The petrogenesis of multi-stage 2.9~1.7Ga TTG and granitic magmatism in the Shaohuashan-Xiaoshan-Xiong'ershan areas on the southern margin of the North China Craton and the implications for the continental crust evolution

The North China Craton (NCC) preserves extensive Archean to Paleoproterozoic tectonic-magmatic and sedimentary records, making it a natural laboratory for studying the multi-stage crustal growth and evolutional mechanism. At present, however, there are still controversies regarding its early continental crust growth mechanism and tectonic evolution processes. The Taihua Complex in the southern margin of the NCC preserves a well-exposed Archean-Paleoproterozoic crystalline basement, comprising multi-stage TTG (tonalite-trondhjemite-granodiorite) and mafic to felsic magmatic assemblages. This study focuses on the 2.9~1.7Ga TTG and granitoid suites in the Shaohuashan-Xiaoshan-Xiong'ershan areas in the southern NCC, integrating systematic petrological, geochronological, and geochemical analyses. The results show that at least seven stages of TTG and granitic magmatic activities have developed in the study areas, including ~2.9Ga tonalite, ~2.7Ga granodiorite, 2.53~2.42Ga tonalite and monzonitic-potassic granite, 2.33~2.27Ga trondhjemite, diorite and monzonitic-potassic granite, 2.22~2.19Ga monzogranite and intrusive granitic melt in TTG gneiss, 1.94~1.81Ga monzonitic-potassic granite and granodiorite, and 1.78~1.76Ga monzonitic-potassic granite. The 2.9~2.3Ga TTG is mainly of medium- to low-pressure type TTG. The ~2.5Ga granitic rocks belong to I-S type granites. The ~2.3Ga, ~2.2Ga, and ~1.7Ga granitic rocks are similar to A-type granites. The 1.94~1.81Ga A- and I-S type granites develop simultaneously. The ~2.9Ga, ~2.7Ga, and ~2.5Ga TTG, and ~2.5Ga granitic rocks record the multi-stage growth and evolution of the early continental crust, which may have formed in a subduction-collision tectonic environment. The ~2.3Ga TTG is generally low-pressure type, resulting from the partial melting of mafic lower crust under a high geothermal gradient. Together with coeval diorite from the ancient enriched mantle and intraplate A-type granites, they indicate an intra-plate extensional setting. The 2.2~2.1Ga A-type granites originated from the remelting of ancient continental crust. Combined with the previously identified 2.3~2.1Ga bimodal volcanic rocks, A-type granites, and low δ18O granites-gabbro-diorite, etc., they indicate recycling of the crust or mantle at different depths in an extensional setting. The 1.94~1.81Ga I-S and A-type granites likely record the Proterozoic subduction-collision processes. The 1.78~1.76Ga A-type granites may be the product of crustal partial melting induced by the thinning of the continental crust under an intraplate extensional setting. The seven-stage Archean to Paleoproterozoic TTG and granitic activities in the southern margin of the NCC have recorded the growth, evolution and tectonic transformation of the continental crust, providing key constraints for revealing the differentiation mechanism of the Earth's lithosphere, and dynamic processes in multiple stages.