Provenance of the Paleoproterozoic Hutuo Group basal conglomerates and Neoarchean crustal growth in the Wutai Mountains,North China Craton:Evidence from granite and quartzite pebble zircon U-Pb ages and Hf isotopes  

作　　者：DU LiLin YANG ChongHui WANG Wei REN LiuDong WAN YuSheng SONG HuiXia GAO LinZhi GENG YuanSheng HOU KeJun 

机构地区：[1]Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [2]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [3]Beijing SHRIMP Center,Beijing 100037,China [4]Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China

出　　处：《Science China Earth Sciences》2012年第11期1796-1814,共19页中国科学（地球科学英文版）

基　　金：supported by China Geological Survey (Grant Nos. 1212010611802,1212010711815 and 1212011120152);National Natural Science Foundation of China (Grant No. 41172171);Basic Foundation of Scientific Research Work from Ministry of Science and Technology of China (GrantNos. J0721 and J0907);National Commission on Stratigraphy of China(Grant Nos. 1212010511702-01 and 1212011120142)

摘　　要：Zircon U-Pb ages(SHRIMP and LA-ICPMS) and Lu-Hf isotope data(LA-ICPMS) are presented for two granite and two quartzite pebbles from the basal conglomerates of the Sijizhuang Formation in the Hutuo Group from the Wutai Mountains area in the North China Craton.These two granite pebbles give zircon 207 Pb/206 Pb ages of 2513±8 Ma and 2527±8 Ma respectively,which are consistent with the emplacement ages of the Wangjiahui grey granite and Guangmingsi or Shifo granite in the Wutai Mountains.Detrital zircons from those two quartzite pebbles are mostly 2550-2490 Ma old with lesser number of 2800-2550 Ma grains,which is similar to the ages of detrital zircons from quartzites in the Gaofan Subgroup of the Neoarchean Wutai Group.Thus,the pebbles in the Hutuo Group basal conglomerates were derived locally from Wutai Mountains Neoarchean sources.Zircons from the Sijizhuang Formation conglomerate granite and quartzite pebbles mostly have positive ε Hf(t) values,a minority with ε Hf(t) values like model depleted mantle(DM) of the same age,but with most showing DM model ages 200-100 Ma.This indicates that most of the source materials were derived from the mantle within the previous 200 million years,whereas some are derived from 2550-2510 Ma juvenile crustal additions.This additional evidence suggests that in the North China Craton there was important initial polycyclic crustal formation and cratonization in the late Neoarchaean,prior to superimposed Palaeoproterozoic orogenic cycles.Zircon U-Pb ages（SHRIMP and LA-ICPMS） and Lu-Hf isotope data（LA-ICPMS） are presented for two granite and two quartzite pebbles from the basal conglomerates of the Sijizhuang Formation in the Hutuo Group from the Wutai Mountains area in the North China Craton.These two granite pebbles give zircon 207 Pb/206 Pb ages of 2513±8 Ma and 2527±8 Ma respectively,which are consistent with the emplacement ages of the Wangjiahui grey granite and Guangmingsi or Shifo granite in the Wutai Mountains.Detrital zircons from those two quartzite pebbles are mostly 2550-2490 Ma old with lesser number of 2800-2550 Ma grains,which is similar to the ages of detrital zircons from quartzites in the Gaofan Subgroup of the Neoarchean Wutai Group.Thus,the pebbles in the Hutuo Group basal conglomerates were derived locally from Wutai Mountains Neoarchean sources.Zircons from the Sijizhuang Formation conglomerate granite and quartzite pebbles mostly have positive ε Hf（t） values,a minority with ε Hf（t） values like model depleted mantle（DM） of the same age,but with most showing DM model ages 200-100 Ma.This indicates that most of the source materials were derived from the mantle within the previous 200 million years,whereas some are derived from 2550-2510 Ma juvenile crustal additions.This additional evidence suggests that in the North China Craton there was important initial polycyclic crustal formation and cratonization in the late Neoarchaean,prior to superimposed Palaeoproterozoic orogenic cycles.

关 键 词：Hutuo Group Sijizhuang Formation conglomerate zircon U-Pb age Hf isotope sedimentary provenance crustal growth 

分 类 号：P597[天文地球—地球化学] P534.2[天文地球—地质学]