苏鲁造山带浅变质岩的成因及其大地构造意义   总被引：2，自引：0，他引：2       下载免费PDF全文

周建波刘建辉  郑常青 《地质学报》2005,79(4):475-486

苏鲁造山带超高压变质带内部及其北缘,出露仅经过绿片岩相变质作用的浅变质岩系。通过对该浅变质岩的区域分布、地质特征及地球化学的综合研究,表明这些浅变质岩系与大别-苏鲁造山带大陆板块俯冲存在密切的成因关系,为扬子板块俯冲过程中被刮削下来的构造残片,构成大陆板块俯冲过程中形成的构造加积杂岩。在此基础上,厘定了苏鲁造山带的构造成因模型,并对苏鲁造山带的东延问题进行了讨论。  相似文献   

黑龙江杂岩的碎屑锆石年代学及其大地构造意义   总被引：18，自引：9，他引：9  

周建波  张兴洲  Simon A WILDE  郑常青  金魏  陈红  韩杰 《岩石学报》2009,25(8):1924-1936

黑龙江杂岩带位于佳木斯地体西缘,为佳木斯地体向西与松嫩地体之间俯冲、拼贴、碰撞而形成的高压变质带.黑龙江杂岩沿牡丹江断裂分布,其构造-岩石组合、变质变形特征等显示其为佳木斯地体向松嫩地体俯冲拼帖的过程中形成的增生杂岩,目前保存下来的杂岩带应为大规模增生楔仰冲到佳木斯地体之上的残余部分.88颗碎屑锆石的全部样品SHRIMPU-Ph年代学测试结果显示三个主要年龄区间:170～220Ma,峰值年龄为183Ma;240～338Ma,峰值年龄为256Ma;450～520Ma,峰值年龄为470Ma.而28个碎屑锆石谐和年龄的年龄谱为两组:240～338Ma,峰值年龄为256Ma;450～500Ma,峰值年龄为470Ma.碎屑锆石年龄数据分析得到,240～338Ma峰期年龄为256Ma的年龄应代表黑龙江杂岩主体岩石的沉积年龄上限;而450～500Ma的年龄谱对应于佳木斯地体的基底变质岩年龄,显示佳木斯地体的基底变质岩曾为黑龙江杂岩的物源区;而170～210Ma,峰期年龄为183Ma的不谐和年龄应为受印支期-早侏罗世构造热事件的扰动年龄,与该区变质单矿物的Ar-Ar年龄相一致,应代表了该区陆-陆碰撞的时代.上述年龄为黑龙江杂岩的形成与演化提供了重要的地质年代学制约,即黑龙江杂岩的原岩成岩时代上限为早三叠世,佳木斯地体向西的俯冲时代主体为印支期,而陆-陆拼贴及碰撞过程主要为晚印支期并可能持续到早侏罗世.这些结果将为揭示我国东北地区构造演化的年代学格架以及三叠纪古亚洲构造域向环太平洋构造域叠加和转换的动力学背景研究提供新的基本地质事实依据.  相似文献   

甘肃北山地区古亚洲南缘古生代岛弧带位置的讨论   总被引：3，自引：1，他引：2  

谢春林  杨建国  王立社  王育习  王静平 《地质学报》2009,83(11):1584-1600

综合研究得出结论:"甘肃北山红石山断裂带以北的雀儿山-英安山地区为一种与俯冲洋壳板块相关的岛弧带,它记录了古亚洲大洋向南缘东天山古陆系统下俯冲消减的整个地史过程".主要依据:①该地区缺少古老基底陆壳;②发育于区内的中奥陶世-泥盆纪不同时代地层中的火山岩和石炭-三叠纪的中酸性侵入岩,主要以钙碱性或TTG或埃达克成分系列为主要标志,揭示深部有消减洋壳板片或岩源的存在;③从中奥陶世和志留纪火山岩的玄武岩、安山岩和英安岩组合,到泥盆纪以安山岩、英安岩为主的流纹岩、玄武岩组合,至三叠纪马鞍山、小草湖中酸性侵入岩序列的部分高钾钙碱性岩石类型组合,反映古亚洲大洋在南侧消减带之上从一种不成熟岛弧到成熟岛弧和大陆边缘弧发育演化的过程;文章提出代表古亚洲大洋南缘消减带的实际位置应在雀儿山-英安山一线以北的蒙古境内,而北山岛弧带实属南侧东天山古陆陆缘增生地体的一部分.  相似文献   

西天山的增生造山过程   总被引：63，自引：2，他引：61  

高俊  钱青  龙灵利  张喜  李继磊  苏文 《地质通报》2009,28(12):1804-1816

西天山位于中亚造山带的西南缘,经历了复杂的增生造山过程。它也是标志塔里木地块北部被动陆缘与西伯利亚地块南侧宽阔活动陆缘最后拼合的构造带。根据近年来的研究进展,将西天山划分为北天山弧增生体、伊犁地块北缘活动陆缘、伊犁地块、伊犁地块南缘活动陆缘、中天山复合弧地体、西天山（高压）增生楔和塔里木北部被动大陆边缘。同时综述了西天山蛇绿岩、高压变质岩、花岗岩类的年代学新资料,讨论了其增生造山的过程。西天山增生造山与早古生代帖尔斯克依古洋、早古生代晚期—晚古生代南天山洋和晚古生代北天山洋3个代表洋盆的演化相关,增生造山结束的时间可能是早石炭世末。二叠纪时期,西天山至整个中亚地区进入后碰撞演化阶段。现有资料证实西天山为晚古生代增生造山带,并非三叠纪碰撞造山带。  相似文献   

保山地体新元古代——早古生代沉积岩碎屑锆石年代学及其构造意义     

马泽良  蔡志慧  戚学祥  何碧竹  陈希节 《地质通报》2019,38(4):546-561

滇西潞西地区位于青藏高原东南缘,大地构造位置上属于保山地体。由于新生代强烈的陆内变形作用,保山地体与青藏高原腹地体的对应关系难以确定。野外观察及LA-ICP-MS锆石U-Pb测年结果表明,潞西新元古代—早古生代地层(震旦系—寒武系蒲满哨群及下奥陶统大矿山组)大部分碎屑锆石Th/U0.1,说明其大多为岩浆成因。U-Pb年龄跨度较大,太古宙—早古生代都有分布,且具有明显的562Ma、892Ma及2265Ma年龄峰,以及较弱的1680Ma和2550Ma年龄峰。保山地体潞西地区沉积岩碎屑锆石年龄分布特征与特提斯喜马拉雅、南羌塘沉积地层碎屑锆石年龄分布特征相似,说明其具有相同的物源——冈瓦纳大陆北部的印度大陆。在新元古代晚期—早古生代,保山地体位于印度大陆北缘,与南羌塘、喜马拉雅地体相邻。伴随着俯冲相关的增生造山过程,保山地体形成相应的新元古代末期—早古生代沉积地层。  相似文献   

Comparative study on two methods for calculating the gravitational potential of a prism     

Jiancheng Han  Wenbin Shen 《地球空间信息科学学报》2013,16(1):60-64

The determination of the gravitational potential of a prism plays an important role in physical geodesy and geophysics. However, there are few literatures that provide accurate approaches for determining the gravitational potential of a prism. Discrete element method can be used to determine the gravitational potential of a prism, and can approximate the true gravitational potential values with sufficient accuracy (the smaller each element is, the more accurate the result is). Although Nagy’s approach provided a closed expression, one does not know whether it is valid, due to the fact that this approach has not been confirmed in literatures. In this paper, a study on the comparison of Nagy’s approach with discrete element method is presented. The results show that Nagy’s formulas for determining the gravitational potential of a prism are valid in the domain both inside and outside the prism.  相似文献   

Continental Architecture and Crustal Growth in the SW Sector of the Central Asia Orogenic Belt: Evidence from Nd Isotope Mapping     

WANG Tao  TONG Ying  JAHN Bor-ming  HUANG Wei  ZHAO Jianxin  HOU Jiyao  LI Zhipei  HAN Baofu  GUO Lei 《《地质学报》英文版》2013,87(Z1):319-320

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Tectono-sedimentary evolution of the Upper Prealpine nappe (Switzerland and France): nappe formation by Late Cretaceous-Paleogene accretion     

Adam Gasinski  Andrzej Slaczka  Wilfried Winkler 《Geodinamica Acta》2013,26(4):137-157

Abstract

The Upper Prealpine nappe of the Swiss and French Prealps consists of a composite stack of various tectonic slivers (Gets, Simme, Dranse and Sarine sub-nappes, from top to bottom). The structural superposition and stratigraphic content of the individual sub-nappes suggests a successive stacking at the South Penninic/Adriatic transition zone during the Late Cretaceous and Early Paleogene. The present paper deals with two aspects. (1) new data obtained from the Complexe de base Series of the Dranse sub-nappe which underlies the Helminthoid Sandstone Formation, and (2) the development of a geodynamic accretionary model for the Upper Prealpine nappe stacking.

The Complexe de base Series reveals a succession of black shales at the base, grading upward into variegated red/green and red shales which were deposited in an abyssal plain environment starved of clastic input. It is overlain by the Helminthoid Sandstone Formation. The combined analysis of planktic and agglutinated benthic foraminifera and comparisons with other Tethyan series suggest an Albian to Campanian age of the Complexe de base succession. Tectonic transport of the abyssal plain segment into a trench environment allowed for the stratigraphic superposition by the Helminthoid sandstone sequence. The present findings combine well with the general scheme of the Upper Prealpine nappe stack and several single results on parts of the nappe stack. We take that opportunity to present a comprehensive model for the tectono-sedimentary evolution of the Upper Prealpine nappe.

We suggest that Late Jurassic-Early Cretaceous asymmetric (?) extension at the South Penninic-Adriatic margin created an extensional alloehthon. Later during the mid-Cretaceous, the start of convergence drove the obduction of oceanic crust on the northern margin of the extensional allochthon. The resulting ophiolitic/continental source supplied clasts to the trench basin in front (Manche turbidite series), and the backarc basin (Mocausa Formation) and abyssal plain (Perrières turbidite series) to the South. During Middle to Late Coniacian the main Adriatic margin was thrusted over the obductionrelated mixed belt and established an incipient accretionary prism containing the former trench, backarc and abyssal plain basin fill series. During this stage the Gueyraz (melange) Complex formed, which separates the trench series from the retroarc and abyssal plain formations. On top of the incipient accretionary prism a forearc basin developed hosting the Hundsrück Formation. The frontal abyssal plain formation (Complexe de base) still received few turbiditic intercalations. From Campanian time on, the forearc basin was bypassed and deposition of the Helminthoid Sandstone Formation occurred on the Complexe de base succession. During the Maastrichtian the abyssal plain and trench fill succession (Dranse nappe) was accreted to the incipient wedge, and in front of a newly active buttress, the Gurnigel trench basin was established. Another accretionary event during latest Paleocene/earliest Eocene added parts of that trench series to the base of the wedge (Sarine nappe). During the Late Eocene the accretionary wedge and remaining trench fill series (Gurnigel nappe) were thrusted en-bloc over the Middle Penninic limestone nappes and partly overtook the latter. Continued shortening of the resulting nappe pile and out-of-sequence thrusting accomplished the overriding of the Middle Penninic units over the former South Penninic Gurnigel trench series (inversion of palaeogeographic domains).  相似文献   

Adaminaby Group west of Batemans Bay: Deformation and metamorphism of the Narooma accretionary complex,NSW     

E. I. Prendergast  R. Offler  H. Zwingmann 《Australian Journal of Earth Sciences》2013,60(7):1049-1066

This study provides new structural data that show that the Adaminaby Group is part of the Narooma accretionary complex and has been overprinted by HT/LP metamorphism associated with Middle Devonian Moruya Suite intrusions. The grade of metamorphism based on Kübler Indices is the same in the Wagonga and Adaminaby Groups at Batemans Bay inferring that these rocks were involved in the same accretionary event. White micas in slates of the Adaminaby Group record apparent K–Ar ages of 384.6 ± 7.9 Ma and 395.8 ± 8.1 Ma. These ages are believed to represent the age of Middle to Upper Devonian Buckenbowra Granodiorite. Kübler Index values indicate lower epizonal (greenschist facies) metamorphic conditions and are not influenced by heating in metamorphic aureoles of the plutons. All b cell lattice parameter values are characteristic of intermediate pressure facies conditions although they are lower in the metamorphic aureole of the Buckenbowra Granodiorite than in the country rock, defining two areas with dissimilar baric conditions. East of the Buckenbowra Granodiorite, b cell lattice parameter values outside the contact aureole (x = 9.033 Å; n = 8) indicate P = 4 kb, and assuming a temperature of 300°C, infer a depth of burial of approximately 15 km for these rocks with a geothermal gradient of 20°C/km. In the metamorphic aureole of the Buckenbowra Granodiorite, b cell lattice parameter values (x = 9.021 Å; n = 41) indicate P = 3.1 kb inferring exhumation of the Adaminaby Group rocks to a depth of approximately 11 km prior to intrusion. A geothermal gradient of 36°C/km operated in the aureole during intrusion. An extensional back-arc environment prevailed in the Adaminaby Group during the Middle to Upper Devonian.  相似文献   

Modeling uncertainty of moving objects on road networks via space–time prisms     

Bart Kuijpers 《International journal of geographical information science》2013,27(9):1095-1117

Moving objects produce trajectories, which are typically observed in a finite sample of time‐stamped locations. Between sample points, we are uncertain about the moving objects's location. When we assume extra information about an object, for instance, a (possibly location‐dependent) speed limit, we can use space–time prisms to model the uncertainty of an object's location.

Until now, space–time prisms have been studied for unconstrained movement in the 2D plane. In this paper, we study space–time prisms for objects that are constrained to travel on a road network. Movement on a road network can be viewed as essentially one‐dimensional. We describe the geometry of a space–time prism on a road network and give an algorithm to compute and visualize space–time prisms. For experiments and illustration, we have implemented this algorithm in MATHEMATICA.

Furthermore, we study the alibi query, which asks whether two moving objects could have possibly met or not. This comes down to deciding if the chains of space–time prisms produced by these moving objects intersect. We give an efficient algorithm to answer the alibi query for moving objects on a road network. This algorithm also determines where and when two moving objects may have met.  相似文献