Geochronology and petrogenesis of Neoproterozoic S‐type granites from the Qilian Block, north‐west China, and their geological implications

Early Neoproterozoic granites rarely outcrop in the Qilian Orogenic Belt (QOB) at the north‐eastern margin of the Qinghai–Tibet Plateau; however, they are vital to understanding the Precambrian evolution of the QOB. Thus, we present an integrated study, comprising petrology, geochronology, and whole...

Full description

Saved in:
Bibliographic Details
Published inGeological journal (Chichester, England) Vol. 54; no. 4; pp. 2364 - 2381
Main Authors Liu, Xiuting, Ren, Erfeng, Li, Binkai, Du, Yongsheng, Gao, Donglin, Ren, Qianhui, Gao, Liang, Li, S.
Format Journal Article
LanguageEnglish
Published Liverpool Wiley Subscription Services, Inc 01.07.2019
Subjects
Anomalies
continental margin arc setting
Continental margins
Depletion
Earth
Enrichment
Geochemistry
Geochronology
Geochronometry
Granite
Igneous rocks
Lava
Magma
Mica
Neoproterozoic
Niobium
Orogeny
Outcrops
Petrogenesis
Petrology
Plutons
Precambrian
Qilian Block
Qilian Orogenic Belt
Rare earth elements
Rocks
Rubidium
Tantalum
Online AccessGet full text

Cover

More Information
Summary:Early Neoproterozoic granites rarely outcrop in the Qilian Orogenic Belt (QOB) at the north‐eastern margin of the Qinghai–Tibet Plateau; however, they are vital to understanding the Precambrian evolution of the QOB. Thus, we present an integrated study, comprising petrology, geochronology, and whole‐rock geochemistry of two Early Neoproterozoic granitic plutons (Baihuagou and Yamacha plutons) in the eastern Qilian Block (QB). The results provide three key findings. First, their magma emplacement age is ca. 900 Ma (i.e., 918 Ma for Baihuagou and 910 Ma for Yamacha), and the two plutons have similar high‐K calc‐alkaline, strongly peraluminous characteristics, with slight enrichment in light rare earth elements; weak negative Eu anomalies; enrichment in large‐ion lithophile elements (e.g., K, Th, Ba, and Rb); strong depletion in Ti; and weak depletion in Nb, Ta, and, Sr. These characteristics indicate that the granites from these plutons are S‐type granites. Second, the two‐mica granite and gneissic granite samples may have been formed by partial melting of ancient crustal material (mainly psammitic rocks), with contributions from a meta‐igneous component, under high‐temperature and low‐pressure conditions. Third, new data from this study, combined with previously reported dates, indicate a continental margin arc setting for the QB during the Early Neoproterozoic (ca. 900 Ma).
ISSN:0072-1050
1099-1034
DOI:10.1002/gj.3301