Chemical composition of sediments from the subducting Cocos Ridge segment at the Southern Central American subduction zone |
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| Authors: | Renjie Zhao Quanshu Yan Haitao Zhang Yili Guan Xuefa Shi |
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| Affiliation: | 1.College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China2.Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China3.Laboratory for Marine Geology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China |
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| Abstract: | Subducted sediments play an important role in the magmatism at subduction zones and the formation of mantle heterogeneity, making them an important tracer for shallow crustal processes and deep mantle processes. Therefore, ascertaining the chemical compositions of different subduction end-members is a prerequisite for using subducted sediments to trace key geological processes. We reports here the comprehensive major and trace element analyses of 52 samples from two holes (U1414A and U1381C) drilled on the subducting Cocos Ridge segment at the Southern Central American (SCA) subduction zone during Integrated Ocean Drilling Program (IODP) Expedition 344. The results show that the SCA subducting sediments contain 51% (wt%) CaCO3, 27% (wt%) terrigenous material, 16% (wt%) opal, and 6% (wt%) mineral-bound H2O+. Compared to the global trenches subducting sediment, the SCA subducting sediments are enriched in biogenic elements (Ba, Sr, and Ca), and depleted in high field strength elements (Nb, Ta, Zr, Hf, and Ti) and alkali elements (K, Rb, and Cs). Meanwhile, the sediments in this area were affected by the carbonate crash event, which could have been caused by a ~800 m rise in the carbonate compensation depth at 11 Ma in the Guatemala Basin. The reason for the sedimentary hiatus at Hole U1381C may be the closure of the Panama Isthmus and the collision between the Cocos Ridge and the Middle America Trench. In addition, the sediments from the subducting Cocos Ridge segment have influenced the petrogenesis of volcanic lavas erupted in the SCA. |
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| Keywords: | subducting sediments IODP Expedition 344 geochemistry Southern Central American subduction zone |
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