Showing papers on "Terrane published in 2005"
TL;DR: In this article, a geodynamic evolution model was proposed to depict when and how the Indian continental lithospheric mantle started thrusting under Asia by involving rollback and breakoff of the subducted Neo-Tethyan slab followed by removal of the thickened Lhasa root.
1,196 citations
TL;DR: The geologic map pattern of the Qiangtang terrane in central Tibet defines a >600km-long and up to 270km-wide east-plunging structural culmination as mentioned in this paper.
Abstract: The geologic map pattern of the Qiangtang terrane in central Tibet defines a >600-km-long and up to 270-km-wide east-plunging structural culmination. It is characterized by early Mesozoic blueschist-bearing melange and upper Paleozoic strata in the core and mainly Triassic–Jurassic strata along the limbs. In the western Qiangtang terrane (∼84°E), the culmination is unconformably overlain by weakly deformed mid-Cretaceous volcanic flows and tuffs. Along the Bangong suture to the south (32°N, 84°E), mid-Cretaceous nonmarine red beds and volcanic rocks lie unconformably on Jurassic suture zone rocks. These relationships demonstrate that west-central Tibet was above sea level during the mid-Cretaceous and experienced significant denudation prior to mid-Cretaceous time. Growth of the Qiangtang culmination is inferred to have initiated during southward emplacement of a thrust sheet of early Mesozoic melange and upper Paleozoic strata during the Early Cretaceous Lhasa-Qiangtang collision. The north-south width of the inferred thrust sheet provides a minimum slip estimate of ∼150 km at 84°E, decreasing eastward to ∼70 km at 87°E.
Paleogene deformation in the Qiangtang terrane is characterized by widely distributed, mainly north-dipping thrust faults that cut Eocene–Oligocene red beds and volcanic rocks in their footwall. Along the Bangong suture, the north-dipping Shiquanhe-Gaize-Amdo thrust system cuts 64 and 43 m.y. old volcanic tuffs in its footwall and accommodated >40 km of post–mid-Cretaceous shortening. The Tertiary south-dipping Gaize–Siling Co backthrust bounds the southern margin of the Bangong suture and marks the northernmost limit of mid-Cretaceous marine strata in central Tibet. Cretaceous deformation and denudation in central Tibet is attributed to northward underthrusting of the Lhasa terrane beneath the Qiangtang terrane along the Bangong suture. This model implies that (1) Cretaceous strata along the Bangong suture and in the northern Lhasa terrane were deposited in a flexural foreland basin system and derived at least in part from the Qiangtang terrane, and (2) the central Tibetan crust was thickened substantially prior to the Indo-Asian collision. Although its magnitude is poorly known, Tertiary shortening in the Qiangtang terrane is more prevalent than in the Lhasa terrane; this difference may be attributed to the presence of underthrust melange in the deeper central Tibetan crust, which would have made it weaker than the Lhasa terrane during the Indo-Asian collision.
664 citations
TL;DR: In this article, it was shown that Indian UHP rocks of the Tso Morari Complex reached UHP depths at 53.3F0.7 Ma and reached the Asian trench no later than 57F1 Ma, providing a metamorphic age for comparison with previous paleomagnetic and stratigraphic estimates.
505 citations
TL;DR: The old terrane of Baltica occupies the mass of northern Europe eastwards to the Urals and lies mostly to the north of the Trans-European Suture Zone The core, the East European Craton, is thick and formed of rocks dating back to well over 3 billion yr, and Protobaltica can be identified as forming part of the supercontinent of Rodinia at about 1 billion yr ago as mentioned in this paper.
456 citations
TL;DR: In this article, the authors report the first geochemical traverse to integrate U-Pb ages and Hf data on single detrital zircons with bulk-rock Sm-Nd-Rb-Sr isotopic measurements across the breadth of the Himalayan orogen, in northwest India.
314 citations
TL;DR: In this article, the authors present new sedimentary data integrated into a regional Mesozoic stratigraphic framework to provide a detailed picture of spatio-temporal variations in deposition and depocenter migration of the northwest Sichuan basin.
Abstract: We present new sedimentary data integrated into a regional Mesozoic stratigraphic framework to provide a detailed picture of spatio-temporal variations in deposition and depocenter migration of the northwest Sichuan basin. The Mesozoic sedimentary evolution is utilized to interpret basin subsidence history and to unravel coeval basin-margin tectonics. The northwest Sichuan basin, together with the Songpan-Ganzi terrane, behaved as a passive margin south of the Qinling Paleo-Tethys from late Paleozoic to early Middle Triassic times and then evolved into a peripheral foreland basin in response to collision of the North and South China blocks since the late Middle Triassic. Coeval with strong north-south contraction of the Songpan-Ganzi terrane in the Late Triassic, sinistral transpressional deformation of the Longmen Shan belt led to flexural subsidence of the adjacent western Sichuan basin. Renewed basin-margin fold-thrust activity triggered recurrence of flexural subsidence of the northwest Sichuan basin since the Middle Jurassic, with the depocenter eventually shifting to the northwestern corner of the basin in the Early Cretaceous. Sedimentary evolution of the northwest Sichuan basin and the basin-margin deformation imply that the South China block had been rotating clockwise relative to the North China block throughout the Mesozoic with an interim period of Early Jurassic tectonic quiescence. A model is advanced that invokes clockwise rotation of the South China block as a driver for tectonic evolution of both the basin and adjoining structural belts and provides an explanation for several salient features that are otherwise puzzling.
290 citations
TL;DR: Wang et al. as mentioned in this paper characterized metamorphosed and unmetamorphosed dikes in terms of their geochemistry and geochronology, and suggested that the North China craton may have been involved in the evolution of the supercontinent Columbia.
Abstract: Widespread magmatic and metamorphic events during the interval 2350-1650 Ma suggest that the North China craton (NCC) may have been involved in the evolution of the supercontinent Columbia. Metamorphosed and unmetamorphosed dikes have been characterized in terms of their geochemistry and geochronology. Dike suite 1 in the northern Wutai-Fuping terrane comprises amphibolite-facies assemblages and has a SHRIMP U-Pb zircon crystallization age of 2147 ± 5 Ma. Dike suite 2, distributed in the northern part of the Huai'an-Fengzhen terrane, has a two-pyroxene granulite assemblage, and yields a SHRIMP metamorphic zircon age of 1929 ± 8 Ma. Dike suite 3 in the Sanggan structural zone between the two terranes is composed of garnet two-pyroxene granulites, and has a SHRIMP zircon age of 1973 ± 4 Ma for the cores and 1834 ± 5 Ma for the rims, defining the time of crystallization and peak metamorphism, respectively. Dike suites 1 and 2 were possibly emplaced close to a continental margin and an arc respectively; where...
272 citations
TL;DR: In this article, a provenance study of Neoproterozoic siliciclastic successions in the stratigraphically and tectonically lowermost and uppermost parts of the Pan-African Gariep Belt (Stinkfontein Subgroup and Oranjemund Group, respectively) in southwestern Africa, as well as in the Rocha Group of the Punta del Este Terrane (Dom Feliciano Belt) in Uruguay, revealed that the ORANJemund and rocha groups can be correlated and most
221 citations
TL;DR: A detailed analysis of the tectonostratigraphic records of Late Archean to Early Paleoproterozoic terranes indicates linkage between global tectonics, changing sea levels and environmental conditions as mentioned in this paper.
211 citations
TL;DR: The 3.12 Ga Whundo Group as mentioned in this paper is an exotic terrane on the western margin of the old (≥3.4 Ga) nucleus of the Pilbara Craton in northwestern Australia.
202 citations
TL;DR: In this article, it is suggested that these events reflect individual accretionary episodes, which together with kinematic indicators and the speed and direction of plate motions, provide constraints for the discussed reconstruction model.
TL;DR: A ~4000 km long ultra-high-pressure metamorphic belt in northern China has been documented on the basis of the discovery of coesite-bearing rocks in the Altun-North Qaidam terrane in the western Central Orogenic Belt (COB), and diamond bearing rocks in Qinling in the central and Dabie-Sulu terrane as mentioned in this paper.
Abstract: A ~4000 km long ultrahigh-pressure metamorphic (UHPM) belt in northern China has been documented on the basis of the discovery of coesite-bearing rocks in the Altun-North Qaidam terrane in the western Central Orogenic Belt (COB), and diamond-bearing rocks in Qinling in the central and Dabie-Sulu terrane in the east. New SIMS and SHRIMP U-Pb dates of zircons from coesitebearing UHPM rocks indicate two UHPM events: one in the early Paleozoic and the other in the Triassic. Coesite-bearing zircons from a North Qaidam gneiss yielded UHP metamorphic ages of 452 ± 13.8 Ma and retrograde ages of 419 ± 6.7 Ma. A diamond-bearing gneiss from Qinling gave a lower intercept age of 502 ± 45 Ma, and an upper intercept age of 1545 ± 100 Ma, whereas a Qinling eclogite sample gave a lower intercept age of 493 ± 170 Ma and an upper intercept age of 1381 ± 82 Ma. The lower and upper intercept ages of the Qinling samples are interpreted as UHPM and protolith ages of the rocks, respectively. Coesite-bearing zircons from a Qing...
TL;DR: In this paper, the authors review geologic, geochemical and paleomagnetic evidence that suggests that the Caribbean-Colombian oceanic plateau in fact represents the remnants of two different oceanic plateaus, both dated as ca. 90 Ma.
Abstract: It is widely accepted that the thickened oceanic crust of the Caribbean plate, its basaltic accreted margins, and accreted mafic terranes in northwestern South America represent the remnants of a single ca. 90 Ma oceanic plateau. We review geologic, geochemical, and paleomagnetic evidence that suggests that the Caribbean-Colombian oceanic plateau in fact represents the remnants of two different oceanic plateaus, both dated as ca. 90 Ma. The first of these plateaus, the Caribbean Plateau, formed ca. 90 Ma in the vicinity of the present-day Galapagos hotspot. Northeastward movement of the Farallon plate meant that this plateau collided with the proto‐Caribbean arc and northwestern South America ,10 m.y. after the plateau’s main phase of formation. Paleomagnetic evidence suggests that the second of these plateaus, the Gorgona Plateau, formed at 268‐308S, possibly at the site of the present-day Sala y Gomez hotspot. Over the next ;45 m.y., this plateau was carried progressively northeastward on the Farallon plate and collided in the middle Eocene with the proto‐Andean subduction zone in northwestern South America. The recognition of a second ca. 90 Ma Pacific oceanic plateau strengthens the link between plateau formation and global oceanic anoxic events.
TL;DR: In this article, strong deformed potassium feldspar-rich dikes are widely distributed in the northern part of the Sulu ultrahigh pressure (UHP) metamorphic terrane, eastern China.
Abstract: Strongly deformed potassium feldspar–rich dikes are widely distributed in the northern part of the Sulu ultrahigh-pressure (UHP) metamorphic terrane, eastern China. The fact that the crystallization ages of these dikes overlap with the age of peak UHP metamorphic conditions implies the presence of melt during metamorphism. Sr isotopic ratios of the dikes are compatible with their origin as partial melts of the dominant felsic Sulu gneiss. Partial melting may be the key to solving several unusual features of the Sulu and other UHP terranes, such as the almost complete lack of mineralogical evidence for UHP conditions and the limited growth of zircon during UHP conditions in the dominant felsic gneiss. In addition, because partial melting will cause a drastic reduction in the strength of the UHP gneisses, the most likely exhumation mechanism is diapiric rise of a low-viscosity, partially molten mass containing entrained blocks of eclogite, and not a thin sheet as usually proposed.
TL;DR: The authors reconstructs the Variscan-Alleghanian orogenic belt, with especial emphasis on the links between Iberia, northwest Africa, and northeast America.
TL;DR: In this article, the Late Paleozoic collision between the North China continental block and the Altaid arc terranes of Mongolia represents one of the earliest and most fundamental tectonic events in the ongoing construction of Asia.
Abstract: The Late Paleozoic collision between the North China continental block and the Altaid arc terranes of Mongolia represents one of the earliest and most fundamental tectonic events in the ongoing construction of Asia. New detrital zircon provenance data from Carboniferous-Permian nonmarine strata on the northern margin of North China imply that the northern margin of the North China block constituted a continental margin arc prior to this collision (~400-275 Ma) and that collision took place via south-directed subduction beneath North China. A significant and widespread climate change took place in North China in mid-Permian time, and is recorded by a change from Carboniferous and Lower Permian humid-climate, coal-bearing sedimentary facies to Upper Permian and Lower Triassic arid-climate redbeds. In northern North China, this climate change is accompanied by a paleocurrent reversal, which indicates the onset of uplift on the northern margin of the North China block. The temporal association of climate chan...
TL;DR: In the south of the Nuuk region of West Greenland, the authors of as mentioned in this paper distinguish two new terranes in the NE, namely, the northernmost Isukasia terrane and the southernmost Kapisilik terrane.
Abstract: In the south of the Nuuk region of West Greenland our 1980s mapping recognized four Archaean gneiss terranes (Fœringehavn, Tre Brodre, Tasiusarsuaq and Akia terranes) with different protolith ages and separate early tectonothermal histories. Later in the Archaean these were juxtaposed and then experienced the same 2700–2500 Ma tectonothermal events. Here we abandon extrapolation of only these four terranes across the whole region, and distinguish two new terranes in the NE. The northernmost Isukasia terrane (previously regarded as the northernmost exposure of the Fœringehavn terrane) consists of Palaeoarchaean rocks (>3600 Ma) tectonically bounded on its south by the 3075–2960 Ma Kapisilik terrane; these were juxtaposed and metamorphosed together by 2950 Ma. The previously recognized Fœringehavn terrane to the SW is another, separate entity of Palaeoarchaean rocks that was juxtaposed with adjacent terranes only after c . 2800 Ma. Hence in an increasingly complex regional model, there were several mid- to Neoarchaean terrane assembly events, with superimposed ‘orogenies’ from c . 2950 Ma until after 2700 Ma. Although the Fœringehavn and Isukasia terranes were incorporated into the later Archaean terrane collage at different times, they might be fragments from a larger Palaeoarchaean complex rifted apart from c . 3500 Ma onwards.
TL;DR: The authors summarizes the history and principles of terrane theory and presents 16 new works that review and synthesize the current state of knowledge for the Gondwana margin, from Australia through New Zealand and Antarctica to South America.
Abstract: The process of terrane accretion is vital to the understanding of the formation of continental crust. Accretionary orogens affect over half of the globe and have a distinctively different evolution to Wilson-type orogens. It is increasingly evident that accretionary orogenesis has played a significant role in the formation of the continents. The Pacific-margin of Gondwana preserves a major orogenic belt, termed here the ‘Australides’, which was an active site of terrane accretion from Neoproterozoic to Late Mesozoic times, and comparable in scale to the Rockies from Mexico to Alaska, or the Variscan-Appalachian orogeny. The New Zealand sector of this orogenic belt was one of the birthplaces of terrane theory and the Australide orogeny overall continues to be an important testing ground for terrane studies. This volume summarizes the history and principles of terrane theory and presents 16 new works that review and synthesize the current state of knowledge for the Gondwana margin, from Australia through New Zealand and Antarctica to South America, examining the evolution of the whole Gondwana margin through time.
TL;DR: The formation of the vast Devonian ultrahigh pressure terrane in the Western Gneiss Region of Norway was investigated by determining the relationship between these ultrahigh-pressure rocks and the structurally overlying oceanic and continental Koli and Seve Nappes in the Trondelag-Jamtland region as discussed by the authors.
Abstract: The formation of the vast Devonian ultrahigh-pressure terrane in the Western Gneiss Region of Norway was investigated by determining the relationship between these ultrahigh-pressure rocks and the structurally overlying oceanic and continental Koli and Seve Nappes in the Trondelag-Jamtland region. Thermobarometry and thermochronology reveal that the oceanic Koli Nappes reached peak conditions of 9–10 kbar and 550–650 °C prior to muscovite closure to Ar beginning at ca. 425 Ma. The continental Seve Nappes attained slightly higher pressures and temperatures (~11–12 kbar and 700–725 °C) and closed to Ar loss in muscovite by 415 Ma in the east and by 400 Ma in the west. In contrast, the ultrahigh-pressure rocks were still deep in the mantle at eclogitefacies pressures at 410–400 Ma. These data, in combination with structural, petrological, and thermochronological data from elsewhere in the orogen, show that the ultrahighpressure metamorphism occurred in the late stages of continental collision, after the earlier stages of ophiolite emplacement and passive-margin subduction.
TL;DR: Babel profiles B, C, 1, 6, 7 and C image the internal architecture of the Southern and Central Finland arcs as mentioned in this paper, which can be associated with both the accretionary Svecofennian orogeny and the following Subjotnian and Jotnian rift-stages.
TL;DR: Zircon and monazite U-Pb dates, garnet Sm-Nd dates and hornblende 40 Ar/39 Ar data from the transpressional Kaoko Belt of the late Neoproterozoic Pan-African Orogenic system confirm three distinct tectono-metamorphic cycles: M1 (655-645 Ma), M2 (580-550 Ma) and M3 (535-505 Ma) as discussed by the authors.
TL;DR: In this article, an integrated sensitive high-mass resolution ion microprobe (SHRIMP) was used to detect U-Pb zircon, geochemical and Sm-Nd isotopic data from the late Archaean Gawler Craton, southern Australia, constrain major basin-forming and magmatic processes to the interval 2560-2500 ǫ.
TL;DR: Scherer et al. as discussed by the authors used U-Pb and Hf isotopic measurements on zircons from the western Superior province to confirm that the area contains at least three distinct terrane types.
TL;DR: In this article, the S-wave velocity structure of Precambrian terranes in Tanzania, East Africa is modelled by jointly inverting receiver functions and surface wave dispersion velocities from the 1994-1995 Tanzania broad-band seismic experiment.
Abstract: SUMMARY The S-wave velocity structure of Precambrian terranes in Tanzania, East Africa is modelled by jointly inverting receiver functions and surface wave dispersion velocities from the 1994‐1995 Tanzania broad-band seismic experiment. The study region, which consists of an Archean craton surrounded by Proterozoic mobile belts, forms a unique setting for evaluating Precambrian crustal evolution. Our results show a uniform crustal structure across the region, with a 10‐15 km thick upper crust with VS = 3.4‐3.5 km s −1 ,o verlying a gradational lower crust with S-wave velocities up to 4.1 km s −1 at 38‐42 km depth. The upper-mantle lid displays uniform S-wave velocities of 4.5‐4.7 km s −1 to depths of 100‐150 km and overlays a prominent low-velocity zone. This low-velocity zone is required by the dispersion and receiver function data, but its depth interval is uncertain. The high crustal velocities within the lowermost crust characterize the entire region and suggest that mafic lithologies are present in both Archean and Proterozoic terranes. The ubiquitous mafic lower crust can be attributed to underplating associated with mafic dyke emplacement. This finding suggests that in East Africa there has been little secular variation in Precambrian crustal development.
TL;DR: In this article, the authors show that a 50% increase in the thickness of the middle and lower crustal layers of the Tibetan Plateau can be explained by the Karakorum-Jiali fault system.
Abstract: (� 5–30 km depth, 5.0 < Vp < 6.4 km/s), a middle crust (� 33–45 km depth, 6.5 < Vp < 6.8 km/s) and a lower crust (depths below � 48 km, 7.0 < Vp < 7.4 km/s). The west-to-east increase in crustal thickness is accomplished by a � 50% thickening of the middle and lower crust. Larger vertical velocity gradients separate these three layers and bound them above (surficial and sedimentary rocks) and below (Moho transition zone). The most notable low-velocity zone in the crust lies at the base of the upper crustal layer. S wave velocity structure is less well constrained but parallels the P wave structure except that Vp/Vs ratios may decrease from west to east in the lower crust. Our data suggest considerable variation in structure along-strike of the Tibetan Plateau and show that interpretations of Tibet as a purely two-dimensional orogen are overly simplistic. The west-east increase in crustal thickness may occur across the Karakorum-Jiali fault system and be an indicator of lateral tectonic escape of the Qiangtang terrane.
TL;DR: In this article, the authors show that the deformation in the subduction channel is largely controlled by kinematic boundary conditions, i.e. underthrusting of the subducting slab.
TL;DR: The CELEBRATION 2000 profile as discussed by the authors was used for the recognition of crustal structure in the border zone between the Precambrian East European Craton (Baltica) and Palaeozoic Europe.
TL;DR: In this paper, detrital zircons from three Neoproterozoic sandstone units from the Cadomia terrane of northern France and the Channel Islands yield ages in three broad groups, namely, late Neo-terozoics (650-600 Ma), early Palaeo-pharaesopharaes (2.4-2.0 Ga), and Archaean (>2.5 Ga).
Abstract: Detrital zircons from three Neoproterozoic sandstone units from the Cadomia terrane of northern France and the Channel Islands yield ages in three broad groups: late Neoproterozoic (650–600 Ma), early Palaeoproterozoic (2.4–2.0 Ga) and Archaean (>2.5 Ga). The lack of Mesoproterozoic zircon crystals, combined with the high abundance of grains between 2.20 and 2.00 Ga, corresponds closely to the ages of exposed rocks in the West Africa Craton, and thus it is suggested that Cadomia was in close proximity to West Africa by c . 580 Ma. In contrast, the main age groups of detrital zircon from the Neoproterozoic Avalon terrane are Mesoproterozoic and there is a distinct gap of ages between 2.40 and 2.05 Ga. These significant differences suggest that the two terranes were in different locations relative to major Gondwanan cratons in latest Neoproterozoic time.
TL;DR: Svalbard is located in the north-west corner of the Barents Sea shelf and the Eurasian Plate, in a key area for interpreting Caledonian and older orogens in the Arctic region as mentioned in this paper.
Abstract: Svalbard is located in the north-west corner of the Barents Sea shelf and the Eurasian Plate, in a key area for interpreting Caledonian and older orogens in the Arctic region. Recent U–Pb dating in the Nordaustlandet Terrane of eastern Svalbard shows this terrane to consist of a Grenville-age basement, overlain by Neoproterozoic to early Palaeozoic platformal sediments, and intruded by Caledonian anatectic granites. Deformation, metamorphism and crustal anatectic magmatism occurred both during the Grenvillian (960–940 Ma) and Caledonian (450–410 Ma) orogenies. This evolution shows great similarities with that of eastern Greenland. In the classical model, eastern Svalbard is placed outboard of central east Greenland in pre-Caledonian time. Alternatively, it may have been located north-east of Greenland and transferred west and rotated anticlockwise during Caledonian continent–continent collision. In the Neoproterozoic, easternmost Svalbard may have been part of a wider area of Grenville-age crust, now fragmented and dispersed around the Arctic.
TL;DR: The current nomenclature for the Lewisian Gneiss Complex has evolved from lithological and structural correlations made prior to any dating as mentioned in this paper, which is more applicable to this new tectonic framework.
Abstract: The current nomenclature for the Lewisian Gneiss Complex has evolved from lithological and structural correlations made prior to any dating. Initial (flawed) geochronological studies gave some names an apparent chronological standing but, as work advanced, fitting events into a coherent regional framework became increasingly difficult. Modern dating studies have shown that the Lewisian Gneiss Complex was progressively assembled from disparate blocks of Archaean continental crust and juvenile Proterozoic arcs, which satisfy the definition of terranes. Each terrane had its own separate accretionary and metamorphic history followed by a common history once juxtaposed against other terranes. Based on a new compilation of modern geochronology allied to the many detailed structural and metamorphic studies, this paper proposes a new systematic terminology for the Lewisian Gneiss Complex that is more applicable to this new tectonic framework.