首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
ThenewlycompiledGeologicalMapofAsiaandEurope(1.5000000)wasoneoftheimportantmapsoftheMinistryofGeologyandMineralResources(MGMR)ofChinaforsubmittingtothe30thInternationalGeologicalCongress.ItwascompiledbytheinstituteofGeology,CAGS.ThemapincludesthewholeAsianandEuropeanterritories,covering50.71millionkm~2,withalengthof3.5mand2.5minwidth.Themainresearchresultsandgreatprogressshownonthemapareasbelow.1.Thegeographicalmap,basedonwhichthegeologicalmapwascompiled,hashighprecisioninmathematics…  相似文献   

3.
The age of the major geological units in Japan ranges from Cambrian to Quaternary. Precambrian basement is, however, expected, as the provenance of by detrital clasts of conglomerate, detrital zircons of metamorphic and sedimentary rocks, and as metamorphic rocks intruded by 500 Ma granites. Although rocks of Paleozoic age are not widely distributed, rocks and formations of late Mesozoic to Cenozoic can be found easily throughout Japan. Rocks of Jurassic age occur mainly in the Jurassic accretionary complexes, which comprise the backbone of the Japanese archipelago. The western part of Japan is composed mainly of Cretaceous to Paleogene felsic volcanic and plutonic rocks and accretionary complexes. The eastern part of the country is covered extensively by Neogene sedimentary and volcanic rocks. During the Quaternary, volcanoes erupted in various parts of Japan, and alluvial plains were formed along the coastlines of the Japanese Islands. These geological units are divided by age and origin: i.e. Paleozoic continental margin; Paleozoic island arc; Paleozoic accretionary complexes; Mesozoic to Paleogene accretionary complexes and Cenozoic island arcs. These are further subdivided into the following tectonic units, e.g. Hida; Oki; Unazuki; Hida Gaien; Higo; Hitachi; Kurosegawa; South Kitakami; Nagato-Renge; Nedamo; Akiyoshi; Ultra-Tamba; Suo; Maizuru; Mino-Tamba; Chichibu; Chizu; Ryoke; Sanbagawa and Shimanto belts.The geological history of Japan commenced with the breakup of the Rodinia super continent, at about 750 Ma. At about 500 Ma, the Paleo-Pacific oceanic plate began to be subducted beneath the continental margin of the South China Block. Since then, Proto-Japan has been located on the convergent margin of East Asia for about 500 Ma. In this tectonic setting, the most significant tectonic events recorded in the geology of Japan are subduction–accretion, paired metamorphism, arc volcanism, back-arc spreading and arc–arc collision. The major accretionary complexes in the Japanese Islands are of Permian, Jurassic and Cretaceous–Paleogene age. These accretionary complexes became altered locally to low-temperature and high-pressure metamorphic, or high-temperature and low-pressure metamorphic rocks. Medium-pressure metamorphic rocks are limited to the Unazuki and Higo belts. Major plutonism occurred in Paleozoic, Mesozoic and Cenozoic time. Early Paleozoic Cambrian igneous activity is recorded as granites in the South Kitakami Belt. Late Paleozoic igneous activity is recognized in the Hida Belt. During Cretaceous to Paleogene time, extensive igneous activity occurred in Japan. The youngest granite in Japan is the Takidani Granite intruded at about 1–2 Ma. During Cenozoic time, the most important geologic events are back-arc opening and arc–arc collision. The major back-arc basins are the Sea of Japan and the Shikoku and Chishima basins. Arc–arc collision occurred between the Honshu and Izu-Bonin arcs, and the Honshu and Chishima arcs.  相似文献   

4.
5.
6.
7.
The Middle-Upper Cambrian boundary is one of the current stratigraphical problems which remain openin the geological world, since there have been no universally acknowledged delimiting standard and stratotype.Acting on the instruction of Profs. Lu Yanhao and An Taixiang the author studied in details the Paibi Section,which is well exposed as a continuous sequence at an easily accessible locality. The Middle-Upper Cambrianboundary strata are composed of biocalcimicrosparite, indicating the sedimentary environment of anunderwater upheaval on the gentle slope along the frontal margin of the Yangtze carbonate platform. For the upper Middle and lower Upper Cambrian agnostid trilobite zones and conodont zones are erected,and a more accurate correlation between the trilobite and conodont sequences is established. Based on these,the Middle-Upper Cambrian boundary is drawn more reasonably and precisely than what was done before. Inshort, the section studied is superior to other known sections of Middle-Upper Cambrian. and it will probablybe an ideal candidate for the Middle-Upper Cambrian boundary stratotype.  相似文献   

8.
Geologie en Mijnbouw -  相似文献   

9.
Summary The Degana pluton hosts one of the few known tungsten deposits in India It is an epizonal, moderately high silica pluton emplaced during the Proterozoic in a posttectonic setting. Though homogeneous in composition, it displays textural heterogeneity from coarse-grained hypidiomorphic to fine-grained porphyritic to hypabyssal granite porphyry. Genetically related rhyolites are also present. Coherency of geochemical and mineralogical attributes in the Degana pluton can be explained by fractional crystallisation. Complex variety of hydrothermal and pneumatolytic features is also present. At shallow depths, emanation differentiation has led to progressive enrichment of Li, Rb, and W. Both the plutonic and volcanic phases of the magma show development of rapakivi texture and other diagnostic characteristics of the rapakivi granites.The Degana granite is a specialised granite and classified as an A-type intraplate anorogenic granite of mantle plume origin. The mineralogy and chemistry of the Degana pluton compares well with the various rapakivi granites of south-eastern Fennoscandia. Chemical and textural characteristics of the Degana pluton provide a constraint on the formation of the rapakivi texture when interpreted in terms of experimentally determined phase equilibria. The mantling process is interpreted as a result of pressure fluctuations due to escape and recharging of volatiles (e.g., H2O and F) accompanying the emplacement of the magma.
Geologie und Geochemie des Degana-Plutons—ein proterozoischer Rapakivi Granite in Rajasthan, Indien
Zusammenfassung Der Degana Pluton enhält eine der wenigen in Indien bekannten Wolfram-Lagerstätten. Es handelt sich hier um einen epizonalen Pluton mit höheren Si-Gehalten, der während des Proterozoikums in ein posttektonisches Setting intrudiert wurde. Obwohl er in seiner Zusammensetzung homogen ist, zeigt er Heterogenität auf dem texturellen Bereich, die von grobkörnig hypidiomorph bis feinkörnig porphyritisch und schließlich bis zu hypabyssischen Granitporphyren reicht. Genetisch verwandte Rhyolite kommen im Untersuchungsgebiet auch vor. Übereinstimmende geochemische und mineralogische Parameter können auf fraktionierte Kristallisation zurückgeführt werden. Eine komplexe Vielfalt von hydrothermalen und pneumotolytischen Erscheinungen ist bemerkenswert. In geringen Tiefen hat die Emanations-Differentiation zu einer progressiven Anreicherung von Li, Rb und W geführt. Sowohl die plutonischen als auch die vulkanischen Erstarrungsprodukte des Magmas zeigen die Entwicklung von Rapakivi-Texturen und anderen diagnostischen Eigenschaften der Rapakivi-Granite.Der Degana-Granit ist ein spezialisierter Granit und ist als ein anorogener Intraplattengranit des A-Typs zu klassifizieren, der auf einen mantle plume zurückgeführt wird. Die Mineralogie und Chemie des Degana-Plutons läßt sich gut mit der verschiedener Rapakivi Granite im südöstlichen Fennoskandien vergleichen. Chemische und texturelle Eigenheiten des Degana Plutons ermöglichen eine Eingrenzung der Bildung von Rapakivi Texturen, sofern sie im Sinne experimentell bestimmter Phasen-Gleichgewichte interpretiert werden. Die Entstehung von Überwachsungen einzelner Kristalle wird als Resultat von Druckschwankungen interpretiert, die auf das Entweichen und die Neuzufuhr von volatilen Phasen (i.e. H2O und F) im Gefolge der Platz nahme des Magmas zurückzuführen sind.
  相似文献   

10.
11.
12.
JamesOgg 《《幕》》2004,27(2):125-126
During the early 1800‘s, the current Cenozoic Era (Phillips,1840) underwent competing schemes of subdivision based on field relationships or on biological evolution.  相似文献   

13.
Structural, metamorphic and geochronological studies of the Chewore Inliers of the Zambezi Belt within the Karoo age Zambezi Rift, allow recognition of a protracted multi-stage evolution, from the Mesoproterozoic to culminating in the Early. Palaeozoic Pan-African Orogeny. Tectono metamorphic events recognised in the Chewore Inliers occur throughout the Zambezi Belt and alternative models for the history of the Zambezi Belt are presented.Four terranes are recognised in the Chewore Inliers, and contacts between them are observed or inferred to be ductile thrusts, along which juxtaposition of the terranes occurred late in the Pan-African metamorphic cycle (M2, at 526 Ma). The oldest portion of the inliers is a metamorphosed sequence of mafic and ultramafic gneisses with an age of 1393 Ma. These constitute what is tentatively called the Ophiolite Terrane, together with closely associated high-P/moderate T schists possibly represents a suture. The other three terranes (Granulite, Zambezi and Quartzite Terranes) experienced a common history of tectonothermal events but show variable degrees of reworking during the latest tectono metamorphic event (M2). Concordant granitic orthogneisses were emplaced at 1087 Ma into supracrustal sequences. No Pan-African supracrustals are recognised in the Chewore Inliers, which are wholly basement gneisses and quartzites that have been reworked during successive orogenies including the Pan-African Orogeny.A high-T/low-P metamorphic event (M1 of possibly 1068–1071 Ma age, with a minimum age of 943 Ma, was responsible for totally recrystallizing the Granulite Terrane during south to north tectonic transport. M1 mineral parageneses are only preserved as inclusion phases and overgrown fabrics in the other terranes. These other terranes were pervasively recrystallised at high-P/moderate T conditions accompanying a clockwise P-T path related to northeast over southwest tectonic transport and crustal over-thickening during the Pan-African metamorphic cycle (M2) at approximately 526 Ma. Reworking of the Granulite Terrane during M2 was minor, leaving M1 fabrics and mineral assemblages preserved with little recrystallization. M2 orogenesis culminated in the juxtaposition of the terranes, rapid uplift through the thermal peak and eventual slow cooling accompanying a multitude of post-tectonic intrusions; pegmatites at 480 Ma, the Chewore Ultramafic Complex and dolerite dykes. The 830 Ma tectonothermal event involving pervasive syn-tectonic granitic orthogneisses in the south Zambezi Belt is not recognised in the Chewore Inliers, suggesting a localised, possibly extensional, regime restricted to the southern part of the Zambezi Belt at 830 Ma.  相似文献   

14.
《Ore Geology Reviews》2011,41(1):27-40
Diyadin mineralization is the first reported gold deposit located in a collisional tectonic environment in Eastern Anatolia. The mineralization is related to N–S and N10–20°W-trending fault systems and hosted within the Paleozoic metamorphic basement rocks of the Anatolide–Toride microcontinent. Calc-schist, dolomitic marble and Miocene and Quaternary volcanic rocks comprise the exposed units in the mineralized area. Geochemical signatures, alteration types and host rock characteristics of the Diyadin gold deposit resemble those of Carlin-type deposits. Mineralization is constrained by alteration of overlying volcanic rocks to younger than ~ 14 Ma (K–Ar).Carbon and oxygen stable isotope measurements of carbonate rocks were made on six drill holes (n = 81) with an additional four samples of fresh carbonate rocks from surface outcrops. Background carbonate rocks have δ13CV-PDB ~ 1.8‰ and δ18OV-SMOW ~ 27‰. Isotopically-altered host rock samples have decreased δ18O (down to ~+11.4‰) and variable δ13C (from − 3.6 to + 4.8‰). Postore carbonate veins and cave-fill material have distinctly different isotopic signatures, particularly carbon (from δ13C = + 8.4 to + 9.8‰). Whether this post-ore carbonate is simply very late in mineralization associated with the gold system, or is a completely different, younger system utilizing the same pathways, is unclear at present. Within the host rock sample set, there is no correlation between gold and δ13C, and a weak correlation between gold and δ18O, indicative of water–rock interaction and isotopic alteration. Both the isotopic data and structural mapping suggest that the main upflow zone for the deposit is near the northern portion of the drill fence. Additional data at multiple scales are required to clarify the relationship(s) between fluid flow and mineralization.  相似文献   

15.
The results of scientific and educational activities of the Chair of Engineering and Ecological Geology in the 2008—2017 period, its structure, scientific and organizing activities, as well as information about state and public recognition of the Chair’s staff works are characterized.  相似文献   

16.
<正>There is a general consensus that Plate Tectonics can explain metallogenesis based on the collisions between oceanic and continental crust.For instance,the large-sized porphyry copper deposits that occur along the Cordillera of the Andes around the east coast of the Pacific,and in the Phillipines,Malaysia and Indonesia along the western coast of the Pacific that sit upon the massive Pacific plates.They are considered to be typical of deposits resulting from collision between the oceanic and continental crust.Many experts,however,have long held a negative view about whether the collision between  相似文献   

17.
The Daposhang section at Muhua, Changshun. Guizhou. is an excellent and attractive DevonianCarboniferous boundary section. The transitional beds between the Devonian and Carboniferous of the sectionare continuous and well exposed. belonging to the deep-water basin facies Abundant fossil groups have beendiscovered from this section: conodonts. ammonoids. trilobites. ostracods. vertebrate microfossils and so on.So far as known. it has the most continuous and complete conodont zonation for the Devonian-Carboniferousboundary beds in the world. It is especially worth pointing out that both typical Siponodella pracsulcata andthe transitional forms between S. praesulcata and S. sulcata have been found from the upper pracsulcata Zoneof the Daposhang section. Evidently. we can not only prove the actual existence of the evolutionary lineagefrom S. praesulcata to S. sulcata, but also exactly define the level of the Devonian-Carboniferous boundary. Inthis paper. the development of the Devonian-Carboniferous boundary beds at the Daposhang section is dealtwith and the section is compared with the Muhua section and the Nanbiancun section which are the candidatesfor the Devonian-Carboniferous boundary stratotype. In the authous opinion the Daposhang section is obvi-ously better than the Muhua and the Nanbiancun sections. hence it can be recommended as one of the candi-dates for the international Devonian-Carboniferous boundary stratotype.  相似文献   

18.
<正>The IGCP 649 project entitled "Diamonds and Recycled Mantle"was approved by UNESCO and IUGS in March 2015.This project is led by an international team of researchers,including Prof.Yang Jingsui of Institute of Geology of CAGS(China),Prof.Yildirim Dilek of Miami  相似文献   

19.
20.
The close relationship between the genesis of coal metamorphism and the evolution of the regional tectonic framework is expounded on the basis of an analysis of the geological factors causing the metamorphic zonation of the Late Palaeozoic coals in southern North China; in terms of the mechanism for the formation of palaeogeothermal anomalies, the effects of thermal groundwater on coal metamorphism is highlighted and a geological model for thermal groundwater metamorphism of coal established; with the concept of the palaeogeotherm-coal metamorphism system, the genesis of coal metamorphism is analysed according to the distribution pattern of three geological factors: heat source, heat-carrier and channel, and heat-collector.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号