Terrane

About: Terrane is a research topic. Over the lifetime, 11025 publications have been published within this topic receiving 442596 citations. The topic is also known as: tectonostratigraphic terrane.

Lithotectonic elements and geological events in the Hengshan-Wutai-Fuping belt: a synthesis and implications for the evolution of the Trans-North China Orogen

Abstract: The Hengshan–Wutai–Fuping belt is located in the middle segment of the Trans-North China Orogen, a Palaeoproterozoic continental collisional belt along which the Eastern and Western blocks amalgamated to form the North China Craton. The belt consists of the medium- to high-grade Hengshan and Fuping gneiss complexes and the intervening low- to medium-grade Wutai granite–greenstone terrane, and most igneous rocks in the belt are calc-alkaline and have affinities to magmatic arcs. Previous tectonic models assumed that the Hengshan and Fuping gneiss assemblages were an older basement to the Wutai supracrustal rocks, but recent studies indicate that the three complexes constitute a single, long-lived Neoarchaean to Palaeoproterozoic magmatic arc where the Wutai Complex represents an upper crustal domain, whereas the Hengshan and Fuping gneisses represent the lower crustal components forming the root of the arc. The earliest arc-related magmatism in the belt occurred at 2560–2520 Ma, marked by the emplacement of the Wutai granitoids, which was followed by arc volcanism at 2530–2515 Ma, forming the Wutai greenstones. Extension driven by widespread arc volcanism led to the development of a back-arc basin or a marginal sea, which divided the belt into the Hengshan–Wutai island arc (Japan-type) and the Fuping relict arc. At 2520–2480 Ma, subduction beneath the Hengshan–Wutai island arc caused partial melting of the lower crust to form the Hengshan tonalitic–trondhjemitic–granodioritic (TTG) suites, whereas eastward-directed subduction of the marginal sea led to the reactivation of the Fuping relict arc, where the Fuping tonalitic–trondhjemitic–granodioritic suite was emplaced. In the period 2360–2000 Ma, sporadic phases of isolated granitoid magmatism occurred in the Hengshan–Wutai–Fuping region, forming 2360 Ma, c. 2250 Ma and 2000–2100 Ma granitoids in the Hengshan Complex, the c. 2100 Ma Wangjiahui and Dawaliang granites in the Wutai Complex, and the 2100–2000 Ma Nanying granitoids in the Fuping Complex. At c. 1920 Ma, the Hengshan–Wutai island arc underwent an extensional event, possibly due to the subduction of an oceanic ridge, leading to the emplacement of pre-tectonic gabbroic dykes that were subsequently metamorphosed, together with their host rocks, to form medium- to high-pressure granulites. At 1880–1820 Ma, the Hengshan–Wutai–Fuping arc system was juxtaposed, intensely deformed and metamorphosed during a major and regionally extensive orogenic event, the Luliang Orogeny, which generated the Trans-North China Orogen through collision of the Eastern and Western blocks. The Hengshan–Wutai–Fuping belt was finally stabilized after emplacement of a mafic dyke swarm at 1780–1750 Ma.

A New Concept of Continental Construction in the Central Asian Orogenic Belt

Abstract: A new concept of continental construction based on four main terms: (1) crustal growth, (2) crustal formation, (3) continental growth and (4) continental formation is presented here. Each of these terms reflects a certain process responsible for the formation of what we call now "continental crust". This concept is applied to the Central Asian Orogenic Belt (CAOB), which is a global major accretionary orogen formed after the closure of the Paleo-Asian Ocean, and to its actualistic analogues - orogenic belts and accretionary complexes of the Western Pacific. The main focuses of the paper are the state of activities in the study of the CAOB, the theoretical basics of the new concept of continental construction, its challenges, prospects and social impacts, main methods of investigation. The main issues of the paperare what has been done in this field of geoscience, which questions remained unaddressed and which problems should be solved. The most important challenges are: (a) dominantly Phanerozoic formation of the CAOB continental crust versus its dominantly Archean growth; (b) to what extent the CAOB continental crust was juvenile or recycled; © whether magmatic arcs or Gondwana-derived terranes were accreted to the Siberian, Kazakhstan, Tarim and North China cratons; (d) what was the balance between continental formation and tectonic erosion based on modern examples from the Western Pacific; (e) what social benefits (mineral deposits) and geohazards (seismicity and volcanism) can be inferred from the study of orogenic belts formed in place of former oceans.

Detrital zircon reference for Cambrian to Triassic miogeoclinal strata of western North America

Abstract: U-Pb analyses of 656 single zircon grains from Cambrian to Triassic miogeoclinal strata provide a latitudinal and temporal reference for the ages of grains that accumulated along the western margin of North America. Comparisons between this detrital zircon reference and the ages of grains in potentially displaced terranes outboard (west) of the miogeocline should help establish when the terranes first arrived in sedimentary proximity to western North America. North-south variations in the ages of grains in Cambrian and Devonian to Triassic strata, which reflect the north-south changes in the age of cratonal rocks near the margin, should also help place constraints on a terrane's paleolatitude during these time periods. The technique cannot be used to determine paleolatitude during Ordovician time, however, because miogeoclinal strata from northern Canada to northern Mexico are dominated by grains shed from the Peace River arch (northwestern Canada).

The West African orogens and circum-Atlantic correlatives

Abstract: 1 Introduction.- 2 Geophysics and the Crustal structure of West Africa.- Geophysics and the Crustal structure of West Africa.- 3 Crystalline Basement of the West African Craton.- Crystalline Basement of the West African Craton.- 4 Cover Sequences of the West African Craton.- Cover Sequences of the West African Craton.- 5 The West African Orogens.- The Pan-African Trans-Saharan Belt in the Hoggar Shield (Algeria, Mali, Niger): A Review.- The Dahomeyide Orogen: Tectonothermal Evolution and Relationships with the Volta Basin.- The Rokelide Orogen.- The Bassaride Orogen.- The Mauritanide Orogen and Its Northern Extensions (Western Sahara and Zemmour), West Africa.- The Moroccan Hercynides.- 6 Circum-Atlantic Correlations.- Terranes within the Iberian Massif: Correlations with West Africa Sequences.- Central-Western Europe: Major Stages of Development During Precambrian and Paleozoic Times.- Late Proterozoic and Early Paleozoic Tectonothermal Evolution of the Eastern Alps.- Northern Appalachians: Avalon and Meguma Terranes.- Exotic Terranes in the Central-Southern Appalachian Orogen and Correlations with West Africa.- Crustal Evolution and the Brasiliano Orogeny in Northeast Brazil.

A new magnetic view of Alaska

Abstract: A new, publicly available aeromagnetic data compilation spanning Alaska enables analysis of the regional crustal character of this tectonically diverse and poorly understood part of the North American Cordillera The merged data were upward-continued by 10 km (mathematically smoothed without assumptions about sources) to enhance crustal-scale magnetic features and facilitate tectonic analysis This analysis reveals a basic threefold magnetic character: (1) a southern region with arcuate magnetic domains closely tied to tectonostratigraphic elements, (2) a magnetically neutral interior region punctuated locally by intermediate and deep magnetic highs representing a complex history, and (3) a magnetically subdued northern region that includes a large deep magnetic high Our tectonic view of the data supports interpretations that Paleozoic extension and continental rift basins played a significant role in the tectonic development of northern and interior Alaska Accretion of oceanic and continental margin terranes could be restricted to the southern region The new magnetic view of Alaska can be compared and contrasted with other Pacific margin regions where convergent margin and accretionary tectonic processes are important INTRODUCTION Alaska, an important part of the North American Cordillera, is a type example for the nature and significance of accretionary tectonics along a convergent continental margin (eg, Coney and Jones, 1985; Plafker and Berg, 1994) The prevailing tectonic interpretation is that this vast part of North America has had a long history of accretion of diverse tectonostratigraphic terranes These terranes are thought to represent a wide variety of oceanic, arc, and continental margin assemblages They form an amalgamated, commonly 30-km-thick crust throughout Magnetic View continued on p 2