Petrogenesis of mafic and felsic rocks from the Comei large igneous province, South Tibet: Implications for the initial activity of the Kerguelen plume

Abstract

The role of the Kerguelen plume in breaking up eastern Gondwana is so far unclear. Recently, the initial magmatic record of the plume has been identified in the Comei igneous province, Tethyan Himalaya. In this contribution, we investigated a group of basaltic intrusions (Juelongpu and Zhaxikang) and felsic lavas (Sangxiu) from the Comei igneous province. Laser ablation-inductively coupled plasma-mass spectrometry zircon U-Pb dating indicates that these mafic and felsic rocks were emplaced in the Early Cretaceous (ca. 140-137 Ma). Probably originating from the Kerguelen plume, the Juelongpu and Zhaxikang mafic rocks are characterized by high incompatible element abundances, high Nb/Y ratios, and oceanic-island basalt- like rare earth element and trace-element patterns. The Sangxiu felsic samples share A-type affinities and were derived by partial melting of crustal rocks. These mafic and felsic rocks represent a magmatic response to the initial activity of the Kerguelen plume. Their ages (ca. 140-137 Ma) are older than the timing of initial breakup of eastern Gondwana (ca. 137-136 Ma), indicating that the plume must have been incubating underneath the supercontinent before the breakup. Recent plate reconstructions coupled with our geochemical and geochronological constraints suggest that the Kerguelen plume head was resident under the Comei area of Greater India at ca. 140 Ma. Our results, in conjunction with previous studies, support the viewpoint that the Kerguelen plume played an active role in breaking up eastern Gondwana.