The 1.5 Ga metamorphic gabbro at the Lixi area, S: chuan Province in the western margin of the Yangtze Block: Implications for the breakup of the Columbia supercontinent

Precambrian strata are widely distributed in the Lixi-Caiziyuan-Tong'an area, which is an important window to study Precambrian geological evolution of the western margin of the Yangtze Block.Petrology, whole-rock geochemistry and zircon U-Pb chronology of metamorphic gabbro in the Lixi area of Huili were studied.The results show that Lixi metamorphic gabbro was formed at 1508±21 Ma.In terms of petrogeochemical composition, it belongs to the subalkaline tholeiitic series, and is slightly enriched in light rare earth elements (LREE) on the whole, with no obvious depletion of high field strength elements such as Nb, Ta, Zr and Hf.Under the influence of later weathering, large ionic lithophile elements such as Ba, Sr incompatible elements are enriched in varying degrees.According to the petrogenesis analysis, the magma experienced a certain degree of separation and crystallization during the ascent, but was not obviously contaminated by the crust, and the mother magma might have come from the depleted asthenosphere mantle.The comprehensive analysis of geochemical and regional geological characteristics shows that the geochemical characteristics of Lixi metamorphic gabbro are similar to the E-MORB basalt, which might be formed in mid-ocean ridges or nearby seamount environment as a response to the breakup of Columbia supercontinent in the Yangtze Block.