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1.
1 Introduction Voluminous literature has resulted from study of the geology and tectonic evironments of post-orogenic granitoids in eastern Tianshan (He et al., 1995; Han et al., 1997; Gu et al., 1999, 2001; Li et al., 2003; Chen et al., 2004). Previous contributions (Hu et al., 1997; Li et al., 2003) indicate that major events of continental collision in northern Xinjiang occurred around 300 Ma. Then, the tectonics converted from compression to extension, resulting in the uplifting of th…  相似文献   

2.
The study of the physicochemical behaviour of colloids and particles in nature has emerged as a scientific problem of critical importance because of the widespread acknowledgement of their significance in controlling the speciation and fate of essential nutrients and contaminants in the aquatic and soil environments (Ledin et al., 1995; Lead et al., 1999, Doucet et al., 200 l; McCarthy et al., 1989; Koterba et al., 1993; Kretzschmar et al., 1999). Se'quaris and Lewandowski (2003) developed a method based on sedimentation and centrifugation steps to fractionate agricultural top soils after suspension in water. However, progress in the field has been limited by the lack of appropriate techniques for the isolation and characterization of colloids and particles in their native form (Lead et al., 1997). The primary difficulties in separation and analysis are colloidal instability and their small size and low concentration. As a result, reliable, unbiased and minimally perturbing methods for sampling and fractionation are primary requirements for the study of colloids and particles if valuable information is to be obtained. In recent years, cross-flow ultra-filtration (CFUF) has become one of the most commonly used techniques for collecting and separating freshwater and marine colloids and particles (Petrus evski et al., 1995; Gustafsson et al., 1999; Benoit et al., 1999; Sigg et al., 2000; Gue'guen et al., 2002; Benedetti et al., 2003). CFUF has hitherto been used for studies of the biogeochemical cycling of a variety of elements, such as carbon (Benner et al., 1992; Santschi et al., 1998), radionuclides (Moran et al., 1992), trace metals (Reitmeyer et al., 1996) and nutrients (Bauer et al., 1996). The purpose of this study was to develop a protocol to fractionate particles in soil, to measure particle size distributions and to quantify chemical characteristics within different particle size fractions.  相似文献   

3.
1. IntroductionThe discovery of the ophiolites (composed of mafic-ultramafics plutons, radiolarian silicalites and the basic metavolcanic rocks) in Mianlue zone was one of the most important progresses in the study on Qingling orogen in recent years (Zhang G W et al., 1995, 1996; Zhang Z Q et al., 1996; Yin et al., 1998; Lai, 1997; Lai et al., 1996; Meng et al., 1999). Many geologists got the conclusions as followings. (1) along the Mianlue zone, the oceanic crust developed in late Paleoz…  相似文献   

4.
Throughout the Phanerozoic the eastern margin of Gondwana and related fragments such as New Caledonia and New Zealand that are now dispersed from it grew through the addition of ophiolites and associated intra-oceanic island arc assemblages.Exactly how and why this occurred remains controversial with two main competingmodelsreferredtoaseither‘quantum’or‘accordion’tectonics.The quantum model envisages continental growth through the additional of discrete intra-oceanic assemblages analogous to contemporary tectonic settings in Taiwan,Timor and Papua New Guinea(Aitchison and Buckman,2012).The alternative regards eastern Australia as the type example of a different style of convergent plate margin referred to as an‘extensional accretionary orogeny’(Collins,2002).The oldest Phanerozoic ophiolites and intra-oceanic island arc assemblages are of Cambrian age and are widely reported from the Lachlan Fold Belt in the eastern Australian states of Victoria and NSW(Spaggiari et al.,2003;Greenfield et al.,2011).Similar rocks are also known from Mount Read in Tasmania(Berry and Crawford,1988;Crawford and Berry,1992;Mulder et al.,2016),the Weraerai terrane and its correlatives in the New England orogen further east in northeastern NSW(Aitchison et al.,1994;Aitchison and Ireland,1995)and Queensland,the Takaka terrane in NW Nelson,New Zealand(Münker and Cooper,1999)and the Bowers terrane in Northern Victoria Land,Antarctica(Weaver et al.,1984;Münker and Crawford,2000;Rocchi et al.,2011;Palmeri et al.,2012).The Late Ordovician saw the development of the intra-oceanic Macquarie island arc(Glen et al.,1998;Glen et al.,2007).This system contains important economic mineral deposits.The way in which these arcrocks developed and were juxtaposedagainst a surrounding suite of Lachlan Fold Belt,eastern Australia remains the subject of investigation(see Aitchison and Buckman,2012 for discussion).In a similar area,enigmatic rocks of the Tumut ophiolite also crop out(Graham et al.,1996;Belousova et al.,2015).Further to the east in the New England orogeny Siluro-Devonian rocks of the Gamilaroi terrane and it’s along strike correlatives near Mt Morgan in Queensland represent another intra-oceanic island arc assemblage emplaced onto the Gondwana margin in the Late Devonian(Aitchison and Flood,1994;Offler and Murray,2011).The Late Carboniferous-Permian saw development of significant intra-oceanic island arc and ophiolitic complexes remnants of which crop out in New Zealand,eastern Australia,and New Caledonia.These include the Brook Street terrane(Spandler et al.,2005;Mc Coy-West et al.,2014)and Dun Mountain Ophiolite Belt in New Zealand(Coombs et al.,1976;Stewart et al.,2016),the Gympie terrane in southeast Queensland(Waterhouse and Sivell,1987;Sivell and Waterhouse,1988)and the Koh terrane in New Caledonia(Meffre et al.,1996;Ali and Aitchison,2002).The youngest on-land association of ophiolitic and intra-oceanic island arc rocks in the region is of Eocene age.Ultramafic rocks are well exposed in New Caledonia where they structurally overlie continental rocks of Gondwana margin affinity that,in the northeast of the island,have experienced eclogite facies metamorphism(Aitchison et al.,1995).The emplacement of these rocks was a widespread regional event with potentially correlative rocks exposed in Papua New Guinea(Parrot and Dugas,1980)as well as Northland and East Cape in New Zealand(Whattam et al.,2005;Whattam et al.,2008).  相似文献   

5.
<正>The podiform chromitites in the Luobusa ophiolite,Southern Tibet,have received much attention because of the presence of ultrahigh-pressure minerals,such as microdiamonds(Bai et al.,1993;Yang et al.,2007;Xu et al.,2009),coesite(Yang et al.,2007)and highly reduced metal phases(Bai et al.,2000;Robinson et al.,2004).The  相似文献   

6.
The Hongliuguo-Lapeiquan mélange (Fig. 1) is seen in the Altyn fault belt (AFB), which is a large-scale sinistral strike-slip fault belt in the central Asia and also a part of the north natural boundary of the Qinghai-Tibetan plateau, separating the Tarim basin from the Qaidam basin (Zheng Jiandong, 1988; Avouac et al., 1993; Chalaron et al., 1995; Ge Xiaohong et al., 1998; Cui Junwen et al., 1996, 1997, 1999; Wang Yan et al., 1999). This mélange extends eastward from Hongliuguo thro…  相似文献   

7.
1. Introduction In recent years, growing attention has been focused on diapirs because of their significance to hydrocarbon accumulation in basins (Barber & Brown, 1988; Martin Hovland et al., 1989; Law et al., 1989; Collier et al., 1990; Lewis et al., 1994; Carmelo Monaco et al., 1996; Hieke et al., 1996; Hieke et al., 1996; Lewis et al., 1996; Limonov et al., 1996; Gallardo & Blackwell, 1999). With more and more effort devoted to the studies of the northern continental marginal basins …  相似文献   

8.
1 Introduction The tectono-thermal evolution of the North China Craton (NCC) in Late Archean to Paleoproterozoic times has long been attractive to many researchers (Wan et al., 2000; Zhao et al., 2000, 2002; Guo et al., 2001; Liu et al., 2002; Zhai and Liu 2003; Zhai, 2004; Yu et al., 2004; Kr?ner et al., 2005; Wilde et al., 2005). Zhao et al. (2000, 2002) proposed a tectono-thermo framework for the evolution of the NCCbased on detailed petrological and geochronological data, and they …  相似文献   

9.
1. IntroductionThe discovery of delicately persevered multicellular algae and possible animal embryos from the terminal Proterozoic Doushantuo Formation has greatly changed our views on the origin and early evolution of metaphyte and metazoan (Chen et al., 1991, 1992; Zhang et al., 1992, 1998; Li et al., 1997; Xiao et al., 1998), and encourages us to look for the evidences of advanced lives in older rocks. Some jellyfish fossils were reported in the Piyuancun Formation (equated with Dengyi…  相似文献   

10.
<正>A series of Ni-Cu sulfide deposits hosted in Early Permian mafic-ultramafic complexes occur along the~500km long linear Huangshan-Jingerquan belt in the East Tianshan at the southern margin of the Central Asian Orogenic Belt(Fig.1)(Zhou et al.,2004;Song and Li,2009;Song et al.,2011;Qin et al.,2011;Deng et al.,2014).Questions for genetic link between these deposits and the  相似文献   

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