Extremely Depleted Carbonferous N-MORB Metabasite at the Chenxing Area (Hainan)and Its Geological Significance
He Huiying
Wang Yuejun
Zhang Yuzhi
Chen Xinyue
Zhou Yongzhi
Abstract：Hainan Island,located between the Indochina and South China Blocks,has undergone compound structural overprin-ting and complex tectonic evolution.However,the Late Paleozoic tectonic regime and amalgamation history of the South China with Indochina Blocks are still on debate.Our investigation identified the highly-depleted greenschist-facies basalt at the Chenx-ing area in the north of the Changjiang-Qionghai fault,Central Hainan Island.This paper presents a set of new geochronologi-cal and geochemical data for these metabasites.The representative sample for Chenxing metabasites gave the plateau age of 328.1±2.6 Ma,representing the eruption age.They have SiO2 ranging from 46.92 % to 52.58 %,TiO2 from 0.48 % to 1.12% and Al2 O3 from 12.34 % to 17.45 %,and could be classified as basalt.These samples show lower K2 O contents,and HFSEs and REEs contents relative to N-MORB.They are characterized by the left-sloping REE pattern and multi-elemental pattern with a geochemical affinity to N-MORB.These samples show extremely highεNd (t)values ranging from 9.02 to 9.85. Such geochemical characteristics for the Chenxing metabasites show the derivation of the MORB source modified by slab-related fluid.In combination with other available data,the Chenxing metabasites in Central Hainan are formed in the back-arc basin or a restricted ocean basin between the South China and Indochina blocks during the Carboniferous in response to the subduction of the Paleotethyan main ocean.
Keywords：metabasitesNd isotopic compositionN-MORBCarbonferouseastern paleotethyan evolutiongeochemistrypetrology
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1361-1375 )