地质学报（英文版）2007，Vol.81Issue(2)：266-277,12.
Chronology and Geochemistry of Volcanic Rocks in the Cretaceous Suifenhe Formation in Eastern Heilongjiang, China
Chronology and Geochemistry of Volcanic Rocks in the Cretaceous Suifenhe Formation in Eastern Heilongjiang, China
摘要
Abstract
Zircon U-Pb ages and geochemical data of volcanic rocks in the Suifenhe Formation in eastern Heilongjiang Province are reported, and their petrogenesis is discussed in this paper. The Suifenhe Formation mainly consists of basalt, andesite, and dacite. Zircon from andesite and dacite are euhedral in shape and show typical oscillatory zoning with high Th/U ratios (0.18-0.57), implying its magmatic origin. Zircon U-Pb dating results by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) indicate that the 206Pb/238U ages of zircons from andesite range within 105-106 Ma, yielding a weighted mean age of 105.5±0.8 Ma (n=14), and that 206Pb/238U ages of zircons from dacite are between 90-96 Ma, yielding a weighted mean age of 93.2±1.3 Ma (n =13). The volcanic rocks from the Suifenhe Formation are subalkaline series and show a calc-alkaline evolutionary trend with SiO2 content of 47.69%-65.47%, MgO contents of 1.42%-6.80% (Mg#= 45-53), and Na2O/K2O ratios of 1.83-3.63. They are characterized by enrichment in large ion lithophile elements (LILE) and lightrare-earth elements (LREE), depletion in heavy rare earth elements (HREE) and high field strength elements (HFSE) (e.g., Nb, Ta, Ti), and low initial 87Sr/86Sr ratios (0.7041-0.7057) and positive εNd(t)values (0.39-4.08), implying that they could be derived from a depleted magma source. Taken together,these results suggest that the primary magma of the volcanic rocks might originate from partial melting of the mantle wedge metasomatized by fluids derived from subducted slab under a tectonic setting of active continental margin.关键词
Suifenhe Formation/volcanic rocks/LA-ICP-MS zircon U-Pb dating/geochemistry/petrogenesis/Cretaceous/Heilongjiang ProvinceKey words
Suifenhe Formation/volcanic rocks/LA-ICP-MS zircon U-Pb dating/geochemistry/petrogenesis/Cretaceous/Heilongjiang Province分类
天文与地球科学引用本文复制引用
JI Weiqiang,XU Wenliang,YANG Debin,PEI Fuping,JIN Ke,LIU Xiaoming..Chronology and Geochemistry of Volcanic Rocks in the Cretaceous Suifenhe Formation in Eastern Heilongjiang, China[J].地质学报（英文版）,2007,81(2):266-277,12.基金项目
This study is financially supported by the National Natural Science Foundation of China (Grant No. 40672038) and the Special Grant of Oil & Gas Research (XQ-2004-07). （Grant No. 40672038）
