Halaqin volcano-sedimentary succession in the central-northern margin of the North China Craton:Products of Late Paleoproterozoic ridge subduction
作者单位：Department of GeologyUniversity ofLeicesterLeicester LE17RHUK
会议名称：《中国科学院地质与地球物理研究所第11届（2011年度）学术年会》
会议日期：2012年
学科分类：070904[理学-构造地质学] 0709[理学-地质学] 07[理学]
基 金：supported by projects no.40730315 and 41072146
关 键 词：North China Craton Late Paleoproterozoic Halaqin volcano-sedimentary succession Ridge subduction Ultra-high temperature metamoiphism
摘 要：The Halaqin volcano-sedimentary succession(HVSS) is tectonically situated on top of the largely Late Archean to Early Paleoproterozoic Yinshan terrane in the central-northern margin of the North China Craton. It comprises greenschist- to amphibolite-facies schists,quartzites,marbles and amphibolites,which were originally pelites,pebbly sandstones,sandstones,limestones and volcanic *** presence of tight to isoclinal folds and thrusts of the HVSS indicates tectonic transport from southeast to northwest (present coordinates).U-Pb ages of detrital zircon grains in the clastic rocks suggest provenance from both the Fengzhen belt in the south and the Yinshan terrane in the *** U-Pb ages of the HVSS volcanic rocks,e.g.,1909±10 Ma,1894±6 Ma,1887±6 Ma,and 1884±8 Ma indicate volcanism in the period～1910-1880 *** zircon age study of the neighbouring Majiadian Group reveals significant～2700 Ma crust growth and～2500 Ma metamorphism events in the Yinshan *** HVSS volcanic rocks have a trimodal geochemical distribution demonstrated by SiO-contents of 45-50 wt.%(basalts), 53-60 wt.%(andesites),and 70-76 wt.%(dacites-rhyolites).The basalts and andesites are tholeiitic in chemistry,and show distinct depletion in high-field strength elements(HFSE,e.g.,Nb,Zr,Ti),compared to neighbouring elements in ***,low-Mg basalts and andesites(MgO 5 wt.%) have more or less flat REE patterns(La/Yb = 0.45-1.76) and LILE.εNd(t= 1890 Ma) values of the basalts and andesites vary from -4.8 to +*** rhyolites and dacites have strongly enriched light trace element patterns(La/Yb = 8.49-47.9) and LILE,but depleted HFSE (e.g.,Nb,Zr,Ti).The basalts and basaltic andesites most likely originated from the asthenosphere contaminated by melts from the lithosphere,whereas the dacites and rhyolites likely originated from