No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The role of accretionary wedges in the growth of continents: Asiatic examples from ARDAND to plate tectonics
Abstract
One of the early triumphs of global comparative tectonics was the recognition of a fairly irregular radial migration of orogenic deformation away from stable continental interiors. Suess interpreted this as continental growth. The theory of continental drift, moulded by Argand's genius into a form capable of answering the demands of continental tectonics, provided the first satisfactory explanation of peripheral continental growth and why it was somewhat haphazard. The composite nature of continents found a ready explanation in the theory of plate tectonics, but suture zones were early stereotyped into Salomon-Calvi's suture lines (his Synaphie), although many orogenic belts do not possess a readily recognisable Indus-type clean suture line. In many mountain belts, zones of continental collision are marked by wide belts of accreted sedimentary rocks, commonly with steep structures, forming trapped accretionary complexes. In his subductionless view of continental drift Argand recognised the importance of accretionary material that he thought had been skimmed off the ocean floor by floating sialic rafts. He portrayed broad, accretionary material-filled suture zones in maps and in sections and contrasted them implicitly with narrow suture lines devoid of such accretionary cushions. As Argand noticed, the architecture of Asia contains numerous examples of large accretionary complexes. In the Altaids they dominate the structure and in the Cimmerides they play a significant role. Only in the Alpides they have a subordinate place in the orogenic architecture, which is a joint function of the size of ocean lost and the amount of sediment supplied. The presence of giant accretionary complexes in continental architecture has important implications for the structure and composition of the lower crust, the nature of continental anisotropies, and the overall growth of the continental crust.
... Devonian non-marine clastics (molasse) lie unconformably over the older, more deformed, Palaeozoic sequences (e.g., Du et al., 2004;Xiao et al., 2009a). Structural vergence is variable across the whole region, but possibly more commonly to the south than the north (Ş engör and Okurogullari, 1991;Allen et al., 2017). ...
... Outcrops of Precambrian rocks are a relatively minor component of the region . Instead of a pattern of adjacent Precambrian basement strips and accretionary Palaeozoic rocks, there is a more continuous exposure of arc-related metasedimentary rocks and volcanic rocks at the south side of the Tarim Block, intruded by granitoids (Ş engör and Okurogullari, 1991;Mattern and Schneider, 2000;Xiao et al., 2002aXiao et al., , 2002bYuan et al., 2002;Xiao et al., 2005;Zhang et al., 2019b). Ophiolite belts and major shear zones have been used to divide the range into three units, the North Kunlun, South Kunlun and Tianshuihai terranes (e.g., Xiao et al., 2005;Zhang et al., 2019b), but the southern two terranes are not highly distinct from each other in terms of their lithologies, age ranges or structure. ...
... Zircon U-Pb ages from meta-volcanic rocks intercalated with the sedimentary rocks yield Cambrian ages (Zhang et al., 2018c), younging northwards from 530-520 Ma in the south to 508 Ma in the north. Devonian red bed molasse sedimentary rocks of the Tisnab Group lie unconformably over older sequences in the region (Ş engör and Okurogullari, 1991). ...
... Various studies have suggested that the WKM was generated by orogenesis caused by the collision of the Tarim and Qiangtang terranes during the late Mesozoic (e.g. Sengor and Okurogullari 1991;Kao et al. 2001;Xiao et al. 2002) and that it was subsequently influenced by distant structural effects induced by India-Asia collision during the Cenozoic (Molnar and Tapponnier, 1975;Kao et al. 2001;Li et al. 2002). The youngest magmatism recorded in the Qinghai-Tibet Plateau occurred in the WKM (Deng 2000;Zhang et al. 2004Zhang et al. , 2008. ...
... Considering the E-W extension of the Tibetan Plateau crust during 18-4 Ma and the tectonic background of the WKM (e.g. Dewey et al. 1988;Sengor and Okurogullari 1991;Coleman and Hodges 1995;Harrison, 1995;Bi et al. 1999;Kao et al. 2001;Li et al., 2002;Dewey et al. 1988;Sengor and Okurogullari 1991;Kao et al. 2001;Xiao et al. 2002;Bi et al. 1999), the Quanshuigou granite porphyries and shoshonites might have developed as a result of lithospheric delamination during the late Miocene post-collisional stage when magmas were emplaced in an extensional zone, as indicated by the presence at that time of the gigantic Altyn Tagh strike-slip fault system. Activation of the Altyn Tagh strike-slip fault generated a set of normal faults and pull-apart basins in its splay, resulting in east-west extension. ...
... Considering the E-W extension of the Tibetan Plateau crust during 18-4 Ma and the tectonic background of the WKM (e.g. Dewey et al. 1988;Sengor and Okurogullari 1991;Coleman and Hodges 1995;Harrison, 1995;Bi et al. 1999;Kao et al. 2001;Li et al., 2002;Dewey et al. 1988;Sengor and Okurogullari 1991;Kao et al. 2001;Xiao et al. 2002;Bi et al. 1999), the Quanshuigou granite porphyries and shoshonites might have developed as a result of lithospheric delamination during the late Miocene post-collisional stage when magmas were emplaced in an extensional zone, as indicated by the presence at that time of the gigantic Altyn Tagh strike-slip fault system. Activation of the Altyn Tagh strike-slip fault generated a set of normal faults and pull-apart basins in its splay, resulting in east-west extension. ...
Post-collisional K-rich magmatic rocks of the Qinghai–Tibet Plateau provide important information for understanding the continental collision and uplift of this plateau during the Cenozoic. However, the source of these K-rich rocks is still debated, and limited investigations have been conducted in the western Kunlun Mountains (WKM) in the northwestern margin of the plateau. In this paper, we present geochemical, geochronological, and Sr–Nd–Hf isotope data for Quanshuigou post-collisional K-rich igneous rocks from the WKM. Geochronological results show that these rocks were emplaced during two stages: (1) ca. 5.3 Ma, as an intrusive suite of granite porphyries; and (2) ca. 4.8 Ma, as a suite of shoshonites. These rocks are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs), and depleted in heavy rare earth elements (HREEs) and high-field-strength elements (HFSEs). Compositions of the granite porphyries classify these rocks as high-K calc-alkaline peraluminous A-type granites. Combining the negative zircon ε Hf(t) values (−6.9 to −1.1) with Hf crustal model ages (TDM2) of 1.16–1.53 Ga and negative ε Nd(t) values (−5.31 to −4.96) with two-stage Nd model ages (TDM2) of 1.22–1.46 Ga, these signatures suggest that the granite porphyries most probably originated from partial melting of thickened lower crust with limited input of mantle-derived magmas. In contrast, the shoshonites have low SiO2 contents (50.84–53.94 wt.%), relatively high Mg# values (50–57), and εNd (t) values ranging from −6.18 to −5.34, with single-stage Nd model ages (TDM1) of 0.97–1.02 Ga. Our analyses show that the parental magma of the shoshonites probably formed by partial melting of EMII-type lithospheric mantle, with the addition of subducted and recycled oceanic sediments. Hence, we conclude that these granite porphyries and shoshonites formed in a post-collisional, extension-related geodynamic setting and that the melting was probably triggered by motion on the Altyn Tagh strike-slip fault system.
... Orogenic researches including the temporal and spatial features of orogens have long been a major task of the international community because they deal with the fundamental principles of the formation and growth of continents (Şengör, 1990;Şengör and Okurogullari, 1991;Şengör et al., 1993;McCulloch and Bennett, 1994;Condie, 1998;Jahn et al., 2004;Kröner et al., 2007;Wu et al., 2007). Since the advent of the plate tectonic paradigm and its application to orogenic analysis, a major breakthrough came with the application and interpretation of the Wilson Cycle of ocean opening and closure (Wilson, 1966;Moores, 1970;Wakabayashi and Dilek, 2000;Dewey, 2005). ...
... Issue 2: oroclinal bending of one single, long-lived ribbon-type arc or continental sliver is the basic mechanism for an orogeny, which may generate only one major ocean perhaps with a back-arc basin (Şengör and Okurogullari, 1991;Şengör et al., 1993;Johnston and Acton, 2003;Van der Voo, 2004;Cawood et al., 2011;Rosenbaum et al., 2012;Johnston et al., 2013). ...
... The Central Asian Orogenic Belt (CAOB,~1000-250 Ma) lies between the Baltica (East European) Craton to the northwest, the Siberia Craton to the north, and the Tarim and North China cratons to the south (Şengör and Okurogullari, 1991;Şengör et al., 1993;Şengör and Natal'in, 1996b;Kröner et al., 2007;Lehmann et al., 2010;Safonova et al., 2011;Jian et al., 2013). The CAOB is one of the largest and longlived accretionary collages worldwide (Fig. 2), the younger part of which (the Altaids) developed from about 600 Ma to 250 Ma (Coleman, 1989;Hu et al., 2000;Jahn et al., 2000Jahn et al., , 2004Jahn, 2001;Zhao et al., 2009;Kröner et al., 2014). ...
The architecture and mechanics of an orogen can be understood in terms of a system of collages that are characterized by a complex assemblage of multiple components, but the fundamental paleogeographic framework and the tectonic relationships between the different components are often insufficiently defined, because of unavailable data. The Central Asian Orogenic Belt (CAOB) provides an ideal opportunity to address the fundamental framework of paleogeography and tectonic relationships between the diverse and many components in this huge collage. In this paper we review several lines of available evidence, which enable us to propose a new tectonic model of huge roll-back in the formation of the accretionary tectonics of the Mongolian collage in Central Asia. In the early Paleozoic the Mongolia collage comprised the southern Siberian and the Tuva-Mongol Oroclines. The Siberia Craton and the Mongolia collage jointly formed a giant "tadpole-shape" within the Paleo-Asian and Panthanlassic oceans; its head (Siberia) was to the south, and the tail (Tuva-Mongol) to the northwest. The structures and tectonic zonation of the Mongolia collage are characteristic of multiple arcs, which have been separately described in detail in different segments southwards from the Southern Siberia-East Sayan, West Sayan-Gorny Altai-Chara, via the Lake Zone-Junggar-Tianshan, Gobi Altai-Beishan-Alxa, to the Manlay-Hegenshan-Baolidao-Solonker segments. Almost all segments underwent Early Paleozoic to Permian, or even Triassic, frontal subduction and accretion, while rifting in the Late Carboniferous to Permian or Triassic occurred in the outward/oceanward (westward) advancing Mongolian collage. Therefore, we suggest that a huge complex roll-back, active from the Carboniferous to Permian or even to late Triassic, facilitated the formation of the Mongolian collage. The outward multiple roll-back process was compatible and almost coeval with the start of the Tuva-Mongol Orocline and rotation of the Siberian Craton, as confirmed by paleomagnetic and structural data. During the roll-back processes an archipelago paleogeography was formed behind the frontal subduction and accretion, in which independent arcs or terranes were amalgamated or collided to form composite arcs or terranes either simultaneously or at slightly different times. The roll-back process was affected by the collision of the Kazakhstan collage along the Chara and Karamay zones in the Early Permian, the collision of the Tarim Craton along the South Tianshan zone in the Early Permian, the collision of the Dunhuang Block along the Liuyuan zone in the Early Permian-Triassic, the collision of the Alxa block along the Qugan Qulu zone in the Permian, and the collision of the North China Craton along the Solonker zone in the Middle-Late Triassic. The tectonic styles and architecture of accretionary orogenic belts like the CAOB are characterized both by the amalgamation of multiple terranes and by oroclinal bending. The systematic anatomy of the multiple roll-back processes and their interactions with the adjacent collages shed light on the evolving orogenic architecture and the crustal accretionary history of orogens.
... The WKO is tectonically divided into the Northern Kunlun (NKT) and Southern Kunlun (SKT) terranes by the Kudi Suture Zone. It is debated whether the SKT represents a micro-continental block separated from the Tarim Craton (Pan and Wang, 1994;Xu et al., 1994;Matte et al., 1996;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013 or an early Paleozoic continental arc terrane related to the subduction of Proto-Tethyan oceanic crust (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Li et al., 1999;Yuan et al., 2002Yuan et al., , 2005; however, it is widely accepted that the early Paleozoic continent-continent or arc-continent collision is generally considered to occur along the Kudi Suture Zone (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Pan, 1996;Li et al., 1999;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Yuan et al., 2002Yuan et al., , 2005. ...
... The WKO is tectonically divided into the Northern Kunlun (NKT) and Southern Kunlun (SKT) terranes by the Kudi Suture Zone. It is debated whether the SKT represents a micro-continental block separated from the Tarim Craton (Pan and Wang, 1994;Xu et al., 1994;Matte et al., 1996;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013 or an early Paleozoic continental arc terrane related to the subduction of Proto-Tethyan oceanic crust (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Li et al., 1999;Yuan et al., 2002Yuan et al., , 2005; however, it is widely accepted that the early Paleozoic continent-continent or arc-continent collision is generally considered to occur along the Kudi Suture Zone (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Pan, 1996;Li et al., 1999;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Yuan et al., 2002Yuan et al., , 2005. ...
... The Kudi Ophiolite in the western WKO may be regarded as direct evidence for the existence of an ancient oceanic basin, suture, and paleo-subduction zone in the Kunlun Orogen. It is widely accepted that the collision between the NKT and SKT occurred during the Middle Ordovician along the Kudi Suture Zone in the Western Kunlun (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Pan, 1996;Li et al., 1999;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Yuan et al., 2002Yuan et al., , 2005, and it has been suggested that the Qimanyute Ophiolite constitutes the eastern extension of the Kudi Ophiolite, which yields a crystallization age of 526 Ma and was obducted at ±432 Ma (Han et al., 2002). This indicates that continent-continent collision, or arc-continent collision, occurred prior to 432 Ma along the Kudi-Qimanyute Suture Zone. ...
... The WKO is tectonically divided into the Northern Kunlun (NKT) and Southern Kunlun (SKT) terranes by the Kudi Suture Zone. It is debated whether the SKT represents a micro-continental block separated from the Tarim Craton (Pan et al., 1994;Xu et al., 1994;Matte et al., 1996;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013 or an early Paleozoic continental arc terrane related to the subduction of Proto-Tethyan oceanic crust (Chang et al., 1989;Sengör, 1990;Sengör & Okurogullari, 1991, Yao & Hsü, 1994Hsü et al., 1995;Yuan et al., 2002Yuan et al., , 2005; however, it is widely accepted that the early Paleozoic continent-continent or arc-continent collision is generally considered to occur along the Kudi Suture Zone (Chang et al., 1989;Sengör, 1990;Sengör & Okurogullari, 1991;Yao & Hsü, 1994;Hsü et al., 1995;Pan, 1996;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Yuan et al., 2002Yuan et al., , 2005. ...
... The WKO is tectonically divided into the Northern Kunlun (NKT) and Southern Kunlun (SKT) terranes by the Kudi Suture Zone. It is debated whether the SKT represents a micro-continental block separated from the Tarim Craton (Pan et al., 1994;Xu et al., 1994;Matte et al., 1996;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013 or an early Paleozoic continental arc terrane related to the subduction of Proto-Tethyan oceanic crust (Chang et al., 1989;Sengör, 1990;Sengör & Okurogullari, 1991, Yao & Hsü, 1994Hsü et al., 1995;Yuan et al., 2002Yuan et al., , 2005; however, it is widely accepted that the early Paleozoic continent-continent or arc-continent collision is generally considered to occur along the Kudi Suture Zone (Chang et al., 1989;Sengör, 1990;Sengör & Okurogullari, 1991;Yao & Hsü, 1994;Hsü et al., 1995;Pan, 1996;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Yuan et al., 2002Yuan et al., , 2005. ...
... A suite of early Paleozoic granitoids occurs in the WKO, and their ages and chemical compositions might provide important constraints on the tectonic evolution of the orogen (Sengör et al., 1991). Early Paleozoic plutons in the western WKO (Fig. 1b) have been extensively studied and classified into four types based on age and composition: (1) granitoids related to oceanic ridge subduction (e.g., the Aoyitake granitoids; Jiang et al., 4 1999); (2) volcanic-arc-type granitoids associated with an active continental margin (e.g., the Kogan, Talongbei, Awaleke, and ~471 Ma Yierba granitoids; Jiang et al., 1999;Yuan et al., 1999Yuan et al., , 2002; (3) granitoids related to syn-and post-orogenic uplift (e.g., the western Datong granitoids; Jiang et al., 1999); and (4) late-or post-orogenic A-type granitoids (e.g., the ~405 Ma north Kudi A-type, and the ~430 Ma Buya high-Ba-Sr granitoids; Yuan et al., 2002;Ye et al., 2008). ...
The Alamas granitoid pluton in the eastern part of the Western Kunlun Orogen, the
northwestern margin of the Tibetan Plateau, is composed of quartz diorite. Zircon separates
from the pluton has SIMS U–Pb age of ~446 Ma. Rocks from the pluton have a narrow range
of SiO2 (56.84–62.57 wt.%), MgO (1.76–2.94 wt.%), and total alkalis (Na2O + K2O =
5.14–9.59 wt.%), and are metaluminous and high-K calc-alkaline to shoshonitic in composition.
They are enriched in light rare earth elements (LREEs), with (La/Yb)N = 14–25, and show
weakly negative Eu anomalies. These rocks are relatively enriched in Sr (472–676 ppm) and Ba
(435–2388 ppm), and depleted in Nb, Ta, Th, and Ti. Their εNd(t) values range from –6.4 to –8.4,
and (87Sr/86Sr)i = 0.7184–0.7200. Zircons from the pluton show εHf(t) values of –1.4 to –8.8, and
δ18O = 6.4‰–9.0‰. Geochemical data indicate that the granitoids were likely derived from the
reworking of an ancient, deep crustal source, influenced by a minor mantle-derived
component. Magmatic differentiation was dominated by the fractional crystallization of
hornblende, biotite, and accessory minerals such as apatite, allanite, and Fe–Ti oxides. In
summary, the Late Ordovician Alamas pluton is an I-type granitoid that was emplaced in a
post-collisional environment, suggesting that this tectonic stage had already initiated prior to
~445 Ma.
... Here was continental growth during the Phanerozoic. This was a most exciting realisation and it became clear that the topic was worth pursuing in more detail (Şengör and Okuroğulları, 1991). However, it was also clear that to do so, we needed help from from Russians to be able to obtain, read and interpret the local literature. ...
... However, it was also clear that to do so, we needed help from from Russians to be able to obtain, read and interpret the local literature. Figure 22-The growth of the Kazakhstan continent (Şengör and Okuroğulları, 1991). ...
This paper is a somewhat enlarged version of my farewell lecture delivered on 23rd March 2022 at the Faculty of Mines of the Istanbul Technical University (ITU). It reviews some of the important developments in geology during the 40 years I was a faculty member at the ITU and the contribution of the ITU geologists to some of these developments. As stipulated in the syllabus, the first hour-and-a half of this lesson we devoted to a discussion of normal faults. As this is my last lesson as a faculty member at the ITU because of the compulsory retirement imposed by law on every professor at age 67 in Türkiye, I gladly respond to a general request that I review in the remaining hour-and-a-half the development of geology in the world during the 40 years I spent at the ITU and ITU's contribution to some of these developments.
... The Malkansu Mn metallogenic zone is tectonically situated in the NKT, at the junction of the western margin of the Tarim basin and the WKOB ( Figure 1B) [40,63]. Although the timing for the formation of the Late Devonian to Early Permian sedimentary sequence in the NKT remains controversial [47,52,[67][68][69], a recent study suggested that these shallow marine carbonate and clastic rocks represent a late Paleozoic to early Mesozoic backarc basin sequence and were deposited in response to the northward subduction of the Paleo-Tethys Ocean [63]. Moreover, geochemical studies of the Carboniferous volcanic rocks have indicated that the NKT was a back-arc extensional environment during the early Carboniferous [70,71]. ...
... The Malkansu Mn metallogenic zone is tectonically situated in the NKT, at the junction of the western margin of the Tarim basin and the WKOB ( Figure 1B) [40,63]. Although the timing for the formation of the Late Devonian to Early Permian sedimentary sequence in the NKT remains controversial [47,52,[67][68][69], a recent study suggested that these shallow marine carbonate and clastic rocks represent a late Paleozoic to early Mesozoic back-arc basin sequence and were deposited in response to the northward subduction of the Paleo-Tethys Ocean [63]. Moreover, geochemical studies of the Carboniferous volcanic rocks have indicated that the NKT was a back-arc extensional environment during the early Carboniferous [70,71]. ...
The specific source of ancient sedimentary manganese (Mn) deposits is commonly complex. Here we use systematic major and trace element data with strontium (Sr) and neodymium (Nd) isotopic analyses of the Ortokarnash Mn(II) carbonate ores and associated carbonate rocks from the Upper Carboniferous Kalaatehe Formation (ca. 320 Ma) in order to constrain the Mn source. This formation consists of three members: the first member is a volcanic breccia limestone, the second member is a sandy limestone, and the third member is a black marlstone with the Mn(II) carbonate interlayers. Petrographic observations in combination with low Al2O3 (<3.0 wt%) and Hf (<0.40 ppm) contents and the lack of correlations between the Al2O3 and ⁸⁷Sr/⁸⁶Sr ratios as well as εNd(t) values demonstrate a negligible influence of terrigenous detrital contamination on both Sr and Nd isotopic compositions of the Mn(II) carbonate ores. The Sr isotopes of Mn(II) carbonate ores are most likely affected by post-depositional alteration, while Nd isotopes remain unaltered. The initial ⁸⁷Sr/⁸⁶Sr ratios in the associated carbonate rocks are likely the result of a mixture of the chemical components (i.e., seawater) and the Al-rich components (e.g., volcanoclastic material), while the detrital effects on Nd isotopes are negligible. In addition, both Sr and Nd isotopes in these non-mineralized wall rocks remained unchanged during post-depositional processes. The relatively low Th/Sc ratios and positive εNd(t) values suggest that the aluminosilicate fraction in the calcarenite and sandy limestone was mainly derived from the weathering of a depleted mafic source, representing the riverine input into the seawater. Given that the Mn(II) carbonate ores are characterized by negative εNd(t) values, these suggest that seafloor-vented hydrothermal fluids derived from interaction with the underlying old continental crust mainly contribute to the source of the Mn(II) carbonates.
... The orogenic architecture of the Altaids is dominated by the evolution of giant subduction-accretion prisms. This style is different from that of the collisional belts familiar from the Alps and the imalaya, and it has been termed Turkic-type (see Ş engör and Okurogullar , 1991Ş engör and Natal'in, 1996a, 1996b. A similar style is known from the Pan-African superorogenic complex (the Saharides), which assembled Gondwana-Land roughly between the Tonian (1000 to 720 Ma) (Windley, 1992, Ş engör and Natal'in, 1996b, Ş engör et al., 2020and 2021 and the Ordovician, and from the North American Cordillera, which has evolved from the Triassic to the present day (e.g., ickinson, 200 ). ...
... In the ilian Shan and aidam regions of China there is at least a triple repetition due to left-lateral strike-slip faulting of an early Palaeozoic through Triassic accretionary complex and magmatic arc, both of which are the easterly continuation of the south-facing (present geographic orientation) uen-Lun accretionary complex and magmatic arc (Ş engör and Okurogullar , 1991). In the Beishan region of China, early Palaeozoic rocks similar to present-day subduction-accretion complexes are separated by high-grade metamorphic rocks. ...
The Altaids is the largest orogenic belt in Central Asia occupying some ~9 million km². It is a Turkic-type orogeny assembled between ~750 and ~ 150 Ma around the western and southern margins of the Siberian Craton. All available data published so far, geological, geophysical, and geochemical—mostly high-resolution UPb ages—document the growth of only three arc systems in Central and Northwest Asia during this time period, an interval throughout which there were no major arc or continental collisions in the area. While the Altaids were being constructed as a Turkic-type orogen, continental crust grew in them by 1/3 of the global average. The Altaids thus added some 3 million km² to the continental crust over a period of 0.6 billion years, typical of Phanerozoic crustal growth rates. The methods of reconstruction employed in elucidating the history of the Altaids are shown to be useful also in late Precambrian orogens built by ordinary plate tectonic processes, but contain no index fossils to erect a biostratigraphy. They also show that without a detailed knowledge of the strain histories of orogenic belts soldering different continental entities, no reconstruction can be even approximatley correct.
... The method we pursued in trying to elucidate the structure and evolution of the Pan-African areas of the Sahara, the northern parts of the Sahel and Arabia is essentially the same as that we had employed earlier in studying the Altaids of Asia (Şengör and Okuroğulları 1991;Şengör et al. 1993, 2014a2018;Şengör and Natal'in 1996a, b;Lom et al. 2018), but slightly modified to adapt to the lack of index fossils and the great paucity of outcrop in the Sahara. It was clear from the outset that the entire area just mentioned formed a single orogenic system, because of the similarity of the tectonic style and temporal evolution, near uniformity of the age intervals marking the origin and deformation of its constituent rocks, and both the observed (mainly in the east in Arabia, Egypt, Ethiopia and Sudan) and the inferred (in the Sahara) onstrike continuity of its structures. ...
... We thus next look for those also to establish the facing of the arc which is in turn checked using the sharpness of the 'magmatic front' (Fig. 8). In magmatic axes, the fronts are sharp, whereas the backs are usually more diffuse (Spiegelman and McKenzie 1987;Şengör and Okuroğulları 1991;Şengör et al. 1993; Fig. 4. Notice that the Tonian magmatic fronts advance in units III to V, whereas they do not move much in units I and II. This is expected as the units III to V have the largest subduction-accretion complexes. ...
A major new Neoproterozoic orogenic system belonging to the larger Pan-African deformational realm, the Saharides, is described in North Africa, which formed from about 900 to 500 Ma ago. The Saharides, a Turkic-type orogenic complex similar to the Altaids of central and northwestern Asia, involved major subduction-accretion complexes occupying almost the entire Arabian Shield and much of Egypt and the small inliers of such complexes farther west to, and including, the Ahaggar mountains. These complexes are formed at least by half from juvenile material representing at least 5 million km2 new continental crust formed during the Neoproterozoic. The Saharides involved no continental collisions until the very end of their history, but evolved by subduction and strike-slip stacking of arc material mainly by pre-collisional coast-wise transport of arc fragments shaved off the Congo/Tanzania cratonic nucleus in a manner very similar to the development of the Nipponides in east Asia, parts of the North American Cordillera and the Altaids. The entire Sahara is shown to be underlain by a double orocline much like the Hercynian double orocline in western Europe and northwestern Africa and not by an hypothetical ‘Saharan Metacraton’. The method here followed may be a fruitful procedure to untangle the structure of some of the Precambrian orogenic belts before life evolved sufficiently to make biostratigraphy feasible.
... The West Kunlun Orogen, located along the northwest Tibetan plateau, extending from the Pamir syntaxis in the west to the Altyn-Tagh and East Kunlun Orogen in the east, is overthrust towards northeast onto the Tarim Basin along the piedmont fault, and separated from the Qiangtang Terrane to the southwest by the Karakorum fault (Fig. 1). Although the orogen is thought to be a collage of continuously southward accreted flysch and plutonic complex (Sengör and Okurogullari, 1991), most geologists argue that it was formed by collision of continental blocks (Pan, 1990(Pan, , 1996Deng, 1995;Ding et al., 1996;Matte et al., 1996;Searle, 1996;Mattern and Schneider, 2000;Zhang et al., 2003bZhang et al., , 2019aWang, 2004;Xiao et al., 2005;Liu et al., 2019). Traditionally, the orogen is subdivided into the Northern, Southern West Kunlun Belt and Tianshuihai Terrane (Bureau of Geology and Mineral Resources of Xinjiang Uygur Autonomous Region (BGMRX), 1993; Pan et al., 1996a;Zhang et al., 2003bZhang et al., , 2019aXiao et al., 2005;Liu et al., 2019), or into the North and South Kunlun Terranes, the Karakorum Terrane, and the Qiangtang Terrane (Yin and Bian, 1995;Ding et al., 1996;Matte et al., 1996;Searle, 1996;Mattern and Schneider, 2000;Wang, 2004). ...
... The subductionrelated quartz diorite and monzonite gave rise ages of 481-452 Ma, and the collisional granodiorite and monzogranite with ages of 442-437 Ma . Combined with regional geology, the Devonain red molasses (Pan, 1990;Sengör and Okurogullari, 1991;Matte et al., 1996;Zhang et al., 2018c) could suggest that the back-arc basin was closed at the Devonian. ...
The Central China Orogenic Belt (CCOB) comprises, from the east to the west, the Tongbai-Dabie, Qinling, Qilian and Kunlun Orogens, and preserves abundant and important amalgamation records of the North China, South China, Qaidam, Tarim and Qiangtang Blocks. The CCOB offers an excellent window to the tectonic evolution from Proto-Tethys to Paleo-Tethys domains and the formation of East Asian continent. In this Centennial Review of Gondwana Research, we assemble comprehensive and multidisciplinary information of geological, geochemical, geophysical and high-precision geochronological dataset from individual orogens of the CCOB, together with a synthesis of Paleomagnetic data, to gain insights on the tectonic framework and evolutionary history of CCOB. The detailed and highly-integrated analysis leads to the following major conclusions. (1) Prior to ca. 550 Ma, break-up of the Rodinia supercontinent led to the formation of Proto-Tethys Ocean, wherein the above crustal blocks were isolated discrete units. (2) During ca. 541–485 Ma, spreading of all the embranchments of the Proto-Tethys Ocean at the early stage and the onset of subduction at the late stage. (3) Up to ca. 485–444 Ma, continued subduction of the Proto-Tethys Oceans resulted in opening and closing of the back-arc basin in the Qinling area. (4) During ca. 444–420 Ma, the Proto-Tethys Oceans along the Qilian and Shangdan were closing. (5) During ca. 420–300 Ma, the Paleo-Tethys Ocean in the Kunlun area inherited the Proto-Tethys Ocean, while the Paleo-Tethyan Mianlue Ocean experienced spreading. (6) At ca. 300–250 Ma, subduction retreat of the Kunlun Ocean occurred from the Aqikekulehu-Kunzhong suture to the Muztagh-Buqingshan-Anemaqen suture. (7) The Paleo-Tethys Ocean underwent eastward diachronous closing processes throughout the Kunlun to Qinling and Dabie areas during ca. 250–200 Ma; (8) The entire CCOB range has evolved into intracontinental deformation since 200 Ma.
... While these isolated attempts of pre-1960s mobilist tectonic approaches to Paleozoic mountain belts are rather well documented by historians of science and geologists (e.g. Frankel, 2012a;Şengör and Okuroğullari, 1991), there seems to be only limited awareness of any pre-1960s tectonicians who applied mobilist models to problems of Precambrian geology. ...
... Hence, one might argue that they were not as enthusiastic as their colleagues working on Phanerozoic tectonics (as e.g. Schmidt, 1976;Şengör, 1976Şengör, , White et al., 1970Şengör and Okuroğullari, 1991), to identify and discuss pre-plate tectonics mobilist forerunners. A third and last, but not the least reason for this neglect might have been the difficult accessibility of some very remarkable pre-1960s geologic syntheses on Precambrian continental displacement, as they were mostly written in French and published in sometimes obscure journals and monographs. ...
This doctoral dissertation is essentially a study in regional Precambrian (Proterozoic) to early Paleozoic geology of the Anti-Atlas area in southern Morocco and, to a lesser degree, the Moroccan Meseta in central Morocco. It is based on 13 weeks of fieldwork, a thorough study of all the relevant literature (including also older and rarely read monographs and papers, an outgrowth of which is the historic chapter 2), and substantial laboratory work (mostly geochronology), with a focus being laid on the sedimentary record of the Anti-Atlas.
The paleogeographic and paleotectonic evolution of the present-day Anti-Atlas and Moroccan Meseta areas is treated within chapters 3 and 4. The sedimentary record of the former area starts with the Paleoproterozoic Taghdhout Group which is only preserved at a few localities and represents the remnants of an older cover of the West African Craton. Based on U/Pb zircon dates from likely volcanogenic rocks (metatuffites), the age of this shallow-marine carbonate platform, dominated by oolite and oncoid grainstones, can be bracketed between ca. 2038 and 1975 Ma. The Taghdout Group later experienced slight tectonic deformation and has been invaded by numerous mafic sills and dykes during the late Paleo- and early Mesoproterozoic. Much later, during the Neoproterozoic, the Taghdout Group became mostly eroded and the development of a passive margin is recorded by the overlying Bleida-Tachdamt Group, with an ocean basin developing to the present-day North of the Anti-Atlas. Although the rifting phase of this margin is not preserved, detrital zircon dates from the well-preserved thermal subsidence phase, indicate that the margin came into being not earlier than the latest Tonian (after 925 Ma), and more probably only during the Cryogenian. Ophiolite obduction (giving rise to a metamorphic sole complex, the Skouraz complex), and accretion of an intra-oceanic arc complex followed collapse of the former passive margin and can be bracketed between ca. 690 Ma and 655 Ma (late Cryogenian). Ongoing lithospheric convergence led to the establishment of a second subduction zone, this time dipping beneath the West African Craton’s northern rim, resulting in a continental magmatic arc superimposed onto the collapsed former passive margin and the obducted/accreted ophiolite/intra-oceanic arc complex. Overstepping Ediacaran terrestrial sedimentary and volcanic successions (the Ouarzazate Supergroup) indicate that the West African Craton and the continental block of the Moroccan Meseta had approached completely by ca. 580 Ma and that hence the complete intervening oceanic basin had been subducted by that time.
Aspects of the paleoclimatic and paleobiologic history of the present-day Anti-Atlas area are dealt with in chapters 5 and 6. Widely distributed Ediacaran terrestrial to deep marine clastic deposits (post-dating ophiolite oduction and arc accretion, but post-dating onset of continental arc magmatism) contain firm evidence for glacial and peri-glacial conditions during the early Ediacaran. Comparative sedimentological studies allow the identification of both terrestrial and marine glacial and glacially influenced deposits, which are best accounted for by invoking a fjord-like landscape with mountain glaciers entering the sea and releasing part of their sedimentary load through ice-bergs. Using high-precision U/Pb zircon geochronology, this glaciation phase can be bracketed between ca. 592 and 579 Ma and could hence correspond to the Gaskiers glaciation reported in Newfoundland. Using recently published paleomagnetic data from the Anti-Atlas, it can be demonstrated that the West African Craton has been partially glaciated, with glaciers calving into the sea, while being located in moderate latitudes.
The paleobiological record (excluding ubiquitous evidence for cyanobacterial life in the form of stromatolites and oncoids) of the Anti-Atlas area starts with a previously almost unknown Ediacara-type fauna of circular impressions and bodily preserved concretions. U/Pb zircon dates and published chemostratigraphic data allow this fauna to be assigned a latest Ediacaran age (between ca. 560 and 542 Ma). We furthermore report the first evidence for higher organized life within the (?latest Ediacaran to early Cambrian) Adoudou Formation, a shallow-marine carbonate system covering the Ouarzazate Group. Based on cross-sectional views, we propose these microscopic fossils to represent the traces of early Cambrian primitive molluscs.
... While these isolated attempts of pre-1960s mobilist tectonic approaches to Paleozoic mountain belts are rather well documented by historians of science and geologists (e.g. Frankel, 2012a;S ßengör & Okurogullari, 1991), there seems to be only limited awareness of any pre-1960s tectonicians who applied mobilist models to problems of Precambrian geology. ...
... Hence, one might argue that they were not as enthusiastic as their colleagues working on Phanerozoic tectonics (as e.g. Schmidt, 1976;S ßengör, 1976;White et al., 1970;S ßengör & Okurogullari, 1991), to identify and discuss pre-plate tectonics mobilist forerunners. A third and last, but not the least reason for this neglect might have been the difficult accessibility of some very remarkable pre-1960s geologic syntheses on Precambrian continental displacement, as they were mostly written in French and published in sometimes obscure journals and monographs. ...
Plate tectonics revolutionized the Earth Sciences during the 1960s and led to a fundamentally new view of tectonic processes inside mountain belts. Application of the new theory to pre-Permian and especially Precambrian orogenic belts developed somewhat reluctantly during the 1970s and 1980s. The present article presents and discusses the ideas of Boris Choubert (1906-1983), a French colonial geologist of Russian origin, which he first developed in 1935. He tried to test Wegener’s theory of continental displacement (a forerunner of plate tectonics) by applying it to Paleozoic and Precambrian orogenic belts around the Atlantic (a topic altogether neglected by Wegener). To achieve this, he produced a fit of the continents across the Atlantic which is almost identical to the famous 1965 fit of Bullard et al. Starting from this Paleozoic continental configuration, he presented an inter-continental synthesis of Precambrian geology and discussed problems from a wide array of topics, ranging from regional tectonics of the West African Craton, questionable Precambrian fossils, tillites (and cap carbonates) to the supposed origin of detrital diamonds in Gabon and Brazil. He also provided probably the first Precambrian plate reconstruction avant la lettre. After his 1935 paper, Choubert worked for decades in Africa and South America and had opportunity to test and refine his synthesis. His example is a call, addressed to present-day geologists working on Precambrian geology in Africa and other regions, to consult the old colonial literature which contains a wealth of factual information and theoretical inspiration which is still of interest today.
... Apart from the cratonic regions, Archaean and Palaeoproterozoic rocks are present as separated inliers in the Sahara Desert. The first step in our approach to the Saharides was to identify the first order tectonic environments) to establish their essential units and to reconstruct the primary orogenic architecture (Şengör and Okuroğulları, 1991;Lom et al. 2018). These are the basic elements of an orogenic setting such as the magmatic arc, the fore-arc and back-arc basins, the fore-arc accretionary complex, the fore-and hinterland fold-and-thrust belts, and molasse basins. ...
Reassessment of the Neoproterozoic evolution of the North Africa and the Arabian Peninsula revealed the presence of a single orogenic belt, the Saharides, starting from the West African Craton in the west to the eastern margin of Arabian Shield in the east. This orogenic event created a large subduction-accretion complex during the Tonian-Cambrian interval as a consequence of convergence between the West African and the Congo cratons. The Saharides are represented by Precambrian inliers such as Ahaggar (or Hoggar) Mountains in Algeria, the Tibesti Massif in Chad, Jebel Uweinat in the intersection of Egypt-Libya-Sudan, the Arabian Shield in the Arabian Peninsula, the Nubian Shield in Egypt, Sudan, Eritrea, Ethiopia, Kenya, and various massifs in Nigeria. Although the evolution of the region embracing the Saharides has been explained by multiple subduction zones and collisions of cratonic pieces involving reactivation of a ‘metacraton’, our analysis showed no continental collisions were involved until the very end of its history. The entire Sahara is shown to be underlain by a double orocline much like the Hercynian double orocline in western Europe and northwestern Africa.
... رسوبات اقیانوسی، پوسته یک فرورانش طی و شده تراشیده فرورانده اقیانوسی ورقه روی از زیرین سنگهای و حاشیه می انباشته هم روی شکل ای گوه توده یک بصورت شناخته فعال حاشیه افزایشی رسوبات عنوان تحت رسوبات این شوند. می جا فرونرفته ورقه روی بر اغلب و شده گیرند (Karig and Sharman, 1975;Cloos, 1984;Sengor and Okurogullari, 1991;Tarbuck and Lutgens, 1994) . چنین تحمل را پایین درجه دگرگونی اغلب تکتونیکی واحد اجزاء سایر کنار در و کرده رنگین آمیزه می یافت تصادمی زون در شو د (Zheng et al., 2005) . ...
The provenance studies and metamorphic conditions of the Gysian colored mélange low-grade active continental margin schists - south of Urmia
... Granitoids, compared with other igneous rocks, are more widespread in orogens and commonly better studied in geochronology and geochemistry. Thus, data of granitoids can provide much information about orogenic processes and continental assembly (e.g., Ş engör and Okurogullari, 1991;, 2018; for instance, age peaks of global granitoids are consistent with events of supercontinental assembly (e.g., Condie et al., 2009;Rogers and Santosh, 2003;Scotese, 2004;Condie and Aster, 2010). ...
The Asian continent consists of many continental blocks that assembled during the Phanerozoic, accompanied by widespread granitoids. By compiling a series of digital maps of igneous rocks with associated zircon U-Pb ages and petrological datasets, we illustrate the spatial-temporal evolution of the granitoids, which shed new light on the assembling process of the Asian continent.
Neoproterozoic granitoids in the Central China Orogenic System evolved from deformed S-type (1100–900 Ma) to weakly or undeformed I-, and A-type granites (850–700 Ma), displaying a transition from syncollisional to postcollisional environment along the northern margin of the South China Craton (or Block), corresponding to the assembly and breakup of Rodinia, respectively. Phanerozoic igneous rocks mainly occur in the Central Asian Orogenic Belt (CAOB) and the Tethyan orogenic system, and record the closure processes of ocean systems, i.e., the Paleo-Asian Ocean (PAO), the Mongol-Okhotsk Ocean, and the Tethyan Ocean, as well as marginal processes along the west Paleo-Pacific Ocean (PPO). The assembly of the Asian continent can be summarized into five major stages. (1) Initial formation of the Siberian-Mongol collage in the PAO domain and the East Asian continental assemblage in the Proto-Tethyan domain, which is evidenced by voluminous 550–500 Ma magmatic belts in the northern CAOB and 520–400 Ma belts in the Central China Orogenic System, respectively. (2) Formation of the North Asian continent through the amalgamation of the above two collages following the closure of the PAO (310–250 Ma). The closure occurred in a double scissor-like manner, as indicated by a westward younging trend of granitoids along the western segment (western Tianshan) of the southern CAOB and an eastward younging trend of granitoids along the central and eastern segment (the Solonker-Xilamulun suture zone) of the southern CAOB. (3) Formation of the East Asian continent by 230–210 Ma through the collision of continental blocks/terranes with the North Asian continent. The processes are recorded by several large (> 1500 km-long) Triassic magmatic belts that evolved from subduction (250–230 Ma) to collision (230–220 Ma). (4) Formation of the main Asian continent through the collision between the East Asian and Siberia-Europe continents, following the closure of the Mongol-Okhotsk Ocean by 150 Ma. This closure also occurred in a scissor-like fashion, as evidenced by an eastward younging trend of 230–150 Ma collision-related granitoids along the Mongol-Okhotsk Suture. (5) Final formation of the Asian continent by the terminal suturing of the Meso- and Neo-Tethys and the final collision between the Indian-Arabian continent and Eurasia, marked by a large 130–120 Ma magmatic belt and a 70–4 Ma leucogranite belt in the southern Tethyan Orogenic System. Continental assembly in north Asia (the PAO domain) was associated with oblique collision and terrene rotation, characterized by curved magmatic belts/oroclines and involved a large volume (ca. > 50%) of juvenile crust; whereas continental assembly in south Asia (the Tethyan domain) was characterized by direct collision, characterized by straight linear magmatic belts and involved a smaller (< 5 %) volume of juvenile crust.
... It is proposed that event was the breakoff of the Iapetus slab at ~428 Ma, prior to termination of the Baltica-Laurentia collision (e.g., Atherton & Ghani 2002;Neilson et al. 2009;Conliffe et al. 2010;. This style of continental collision more widely termed the "Turkic-type orogen" (Şengör & Okuroğullari 1991) is of potential relevance to Scotland, because the switch from subduction and continental arc magmatism to slab breakoff and rapid uplift is widely associated with critical metal mineralisation (e.g., Richards 2009Richards , 2015. ...
Scottish “Newer” Granites record the evolution of the Caledonides resulting from Iapetus subduction and slab breakoff during the Silurian-Devonian Scandian Orogeny, but relationships between geodynamics, petrogenesis and emplacement are incomplete. Laser ablation U-Pb results from magmatic zircons at the Cluanie Pluton (Northern Highlands) identify clusters of concordant Silurian data points. A cluster with a weighted mean ²⁰⁶ Pb/ ²³⁸ U age of 431.6 ± 1.3 Ma (2 confidence interval, n = 6) records emplacement whilst older points (clustered at 441.8 ± 2.3 Ma, n = 9) record deep crustal hot zone magmatism prior to ascent. The Cluanie Pluton, and its neighbour the ∼428 Ma Clunes tonalite, have adakite-like high Na, Sr/Y, La/Yb and low Mg, Ni and Cr characteristics, and lack mafic facies common in other “Newer Granites”. These geochemical signatures indicate the tapping of batches of homogenised, evolved magma from the deeper crust. The emplacement age of the Cluanie Pluton confirms volumetrically modest subduction-related magmatism occurred beneath the Northern Highlands before slab breakoff, probably as a result of crustal thickening during the ∼450 Ma Grampian 2 event. Extensive new in-situ geochemical-geochronological studies for this terrane may further substantiate the deep crustal hot zone model and the association between Caledonian magmatism and potentially metallogenesis. The term “Newer Granites” is outdated as it ignores the demonstrated relationships between magmatism, Scandian orogenesis and slab breakoff. Hence, “Caledonian intrusions” would be a more appropriate generic term to cover those bodies related to either Iapetus subduction or to slab breakoff.
Supplementary material: https://doi.org/10.6084/m9.figshare.c.6305927
... These two tectonic settings control the final orogenic architecture through geological processes both at depth and at the surface, including for example: the inversion of a passive margin, the emplacement of tectonic nappes, strike-slip faulting, the accretion of volcanic arcs, crustal magmatism, suture zone deformation and regional metamorphism (van der Pluijm and Marshak, 2004). Nevertheless, it remains key to differentiate accretionary orogens (Sengör and Okurogullari, 1991), where there is sequential amalgamation of terranes to a continental margin (e.g., the Cenozoic North American Cordillera or the Paleozoic Altaids Belt in Central Asia), from collisional orogens (Windley, 1992) where subduction leads to ocean-continent convergence (e.g., Andes of South America) and then continent-continent collision (e.g., Himalaya). ...
Orogens develop in convergent settings involving two or more continental and/or oceanic plates. They are traditionally defined as zones of crustal deformation associated with mountain building resulting from either accretion of a terrane and/or an arc, continent-continent collision or rift-inversion. However, this definition does not consider the genetic link between an oceanic domain and an intracontinental rift, even though extension associated with a scissor-shape opening can be demonstrated in many ocean-floored
basins. Consequently, we propose a new concept of orogenic evolution based on the development of extensional margins subsequently subjected to crustal shortening.
Thus orogens that develop as a result of the closure of wide basins, are distinguished from mountain belts developed above subduction zones or that result from continental
collision and inverted intra-continental rifts. Our review of several key orogens identifies similarities and differences in geodynamic processes through geological time including prior to the onset of plate tectonics ca. 2.5 Ga. We propose that mapping based on comparative tectonics is a good way to constrain such an evolution, and that this can start with a global-scale map of past-to-modern orogens aimed at re-exploring mountain building concepts spatially and temporarily. This is the primary objective of IGCP 667 project “World Map of Orogens”.
... These two tectonic settings control the final orogenic architecture through geological processes both at depth and at the surface, including for example: the inversion of a passive margin, the emplacement of tectonic nappes, strike-slip faulting, the accretion of volcanic arcs, crustal magmatism, suture zone deformation and regional metamorphism (van der Pluijm and Marshak, 2004). Nevertheless, it remains key to differentiate accretionary orogens (Sengör and Okurogullari, 1991), where there is sequential amalgamation of terranes to a continental margin (e.g., the Cenozoic North American Cordillera or the Paleozoic Altaids Belt in Central Asia), from collisional orogens (Windley, 1992) where subduction leads to ocean-continent convergence (e.g., Andes of South America) and then continent-continent collision (e.g., Himalaya). ...
Orogens develop in convergent settings involving two or more continental and/or oceanic plates. They are traditionally defined as zones of crustal deformation associated with mountain building resulting from either accretion of a terrane and/or an arc, continent-continent collision or rift-inversion. However, this definition does not consider the genetic link between an oceanic domain and an intracontinental rift, even though extension associated with a scissor-shape opening can be demonstrated in many oceanfloored
basins. Consequently, we propose a new concept of orogenic evolution based on the development of extensional margins subsequently subjected to crustal shortening.
Thus orogens that develop as a result of the closure of wide basins, are distinguished from mountain belts developed above subduction zones or that result from continental
collision and inverted intra-continental rifts. Our review of several key orogens identifies similarities and differences in geodynamic processes through geological time including prior to the onset of plate tectonics ca. 2.5 Ga. We propose that mapping based on comparative tectonics is a good way to constrain such an evolution, and that this can start with a global-scale map of past-to-modern orogens aimed at re-exploring mountain building concepts spatially and temporarily. This is the primary objective of IGCP 667 project “World Map of Orogens”.
... The North China Block is bordered to the north by the Manchurides (Şengör and Natal'in, 1996;Xiao et al., 2003), to the south-southwest by the Qinling-Dabie orogenic belt, to the west by the Qilian part of the Kuen-Lun (Şengör and Okuroğulları, 1991), and to the east by the Su-Lu Belt (Fig. 12), although the Tan-Lu fault (Lu et al., 1983;Dou, 1997, Huang et al., 2015) and the associated Cainozoic Bo-Hai Basin (Allen et al., 1998;Yang and Xu, 2004) have very largely disrupted its older structure since the Mesozoic. Many models have been proposed to explain the tectonic evolution of what has long been called the North China Craton and its relationship with the neighboring Proterozoic and Phanerozoic orogenic belts (Kusky and Li, 2003;Zhai et al., 2010;Zhao and Zhai, 2013;Santosh et al., 2016;Kusky et al., 2016Kusky et al., , 2020. ...
To the memory of Nicholas John (Nick) Archibald (1951−2014), master of cratonic geology.
Cratons, defined by their resistance to deformation, are guardians of crustal and lithospheric material over billion-year time scales. Archean and Proterozoic rocks can be found in many places on earth, but not all of them represent cratonic areas. Some of these old terrains, inappropriately termed “cratons” by some, have been parts of mobile belts and have experienced widespread deformations in response to mantle-plume-generated thermal weakening, uplift and consequent extension and/or various plate boundary deformations well into the Phanerozoic.
It is a common misconception that cratons consist only of metamorphosed crystalline rocks at their surface, as shown by the indiscriminate designation of them by many as “shields.” Our compilation shows that this conviction is not completely true. Some recent models argue that craton formation results from crustal thickening caused by shortening and subsequent removal of the upper crust by erosion. This process would expose a high-grade metamorphic crust at the surface, but greenschist-grade metamorphic rocks and even unmetamorphosed supracrustal sedimentary rocks are widespread on some cratonic surfaces today, showing that craton formation does not require total removal of the upper crust. Instead, the granulitization of the roots of arcs may have been responsible for weighing down the collided and thickened pieces and keeping their top surfaces usually near sea level.
In this study, we review the nature and origin of cratons on four well-studied examples. The Superior Province (the Canadian Shield), the Barberton Mountain (Kaapvaal province, South Africa), and the Yilgarn province (Western Australia) show the diversity of rocks with different origin and metamorphic degree at their surface. These fairly extensive examples are chosen because they are typical. It would have been impractical to review the entire extant cratonic surfaces on earth today. We chose the inappropriately named North China “Craton” to discuss the requirements to be classified as a craton.
... The Malkansu Mn metallogenic zone is situated at the junction of the western margin of the Tarim basin and the West Kunlun orogenic belt, falling in the North Kunlun terrane ( Fig. 1B) (Gao et al., 2018;Zhang, C.-L., et al., 2018a). Although the timing for the formation of the Late Devonian to Early Permian sedimentary sequence in the North Kunlun terrane remains controversial (Sengör and Okurogullari, 1991;Pan, 1996;Matte et al., 1996;Xu et al., 1996;Jia, 1997;Yin and Harrison, 2000), Zhang, C.-L., et al. (2018b) suggest that these shallow marine carbonate and clastic rocks represent a late Paleozoic to early Mesozoic back-arc basin sequence that were deposited in response to the northward subduction of the Paleo-Tethys ocean. Moreover, geochemical studies of the Carboniferous volcanic rocks indicate that the North Kunlun terrane was a back-arc extensional environment during the early Carboniferous (Yun et al., 2015;Ji et al., 2018). ...
The Upper Carboniferous Ortokarnash manganese ore deposit in the West Kunlun orogenic belt of the Xinjiang province in China is hosted in the Kalaatehe Formation. The latter is composed of three members: (1) the 1st Member is a volcanic breccia limestone, (2) the 2nd Member is a sandy limestone, and (3) the 3rd Member is a dark gray to black marlstone containing the manganese carbonate mineralization, which, in turn, is overlain by sandy and micritic limestone. This sequence represents a single transgression-regression cycle, with the manganese deposition occurring during the highstand systems tract. Geochemical features of the rare earth elements (REE+Y) in the Kalaatehe Formation suggest that both the manganese ore and associated rocks were generally deposited under an oxic water column with Post-Archean Australian Shale (PAAS)-normalized REE+Y patterns displaying characteristics of modern seawater (e.g., light REE depletion and negative Ce anomalies). The manganese ore is dominated by fine-grained rhodochrosite (MnCO3), dispersed in Mn-rich silicates (e.g., friedelite and chlorite), and trace quantities of alabandite (MnS) and pyrolusite (MnO2). The replacement of pyrolusite by rhodochrosite suggests that the initial manganese precipitates were Mn(IV)-oxides. Precipitation within an oxic water column is supported by shale-normalized REE+Y patterns from the carbonate ores that are characterized by large positive Ce (>3.0) anomalies, negative Y (~0.7) anomalies, low Y/Ho ratios (~20), and a lack of fractionation between the light and heavy rare earth elements ((Nd/Yb)PAAS ~0.9). The manganese carbonate ores are also 13C-depleted, further suggesting that the Mn(II) carbonates formed as a result of Mn(III/IV)-oxide reduction during burial diagenesis.
... Farther east, they form the main body of western Hindu Kush and the northern Pamirs, where they show a much more varied development, including limestones, in places older crystalline rocks, and pre-late Carboniferous ophiolites (Sborschikov et al. 1974;Stöcklin 1977;Kravchenko 1979;Wolfart and Wittekindt 1980;Bazhenov and Burtman 1982;Natal'in and Ş engör 2005). In the Sino-Cimmerides farther east, there is an even richer development of this association in the Kuen-Lun System (Belyaevsky 1976;Ş engör and Okurog ulları 1991), which culminates in the Songpan-Ganzi System (Ş engör 1984;Ş engör and Natal'in 1996;Burchfiel and Chen 2013). ...
The McKenzie et al. (2019) model concerning the cause of the deep earthquakes in the Hindu Kush region in Asia greatly resembles the hidden subduction model proposed earlier. However, in the case of the Hindu Kush, the age of the disappearance of the Tethyan waters was early Jurassic and the sutures were overlain by early Cretaceous sedimentary cover. The question then becomes how long a “subcutaneous” oceanic lithosphere can survive within a continent. It seems that the “oceanic” basement of the North Caspian Depression has been there since the late Palaeozoic, which is encouraging for the McKenzie et al. model. Whether an already subducted slab can also survive for more than 100 million years attached to its continental continuation remains an unanswered question. In the examples with which we are familiar (eastern Turkey, Apennines, Magrebides, Betic and Rif cordilleras), subducted lithosphere became detached at most 25 million years after collision.
... Third, tomography and receiver function studies revealed a low velocity anomaly in the mantle beneath the Tian Shan, potentially representing present-day mantle upwelling (Roecker et al., 1993;Kosarev et al., 1993;Huang et al., 2006), which suggests a potentially hotter Moho for at least several million years during active upwelling. In contrast, although the proto-southern Asia also involves multiple accreted terranes that began to amalgamate northward since the Early Mesozoic (Sengor and Okurogullari, 1991;Yin and Harrison, 2000), a much lower Moho temperature of ~500-600 °C for the proto-southern Asia has been estimated based on the uplift rate and current elevation of the Tibetan plateau (Rey et al., 2010). From this study, the Tian Shan should have a higher Moho temperature than that of the proto-southern Asia by >100 °C, which could be supported by the evidence mentioned above. ...
... , , [98,99] . ? ...
... Magmatic arcs are the most prominent structure among the major orogenic features and generally formed in the convergent plate boundaries (Lom et al., 2018;Sengor and Okurogullari, 1991). In the northern Dunhuang region, the Sanweishan area is occupied by the widespread Paleozoic granitoid plutons with arc-affinity geochemical signatures (Wang et al., 2016a;Zhang et al., 2009;Zhao et al., 2015cZhao et al., , 2017 and the sporadic andesitic-dacitic-rhyolitic volcaniclastic rocks and dacitic porphyries. ...
The Dunhuang region is located to the south of the Central Asian Orogenic Belt and connecting the Tarim Craton westerly and North China Craton easterly, respectively. It is an important position for understanding the geodynamics and tectonic framework of Central Asia. However, the issue about whether it is a Phanerozoic orogen or a Precambrian block is still controversial. Magmatic arcs are the most prominent and laterally persistent structural elements of orogenic belts and used to reconstruct now-disrupted orogenic belts. This paper concerns the petrogenesis and tectonic setting of andesitic-dacitic-rhyolitic volcaniclastic rocks and dacitic porphyries in the Sanweishan area, northern Dunhuang region. Volcaniclastic rocks overlie the metasedimentary rocks by fault and dacitic porphyries intrude into the metasedimentary rocks. The calc-alkaline signature and relative enrichment of large-ion lithophile elements of volcaniclastic rocks and dacitic porphyries seemingly favor a subduction setting. Zircon U-Pb dating results reveal the deposition at 424–414 Ma for volcaniclastic rocks and emplacement at ca. 364 Ma for dacitic porphyries. The coeval granitoid plutons in the Sanweishan area show arc geochemical signature and are originated from partial melting of the subducted sediments based on the available data. Paleozoic volcanic-subvolcanic rocks and plutons in this area probably represent a magmatic arc developed on the accretionary complex, resembling the arc magmatic rocks formed in the Nankai complex, SW Japanese Island arc. Our results provide constraints on the existence of the Paleozoic magmatic arc in the northern Dunhuang region and suggest the so-called “Dunhuang block” is virtually a Phanerozoic orogen rather than a Precambrian block.
... It is verified that the Paleo-Asian Ocean experienced strong evidence of post-arc expansion and arc-land collision. (a) A tectonic model to show the overlap of magmatic arcs and subduction-accretion wedges as a magmatic front (active arc) migrates oceanward (modified after [15,62]); (b) cross section from Hegenshan to Ongniud. The deep structure is based on the interpretative geophysical section of [39], and the surface structure is based on [15,24,27,51,[63][64][65] The Solon suture zone is from the Solon Mountains ophiolite belt in the west. ...
The Xar Moron suture zone is located on the suture of North China Craton and Siberian Craton, which is one of the research hotspots in the Geoscience. In this paper, the western section of the Xar Moron suture zone is taken as the research object. Based on geological and geodynamic analysis, the tectonic and evolution stages of the study area were divided, the evolution model of the subduction and closure of the Paleo-Asian Ocean in the study area, the collision of plates and plates is established. The results show that Xar Moron fault is a suture, and there are obvious differences between the crustal structures on both sides of the fault, outcrop volcanic rocks are distinguished by high potassium calcium alkaline series and their magmatic source is a mixture of crust source and mantle source. The study area is divided into four tectonic evolution stages, C 2 -P 2 , P 2 -P 3 , P 3 -T 3 and After T 3 stage. It is estimated that in the late Permian to early Triassic, Paleo-Asian Ocean has experienced the post-arc dilation, the arc-continent collision and the pre-arc accretion stage. It established the subduction and closing evolutionary mode of the Paleo-Asian Ocean in the Xar Moron suture zone, which provide a reference for the study of the dynamic mechanism of the formation of the fault zone.
... This view is reinforced by the temporal and spatial characteristics of regional magmatism in the Western Kunlun Terrane: (1) The Kudi Ophiolite (502 Ma, Xiao et al., 2003) in the western WKO may be regarded as direct evidence for the existence of an ancient oceanic basin and proto-subduction zone in the Kunlun Orogen. It is widely accepted that the collision between the NKT and SKT occurred along the Kudi Suture Zone in the Western Kunlun (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Pan, 1996;Li et al., 1999;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Liu et al., , 2011aLiu et al., ,b, 2015Yuan et al., 2002Yuan et al., , 2005. Furthermore, the Qimanyute Ophiolite constitutes the eastern extension of the Kudi Ophiolite, which yields a crystallization age of 526 Ma and was obducted at ±432 Ma (Han et al., 2002). ...
The contemporaneous mafic and intermediate dikes of a continental magmatic arc provide a window into the magma feeding system at depth. Here we integrate data on the elemental and Sr-Nd-Hf isotope geochemistry, petrology, mineralogy, and zircon geochronology of late Permian dikes in the East Kunlun Orogen, northern Tibetan Plateau, discuss the petrogenesis of the dikes, and reconstruct the nature and relationship of different magma reservoirs. The dikes are porphyritic diabases, lamprophyres and diorite porphyries that crystallized between 259 and 255 Ma, coeval with their host granodiorites. Geochemical and Sr-Nd-Hf isotopic data indicate the parental magma of the porphyritic diabases and lamprophyres was derived from enriched lithospheric mantle. This magma underplated the crust and underwent varying degrees of magma recharging, crustal assimilation, and fractional crystallization dominated by olivine, pyroxene, and hornblende. This evolved basaltic magmas ascended through the crust, undergoing further differentiation, and some magma entered mid-crustal reservoirs occupied by felsic crystal mushes, rejuvenating the mushes. The subsequent mixing of mafic and felsic materials formed the precursor magmas of the intermediate dikes. Our new data reveal that the magmas stagnated mainly in reservoirs at two levels, 26–32 and 9–18 km, based on hornblende barometry. The underplating, assimilation, and replenishment of basaltic magmas in the lower crust, and their eventual emplacement and differentiation in a mid-crustal reservoir, controlled the mineralogy and geochemistry of the mafic dikes, while the rejuvenation of crystal mushes, the mixing of mafic and felsic materials, and differentiation account for the compositional features of the diorite porphyries. This study shows that the trans-crustal magma feeding system, which controls the compositions of several dispersed but interconnected magma reservoirs, is the key to understanding the compositional diversity and igneous petrogenesis in continental arcs.
... Such giant orogenic Au and porphyry Cu deposits are yet to be discovered in the Xinjiang CAOB, although many high-quality small to medium sizes Cu-Au deposits have also been discovered, implying substantial exploration potential. The Paleo-Tethyan Orogenic Belt, represented by the Pamir and Kunlun mountains extending across southern Xinjiang, Tajikistan, Afghanistan and Pakistan, was mainly formed by the Devonian to Triassic subduction, accretion and collision between the Tarim block and Tibetan terranes (Sengor and Okurogullari, 1991;Xiao et al., 2002). Unlike the CAOB, no giant orogenic Au or porphyry Cu deposits were discovered in the PTOB, yet important Fe, REE and Pb-Zn ore deposits have been discovered (Yu, 2010). ...
The Xinjiang Uygur Autonomous Region in NW China occupies around 1/6 of the total China land size, and contains components of both the Central Asian Orogenic Belt (CAOB) and Paleo-Tethyan Orogenic Belt (PTOB). The Paleozoic CAOB is situated in the northern and central parts of Xinjiang, whilst the Paleozoic-Mesozoic PTOB is mainly located in the southern part of Xinjiang. These orogenic belts were formed by the multiphase Paleozoic-Mesozoic terrane accretions and collisions enacted by the Paleo-Asian Ocean and Paleo-Tethys closure, a process that has also generated many well-endowed tectono-metallogenic belts. From north to south, these belts include the Chinese Altay, the Junggar, the Chinese Tianshan and the Kunlun, Alytn and Qimantage mountains. Since the late 1990s, especially in the past 10 years, many Au, Cu, Fe and Pb-Zn deposits have been discovered. These ore deposits commonly show clear but complex relationships with the orogenic processes. Detailed studies of these mineral systems and their associated magmatic-metamorphic events and structural deformation would significantly improve our understanding of the metallogenic evolution of the CAOB and PTOB in Xinjiang. The 33 papers presented in this special issue, which represents the first collective work of Xinjiang mineral resources in international journals, are aimed to convey the latest research findings on key Au, Cu, Fe-(Cu), Pb-Zn and other metal deposits in Xinjiang. It is our wish that this special issue could enhance our knowledge on the nature and evolution of the metallogenesis in the Xinjiang orogens, and reinforce the foundation for future mineral research and exploration.
... This view is reinforced by the temporal and spatial characteristics of regional magmatism in the Western Kunlun Terrane: (1) The Kudi Ophiolite (502 Ma, Xiao et al., 2003) in the western WKO may be regarded as direct evidence for the existence of an ancient oceanic basin and proto-subduction zone in the Kunlun Orogen. It is widely accepted that the collision between the NKT and SKT occurred along the Kudi Suture Zone in the Western Kunlun (Chang et al., 1989;Sengör, 1990;Sengör and Okurogullari, 1991;Yao and Hsü, 1994;Hsü et al., 1995;Pan, 1996;Li et al., 1999;Mattern and Schneider, 2000;Jiang et al., 2002Jiang et al., , 2013Liu et al., , 2011aLiu et al., ,b, 2015Yuan et al., 2002Yuan et al., , 2005. Furthermore, the Qimanyute Ophiolite constitutes the eastern extension of the Kudi Ophiolite, which yields a crystallization age of 526 Ma and was obducted at ±432 Ma (Han et al., 2002). ...
The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto‐ and Paleo‐Tethys from early Paleozoic to early Mesozoic. This paper presents new LA‐ICPMS zircon U‐Pb ages and Lu‐Hf isotopes, whole‐rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons (466–455 Ma) and their Silurian mafic dikes (∼436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high‐K calc‐alkaline characteristics, with (⁸⁷Sr/⁸⁶Sr)i value of 0.7129–0.7224, εNd(t) values of –9.3 to –7.0 and zircon εHf(t) values of –17.3 to –0.2, indicating that they were formed by partial melting of ancient lower‐crust (metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto‐Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial ⁸⁷Sr/⁸⁶Sr ratios of 0.7101–0.7152 and εNd(t) values of –3.8 to –3.4 and zircon εHf(t) values of –8.8 to –4.9, indicating that they were derived from enriched mantle in response to post‐collisional slab break‐off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto‐Tethys.
... The common expression of a subduction zone is its magmatic arc. Properly identifi ed and well-dated magmatic rocks, or even their sedimentary derivatives (Dickinson and Suczek, 1979;Dickinson, 1985;Weltje, 2006), can be used as indicators of geodynamic environments, and even as reliable witnesses of geodynamic evolution (Dickinson, 1975;Fyfe and McBirney, 1975;Miyashiro, 1975aMiyashiro, , 1975bGill, 1981;Pearce et al., 1984a;Barbarin, 1999), which means if a magmatic arc can be identifi ed in some way, it is possible to locate the subduction zone, and consequently the former plate boundary (Şengör and Okuroğulları, 1991). There are exceptions to this, where the magmatic arc is absent, as in the Alps and in the western Mediterranean Alpide chains in general; where the maximum width of the subducted ocean was narrow (400-600 km; Şengör, 1991;Chenin et al., 2017) and the lithosphere is poor in volatiles (Ivanov, 1983); or in very low-angle subduction zones (less than 20°), such as the Pampean fl at-slab segment between 27°S and 33°S latitudes in the Andes ( Fig. 2; Barazangi and Isacks, 1976;Dickinson and Snyder, 1978;Jordan et al., 1983). ...
Orogenic belts, the main factories of continental crust and the most efficient agents of continental deformation, are commonly extremely complex structures. Every orogenic belt is unique in detail, but they are generally similar to each other, having mainly been products of subduction and continental collision. Because of that common origin, they all share common functional organs, such as magmatic arcs, various back-arc and retro-arc features, and multifarious fore-arc environments, collisional sutures, etc. The modern orogenic belts usually display adequate detail about these organs, enabling us to identify them even when they are deformed or otherwise dislocated. In reconstructing now-disrupted orogenic belts, we are after one or more Ariadne’s threads to follow the original structure from one package of rock to another. The most prominent, laterally persistent, and easy-to-follow structures among the major orogenic features are the magmatic arcs. As they are the common expression of their subduction zones, they form linear or arcuate lines along the strike, and they usually move episodically inwards or outwards, being located behind sharply defined magmatic fronts. Present-day dating techniques provide high-resolution dates from magmatic rocks, and the migration of the magmatic front is easily detectable. They form the main Ariadne’s thread in orogenic studies. Where they are absent, the most helpful structures possessing lateral persistence are the now-deformed Atlantic-type continental margins and suture zones.
We chose two major fossil orogenic belts, namely, the Tethysides, and the Altaids, to emphasize the methodology of comparative anatomy of orogenic belts. There have been many theories regarding the evolution of these orogenic belts. However, they are either local, only dealing with a small portion of orogen, or they are in conflict with presently active processes. We underline the importance of magmatic fronts as reliable witnesses of the geodynamic evolution of major orogenic collages. This paper aims to disperse the mist upon the reconstructions of complexly deformed orogenic belts with the simplest possible interpretations that help us to form testable hypotheses that can be checked with a variety of geological databases.
... Accretionary orogens are considered as the hall marks of continental growth on the globe (Şengör and Okurogullari, 1991;Rudnick, 1995;Condie and Chomiak, 1996;Baba, 2002;Chen and Jahn, 2004;Jahn et al., 2004;Li et al., 2006a,c;Kröner et al., 2007;Rino et al., 2008;Cawood et al., 2009;Condie et al., 2009). The Central Asian Orogenic Belt (CAOB) is one of the world's largest and complex accretionary orogens built through prolonged subduction-accretion processes from the Neoproterozoic to Permian assembling several continental and oceanic terranes (Jahn et al., 2000;Kovalenko et al., 2004;Windley et al., 2007;Cawood et al., 2009;Han et al., 2011;Wang et al., 2011;Xiao and Santosh, 2014;Xiao et al., 2010Xiao et al., , 2015. ...
... Belts of oceanic fragments, flysch, and melange are widespread in Turkey and comprise more than one third of the exposed geology in central Asia. These belts are commonly interpreted to represent in situ suture zones separating distinct micro-continents or arcs [Hsü et al., 1995;Sengör and Natal'in, 1996] and have been used to highlight the important role of accretionary complexes in the evolution of continental crust [Sengör and Okurogullari, 1991]. The possibility that some of these belts may represent materials that were underthrust beneath, and subsequently exhumed within, continental interiors would have major implications for paleotectonic reconstructions, the age, composition, and structure of the lower continental crust, and magmagenesis subsequent to ocean closure. ...
... The region north of the Solonker suture zone is called the northern orogen, which is considered to reflect the growth of southern Mongolia (Sengör et al., 1993;Sengör & Okurogullari, 1991). The seismic profile passes through the Baolidao, Hegenshan, and Uliastai belts, from south to north (see Figure 1). ...
The northeastern(NE) Tibetan Plateau is an ideal place for the study of plateau uplift and evolution. Its lithosphere records the process of the lithospheric deformation transforming from the Tibet to the stable Alashan and Ordos blocks. Here, using the dense passive-source seismic profile across the NE Tibet and the regional seismic networks of Gansu and Qinghai Provinces, we isolate S receiver functions from the teleseismic S and SKS wave data and resolve the spatial distribution of the lithosphere-asthenosphere boundary(LAB) across the NE Tibetan Plateau. Our observations demonstrate that:1) Beneath the northeastern Songpan-Ganzi terrane and the West Qinling orogenic belt, the LAB lies at 110~130 km which dips at a shallow angle to the northeast, and none lithospheric offset is observed beneath the East Kunlun fault. The smooth LAB may indicate an intact lithosphere between these two blocks; 2) The lithospheric thickness is 135~150 km beneath the Qilian block, and the LAB phases are dispersive beneath the Qilian orogenic belt, in the western part of the Qilian block. The dispersive LAB phases may imply a complex tectonic lithosphere; 3) The LAB of the Alashan block lies at 130~150 km, which seems to converging beneath the Qilian block, but dose not across the Haiyuan fault, yet; 4) The lithospheric thickness of the Ordos block is 160~170 km, which imply a thick and rigid craton lithosphere.
The geologic framework of China is dominated by three major Precambrian continental blocks (North China, South China, and Tarim) and their surrounding orogenic belts. The Phanerozoic tectonics of China are represented by three orogenic systems that formed via amalgamation of these blocks and subduction/accretion along most of their margins. These orogenic systems include the Early Cambrian to early Mesozoic Altaids in the north, the Early Cambrian to Cenozoic Tethysides in the south, and the Mesozoic to present Nipponides in the east.
The Altaids in northern Xinjiang, Beishan, Alxa, Inner Mongolia, and northeastern China comprises a huge orogenic collage of the Central Asian orogenic belt. The Altaids formed by substantial Phanerozoic continental growth by ocean closure and terrane accretion in the Permian-Triassic until its termination by collision with the Tarim and North China blocks in the Permo-Triassic. Southward subduction of the Mongol-Okhotsk oceanic plate beneath the North China block led to widespread magmatism and deformation in the Mesozoic.
The Tethysides that occupy most of the area south of the Tarim and North China blocks acted as a major bulwark against the collision of several continental blocks, including the South China block. The western Tethysides in China is occupied by the Kunlun-Altyn-Qilian and Himalaya-Tibetan orogens that record a long amalgamation history involving the evolution of the Proto-, Paleo-, and Neo-Tethys Oceans. The Tethys Ocean was finally terminated by collision between the Indian continent and the southern margin of the Eurasian continent, giving rise to the bulk of the Tibetan Plateau. The development of the eastern Tethysides in China was dominated by Triassic amalgamation between the South China and North China blocks, which gave rise to the Qinling-Dabie-Sulu orogens, and coeval collisions with microcontinental blocks such as the Indochina block in the southeastern Tibetan Plateau.
The evolution of the Nipponides started in the late Paleozoic to Triassic along the eastern margin of the Chinese mainland as a result of subduction of the Paleo-Pacific Ocean. The development of the Nipponides in the Jurassic led to extension of the Altaids in northeastern China and deformation along complicated compressional and strike-slip structures in the eastern North China block. This was followed by delamination of the lower crust of the eastern half of the North China block in the Early Cretaceous. The latest development of the Nipponides in the past few million years led to formation of marginal seas and back-arc basins off coastal China, and to recent continent-arc collision in Taiwan Island.
The early Paleozoic history of China was dominated by separation of the Tarim, North China, and South China blocks from Gondwanaland and their drift across the Panthalassic Ocean. The Tarim-Alxa-North China-South China backbone that formed in the Permian-Triassic played an important role in the construction of China. According to the temporal-spatial history of the Tarim-Alxa-North China-South China block and its surrounding orogens, we postulate that most of the Paleo-Asian Ocean originally belonged to, or was part of, the Paleo-Pacific (Panthalassic) Ocean. Therefore, only two major oceanic plates were responsible for the construction of the Chinese landmass in the Phanerozoic, i.e., the Pacific (Panthalassic) and the Tethys. The Pacific Ocean encompassed a major long-lived, external ocean, and the Tethys Ocean was an internal ocean within Pangea.
The Cimmerian Continent is the narrow continental strip that rifted from the northeastern Gondwana-Land margin mostly during the Permian between the present-day Balkan regions and Indonesia and collided with the Laurasian margin sometime between the latest Triassic and the late Jurassic, in places possibly even in the earliest Cretaceous. In contrast to the initial definition and most subsequent models, the Cimmerian Continent did not leave Gondwana-Land in one piece, but such submarine platforms as the Sakarya, Menderes-Taurus and Kırşehir in Turkey, and what is herein called the Greater Lhasa from Afghanistan to Myanmar began separating both from Gondwana-Land and from the rest of the Cimmerian Continent at about the same time during the Permian. By contrast, the northern part of the Cimmerian Continent remained as a large, single-piece, island arc-type ribbon continent from Turkey to Malaysia comprising the units of the Rhodope-Pontide Fragment in Turkey, most of Transcaucasia and Iran, the Farah, western Qiangtang, Bao-Shan and the Shan States blocks and western Thailand and Malaysia throughout its independent history. This coherent ‘ribbon continent’, perhaps the largest documented in earth history, was almost wholly an ensialic arc only in places having generated Mariana-type ensimatic offspring. Thus, the northern margin of the Cimmerian Continent was of Pacific-type and not Atlantic-type as claimed by many authors in the literature. Naming its various parts individually helps description but should not be allowed to mislead interpretations in terms of individual, so-called ‘terranes’, as often happens. It seems that many of the oceanic basins that opened within and behind the Cimmerian Continent, including the Neo-Tethys, were back-arc basins and the Cimmerian continent had a serpentine motion as it traversed the Tethyan realm. It is therefore impossible to reconstruct synthetic isochrons to track the northerly migration of the large ribbon continent (except for purposes of simple visualisation of the journey of the Cimmerian Continent across the Tethyan realm). The Cimmerian Continent also had a complex internal tectonics, involving much along the strike-slip faulting, presumed to have been controlled by the age, subduction angle, rate of subduction, and the topography of the floor of the Palaeo-Tethys.
The Central Asian Orogenic Belt (CAOB) was generated through multiple collisional and accretionary events in the Paleo-Asian Ocean, a major global ocean that existed from the late Neoproterozoic into the late Paleozoic. Nevertheless, the question of when the Paleo-Asian Ocean finally closed has notoriously been enigmatic, especially due to the absence of large-scale investigations. The South Tianshan-Solonker Suture, is the largest and southernmost suture within the CAOB, and records the ultimate collision between the Tarim-North China cratons with the Siberia craton, and is commonly interpreted as marking the eventual closure of the Paleo-Asian Ocean. In this paper, we synthesize and evaluate relevant Chinese papers on the area, which are not readily available to an international audience, and extend this across the full length of the suture zone. Based on this review, we can divide the suture zone into four distinct segments, which are, from west to east: the South Tianshan Belt, the Beishan Belt, the Solonker Belt and the Yanji Belt. This enables us to provide a more systematic understanding of the nature and development of the South Tianshan-Solonker suture.
Geochronological data from Paleozoic cover rocks and high-pressure metamorphic rocks show that during the late Carboniferous, the western section of the Paleo-Asian Ocean closed when the Tarim Craton moved northward to collide with the Kazakhstan-Yili Block, thus marking the initial development of the South Tianshan Belt. The Beishan Belt to the east formed when the Dunhuang-Alxa blocks were transported northward to collide with the Tuva-Mongolia Block, with the youngest zircon UPb data from ophiolites indicating that closure of the local Beishan Ocean was in the early-middle Permian, although its final closure may not have been until the early late Permian along the northern margin of the Alxa Block, thus making it slightly younger than the South Tianshan Belt. Further to the east, the available petrographic, geochronological and paleontological data from the Solonker Belt indicate that this belt was formed in the middle-late Permian, during which time bi-directional subduction occurred and the North China and Siberia cratons were amalgamated during an ‘Appalachian-type’ orogeny. Furthermore, we observe that a transition in polarity from northward to bi-directional subduction occurred along the boundary between the Beishan and Solonker belts, which may be related to the East Gobi Transform Fault. In contrast, under the influence of the westward subduction of the Paleo-Pacific Ocean, the Jiamusi-Khanka Block moved southwestward along the Yilan-Yitong Fault in the middle-late Triassic (230–220 Ma) to amalgamate with the North China Craton.
The formation of the South Tianshan-Solonker Suture can be characterized by four distinct west-to-east accretion/collision events that lasted from the late Carboniferous to the late Permian. The South Tianshan Belt, the Beishan Belt and the Solonker Belt therefore demarcate, respectively, the amalgamation between the Tarim Craton and the Kazakhstan-Yili Block, the Dunhuang-Alxa Block and the Tuva-Mongolia Block, and the North China Craton with the Siberia Craton, representing the final closure of the Paleo-Asian Ocean. During the middle-late Triassic, the Yanji Belt in the far east was influenced by the Paleo-Pacific tectonic domain as a result of amalgamation between the Jiamusi-Khanka Block and the North China Craton.
The rising demand of strategic metals, especially lithium, necessitates discovery of new resources to meet the global supply chain. Recently, several pegmatite-hosted rare metal (Li-Rb-Be-Nb-Ta) deposits have been discovered in the Western Kunlun orogenic belt, making it a new world-class rare metal resource (estimated ~7 Mt Li2O and 0.16 Mt BeO). Understanding the metallogenesis of this belt is critical to further evaluate the rare metal potential. In this study, columbite-tantalite (coltan) and monazite from rare metal pegmatites and zircon from potential parental granites were collected from five representative rare metal pegmatite deposits in the western, middle, and eastern parts of the Western Kunlun orogenic belt for U-Pb geochronology. The results indicate that despite the distances of the sampling localities in different parts of the Western Kunlun orogenic belt, the ages of pegmatite-hosted rare metal mineralization fall in a narrow range of ca. 208–204 Ma. These rare metal pegmatites are temporally and spatially related to adjacent postorogenic granites emplaced following the closure of the Paleo-Tethys Ocean. The compositional characteristics of K-feldspar, biotite, and muscovite of the granites and pegmatites, along with regional mineralogical and textural zonation of the pegmatites, suggest that the rare metal pegmatites were derived from the volumetrically much more important, highly fractionated granitic intrusions. We propose that, in combination with the data from previous studies, the 218–204 Ma interval represents a newly recognized rare metal metallogenic period linked with granitic intrusions in the Western Kunlun orogenic belt, revealing a 600-km-long late Triassic rare metal pegmatite belt composed of multiple ore fields formed in a similar metallogenic setting. These results emphasize the importance of identifying fertile, Late Triassic to Early Jurassic granitic intrusions for rare metal pegmatite exploration. Furthermore, combined with recent studies on the Songpan-Ganzi rare metal pegmatite belt along the eastern segment of the Paleo-Tethys, this study further highlights the great potential of rare metal resources in this global tectonic zone.
A suture is a tectonic boundary that separates two plates. It varies in size and appearance in different types of orogenic belts. In this study, based on the definition of suture and suture interface, we present several examples of classic orogenic belts and discuss the deformation of the suture interface and the implications to the analysis of the tectonic framework of the orogenic belt and associated sedimentary basins. The decollement formed in the subduction stage is a high strain bond without physical thickness, and it is kept at the bottom of the accretionary complex when the collision happens. Because this surface strictly separated the basins with provenance connections to the upper and lower plates, it would be much convenient to deal with the provenance study if it is regarded as the suture interface. The ophiolitic belt, high-pressure metamorphic belt, and major fault can indicate the approximate location of a suture. Still, they cannot be regarded as the exact indicator of suture interface. The decollement was almost flat in the subduction stage, but its successor, the suture interface, can be deformed by thrust and strike-slip faults at and after the moment of collision. In classic orogenic belts such as the Alps, the Himalayas, and the Eastern Junggar, the suture interface had experienced long-distance thrust towards the foreland, coupled with folding deformation. It leads to the result that the suture interface exposed as a complicated cross-finger shape on the surface after the weathering and erosion and even expose multiple times due to the appearance of klippen and tectonic windows. The suture interface naturally exhibits Z-shape in the opposite subduction system and develops a more complicated structure after the deformation and collision. In the Sulu-Dabie orogenic belt, multiple-stage deformation, especially the strike-slipe fault that cut the whole orogenic belt and the suture interface into separate blocks, was applied to the original simple suture interface, which significantly modified the outcropped suture interface at the surface. The complex structure of the suture interface must be a serious consideration when it comes to analyzing the framework of the orogenic belt, especially with sedimentary tectonic tools. A wrong suture interface could lead to a wrong tectonic interpretation of the sedimentary basin.
Access the article here: https://authors.elsevier.com/a/1d5Cb_IgSHZ7H
Reconfigurations of magmatic arcs through time have been recognized since pioneering works, describing inland and trenchward arc migrations or magmatic shut-off lasting for several millions of years. These modifications present variable magnitudes and rates of arc migration and magmatic broadening, and different arc quiescence time spans. The time-space behavior of magmatic arcs has been attributed to a diversity of geodynamic processes acting at convergent margins largely associated with modifications in the upper-plate or changes in plate kinematics. Identifying a geodynamic process responsible for a particular spatiotemporal arc history from the geological record is not straightforward. This task is further complicated where more than one process influencing arc position acted in concert. To assess these issues, it is essential to have a deep understanding of how each process influences the space-time arc behavior and modifies the geological context. To date, a joint comparison highlighting similarities and differences in how these phenomena impact arc dynamics and the associated geological framework is still missing from the literature. In this study, we provide a state-of-the-art synthesis of processes controlling arc migration and quiescence. Then, we extract diagnostic elements from the literature to build a synthetic table to aid in the task of discerning a dominant geodynamic process from the geological record. In this task, we considered the first-order characteristics of the space-time arc evolution and diagnostic features of the geological context associated with each geodynamic process. Finally, this synthesis stresses that the combination of both perspectives, understanding the space-time arc pattern and the associated geological framework, provides the best approach to unravel a dominant process controlling arc migration and shut-off.
The world’s largest and economically valuable nephrite deposits are distributed along the Western Kunlun Orogen in northwestern China. During the past 20 years, extensive white and brown nephrite deposits have been discovered in both China and Russia, and several of these deposits have been found in South Altyn Tagh in the eastern part of the Western Kunlun Orogen. However, the timing of formation, genesis, petrographic characteristics, mineralogical composition, and reasons for the white–brown color of the nephrite remain unclear. We
analyzed 50 samples of white, brown, and white–brown nephrite from the Tiantai nephrite deposit in Qiemo County with the aim of understanding the processes of formation, age, and diversity of these nephrites. Three main types of nephrite can be distinguished: white, brown, and dark brown. X-ray diffraction and petrographic studies indicate that the brown and dark-brown nephrite samples have fewer mineral inclusions compared with the white nephrites. The nephrite formed during early retrogression through the sequence of diopside skarn → coarse-grained tremolite skarn and coarse-grained tremolite → fine-grained tremolite. The higher bulk Fe content of the white nephrite (0.76 wt% FeO) relative to the brown nephrite (0.39 wt%), and the uniform, very low Fe2O3 contents of both of these color varieties (<0.15 wt%), suggest that the brown coloration is unrelated to Fe content and oxidation state. The white nephrite is characterized by a wide range of SiO2 contents (49.6–56.7 wt%), in contrast to the brown nephrites, which are characterized by nearly constant SiO2 contents (~58 wt%), close to the ideal content for tremolite. On average, the white nephrite is enriched in Al2O3 (3.22 wt%) and water (3.96 wt% loss on ignition) and depleted in CaO (12.35 wt%) relative to the brown nephrite (0.80 wt% Al2O3, 2.23 wt% loss on ignition, 12.95 wt% CaO). These characteristics, combined with greater transparency and higher Al and water contents in the chlorite formula relative to that of tremolite, as well as a near-absence of Ca in the chlorite formula, can explain the lower transparency and associated more intense coloration (i.e., yellow to brown) of the brown nephrite in terms of the lower modal abundance of chlorite. The spatial distribution of selected elements agrees with this hypothesis, whereby the brown-colored zones are dominated by Ca- and Srrich (substituting Ca) domains reflecting the highest modal volume of the tremolite. In contrast, the white zones are characterized by a substantially higher volumetric ratio of Al-rich domains, reflecting the higher chlorite content. Thus, the different coloration is not caused by specific elements, but by modal proportions of tremolite and chlorite. The slightly higher average Cr (10.1 ppm) and Ni (6.4 ppm) contents of brown nephrite, relative to white nephrite (8.7 ppm Cr and 5.5 ppm Ni), might also contribute to the color intensity and brown coloration. Ore forming fluids involved in the formation of the studied nephrite have isotopic compositions of δ18O = 1.5‰ to 9.4‰ (330–430 ◦C) and δD = –87‰ to –50‰ (330–450 ◦C), suggesting that the formation of the Mg-skarn deposit was related to metasomatism of dolomite by fluids derived from local granite/granodiorite intrusions. Zircons from three brown–white samples yield concordant SHRIMP ages of 438 ± 14 Ma (2σ, MSWD=10.4), 916 ± 10 (2σ, MSWD = 1.5), 438 ± 9 Ma (2σ, MSWD = 5.3), and 431.1 ± 2.5 Ma (2σ, MSWD = 2.4). The younger ages (ca. 430 Ma) are close to those for placer nephrite from the Yurungkash and Karakash rivers, as well as those for Yecheng, Alamas, and Buya granodiorites, and probably represent the primary formation ages of nephrite within the Hetian Nephrite Belt. Overall, these ages indicate that the primary deposits formed during pre- or post-orogenic stages in the Western Kunlun Orogen. 40Ar/39Ar dating of hydrothermal muscovite and phlogopite intergrown with tremolite in the nephrite yielded ages of 418.8 ± 3.4 Ma (2σ, MSWD = 0.65), 379.5 ± 3.0 Ma (2σ, MSWD = 0.81), and 354.5 ± 3.6 Ma (2σ, MSWD = 0.71), which suggest multiple metasomatic activity. The similar formation ages of nephrites from Altyn Tagh (433 Ma) and from the previously studied areas of West Kunlun (441–378 Ma) and East Kunlun (416 Ma) indicate that these nephrites formed during the closure of the Proto-Tethys and in the accompanying post-collisional extensional environment.
The Western Kunlun orogenic belt (WKOB) located south of the Tarim Basin and the north-western margin of the Tibetan Plateau, was previously considered a complex orogenic belt that closed along the Kudi-Qimanyute suture zone (KQSZ) and Mazar–Kangxiwar suture zone (MKSZ) from north to south during Proto- and Paleo-Tethys. The MKSZ between the South Kunlun and Tianshuihai terranes was interpreted as the southern boundary of the WKOB that formed during the subduction of the Paleo-Tethys oceanic crust. However, the evolution of the MKSZ in the Proto-Tethys Ocean remains controversial. We newly recognized seamount formation with pillow basalts and carbonate cap from Dongguashan group on Tianshuihai terrane. The pillow basalts had geochemical features of typical oceanic island basalts (OIBs). Zircon U–Pb dating revealed that this basalt had a crystallization age of 465 ± 6.6 Ma, with a gap of more than 10 Ma between the pillow basalts and fossils in the seamount. This implied that the basalt base reached the carbonate compensation depth. Accordingly, the seamount depositional age was restricted to the Late Ordovician. Detrital zircon showed that part of the clastic unit at the top of the Dongguashan group originated from the South Kunlun and Tianshuihai terranes, suggesting that the analysed sediments probably formed in the remnant of the Proto-Tethys Ocean and were deposited on the top of or accreted into the seamount during oceanic crust subduction. This discovery provides robust evidence of the MKSZ undergoing an evolution with Proto-Tethys. Moreover, our results supported the approach that an accretionary wedge, including the Late Ordovician seamount in the southern MKSZ, should be considered part the WKOB.
The study area is situated in the southeastern segment of the Central Asian Orogenic Belt (CAOB) across the more than 500 km wide accretionary collision zone between the Mongolian Arcs to the north and the North China Craton to the south (Figs. 1.3 and 2.1). Its central position provides an ideal opportunity to ascertain the exact location and timing of the formation of the cryptic Solonker Suture Zone, and evaluate existing suggestions [23].
Continental transform faults commonly do not obey the kinematic rules of plate tectonics, because at their ends lithosphere is rarely created or destroyed. Earthquakes along them reach depths of some 20 km maximum, except in rare shortening segments, where deeper hypocenters have been detected. They are rarely confined to simple faults, but form broad zones of extensive fracturing containing commonly more than one major strike-slip fault, thus forming major keirogens. Transform faults connecting two divergent plate boundaries in oceans (ridge-ridge type) maintain their lengths, whereas in continents they become shorter or longer depending on whether the extensional zones at their ends migrate toward each other or away from each other, respectively. If the extensional zones migrate toward each other, the separating transform fault eventually disappears and begins growing with an opposite sense of motion. In oceans, a transform fault connecting two subduction zones (trench-trench type) facing each other becomes shorter and eventually disappears only to grow in the opposite direction with a reversed sense of motion. An oceanic transform fault connecting two subduction zones with the same facing does not change its length. If, however, a continental transform fault connects two areas of shortening it becomes shorter with time, provided the loci of shortening do not migrate from one another faster than the shortening itself. Continental transform faults leave behind “tail zones.” Such “tail zones” are not similar to oceanic fracture zones, but have fundamentally different tectonic characteristics. Where continental transform faults are involved in triple junctions, they commonly lead to the formation of “continental holes” resulting in the formation of “incompatibility basins.” All such deviations from the behavior of their oceanic cousins, the continental transform faults owe to the low shear resistance of the continental crust and the floatability of the continental lithosphere.
The Central Asian Orogenic Belt (CAOB) was formed during the termination of the Paleo-Asian Ocean in the Paleozoic. However, the mechanism and process of the Paleo-Asian Ocean closure and CAOB formation remain controversial. This study presents a seismic image from the northern North China Craton to southern Mongolia derived from P and S receiver function analyses of the teleseismic records from a dense array. Our observations reveal a thicker lithosphere in the southern CAOB than in the Bohai Bay basin, which suggests that this Paleozoic orogen was less affected by the lithosphere reactivation in the eastern North China Craton during the Late Mesozoic. The imaged lithosphere-asthenosphere boundary of the southern CAOB deepens southward and reaches a greatest depth of approximately 130 km beneath the Xilinhot fault, the northern boundary of the Solonker suture zone. The Moho displays a local uplift of approximately 5 km beneath the Linxi fault, the southern boundary of the Solonker suture zone. These features imply that the Solonker suture zone is the most plausible site of the lithosphere collision between the opposing continental margins. Additionally, a southward dipping intracrustal interface, whose depth extends from ~16 km beneath the Baolidao belt to ~20 km beneath the Linxi fault, is interpreted to be associated with the subduction of the Paleo-Asian Oceanic slab. Additionally, the absence of lithosphere-asthenosphere boundary phases beneath the Bainaimiao arc is inferred to be caused by the upwelling of hot mantle material after assembly of the CAOB.
The largest mountain belt in Central Asia (∼9 million km2) is called the
Altaids. It was assembled between ∼750 and ∼130 Ma ago around the western
and southern margins of the Siberian Craton, partly on an older collisional
system (the “Urbaykalides”). Geological, geophysical, and geochemical
data—mostly high-resolution U-Pb ages—document the growth of only
three arc systems in Central and Northwest Asia during this time period, an
interval throughout which there were no major arc or continental collisions
in the area. While the Altaids were being constructed as a Turkic-type orogen,
continental crust grew in them by 1/3 of the global total. The Altaids
thus added some 3 million km2 to the continental crust over a period of
0.6 billion years, typical of Phanerozoic crustal growth rates.
The largest mountain belt in Central Asia (∼9 million km2) is called the Altaids. It was assembled between ∼750 and ∼130 Ma ago around the western and southern margins of the Siberian Craton, partly on an older collisional system (the “Urbaykalides”). Geological, geophysical, and geochemical data—mostly high-resolution U-Pb ages—document the growth of only three arc systems in Central and Northwest Asia during this time period, an interval throughout which there were no major arc or continental collisions in the area. While the Altaids were being constructed as a Turkic-type orogen, continental crust grew in them by 1/3 of the global total. The Altaids thus added some 3 million km2 to the continental crust over a period of 0.6 billion years, typical of Phanerozoic crustal growth rates.
The Xinjiang Uygur Autonomous Region in NW China occupies around 1/6 of the total China land size, and contains components of both the Central Asian Orogenic Belt (CAOB) and Paleo-Tethyan Orogenic Belt (PTOB). The Paleozoic CAOB is situated in the northern and central parts of Xinjiang, whilst the Paleozoic-Mesozoic PTOB is mainly located in the southern part of Xinjiang. These orogenic belts were formed by the multiphase Paleozoic-Mesozoic terrane accretions and collisions enacted by the Paleo-Asian Ocean and Paleo-Tethys closure, a process that has also generated many well-endowed tectono-metallogenic belts. From north to south, these belts include the Chinese Altay, the Junggar, the Chinese Tianshan and the Kunlun, Alytn and Qimantage mountains. Since the late 1990s, especially in the past 10 years, many Au, Cu, Fe and Pb-Zn deposits have been discovered. These ore deposits commonly show clear but complex relationships with the orogenic processes. Detailed studies of these mineral systems and their associated magmatic-metamorphic events and structural deformation would significantly improve our understanding of the metallogenic evolution of the CAOB and PTOB in Xinjiang. The 33 papers presented in this special issue, which represents the first collective work of Xinjiang mineral resources in international journals, are aimed to convey the latest research findings on key Au, Cu, Fe-(Cu), Pb-Zn and other metal deposits in Xinjiang. It is our wish that this special issue could enhance our knowledge on the nature and evolution of the metallogenesis in the Xinjiang orogens, and reinforce the foundation for future mineral research and exploration.
Oblique plate convergence is common, but it is not clear how the obliquity is achieved by continental fold-and-thrust belts. We address this problem in the Qilian Shan, northeastern Tibetan Plateau, using fieldwork observations, geomorphic analysis and elastic dislocation modeling of published geodetic data. A thrust dips SSW from the northern range front, and underlies steeper thrusts in the interior. Cenozoic thrust-related shortening across the Qilian Shan is ~155-175 km, based on two transects. Elastic dislocation modeling indicates that horizontal strain in the interseismic period is consistent with oblique slip on a single low angle detachment thrust below ~26 km depth, dipping SSW at ~17o. We suggest this detachment is located above North China Block crust, originally underthrust during Paleozoic orogeny. Horizontal shear strain is localized directly above the up-dip limit of creep on the detachment, and is coincident with the left-lateral Haiyuan Fault. This configuration implies oblique slip on the detachment below seismogenic depths is partitioned in the shallow crust onto separate strike-slip and thrust faults. This is consistent with strain partitioning in oceanic subduction zones, but has not previously been found by dislocation models of continental interiors. The marginal, strike-slip, Altyn Tagh Fault influences thrusting within the Qilian Shan for 100-200 km from the fault, but does not control the regional structure, where Paleozoic basement faults have been reactivated. The Qilian Shan resembles the main Tibetan Plateau in nascent form: active thrusts are marginal to an interior that is developing plateau characteristics, involving low relief, and low seismicity.
In the Alps, relicts of pre-Variscan basement are composed of metagreywackes and metapelites (partly migmatic) with intercalated amphibolites and sheets of Cambro–Ordovician peraluminous metagranitoids. Such gneiss terranes are the result of an orogenic type, which was globally widespread in early Paleozoic times. It caused the formation of several 100 km wide cratonized subduction–accretion complexes (SACs) hosting peraluminous arcs at the periphery of Gondwana. “Cenerian orogeny” is a newly suggested term for these early Paleozoic events, which culminate in the Ordovician. The justification for a separate name is given by three characteristics, which are significantly different compared to the Cadomian, Caledonian and Variscan orogenies: the age, the paleogeographic position and the tectonic setting. Other parts of the southern and central European crust might also have been generated by the cratonization of peri-Gondwanan SACs during the Cenerian orogeny.
The small intrusions consist of oligoclase granites are closely related with W-Sn mineralization in Baiganhu-Jialesai mineralization belt. The results of LA-ICP-MS U-Pb isotope dating show that oligoclase granite containing tungsten and tin ores was formed in 429. 5±3. 3 Ma. The ∈Hf (t) values of oligoclase granite vary from -11. 05 to 7. 40 with average of -1. 26, and the peak value of T2DM vary from 944 Ma to 2 111 Ma with average of 1 492 Ma. Because of crystal fractionation and fluid activity during the latest stage of magma evolution, geochemical data of oligoclase granite are characterized with rich Rb, Cs, Nb and Sn, depleted Ba, Zr, Hf, Th, Sr, Ti, V and La. The granites in Baiganhu-Jialesai mineralization belt were derived from the melting of ancient felsic crust because of mantle underplating during the extension environment, and oligoclase granite was formed in the latest stage of magma evolution. There are two oreforming stages in Baiganhu W-Sn deposit. In the first stage, during the intruding process of magmas containing tungsten and tin into wall rocks in early Silurian period, the batholith consist of monzonite granite was formed in deep, and small intrusions consist of oligoclase granites were formed in shallow. Then, the skarn-type and greisen-type tungsten ore bodies were formed in the top and contact belt of the small intrusions. In the second stage, after the fluid of latest magma evolution leaching metals from wall rocks, such as W and Sn, the quartz-veined tungsten ore bodies were formed along the fissures.
ResearchGate has not been able to resolve any references for this publication.