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Geochemical Characteristics and Geological Significance of Early Permian Baya'ertuhushuo Gabbro in South Great Xing'an Range
Author(s) -
Jianfeng LIU,
Xiaoguo CHI,
Zhi ZHAO,
Xingzhou ZHANG,
Zhihong MA,
Tiefu WANG,
Zhaochu HU
Publication year - 2011
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/j.1755-6724.2011.00384.x
Subject(s) - gabbro , geology , geochemistry , zircon , lile , basalt , petrogenesis , trace element , volcanic rock , petrology , partial melting , volcano
Field geological investigation and geochemical analysis are carried out on Baya'ertuhushuo Gabbro in South Great Xing'an Range. Field investigation reveals that the gabbro is a magmatic intrusion rather than a component of an ophiolite suite as previously thought. Zircon laser ablation inductively coupled plasma mass spectroscopy (LA‐ICP‐MS) U‐Pb dating indicates the gabbro was formed in 274–275 Ma, just as the widespread volcanic rocks of Dashizhai Formation (P 1 d ), monzogranites and miarolitic alkali‐feldspar granites in the study area. The gabbro has SiO 2 content between 47.23 wt% and 50.17 wt%, high MgO and FeO T contents of 6.95–11.29 wt% and 7.32–12.24 wt%, respectively, and it belongs to low‐K tholeiitic series in the SiO 2 ‐K 2 O diagram. The Chondrite‐normalized rare earth element (REE) patterns and primitive mantle‐normalized spider diagrams of the gabbro are similar to those of Normal Mid‐Ocean Ridge Basalt (N‐MORB) except for the enrichment of large ion lithophile elements (LILE), such as Rb, Ba and K. In trace element tectonic discriminative diagrams, the samples are mainly plotted in the N‐MORB field, and Zircon in situ Lu‐Hf isotopic analysis also indicates the gabbro originated from depleted mantle. Through synthetic studies of the geochemical characteristics and petrogenesis of Baya'ertuhushuo gabbro, volcanic rocks of Dashizhai Formation and granitoids in the area, it is suggested that the early Permian magmatism in the Xilinhot‐Xiwuqi area formed in the tectonic setting of asthenosphere upwelling, which was caused by breaking‐off of the subducted Paleo‐Asian Ocean slab.