Mineralization during Collisional Orogenesis and Its Control of the Distribution of Gold and Other Deposits in the Junggar Orogen, Xinjiang, China

The Junggar orogen, Xinjiang, China, is an important part of the Ural-Mongolian orogen.The collisional orogenesis in this region occurred primarily in the Carboniferous and Permianwith an evolutional process of early compression and late extension. Mineralization of gold andother metals in the Junggar orogen occurred mainly in the Permian and in a few cases in theLate Carboniferous. The deposits are largely distributed in areas where collisional orogenesiswas intensive and formed in a transitional stage from compression to extension. Therefore, goldmineralization in the Junggar orogen is fully consistent with the collisional orogenesis in time,space and geodynamic setting. This indicates that the mineral deposit model of collisionalorogenesis is applicable to prospecting and study of ore deposits in the Junggar orogen.Furthermore, the factual distribution of gold and other deposits in this region is just the same asthe collisional orogenic model presents.

Indosinian Orogenesis in the Lhasa Terrane, Tibet: New Muscovite ^(40)Ar-^(39)Ar Geochronology and Evolutionary Process

Muscovite 40 Ar-39 Ar dating of muscovite-quartz schist, eclogite and retrograde eclogite indicates an Indosinian orogenesis occurred at 220-240 Ma in the Lhasa terrane, which is caused by the closure of Paleo-Tethyan ocean basin and the following collision of the northern Lhasa terrane and southern Gondwana land. This Indosinian orogenesis is further confirmed by the regional sedimentary characteristics, magmatic activity and ophiolite mélange. This evidence suggests that the Indosinian orogenic belt in the Lhasa terrane is widely distributed from the Coqen county in the west, and then extends eastward through the Ningzhong and Sumdo area, finally turning around the eastern Himalayan syntaxis into the Bomi county. Based on the evolutionary process, the geological development of Lhasa terrane from early Paleozoic to early Mesozoic can be divided into seven stages. All of the seven stages make up a whole Wilson circle and reveal a perfect evolutionary process of the Paleo-Tethys ocean between the northern Lhasa terrane and southern Gondwana land. The Indosinian orogenisis is a significant event for the evolution of the Lhasa terrane as well as the Tibetan Plateau.

Survival Conditions of Folding in Different Depth During Orogenesis-Deformation in Texas Creek and Chester Dome, USA

A succession of 5 FIA trends（foliation intersection or inflection axes in porphyroblasts） preserved in high temperature-low pressure regime PreCambrian rocks in the Texas Creek, Arkansas River region reflected by the fold axial plane traces and schistosity data in this region. Similar fold axial plane trace data measured in Palaeozoic rocks in Chester Dome, Vermont, which is high temperature to medium pressure regime, only preserve the effects of the youngest FIAs of the all 5 FIA sets that obtained in this region. The other three FIA sets have no equivalent fold axial planes. This difference from shallow to deeper orogenic regimes reflects decreasing competency at greater pressure with collapse and unfolding of earlier formed folds. The greater overlying load of rocks has tended to flatten all but the very largest early-formed structures, preserving only those folds that were more recently developed.

He Grenville Orogenesis Recorded by Monazite from the Paragneiss of North Qaidam UHP Metamorphic Belt, Western China

The poly-phase orogeny information included in one orogenic belt is the key for studying the regional tectonic evolution at different time period.It also has important significance of understanding the rock association and

Orogenesis: Cause of Sedimentary Formations

Experiments on stratification discussed here have revealed the mechanical nature of lamination as well as the role of turbulent current as agent of stratification. They challenge Steno’s principle that superposed strata are successive sedimentary layers. They show that relative chronology should not be referred to as “stages” but as “sequences” of series. The rock formation studied by Lalomov shows that the duration of sedimentation could be considerably shorter than indicated by the Geological Time Scale. The latter scale corresponds to large marine transgressions and regressions that can result from the shift of polar axis following such major orogeneses as the Caledonian, Hercynian and Alpine.

Mesozoic fill-sequences in Hefei Basin: Implication for Dabie Orogenesis, central China

A research on the Mesozoic fill-sequences of Hefei basin, locatedat the north foot of Dabie Mountains, shows two-phase evolution. The first phase, early- to mid-/late-Jurassic, is characterized by terrestrial clastic deposits, with four times of reverse-grading units at least, and forms greatly thick molass reconstruction in the mid-/late-phase, which reflects gradually strong thrusting-orogenesis in the north Dabie and flexural depression in the north foreland of Dabie Mountains. The second phase, late-Jurassic to Cretaceous, includes two-episode rifting processes. The first episode (J3) shows calc-alkalic and alkali volcanic rocks interstratified pyroclastic rocks, which may reflect upwelling igneous magma from mantle-source due to the Yangtze continent slab breakoff induced by deep subduction process. A suite of lacustrine, fluvial and piemount facies, about 3000?/FONT>3500 m in thickness, develops in the second episode (J3 -K1), which reflects regional extensional setting and intense elevator diversity of mountain-basin in the study area. This research renews and deepens cognition for the Mesozoic Dabie orogenesis.

Progress and records in the study of endogenetic mineralization during collisional orogenesis

To develop and perfect the theory of plate tectonics and regional metallogeny, metal-logenesis during collisional orogenesis should be thoroughly studied and will attract increasing at-tention of more and more scientists. This paper presents the main aspects of research and discus-sions on metallogenesis during collisional orogenesis after the development of plate tectonics, and accordingly divides the study history into two stages, i.e. the junior stage during 1971-1990 and the senior stage after 1990. Beginning with the negation of mineralization in the collision regime by Guild (1971), the focus of study was put on whether there occurred any mineralization during collisional orogenesis at the junior stage. At the senior stage, which is initiated by the advance of met-allogenic and petrogenic model for collisional orogenesis, scientists begin to pay their attention to the geodynamic mechanism of metallogenesis, spatial and temporal distribution of ore deposits, ore-forming fluidization, relationship

Metallogenesis of the Ertix gold belt, Xinjiang and its relationship to Central Asia-type orogenesis

The Ertix gold belt is located on the boundary of the Kalatongkearc and the Kelan back-arc basin of D-C1. Most scholars used to interpret the formation and distribution of the gold deposits in the Ertix tectonic belt in terms of the petrogenic and metallogenic models for active continental margins. However, enormous data of isotopic dating and geologic research show that the mineralization was obviously later than the oceanic subduction, whereas exactly simultaneous with the collisional orogenesis during C2-P, especially at the transition stage from collisional compression to extension. Based on study of metallogenic time, tectonic background, ore geology, ore fluid nature, ore material source, etc., we reveal that all the gold deposits possess the character of orogenic deposits formed in collisional orogenic system, and that their ore-forming materials mainly have derived from the stratigraphic terranes south to individual deposits. Accordingly, the theoretical tectonic model for collisional metallogenesis and petrogenesis is employed to explain the formation of the Ertix gold belt and to determine the gold exploration directions.

Prototethyan orogenesis in southwest Yunnan and Southeast Asia

The Prototethyan Ocean has been suggested as an Early Paleozoic Ocean developed at the Gondwana northern margin. However, its spatial pattern, subduction style and closure time in SW Yunnan and SE Asia still remain unknown. The Prototethyan evolution in SW Yunnan and SE Asia and its internal connection with the South China Kwangsian(Ordo-Silurian)intracontinental orogenesis are also poorly constrained. By summarizing and analyzing the Early Paleozoic geological records in the Sibumasu and Indochina blocks, the eastern South China and SW Japan, this paper proposes the existence of a giant OrdoSilurian igneous belt along the Gondwana northern margin. A preliminary limitation has been obtained regarding the source nature and migration pattern of the igneous belt. Our data allow us to propose a model of the Early Paleozoic Andean-type active continental margin along the East Gondwana northern margin. This is the foundation to determine the southward subduction of the southern branch of the eastern Prototethyan Ocean underneath the Sibumasu and Indochina blocks along the YunxianMenghai(SW Yunnan)-Thailand Peninsula and the Tam Ky-Phouc Son suture in Central Vietnam, respectively, and the eastward linkage with the Early Paleozoic Osaka subduction zone in SW Japan across the peripheral Sanya area. These data synthetically indicate an easterly-diachronous and propagating Andean-type Cambrian(Furongian)-Silurian(Llandovery) orogenesis along the Gondwana northern margin from Nepal, NW India, South Tibet, Qiangtang to Central Vietnam across South Indochina and Sibumasu. This paper reconstructs the Early Paleozoic locations of the Sibumasu and Indochina fragments, as well as SW Japan and South China continent in the Gondwana northern margin, and proposes the far-field effect on the South China Kwangsian intra-continental orogenesis from the subduction of the Early Paleozoic Prototethyan southern branch.

Records of Indosinian Orogenesis in Lhasa Terrane, Tibet

Based on the deformation characteristics of the ductile shear zones in Sumdo （松多） Group, the quartz fabric by EBSD （electron backscatter diffraction）, the data of muscovite 40Ar-39Ar geochronology （220-230 Ma） from ductile shear zones and the zircon SHRIMP U-Pb chronology （190 Ma） of granites in Sumdo region, Lhasa （拉萨） terrane is thought to have experienced an important Indosinian orogenic event at 220-230 Ma, which caused the closure of the paleo-Tethys Ocean along the tectonic zone of eclogite and the collision between northern part and southern part of the Lhasa terrane. The zircon SHRIMP U-Pb chronology of 190 Ma for biotite adamellite, with the distributing characteristics of the granite massif intruding in Sumdo Group, indicates that the biotite adamellite should be the late orogenic or post-orogenic granite resulting from the Indosinian orogenesis. The discovery of Indosinian orogenic belt in Lhasa terrane expansed the southern boundary of Indosinian orogenic belt in Qinghai （青海）-Tibet plateau to Lhasa terrane from Qiangtang （羌塘） terrane, which changed the understanding about the distribution of Indosinian orogenic belt in Qinghai-Tibet plateau and extended the ＂T＂ type Indosinian orogenic belt in China. The study is very important for the formation and distribution of paleo-Tethys Ocean in Tibet. The ancient terrane framework and evolution of Qinghai-Tibet plateau need further research.

Second International Workshop on Tethyan Orogenesis and Metallogeny in Asia (IWTOMA) and Silk Road Higher Education Cooperation Forum

The Second International Workshop on Tethyan Orogenesis and Metallogeny in Asia （IWTOMA） and Silk Road Higher Education Cooperation Forum will be held from October 16 to 18, 2015, in Wuhan, Hubei Province, Central China, following a very successful workshop in 2014. The conference is hosted by China University of Geoseiences （CUG）, co-sponsored with he National Natural Science Foundation of China, the State Key Laboratory of Geological Processes and Mineral Resources （Wuhan）, and the State Key Laboratory of Continental Tectonics and Dynamics （Beijing）.

Multiple Successions of Soliation Development in Shallow Versus Deep Orogenic Regimes and Their Relationship to Regional Folding

With the realization that rocks with a schistosity parallel to bedding(S0 parallel S1)have undergone lengthy histories of deformation that predate the obvious first deformation(e.g.Bell et al.,2003; Sayab,2006;Yeh,2007)came recognition that large scale regional folds can form early during this process and be preserved throughout orogenesis(e.g.,Ham & Bell,2004;Bell & Newman,2006).This history is lost within the matrix because of reactivational shear

TECTONIC CHARACTERISTICS OF TAIWAN CHANNEL AND ITS ENVIRONS IN LATE MESOZOIC

Taiwan Channel and environs developed typical collision structural zones in the Zhejiang-Fujian coast and Taiwan central mountain, analysis of which revealed their Late Mesozoic collision orogenesis.

Formation of Foliations and their Related Minerals from Diagenetic to Medium-grade Metamorphic Rocks:A Case Study of the Hongyanjing and Liao-Ji Backarc Basins,China

Deciphering the relationship between polyphase tectonic foliations and their associated mineral assemblages is significant in understanding the process from diagenesis to low-/medium-/high-grade metamorphism.It can provide information related to strain,metamorphic conditions and overprinting relationships and so help reveal the tectonic evolution of orogenesis.In this study,we predominately focus on the formation of foliations and their related minerals,as developed in two separate basins.First of all,two stages of axial plane cleavages(S1 and S2)were recognized in the Hongyanjing inter-arc basin,the formation of the S1 axial plane cleavage is associated with mica rotation and elongation in mudstones in the local area.The pencil structure of S2 formed during the refolding phase,the minerals in the sedimentary rocks not changing their shape and orientation.Secondly,in the Liao-Ji backarc basin,foliations include diagenetic foliation(bedding parallel foliation),tectonic S1 foliation(secondary foliation or axial plane cleavage of S0 folding)and crenulation cleavage(S2).The formation mechanism of foliation changes from mineral rotation or elongation and mineral solution transfer in S1 to crystal-plastic deformation,dynamic recrystallization and micro-folding in S2.Many index metamorphic minerals formed from low-grade to medium-grade consist of biotites,garnets,staurolite and kyanite,constituting a typical Barrovian metamorphic belt.Accordingly,a new classification of foliation is presented in this study.The foliations can be divided into continuous and disjunctive foliations,based on the existence of microlithons,detectable with the aid of a microscope.Disjunctive foliation can be further sub-divided into spaced foliation and crenulation cleavage,according to whether(or not)crenulation(micro-folding)is present.The size of the mineral grains is also significant for classification of the foliations.

EVOLUTION OF THE DIWA-TYPE CENTRAL OROGENIC BELT OF CHINA

The orogenic process of the Central Orogenic Belt (COB) of China can basically be divided into two stages. The first stage was in the period of geosynclinal inversion or in the period of convergence of ancient 1andmasses. The second stage wholly occurred in an intracontinental environment within the diwa regime. The modern mountain ranges are rnainly the products of the second stage. This paper elaborates them in the light of information from different parts of the orogenic belt.

Cosmic Expansion: The Dynamic Force Source for All Planetary Tectonic Movements

In this paper, the relationship between the geodynamics and cosmic expansion is analyzed and demonstrated from the basic physical principles and various natural phenomena, and the conclusion is drawn that cosmic expansion is the dynamic force source of all planetary tectonic movements in the universe. The energy for the formation and change of landscape and the energy of earthquakes and volcanic eruptions all come from the cosmic expansion. With the cosmic expansion, the energy density of space is decreasing, the atoms and molecules of all matter in the universe are growing, and the magma is expanding and producing gases. As the earth’s internal pressure rises, the mechanical energy that accumulates within the magma forms the driving force of the earth’s various tectonic movements, and the release of these energy and matter (expansive magma and high-pressure gases) leads to the formation and the changes of the landform (such as orogenesis, epeirogenesis, the formation of the earth’s plates, the Earth expansion, the seafloor spreading, and the continental drift), as well as to earthquakes and volcanic eruptions. In this paper, the causes of all kinds of earthquakes, especially deep focus earthquakes, are given and almost all known seismic phenomena are explained, the basic principle and method of earthquake prediction are given, and the direction is pointed out for the elimination of earthquakes and the utilization of earthquake energy. Based on the same principle of physics, this paper also shows that the Ice-Age is caused by the acceleration of the speed of the motion of the solar system relative to the Milky Way in certain regions of the Milky Way. The greater the speed of the solar system relative to the Milky Way, the greater the drop in Earth surface temperature.

Metallogenic geodynamic background of Mesozoic gold deposits in granite-greenstone terrains of North China Craton

The spatial distribution map of 65 mid-large gold-deposits hosted in the granite-greenstone terrains of the North China Craton is first drawn. These gold deposits mainly concentrate in the Mesozoic remobilized Yinshan-Yanshan-Liaoning-Jilin intracontinental collisional orogenic belt, the northern Qinling and the Jiaodong Mesozoic collisional orogenic belts, and the Mesozoic intracontinental fault-magmatic belts developed along the Taihangshan and the Tan-Lu faults; their mineralizing time is predominantly Jurassic-Cretaceous, i.e. the Yanshanian. The metallogenic geodynamic background is exactly the compression-to-extension transition regime during continental collision.

Geological and geochemical character and genesis of the Jinlongshan-Qiuling gold deposits in Qinling orogen: Metallogenic mechanism of the Qinling-pattern Carlin-type gold deposits

The Qinling Carlin-type gold deposit belt is the second largest Carlin-type gold ore concentrated area in the world and occurs in Mesozoic intracontinental collisional orogen, contrasting to the Carlin-type gold deposits in the Basin and Range province in Cenozoic active continental margin of West America. With ore-forming ages focussed at the range of 197.45-129.45 Ma, its metallogenic geodynamic background was the decornpression-pyrogenation regime at the transition stage from collisional compression to extension, indicating that gold mineralization synchronized with the Mesozoic continental collision. Geochemical studies discover that ore fluids and materials mainly came from the Hercynian-lndosinian tectonic layer. Mesozoic intracontinental subduction of Hercynian-lndosinian association along the Shuanghe-Gongguan fault led to the formation of Jinlongshan-Qiuling gold deposits. Accordingly, the tectonic metallogenic model is established for Qinling-pattern Carlin-type gold deposits.

Mesozoic basin-fill records in south foot of the Dabie Mountains: Implication for Dabie Orogenic attributes

Five evolutional phases are found from Mesozoic basin-fill sequences in the northern Jianghan basin, the south foot of the Dabie Mountains: (i) Early Triassic to the early period of Late Triassic showing continental shelf marine and paralic deposits; (ii) the middle-late period of Late Triassic indicating the uplift and erosion in compressional tectonic setting; (iii) the late period of Late Triassic to Early-Middle Jurassic showing peneplain terrestrial and fluvial clastic deposits in-terlayered with coal-seams; (iv) Late-Jurassic to Early-Cretaceous characterized by cycle fills of acidic volcanic rocks interstratified with pyroclastic rocks in intracontinental extension tectonic re-gime; (v) a lot of coarse clastic deposits similar to molasses occur in Late-Cretaceous mainly. Based on the compositions of detrital sandstones and conglomerates, combined with the analysis of sedimentary facies, it is indicated that most clasts sourced from the Yangtze continent from phase one to phase three, whose provenances are attributed to 搑ecycled orogenic belt?types. On the other hand, detrital assemblages of the fifth phase deposits are mainly related with pre- Mesozoic metamorphic rocks of the Dabie Mountains, subjected to 揳rc orogenic belt?provenance types. In the Mesozoic basins of the south foot of the Dabie Mountains, it is proved that there are no direct depositional records corresponding to 揕ate Triassic syn-collisional orogenesis? Molasse depositional records of Upper Cretaceous distinctly reflect post-collisional orogenesis of the Dabie Mountains (intracontinental orogenesis) and intensive exhumation in extensional tectonic regime. This paper further discusses the inconsistent relations existing between basin-fill records at the south and north feet of the Dabie Mountains and the uplift models of the Dabie Mountains pub-lished, and indicates their key problems.

Three evolutionary stages of the collision orogenic deformation in the Middle Yangtze Region

A discussion of collision orogenic deformation has been made for the Middle Yangtze Region. Based on its deformation assemblage orders, three developing stages are classified successively as compression thrust uplift, strike-slip escape rheology and tension extension inversion. The collision orogenesis of the studied region has been divided into three developing periods of initial, chief and late orogeny. Based on the data from Wugong Mts., Jiuling Mts. and Xuefeng Mts.,for each stage, its variation of stress and strain axes, the conversion of joint fractures and their relative tectonic evolution are described, models are plotted and corresponding explanations are made for the rock chronology dating value in the same tectonic period.