Post-Collisional Ductile Extensional Tectonic Framework in the UHP and HP Metamorphic Belts in the Dabie-Sulu Region, China

The present-day observable tectonic framework of the ultrahigh-pressure (UHP) and high-pressure (HP) metamorphic belts in the Dabie-Sulu region was dominantly formed by an extensional process, mostly between 200 and 170 Ma, following the Triassic collision between the Sino-Korean and Yangtze cratons. The framework that controls the present spatial distribution of UHP and HP metamorphic rocks in particular displays the typical features of a Cordilleran-type metamorphic core complex, in which at least four regional-scale, shallow-dipping detachment zones are recognized. Each of these detachment zones corresponds to a pressure gap of 0.5 to 2.0 GPa. The detachment zones separate the rocks exposed in the region into several petrotectonic units with different P-T conditions. The geometry and kinematics of both the detachment zones and the petrotectonic units show that the exhumation of UHP and HP metamorphic rocks in the Dabie-Sulu region was achieved, at least in part, by non-coaxial ductile flow in the mul     

Location of Triassic Tectonic Suture Between Collided Sino-Korean and Yangtze Cratons in Dabie-Sulu Region, China

INTRODUCTIONTheageofultrahigh-pressuremetamorphism(UHPM)andhigh-pressuremetamorphism(HPM)hasbeendeterminedat24OMato2loMabyseveralchronologicalmethods(Lietal.,1998;Maruyamaetal.,l998iAmesetal.,l9961Hack-erandWang,l995;Johnetal,,1994).Theseagedatare-f1ecttheTriassicobliquecollisionbetweentheSino-KoreanandYangtzecratons.ThermobarometricestimatesoftheUH-PMandHPMintheDabie-SuluregionshowthatthecoldcontinentalcrustmaterialoftheYangtzecratonwasunder-thrust,alongthesuture,northwardtoma…     

The expert system for earthquake prediction (I)—the overall design and main structure

The Expert System For Earthquake Prediction (ESEP) is summarized in this paper. ESEP embraces three subsystems: long-middle term prediction system, annual prediction system and middle-short term prediction system. Each of the subsystems is composed of seven modules: the controlling module, the data base module, the expert knowledge base module, the method base module, the fact preparation module, the reasoning and decision-making module and the plotting and displaying module. The reasoning model ESEP/R and the knowledge expression model ESEP/K are set up in the ESEP, and new evidence combinations, CON (confine), W (weigh), and SYN (synthesize), have been proposed. The distinctive features of the ESEP are: (1) systemized; (2) several experts’ knowledge can be synthesized; (3) a large amount of data and experts’ experience is embraced; (4) four reasoning models and the synthetic decision-making technic are adopted; (5) several software environments are used; (6) modularization; and (7) possessing the friendly user interfaces. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 1–8, 1992.     

活动断裂带的壤中气汞量测量研究

在覆盖区应用壤中气汞量测量研究活动断裂是一种新方法,它不仅能较准确地确定活动断裂的位置,还可以确定其产状,规模,活动性及相对强度,甚至可以作为确定断裂力学性质的参考,本文简棕了断裂带壤中气汞量测量的基本原理,并以长江三峡,长春,吉林等地利用该种方法研究活动断裂的成果为例,说明该项研究的效果及应用前景。     

聚煤盆地富煤规律研究综述及展望

聚煤盆地富煤规律是煤地质学研究之焦点。富煤规律研究的突出进展主要包括聚煤模式、富煤带和富煤单元以及现代泥炭比较沉积学研究。尤其是近年来富煤单元和现代泥炭比较沉积学研究更清楚地揭示煤赋存规律与成因煤相和工艺煤相之间的内在联系,从而为聚煤盆地优质煤的预测提供有效的方法。     

造山带的网结状构造样式

网结状构造样式是造山带地壳结构的一个重要特征,表现为线状强应变带与夹持其间的透镜状弱应变域规律组合格式。这种网结状型式在几何学上具有尺度不变性,并具三维特征,理论分析和实际观察指出,这种网结状构造样式,是在应变软化作用及变形分解作用控制下递进发育而成的,而造山带地壳结构的不均一性、组成造山带岩石的流变学特征以及变形物理环境,又是控制应变软化及变形分解作用的主要因素。     

吉林省北部西土山火山岩的地质特征及其形成的地质时代

本文以实际资料，叙述了西土山火山岩的地质、岩石化学、微量元素、稀土元素等方面的特征。与中国晚三叠世火山岩对比较吻合。且以较丰富的古生物及同位素年龄资料论证了西土山火山岩的地质时代属晚三叠世。     

吉林省北部A型花岗岩的初步认识

分布在吉林省北部的香水、治安一带的正长花岗岩、碱长花岗岩，研究后认为属Ａ型花岗岩。其行征钾长石为微斜长石一条纹长石，斜长石大部分为奥长石Ａｎ＝１３－１７。并有碱性碱物无辉石。     

Late-Stage Ductile Deformation in Xiongdian-Suhe HP Metamorphic Unit, North-Western Dabie Shan, Central China

New structural and petrological data unveil a very complicated ductile deformation history of the Xiongdian-Suhe HP metamorphic unit, north-western Dabie Shun, central China. The finegrained symplectic amphibolite-facies assemblage and coronal structure enveloping eclogite-facies garnet,omphacite and phengite etc., representing strain-free decompression and retrogressive metamorphism,are considered as the main criteria to distinguish between the early-stage deformation under HP metamorphic conditions related to the continental deep subduction and collision, and the late-stage deformation under amphibolite to greenschist-facies conditions occurred in the post-eclogite exhumation processes.Two late-stages of widely developed, sequential ductile deformations D3 and D4, are recognized on the basis of penetrative fabrics and mineral aggregates in the Xiongdian-Suhe HP metamorphic unit, which shows clear, regionally, consistent overprinting relationships. D3 fabrics are best preserved in the Suhe tract of low post-D3 deformation intensity and characterized by steeply dipping layered mylonitic amphibolites associated with doubly vergent folds. They are attributed to a phase of tectonism linked to the initial exhumation of the HP rocks and involved crustal shortening with the development of upright structures and the widespread emplacement of garnet-bearing granites and felsic dikes. D4 structures are attributed to the main episode of ductile extension (D^24) with a gently dipping foliation to the north and common intrafolial, recumbent folds in the Xiongdian tract, followed by normal sense top-to-the northductile shearing (D^24) along an important tectonic boundary, the so-called Majiawa-Hexiwan fault (MHF), the westward continuation of the Balifan-Mozitan-Xiaotian fault (BMXF) of the northern Dabie Shan. It is indicated that the two stages of ductile deformation observed in the Xiongdian-Suhe HP metamorphic unit, reflecting the post-eclogite compressional or extrusion wedge formation, the subhorizontal ductile extension and crustal thinning as well as the top-to-the north shearing along the high-angle ductile shear zones responsible for exhumation of the HP unit as a coherent slab, are consistent with those recognized in the Dabie-Sulu UHP and HP metamorphic belts, suggesting that they were closely associated in time and space. The Xiongdian-Suhe HP metamorphic unit thus forms part of the Triassic(250-230 Ma) collision orogenic belt, and can not connect with the South Altun-North Qaidam-North Qinline UHP metamorphic belt formed durin~ the Early Paleozoic (500-400Ma).     

Multi-Layered Low-Angle Ductile Detachment System in Dabie-Sulu UHPM and HPM Belts,China

INTRODUCTIoNTheDabie-Suluregion,Chinahasbeenrecognizedasthelargestultrahigh-pressuremetamorphic(UHPM)(peakp>2.7GPa)andHPMbeltsintheworld,andattractedexten-siveinterestfrominternationalgeoscientists.AwealthofpublicationsexistsabouttheoccurrenceofUHPMindexmin-erals,thegeochronology,metamorphicPTpaths,andthelarge-scaleconceptualtectonicevolutionofUHPMandhigh-pressuremetamorphic(HPM)rocksintheDabie-Suluregion.Morerecentoverviewsaregiven'byErnstetal.(1995),Liouetal.(l996),andHackere…