Petrology of rodingite derived from eclogite in western Tianshan, China |
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| Authors: | X-P LI L ZHANG C WEI Y AI J CHEN |
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| Institution: | The Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871, China (); College of Geoinformation Science &Engineering, Shandong University of Science and Technology, Qingdao 266510, China |
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| Abstract: | This study reports a new rodingite type which was derived from eclogite enclosed in the ultramafic rocks of Changawuzi ophiolites, western Tianshan, China. Based on petrographical investigations, rodingite, partial rodingitized rock and completely rodingitized rock are characterized in this paper. These rocks show a continuous variation in their bulk compositions, mineralogy and their textural properties from eclogite to rodingite. The completely rodingitized rocks can be further divided into prehnite rodingites, hydrogrossular‐diopside rodingite and vesuvianite rodingites on the basis of the mineral assemblage and textural character. The chemical potential path of μ(SiO2)–μ(CaO/MgO) can be used to constrain the evolution of two stages of rodingitization. The first rodingitization possibly started under conditions of 410–430 °C and 7–9 kbar at upper greenschist facies, and resulted from a secondary serpentinization during exhumation of the subducted slab. A second and pervasive rodingitization took place under conditions of 250–350 °C and 2–10 kbar from greenschist to subgreenschist facies. The P–T path presented shows a retrograde evolution from eclogite to rodingite. We conclude that the process of rodingitization may also take place under subduction zone conditions in addition to its more common occurrence under ocean‐floor metamorphic conditions. |
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| Keywords: | rodingite eclogite subduction zone western Tianshan China |
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