Geological and Geochemical Features of Delisitannan Basalts and Their Petrogenesis in Buqingshan Tectonic Mélange Belt, Southern Margin of East Kunlun Orogen
Li Ruibao
Pei Xianzhi
Li Zuochen
Chen Youxin
Liu Chengjun
Pei Lei
Xu Tong
Liu Zhanqing
Wei Bo
Abstract：OIB-type basalts outcropped in the Buqingshan tectonic mélange belt,southern margin of East Kunlun,are closely related to mantle plume petrogeneticly.The MOR-type basalts are also another types of seamount basalts developed in the Pal-eotethys ocean.The Delisitannan basalts in Buqinshan area are located in the southern margin of the East Kunlun region.Field investigations show that the basalts are composed of pillow basalts,fumarolic-amygdaloidal basalts,breccia basalts and mas-sive basalts,which are covered by lamellar fuchsia silicon mudstone.Geochemical data show that the basalts are subdivided into abyssal tholeiite and oceanic ridge tholeiite series.The contents of REE range from 34.5 1×10 -6 -61.60×10 -6 ,LREE/HREE=0.89-1.37,(La/Yb)N =0.30-0.56.The chondrite-normalized REE pattern shows left-dipped incline and weak negative Eu abnormity (δEu=0.90-1.18),which is identical to NMORB REE distribution pattern.The Delisitannan basalts are aschistic in HSFE (Nb,Ta,Zr,Hf),and Zr/Nb ratios range from 24.59-57.69,Nb/La ratios range from 0.45-0.94,Hf/Ta ratio ran-ges from 18.29-31.94,which are all similar to those of NMORB basalts,and are obviously different from EMORB and OIB basalts.All of the trace element characteristics indicate that the basalts formed in an NMORB tectonic environment.The petro-genesis study shows that the rocks originated from depleted mantle,and are the product of 10% partial melting of mantle lherzolite roughly.
Keywords：East KunlunbasaltBuqingshanpaleotethyan oceangeochemistrypetrology
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1148-1162 )