安岩、玄武安山岩和粗面岩组成,锆石U-Pb年龄为17.2Ma。三类岩石均表现出相对富集大离子亲石元素以及相对亏损高场强元素的地球化学特征。玄武粗安岩和玄武安山岩样品具有相似且富集的Sr-Nd-Pb同位素组成,其较低的Dy/Yb和整体较高且变化范围较大的Ba/La、Zr/Hf比值表明这两类钾质基性岩石起源于受到俯冲陆源沉积物起源流体/熔体交代的尖晶石相岩石圈地幔的低度部分熔融。相比之下,同时代粗面岩具有更亏损的Sr-Nd同位素组成,其均匀的同岩浆锆石Hf同位素组成排除了在岩浆演化过程中发生显著地壳混染或者岩浆混合作用的可能。而较高的Y和Yb含量、相对较低的Sr/Y和（La/Yb）_N比值则表明这种粗面质岩浆起源于中-上地壳的部分熔融。考虑到地震层析结果和Pelagonia陆块与Apulian陆块初始碰撞的时间,研究区各类碰撞后钾质岩浆活动可能反映了深俯冲的Pindos洋壳在中新世发生了板片断离过程。  相似文献