准噶尔盆地陆梁地区基底火山岩的岩石地球化学及其构造环境

Translated title of the contribution: Geochemical characteristics and geological environment of basement volcanic rocks in Luliang, central region in Junggar basin

Fang Zheng Wang*, Mei Zhen Yang, Jian Ping Zheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

Basement volcanic rocks in Luliang uplift in the central region of the Junggar basin are dominated by soda-rich basalts and rhyolites and shows a bimodal, intraplate suite. The basalts are characterised by the occurrence of olivine in phenocrysts and groundmass. Pyroxenes in samples are augite. Feldspars are acid plagioclases (An:30∼50). The whole-rock CIPW results show that most samples contain Ne(2.8%∼4.6%), Ol(19.3%∼10.1%), and Di(10.2%∼24.6%). The mineral- assemblage is Ne+Ol+Di+An. Basalts plotted in the alkalic area on the diagram are Si-Alkaline. Mg# numbers are smaller than 65. The total REE ranges from 110.29∼158.06 μg/g, (La/Y)N varies from 3.10-4.51. δEu varies from 0.93∼1.04. Trace elements of basalts are characterized by moderate enrichment in LILE ralative to LREE, moderate depletion in Nb, Ta relative to LREE and LILE, Ni and Gr are lower than that of reference value of primitive magma. These characteristics indicate that basalts in Luliang belong to alkali-olivine basalt. Basalt has higher positive initial εNd(7.20∼8.38) and lower 87Sr/86Sr, while rhyolite has lower initial positive εNd (5.64∼6.60) and higher 87Sr/86Sr. These differences are attributable to the absence or presence respectively of a significant crustal component, but basalt and rhyolite were derived from the same depleted mantle source. Rb-Sr isochron age and zircon crystal ages vary from 323Ma∼395Ma. The conclusions can be made that basalts were originated from a depleted mantle and then differentiated and contaminated by crust, and the basement volcanics were formed in the continental rifting environment which was related to limited extension during D-C. Therefore, the Luliang uplifting in basin can be explained to be a continental rift.

Translated title of the contributionGeochemical characteristics and geological environment of basement volcanic rocks in Luliang, central region in Junggar basin
Original languageChinese
Pages (from-to)9-16
Number of pages8
JournalActa Petrologica Sinica
Volume18
Issue number1
Publication statusPublished - 2002
Externally publishedYes

Keywords

  • Alkali-olivine basalt
  • Basement volcanics
  • Continental rifting
  • Junggar basin
  • Luliang
  • Rhyolite

Fingerprint

Dive into the research topics of 'Geochemical characteristics and geological environment of basement volcanic rocks in Luliang, central region in Junggar basin'. Together they form a unique fingerprint.

Cite this