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Discovery and Geological Significance of Neoproterozoic Metamorphic Granite in Jimo, Shandong Province, Eastern China
Author(s) -
ZHU Decheng,
LÜ Dawei,
SHEN Xiaoli,
YANG Qing,
LI Dandan,
REN Tianlong,
YANG Shipeng
Publication year - 2016
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.13023
Subject(s) - geology , metamorphic rock , geochemistry , metamorphism , gneiss , zircon , rodinia , protolith , granulite , metamorphic core complex , greenschist , lile , metamorphic facies , petrology , partial melting , crust , tectonics , geomorphology , craton , facies , seismology , extensional definition , structural basin
Abstract During the 1:50000 regional geological survey in Jimo, east Shandong Province, Paleoproterozoic metamorphic supracrustal rocks and Neoproterozoic metamorphic plutonite were newly discovered. These rocks displayed inclusions which had occurred in the Mesozoic granite, and the main lithologies are schist, granulite, marble, and granitic gneiss. Geochemical analyses suggest that Neoproterozoic metamorphic plutonite are characterized by high‐K, metaluminous to weakly peraluminous. They are enriched in LILE and depleted in HFSE, with moderately enrichment of LREE, weak fractionation of LREE from HREE and negative Eu anomalies. The surface age of plutonic rocks in the survey area is 770.2±2.4 Ma, representing the age of magma crystallization, which is agreement with the the Neoproterozoic magmatic event after Rodinia supercontinent in the northern margin of Southern China continental block. In addition, the age of sporadic distribution (298 Ma and 269 Ma) is mixed zircon age, representing the rocks experienced metamorphism in Indosinian period. According to the associated mineral assemblages, and the characteristic metamorphic minerals and temperature pressure conditions, four metamorphic facies were identified, including amphibolitic, epidote amphibolite, greenschist, and mid‐high pressure greenschist. Analysis of tectonic setting suggests that granitic gneiss is formed in an extensional environment and was involved from the continental margin magmatic arc to intraplate environment. Jimo is distributed in the east of Zhuwu fault, and has the same Spatial distribution location with the Weihai uplift UHP metamorphic belt rocks. The metamorphic rocks in Jimo area have similar geochemical characteristics of elements, tectonic setting and retrograde metamorphism with that in the Sulu UHP metamorphic belt. Therefore, Zhuwu fault may be the boundary fault of Sulu UHP metamorphic belt.