Middle Paleoproterozoic tectonic evolution of the North China Craton: Constraints from the A-type granites in the Wutai area

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2025-02-05 DOI:10.1016/j.precamres.2025.107711

Jingyu Wang , Yujing Wang , Wei Hong , Caiyun Lan , Jingjing Fan , Xiaoping Long

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Abstract

The Paleoproterozoic tectonic evolution of the Trans-North China Orogen of the North China Craton (NCC) has long been controversial. One of the key factors is the difference in the understanding of the A-type granites in the middle Paleoproterozoic. In this study, whole-rock geochemistry and Nd isotope, zircon U-Pb and Hf-O isotope, and zircon H₂O content are reported for middle Paleoproterozoic syenogranite, monzogranite, and alkali-feldspar granite in the Wutai area. LA-ICP-MS zircon dating results show that the intrusions have emplacement ages from 2117 to 2133 Ma. The 2.1 Ga granites in the Wutai area exhibit elevated SiO₂ (72.20–78.01 wt%), K₂O + Na₂O (7.32–8.78 wt%) and Zr + Nb + Y + Ce (> 528 ppm) concentrations, high FeOt/(FeOt + MgO) (0.78–0.89), 10000*Ga/Al (> 3) and K₂O/Na₂O (1.0–1.9) ratios, low TiO₂/MgO ratios (0.4–1.4), and significant depletion of Ba, Sr, Eu, as well as high zirconium saturation temperatures (785–892°C), showing typical characteristics of aluminous A-type granites. The samples display characteristics of relatively enriched zircon Hf isotopes (εHf(t) = −5.6 to + 2.7), whole-rock Nd isotopes (εNd(t) = −2.9 to + 0.3), and old two-stage Hf model ages (2.56–3.05 Ga) similar to those of Neoarchean TTG gneisses in the same area. Furthermore, the oxygen isotope composition of zircon (δ¹⁸O = 4.7 to 7.4 ‰) are lower than those of zircons from the A-type granites derived from meta-sedimentary melts, indicating that the A-type granites are predominantly derived from the partial melts of Archaean TTGs. These granites contain both ilmenite and magnetite, indicating a relatively oxidizing environment. Zircon (log(fO₂) = −14.9 to − 7.8) and biotite (log(fO₂) = −13.5 to − 11) also show high oxygen fugacity. The water content of zircon is 104–842 ppm, with an average of 414 ppm, showing a relatively wet environment. These oxidised and water-rich A-type granites are likely to form in a back-arc extensional setting. Combined with the published NCC data, the Trans-North China Orogen is inferred to be an Andean-type continental arc setting in the middle Paleoproterozoic, suggesting the possibility of continuous subduction in the Paleoproterozoic.

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来源期刊

Precambrian Research 地学-地球科学综合

CiteScore

7.20

自引率

28.90%

发文量

325

审稿时长

12 months

期刊介绍： Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.