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Zircon U–Pb dating and whole‐rock geochemistry of volcanic rocks in eastern Heilongjiang Province, NE China: Implications for the tectonic evolution of the Mudanjiang and Paleo‐Pacific oceans from the Jurassic to Cretaceous
- Source :
- Geological Journal. 55:1866-1889
- Publication Year :
- 2020
- Publisher :
- Wiley, 2020.
-
Abstract
- The eastern Heilongjiang Province, NE China, is located in the eastern CAOB (Central Asian Orogenic Belt). Previous studies suggest that subduction of the Mudanjiang and Paleo-Pacific oceans had been initiated in this area during the early Mesozoic. However, research on the Mesozoic volcanic rocks is insufficient, limiting our understanding of the relationship between magmatism and subduction process. To solve the problem, seven volcanic rocks in the Lesser Xing'an-Zhangguangcai Range and the Jiamusi Block were collected for zircon U-Pb dating (SHRIMP) and whole-rock geochemical analysis. Most samples from the Lesser Xing'an-Zhangguangcai Range are Jurassic in age (189-178 Ma), including andesite, trachyandesite, trachydacite, and rhyolite. The andesitic to trachytic rocks were generated by magma mixing at an active continental margin, whereas the rhyolite is highly fractionated I-type. All the samples from the Jiamusi Block and one basaltic andesite from the Lesser Xing'an Range are late Early Cretaceous in age (ca. 100 Ma) and were formed in a back-arc extensional setting (roll-back). Fractional crystallization was important in the generation of most Cretaceous rocks (basalt to trachydacite). However, magma mixing or crustal contamination was required to explain some andesites from the Jiamusi Block showing extremely low Cr, Ni, and Mg#. When integrated with the coeval blueschist-facies metamorphism, the Early Jurassic volcanism indicates an active continental margin in the Lesser Xing'an-Zhangguangcai Range due to the westward subduction of the Mudanjiang Ocean. After the closure of the Mudanjiang Ocean, two NE/NNE trending sinistral strike-slip faults in NE China were triggered, accompanied by the slab roll-back of the Paleo-Pacific oceanic plate. The Jurassic continental arc and accretionary complexes in NE China were cut through by the two strike-slip faults and bended to form small oroclines. At ca. 100 Ma, numerous accretionary complexes were accreted along the eastern margin of the CAOB, further forcing the retreat of trench and slab roll-back. The late Early Cretaceous intra-continental volcanism was generated in the Lesser Xing'an-Zhangguangcai Range and Jiamusi Block during this roll-back process.
- Subjects :
- geography
geography.geographical_feature_category
Subduction
020209 energy
Andesite
Geochemistry
Metamorphism
Geology
02 engineering and technology
010502 geochemistry & geophysics
01 natural sciences
Continental arc
Volcanic rock
Basaltic andesite
Continental margin
0202 electrical engineering, electronic engineering, information engineering
0105 earth and related environmental sciences
Zircon
Subjects
Details
- ISSN :
- 10991034 and 00721050
- Volume :
- 55
- Database :
- OpenAIRE
- Journal :
- Geological Journal
- Accession number :
- edsair.doi...........ccaa4d4d139d297ebedae7d2a50d9518