In:
Geological Magazine, Cambridge University Press (CUP), Vol. 149, No. 5 ( 2012-09), p. 753-767
Abstract:
The Chehugou granite-hosted molybdenum deposit is typical of the Xilamulun metallogenic belt, which is an important Mo–Ag–Pb–Zn producer in China. A combination of major and trace element, Sr and Nd isotope, and zircon U–Pb isotopic data are reported for the Chehugou batholith to constrain its petrogenesis and Mo mineralization. The zircon SIMS U–Pb dating yields mean ages of 384.7 ± 4.0 Ma and 373.1 ± 5.9 Ma for monzogranite and syenogranite and 265.6 ± 3.5 Ma and 245.1 ± 4.4 Ma for syenogranite porphyry and granite porphyry, respectively. The Devonian granites are calc-alkaline with K 2 O/Na 2 O ratios of 0.44–0.52, the Permian granites are alkali-calcic with K 2 O/Na 2 O ratios of 1.13–1.25, and the Triassic granites are calc-alkaline and alkali-calcic rocks with K 2 O/Na 2 O ratios of 0.78–1.63. They are all enriched in large-ion lithophile elements (LILEs) and depleted in high-field-strength elements (HFSEs) with negative Nb and Ta anomalies in primitive mantle-normalized trace element diagrams. They have relatively high Sr (189–1256 ppm) and low Y (3.87–5.43 ppm) concentrations. The Devonian granites have relatively high initial Sr isotope ratios of 0.7100–0.7126, negative ɛ Nd ( t ) values of −12.3 to −12.4 and 206 Pb/ 204 Pb ratios of 16.46–17.50. In contrast, the Permian and Triassic granitoids have relatively low initial 87 Sr/ 86 Sr ratios (0.7048–0.7074), negative ɛ Nd ( t ) values of −10.1 to −13.1 and 206 Pb/ 204 Pb ratios of 17.23–17.51. These geochemical features suggest that the Devonian, Permian and Triassic Chehugou granitoids were derived from ancient, garnet-bearing crustal rocks related to subduction of the Palaeo-Asian Ocean and subsequent continent–continent collision between the North China and Siberian plates.
Type of Medium:
Online Resource
ISSN:
0016-7568
,
1469-5081
DOI:
10.1017/S0016756811000987
Language:
English
Publisher:
Cambridge University Press (CUP)
Publication Date:
2012
detail.hit.zdb_id:
956405-6
detail.hit.zdb_id:
1479206-0
SSG:
13
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