Geochemistry and detrial zircon geochronology of Carboniferous detrital rocks in the northern margin of Dabie Mountains, central China and constraints to distinguishing the provenance tectonic attribute
大别山北缘石炭系碎屑岩地球化学及碎屑锆石年代学分析及其对物源区大地构造属性判别的制约

The Carboniferous is a suite of un-metamorphosed or slightly metamorphosed sedimentary strata in the northern margin of the Dabie Mountains,and it recorded the information of the provenance and the Paleozoic tectonic evolution. The authors analyze the compositions of major,trace and rare elements,the detrital compositions of sandstone and the dating of detrital zircons in the study area,and investigate the tectonic attribute and evolution of the provenance. Medium-fine grain quartz sandstone and feldspar-quartz sandstone are the major in the study area. The QFL averages of sandstones are Q 76. 2% ,F 15. 9% ,L 7. 9% and Q / ( F + L) 4. 26; the major element oxide averages of Carboniferous sandstones are SiO 2 63. 69% ,Al 2 O 3 11. 25% ,MgO 3. 66% ,CaO 5. 15% ,Fe 2 O T 3 6. 15% ,K 2 O 1. 68% and Na 2 O 0. 68% ; the part characteristic trace elements like Th,U,Hf,Sc,Zr,Y have averages of 10. 78 × 10 - 6 ,2. 64 ×10 - 6 ,4. 39 ×10 - 6 ,15. 67 ×10 - 6 ,166 ×10 - 6 and 25. 33 × 10 - 6 ,respectively; and the ratios of Rb/Sr,Th/U,La/Y, La / Sc and Th / Sc are respectively 1. 49,4. 10,14. 75,31. 92 and 0. 89; the average of ΣREE is 146. 2 × 10 - 6 ( 54. 11 ×10 - 6 ～ 256. 0 × 10 - 6 ) ,δEu is 0. 64,light REE enrichment. La/Yb is 12. 58( 3. 94 ～ 15. 42) ,and ( La/Yb) N is 9. 02. The dating of detrital zircons shows that the major U-Pb age of zircons in Early Carboniferous are about 400 ～ 500Ma,while in Late Carboniferous the ages of zircons are mostly 900 ～ 1300Ma and secondly 2000 ～ 2800Ma. These reveal that the Carboniferous sediment derived from different provenance,including the Early Paleozoic island-arc system,Middle-Late Proterozoic basement of Yangtze Craton,Early-Middle Proterozoic basement of North China.