The zircon upb dating displayed two ages of magmatism, 14. The yakuno ophiolite in southwest japan is considered to have been obducted by the collision between an intraoceanic islandarcbackarc basin intraoiabab system and the east asian continent during the late paleozoic. Modern studies of crustal evolution require significant knowledge, not only of the potential source regions for granites, but also of the transport paths and emplacement mechanisms operating during granite genesis. Upb accessory mineral isotopic data nuplasma table dr2. Typical examples of anatexis would be the generation of granitic melts partially melted aluminous crustal rocks, basalts partially melted mantle peridotite, and migmatitic rock. Crustal anatexis and formation of two types of granitic magmas in the kontum massif, central vietnam. Ultrametamorphism and crustal anatexis request pdf. On the basis of their petrological and geochemical characteristics, these different plutonic suites are interpreted to involve crustal anatexis and the intrusion of mantlederived magmas. In contrast, for values offs such that fscrit fs, momentum transport is. Although the source is likely to vary from region to region hedenquist and lowenstern, 1994, conventional wisdom views metals as indigenous to the region of magma generation e. Temperaturedependent thermal diffusivity of the earths crust and implications for magmatism. Feb 16, 2007 granitic plutonism is the principal agent of crustal differentiation, but linking granite emplacement to crust formation requires knowledge of the magmatic evolution, which is notoriously difficult to reconstruct from bulk rock compositions.
Rate and geometry of subduction and composition and age of subducted sediments. Introduction magmatism in zones of plate convergence displays various petrologic and geochemical characteristics that are interpreted to reflect the source of the magma e. Thus, characterization of the geochemical and isotopic nature of anatectic melts in highgrade metamorphic terrains would help to better understand the sources of such heterogeneity and their potential magnitude. The first two episodes of crustal anatexis occurred during the late triassic at c. The role of crustal anatexis at various crustal levels in generating geochemical and isotopic heterogeneities is poorly understood. These papers concluded that anatexis of lower to midcrustal regions is likely characterized by. Read crustal anatexis and formation of two types of granitic magmas in the kontum massif, central vietnam. Anatexis definition of anatexis by the free dictionary. Hightemperature crustal anatexis in a clockwise ptt. Use features like bookmarks, note taking and highlighting while reading hightemperature metamorphism and crustal anatexis the mineralogical society series book 2. Regional crustal thickness and precipitation in young.
The concentration of phosphorus in anatectic melt is controlled by the growth and breakdown of. Hightemperature metamorphism and crustal anatexis j. Introduction crustal melting is a fundamental process both for chemical differentiation and for facilitating ductile deformation of the earths continental crust. Along the andes, the highest mountains and thickest crust. Read the role of fluids in crustal processes at nap. Anatexis definition is any process by which plutonic rocks are dissolved and again converted into magmas. Neodymium, strontium, and traceelement evidence of crustal anatexis and magma mixing in the idaho batholith, the nature and origin of cordilleran magmatism, j. Temperaturedependent thermal diffusivity of the earths. Fertility of crustal rocks during anatexis volume 87 issue 12 alan bruce thompson skip to main content we use cookies to distinguish you from other users and to provide you with a better experience on our websites. We unlocked the plutonic archive through hafnium hf and oxygen o isotope analysis of zoned zircon crystals from the classic hornblendebearing itype. Crustal thickness is related to climate through precipitationinduced erosion.
Paleogene crustal anatexis and metamorphism in lhasa terrane. Dec, 2018 partial melting of continental crust and evolution of granitic magmas are inseparably linked to the availability of h 2 o. The highgrade metamorphic belt of the eastern ghats, india, displays polyphase deformation structures, a complex metamorphic record and dehydration melting in different crustal protoliths. The role of fluids in crustal processes addresses this lack of attention with a survey of what experts know about the role of fluids in the earths crust and what future research can reveal. Jan 01, 2012 read paleogene crustal anatexis and metamorphism in lhasa terrane, eastern himalayan syntaxis. It consists of mafic metamorphic rocks and felsic to mafic later intrusions. Statistical geochemistry reveals disruption in secular. Severe aridity, hence low erosion rates, helps to account for the. Evolution of the melt source during protracted crustal. Pdf hightemperature crustal anatexis in a clockwise pt. Tectonophysics, 43 1977 411 41 eisevier scientific publishing company, amsterdam printed in the netherlands crustal anatexis. Anatexis via latin from greek roots meaning to melt down refers to the partial melting of rocks. The role of enthalpy power is tested by varying the enthalpy or temperature along the base of the crustal block while maintaining a fixed temperature at the top.
Several microstructural lines of evidence show that melt extraction was assisted by deformation during foliation development, and that on the scale of the xenoliths up to 50 cm melt escaped mainly by flow along foliation planes. Evidence from upb zircon ages and hf isotopic compositions of the nyingchi complex, gondwana research on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Implications for the growth and differentiation of continental crust. Implications for magma processes in collision zones author links open overlay panel m. Pdf melt inclusions and crustal anatexis at ultrahigh.
The role of fluids in crustal processes the national. Eoceneoligocene granitoids in southern tibet constraints. In continental collision belts, regional highgrade metamorphism accompanied by crustal anatexis has long been of interest to petrologists e. The goal of this paper is to present new petrological and geochemical data from the livradois. Implications for anatexis in the deep to very deep continental crust and active continental margins, journal of petrology 37, 661691. Crustal anatexis, accompanied by melt extraction and ascent of magma to upper crustal levels, constitutes the most important mechanism of geochemical differentiation of the continental crust e. Fifteen andesitedacite stratovolcanoes on the volcanic front of a single segment of the andean arc show alongarc changes in isotopic and elemental ratios that demonstrate large crustal contributions to magma genesis. Melting of crustal rocks during continental collision and.
An h2osaturated granitoid just above the solidus at a will quickly intersect the. Wyllie department of the geophysical sciences, university of chicago, chicago, illinois 60637 u. Implications for the growth and differentiation of continental crust federica raia and frank j. Oct 19, 2004 crustal thickness is related to climate through precipitationinduced erosion. Pdf on nov 30, 2018, omar gianola and others published melt inclusions and crustal anatexis at ultrahigh temperature conditions find, read and cite all the research you need on researchgate. Dr20104 the contribution of crustal anatexis to the tectonic evolution of indian crust beneath southern tibet b300852 king et al. In this book we suggest an alternative model for the origin of granite in terms of insitu meltingintracrustal convection that physically determines the process from partial melting of midupper crustal. The calculated paths envelope small regions or pt space, thus identifying which mineral reactions are important for crustal anatexis and at which pt conditions future experiments should be made. Request pdf on jan 5, 2016, bhattacharya s and others published high temperature crustal anatexis find, read and cite all the research you need on researchgate. The distribution of h 2 o between cordierite and granitic melt. Them is overwhelming and incontrovertible petrological and geophysical evidence for. Cordierite as a sensor of fluid conditions in high. Shallow crustal metamorphism during late cretaceous anatexis in the sevier hinterland plateau. The rheological and chemical behaviour of the lower crust during anatexis has been a major focus of geological investigations for many years.
Hightemperature melting in pelitic and greywackelike precursors in a clockwise p t path, decompression and subsequent isobaric cooling have recently been described from the southcentral. A late paleozoic crustal section of an intraoceanic island arc occurs in the middle unit munit of the asago body from the yakuno ophiolite, sw japan. The role of fluids in crustal processes addresses this lack of attention with a survey of what experts know about the role of fluids in the earths crustand what future research can reveal. Granite, magma, anatexis, mixing, high kmg magma, mantle, hercynian, french massif central 1. Traditionally, anatexis is used specifically to discuss the partial melting of crustal rocks, while the generic term partial melting refers to the partial melting of all rocks, in both the crust and mantle. A 1d numerical model of anatexis in volcanic rifts, taking into account lithospheric extension, emplacement of mafic magma at crustal levels, various crustal compositions and prerift conditions, has been developed and applied to the rapakivi granites in southern finland and silicic magmatism in the oslo graben, southeast norway. Early paleozoic crustal anatexis in the intraplate wuyi. Ma is a syenogranite equivalent compositionally to topaz rhyolites. Pdf crustal anatexis and evolution of granitoid magma in. The difficulty of identifying the presence of water during crustal melting.
In a dynamically evolving crust during uplift, thermal buffering by. View enhanced pdf access article on wiley online library html view. The relative contributions of crustal anatexis and. Westerly winds warm passing over the atacama desert.
Download free pdf water and other fluids play a vital role in the processes that shape the earths crust, possibly even influencing earthquakes and volcanism. Spera department of geological sciences and institute for crustal studies, university of california, santa barbara abstract. Fertility of crustal rocks during anatexis cambridge core. It is believed that anatexis is the process largely responsible for the formation of migmatites. Severe aridity, hence low erosion rates, helps to account for. H 2 oundersaturated liquids can exist with quartzfeldspar assemblages through hundreds of degrees with little change in. Constraints on crustal anatexis and tectonic evolution of the himalayan orogen zengqian houn, yuanchuan zheng, lingsen zeng, lie gao, kexian huang, wei li, qiuyun li, qiang fu, wei liang, qingzhong sun institute of geology, chinese academy of geological sciences, beijing 37, pr china. Migmatites record multiple episodes of crustal anatexis. Winter 2001 pressuretemperature phase diagram showing solidus curves for h2osaturated and dry granite. Episodic crustal anatexis and the formation of paiku composite leucogranitic pluton in the malashan gneiss dome, southern tibet. Request pdf on jan 1, 2008, bernard bonin and others published ultrametamorphism and crustal anatexis find, read and cite all the research you need on researchgate. Crustal anatexis and melt extraction during deformation in. Hightemperature metamorphism and crustal anatexis the mineralogical society series book 2 kindle edition by ashworth, j. Crustal anatexis and its relation to the exhumation of.
Fluids affect the movement of chemicals and heat in the crust, and they are the major factor in the formation of hydrothermal ore deposits. H 2 o incorporation in cordierite and its application to highgrade metamorphism and crustal anatexis s. The other two episodes of anatexis occurred during the jurassic period at c. The overview discusses factors that affect fluid movement and the coupled equations that represent energy and mass transport processes, chemical reactions. Magmatic and crustal differentiation history of granitic. Crustal anatexis and formation of two types of granitic. Long1, emmanuel soignard2 1school of the environment, washington state university, pullman, washington 99164, usa. Hence knowledge of the mechanisms and kinetics of anatexis, as well as of the processes of magma segregation, accumulation and transfer, is essential. Syntectonic anatexis and magmatism in a midcrustal. Upb accessory mineral isotopic data axiom table dr3.
Here we present a study of geochemistry, zircon upb chronology and hf isotopes on the yamarong leucogranites from tsona area, eastern himalaya, to explore the petrogenesis of the rocks, and to further expain related problems of continental crustal anatexis. In the absence of a free aqueous fluid, melting takes place at relatively high temperatures by dehydration of hydrous minerals, whereas in its presence, melting temperatures are lowered, and melting need not involve hydrous minerals. Read syntectonic anatexis and magmatism in a mid crustal transpressional shear zone. Crustal melting, also named anatexis, can occur at various depths if suitable values of thermodynamic parameters are reached. Generation of metalrich felsic magmas during crustal anatexis.
Implications for magma processes in collision zones, gondwana research on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Hightemperature crustal anatexis in a clockwise ptt path. Anatexis can occur in a variety of different settings, from zones of continental collision to midocean ridges. This perception shift was perhaps led by three seminal papers published in the mid1980s clemens and vielzeuf, 1987. Furthermore, scientists have recently discovered that partial melting plays an increasingly important role in active crustal processes. Issn print 0026461x full text not available from this archive. In the case of granitoids from the panafrican damara mobile belt namibia, many of the leucogranites and. May 23, 2012 statistical sampling of a large geochemical database reveals a pervasive discontinuity about 2. Current ideas of granite formation involve lower crustal melting, segregation, ascent as dykes or diapirs and emplacement in the upper crust. Therefore, it is of 52 fundamental importance for our understanding of crustal anatexis to have a thorough knowledge of the phase relationships in the rock series gabbro tonalitranodioriteranitehgo.
Anatexis, in geology, the differential, or partial, melting of rocks. New sims shrimp zircon upb determinations for amphibolite and metagabbro of bab origin within the yakuno ophiolite yield ages of 293. In addition to the melting temperature of each individual mineral, pressure, temperature. Crustal differentiation is mainly achieved through partial melting and segregation of felsic melt from more mafic residue brown and rushmer, 2006, hawkesworth and kemp, 2006, kemp et al. Major and trace element models of recently published vapourabsent mica dehydration melting experiments are used to identify granitoids generated by muscovite and biotite dehydration melting, and to distinguish between plagioclaselimited and biotitelimited, biotite dehydration melting. Introduction extreme values of pressure and temperature can be reached by continental and oceanic crustal formations in certain circumstances because of either deep burial, or anomalous heat flow, or both. Ii ultrametamorphism and crustal anatexis bernard bonin encyclopedia of life support systems eolss the uhpm space is composed of the other eclogite subfacies, namely.
Experimental approaches experimental approaches to the problem of anatexis of the deepseated crustal rocks include the following. Each mineral in a rock has its own melting temperature, which is decreased to varying degrees by its close association with other minerals. Ii ultrametamorphism and crustal anatexis bernard bonin encyclopedia of life support systems eolss 1. Melting of vapourabsent tonalite at 10 kbar to simulate. Deep crustal anatexis, magma mixing, and the generation of. Shallowcrustal metamorphism during late cretaceous. The relevant viscosity is the viscosity of the magmatic suspension which is a function. It is, we hope, timely to summarize recent petrological advances contributing to this field of active interest. This second volume in the new series produced by the mineralogical society is concerned with the study of rocks from the deep continental crust. Introduction magmatism in zones of plate convergence displays various petrological and geochemical characteristics that reflect the source of the magma e. Peak temperature conditions from the grant range, eastern nevada, u. Eocene magmatism from the liemai intrusion in the eastern. Geochemistry of phosphorus and the behavior of apatite.
During both prograde and retrograde metamorphism, limited influx of free hydrous fluids may result in small volumes of very hydrous melts, which cannot ascend far if at all before reaching their. The paleocene leucogranites found in the eastern syntaxis show evidence of regional crustal anatexis and associated coeval granulitefacies metamorphism guo et al. Pdf crustal evolution of a paleozoic intraoceanic island. Distribution of h2o between cordierite and granitic melt. Crustal contributions to arc magmatism in the andes of.
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