Age and Geochemistry of the Granitic Porphyry from the Northwestern Zhejiang Province, SE China, and Its Geological Significance

详细信息

责任者：Li Zilong (Department of Earth Sciences ; Zhejiang University ; Hangzhou 310027 ; China) ; Zhou Jing
刊名：Acta Petrologica Sinica
出版年：2013
卷期：29(10)
关键词：花岗斑岩 ; granite porphyry ; 岩石地球化学 ; lithogeochemistry ; 浙江 ; Zhejiang Province
页码：p.3607-3622
图表：12 illus., 3 tables, 78 refs.
分类号：0801
issnNo：ISSN1000-0569
isbnNo：CN11-1922/P

摘要

Granites and diabases in the Mesozoic are two very important rock types in South China. We newly found granitic porphyry and two episodes of diabases within the Mugna Neoproterozoic gneissic granitic pluton in Chunfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">＇font> an area of the Northwestern Zhejiang Province font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>ZXBfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font> of SE China. The age of 142. 2 font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">±font> 1.2Ma was obtained from the granitic porphyry by zircon U-Pb dating, belonging to the Early Cretaceous. Geochemically, the granitic porphyry is characterized by high SiO2, K2O font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">±font> Na20 contents and K2O/ Na2O, and being a peraluminous granite series. It was enriched Rb and light rare earth elements as well as high field strength elements font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>Ta, Ce, Zr, Hffont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font> , and having moderate Nb depletion in the primitive mantle normalized diagram, indicating a source derived from subduction-related materials and/or crustal contamination. The early-stage diabase has similar chemical characters compared to the Mugua granitic porphyry. The late-stage diabase with no Eu anomalies has distinct composition compared to that of the early-stage diabase and granite porphyry with negative Eu anomalies. Granitic porphyry has Y/Nb ratios font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">〉font> 1.2, and depleted in Nb, Ti and Sr, indicating crustal origin with subduction zone signatures. Sr-Nd-Pb isotopic components show that the granitic porphyry has font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>^87Sr/ ^86Srfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font>; values of 0. 71134 font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font> 0. 71748 and font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">εfont>Nd font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>tfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font> values of - 3.3 font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font> - 6. 4, font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>^206pb/^204pbfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font> i values of 18.49 font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font> 18.56, font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>^207 pb/^204pbfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font>i values of 15.62 - 15.65 and font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>^208 pb/^204 Pb font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font>i values of 38.57 -38. 68 ;and the early-stage diabase has font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>^87 Sr/^86 Srfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font>i values of 0. 71408 0font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font>73010 and font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">εfont>Nd font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>tfont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font> values of -0.05font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font> font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">＋font> 0. 85. Based on the above study combined with the previous study, we suggest that the ZXB granitic porphyry may be derived from the Mesoproterozoic metamorphic rocks by partial melting induced by the heat of the deep mantle-derived hot magma upwelling. The diabases may be derived from mantle source. A geological comparison between ZXB and adjacent areas, we propose that the formation mechanism of the Early Cretaceous granitic porphyry and diabases in the ZXB as follows. A subduction and collision process between the paleo-Pacific plate and Eurasian continent accompanied by inland remobilization of the deen bit faults in South China was started since ca. 170Ma. The ZXB granitic oorohvrv and A-tvoe font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font>ranites may be formed under aninland extensional setting during the Early Jurassic font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">（font>123 font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font> 145Mafont>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">）font>. It entered a strong subduction and collision process from the Pacific plate with the Eurasian plate during the age of 117 font>font-family: 宋体; mso-ascii-font-family: calibri; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">～font> 121Ma. After the age of ca. 117Ma, there are large amounts of felsic volcanic rocks and A-type granites and diabase dykes in the southeastern coastal area of China formed under the extensional setting.font>

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