麻粒岩的研究进展与方法   总被引：2，自引：0，他引：2  

魏春景  张媛媛  董杰 《岩石学报》2021,37(1):52-64

近年来,有关麻粒岩的研究取得了长足进展,本文讨论了4个相关问题:(1)麻粒岩的大地构造环境与P-T轨迹.麻粒岩可以形成于4种大地构造环境中:(a)碰撞造山带以形成高压麻粒岩为特征,为中压相系,包括曾位于地壳浅部的岩石经历构造埋深达到变质峰期后再折返的过程,为顺时针型P-T轨迹;也包括曾经历洋壳或陆壳俯冲形成的高压-超高...  相似文献   

冲绳海槽高热流值区的特征     

李常珍  金保生 《海洋科学》1998,22(5):50-52

研究表明,冲绳海槽是一个罕见的高热流值区,是个活动的弧后裂谷,而且热水活动,地震活动,火山活动与之有密切的联系。  相似文献   

Structural Analysis of the Luowei Orefield in Xidamingshan,Guangxi, China     

Saisai Li  Zuohai Feng  Wei Fu  Zemin Li  Rongguo Hu 《Resource Geology》2020,70(1):89-107

Many types of hydrothermal deposits (e.g. W, Bi, Pb, Zn, Ag) are confined by faults and hidden granodiorite in the Luowei Orefield in Xidamingshan, Guangxi, China. The orebodies in the Luowei W–Bi deposit are predominantly layered and distributed along bedding in sandstones of the Cambrian Xiaoneichong Formation. The orebodies in the Lujing Pb–Zn deposit are controlled mainly by west‐south‐west (WSW)‐trending faults, and those in the Fenghuangshan Ag deposit are controlled mainly by west‐north‐west (WNW)‐trending faults, which were reverse faults during mineralization and were later reactivated as sinistral strike‐slip faults. The Luowei fault was formed postmineralization and resulted in sinistral displacement of the subsurface granodiorite and the Cambrian strata. A tectonomagmatic mineralization model of the Luowei Orefield is proposed, and the following conclusions were made. (i) Under a regional N–S compressive stress regime, WSW‐ and WNW‐trending reverse faults and N–S‐trending tensional fractures were formed. (ii) Magma intruded along the tensional fractures. Under the force of magmatic thermodynamics, mineralizing fluid migrated along bedding planes in sandstones and formed W–Bi orebodies at favorable sites. Some fluid migrated along WSW‐ and WNW‐trending faults to sites farther from the magma source, forming vein‐type Pb–Zn and Ag orebodies. (iii) After mineralization, under ~E–W compression, a NW‐trending left‐lateral slip fault was formed, cutting the subsurface granodiorite and orebodies. Concurrently, sinistral shear slip occurred on WNW‐trending ore‐controlling faults. However, the small displacement on these faults did not change the overall distributions of the rock mass and orebodies.  相似文献   

Source-to-sink of Late carboniferous Ordos Basin: Constraints on crustal accretion margins converting to orogenic belts bounding the North China Block     

《地学前缘(英文版)》2020,11(6):2031-2052

The Upper Carboniferous Benxi Formation of the Ordos Basin is the lowest strata overlying Middle Ordovician above the major ca. 150-Myr sedimentary gap that characterizes the entire North China Block (NCB). We apply an integrated analysis of stratigraphy, petrography, and U–Pb dates and Hf isotopes on detrital zircons to investigate its provenance and relationships to the progressive collisions that formed the Xing’an-Mongolia Orogenic Belt to the north and the Qinling Orogenic Belt to the south. The results show that, in addition to regional patterns of siliciclastic influx from these new uplifted sources, the Benxi Formation is composed of two sequences corresponding to long-term glacial-interglacial cycles during the Moscovian to lower Gzhelian stages which drove global changes of eustatic sea level and weathering. The spatio-temporal distribution of sediment isopachs and facies indicate there were two sediment-infilling pulses, during which the southern and the northern Ordos Basin developed tidal-reworked deltas. The age spectra from detrital zircons, trace element patterns and ε_Hf(t) values reveal that the siliciclastics forming the southern delta was sourced in the Qinling Orogenic Belt, whereas the northern delta was derived from the Xing’an-Mongolia Orogenic Belt. The source-to-sink evolution of this Upper Paleozoic system records the progressive development of orogenic belts and uplifts forming on the southern and northern margins of the NCB prior to its collisions with the South China and the Siberian plates, respectively.  相似文献   

The lower carboniferous (dinantian) of the Swords area: Sedimentation and tectonics in the Dublin Basin,Ireland     

Gareth L. L. Jones  Ian D. Somerville  Peter Strogen 《Geological Journal》1988,23(3):221-248

The litho- and biostratigraphy of the Lower Dinantian succession in a deeper part of the Dublin Basin is described. The sub-Waulsortian Malahide Limestone Formation (emended) is described fully for the first time, and has proved to be very much thicker than was previously suspected, in excess of 1200 m. Succeeding the ‘Lower Limestone Shale’ unit, which is transitional from the underlying Old Red Sandstone facies, the following six new members are recognized: Turvey Micrite Member, Swords Argillaceous Bioclastic Member, St. Margaret's Banded Member, Huntstown Laminated Member, Dunsoghly Massive Crinoidal Member and Barberstown Nodular Member (top). The Malahide Limestone Formation is overlain by ‘Waulsortian’ limestones of the Feltrim Limestone Formation (new name) which form overlapping and isolated mudmounds with complex relationships with their enclosing non-mound facies. Though very much thicker, the Courceyan succession is comparable with that elsewhere on the south side of the Basin, and is part of the Kildare Province (Strogen and Somerville 1984). Isopach maps for the region show that this province and the North Midlands are separated by the deepest part of the Dublin Basin, named the ‘East Midlands Depocentre’, in which a shale-dominant facies is present. The top of the ‘Waulsortian’ is of early Chadian age. Formations younger than this are dominated by basinal calcareous shales (Tober Colleen Formation) and by storm deposits and calciturbidites with appreciable terrigenous input from the east (Rush Formation). The Courceyan main shelf conodont biozones are also greatly thickened in this area. The Pseudopolygnathus multistriatus Biozone (> 300 m thick) is succeeded by a very thick (> 900 m) Polygnathus mehli Biozone. The base of the Chadian is considered to occur below the top of the Feltrim Limestone Formation and, although equivocal, may be diagnosed in the Dublin Basin by the first appearance of the problematic microfossil Sphaerinvia piai and a primitive form of the calcareous alga Koninckopora. In the late Courceyan, the Swords area was part of a gently sloping shelf extending northwards into the basin. During deposition of the Feltrim Limestone Formation there was major deepening and there is evidence of initial break up of the Dublin Basin by faulting into separate blocks. By Chadian time the Basin was definitely subsiding by fault displacements and basinal limestones contain shallow water faunas and littoral sand and pebbles derived by turbidite flows from the margins of the higher blocks. The early subsidence was apparently by pure flexure, but in the Viséan the Dublin Basin was fault-controlled, differing from the adjacent Shannon Basin in having both margins strongly faulted.  相似文献   

Siliciclastic influx and burial of the Cenozoic carbonate system in the Gulf of Papua     

Evgueni N. Tcherepanov  André W. Droxler  Philippe Lapointe  Kenneth Mohn  Odd A. Larsen 《Marine and Petroleum Geology》2010

An extensive carbonate system in the Gulf of Papua (GoP), developed in the late Oligocene–middle Miocene, was buried by huge influx of siliciclastics originated from Papua New Guinea. Major episodes of siliciclastic influx in the carbonate system are related to tectonic activity in the fold and thrust belt during the Oligocene Peninsular Orogeny, late Miocene Central Range Orogeny, and late Pliocene renewed uplift and exhumation of peninsular region. Siliciclastics did not influence the carbonate deposition during the late Oligocene–middle Miocene, since they were accumulated in the Aure Trough, proximal foreland basin protecting the carbonate system. The most significant burial of the carbonate system started during the late Miocene–early Pliocene in the result of the Central Range Orogeny. However, the largest influx was related to the renewed uplift of the Papuan Peninsula during the early late Pliocene. The shelf edge prograded ∼150 km and formed more than 80% of the modern shelf. This high siliciclastic influx was also enhanced by the “mid” Pliocene global warmth period and intensified East Asian monsoons at 3.6–2.9 Ma. Although many publications exist on carbonate–siliciclastic mixing in different depositional environments, this study helps understand the carbonate–siliciclastic interactions in space and time, especially at basinal scale, and during different intervals of the carbonate system burial by siliciclastic sediments.  相似文献   

Tectonic deformation of a channel sandstone     

M. E. Tringham 《Geological Journal》1985,20(3):247-255

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Middle carboniferous marine transgression,Bjørnøya,Svalbard: facies sequences from an interplay of sea level changes and tectonics     

J. Gjelberg  R. Steel 《Geological Journal》1983,18(1):1-19

The Svalbard Platform, in middle Carboniferous time, was dominated by a series of NNW-SSE oriented, asymmetric rift basins. The Landnørdingsvika Formation represents the infill of one such basin in the Bjørnøya (Bear Island) area and consists of red beds deposited during a regional rise of sea level. The basin was filled mainly from the west and southwest across a Carboniferous fault zone, the West Bjørnøya. Fault, which bounded the deep edge of the basin. The basin succession is dominated by floodplain and coastal plain deposits in its lower part and fanglomerates interbedded with shallow marine clastics and carbonates in its upper part. The marine facies gradually increase in volume upwards and culminate in the overlying, carbonate-dominated Kapp Kåre Formation (Moscovian). This continental-marine transition, which has also been identified in the other Svalbard basins, thus reflects an important middie-late Palaeozoic transgression. Analysis of the facies sequences shows that there are repeated submergence-emergence events which are superimposed on the longer term transition. These are interpreted in terms of repeated basin floor tilting and sinking against the upland block.  相似文献