In:
Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 57, No. 2 ( 2020-02), p. 249-266
Abstract:
Late Mesozoic granitic rocks are widely distributed in the Sulu orogenic belt, but the source, tectonic affinity, and associated geodynamic setting that produced the respective magmas remain controversial. To provide insights into these issues, we present field-based petrological, whole-rock major and trace element and Sr–Nd isotope geochemical, zircon U–Pb dating, and Lu–Hf isotope studies on two types of granite porphyry dykes that are newly recognized from the central Sulu belt. U–Pb dating of magmatic zircons from both types yields consistent ages that vary between 124 ± 2 and 118 ± 2 Ma, constraining the timing of intrusion as Early Cretaceous. The granitic rocks have high-K calc-alkaline peraluminous compositions with low Mg# values and are characterized by fractionated rare earth element patterns with strong depletion in high field strength elements. Compared with type I of the granite porphyry dykes, type II exhibits higher SiO 2 but slightly lower Na 2 O and K 2 O abundances, contains higher Rb/Sr and 87 Sr/ 86 Sr ratios, and shows more pronounced negative Eu, Sr, and Ba anomalies. Both types I and II have high initial 87 Sr/ 86 Sr ratios of 0.709–0.711 and negative ε Nd (t) values of −19.8 to −18.4. The magmatic zircons possess negative ε Hf (t) values of −29.1 to −20.8, with mostly Neoarchean Hf model ages of 3001–2478 Ma. These features, together with the presence of Neoproterozoic inherited zircons, indicate that the two types of granite porphyries successively crystallized from a joint granite magma that derived from partial melting of the continental crust of the Yangtze Craton. Therefore, an interrelationship between the granite porphyry dykes and massive magmatic granitoids from adjacent regions in the Sulu belt may be documented, recording evidence of a joint ancient crustal reworking and recycling in a fossilized continental subduction zone during the Early Cretaceous.
Type of Medium:
Online Resource
ISSN:
0008-4077
,
1480-3313
DOI:
10.1139/cjes-2019-0003
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
2020
detail.hit.zdb_id:
417294-2
detail.hit.zdb_id:
1491201-6
SSG:
16,13
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