Rutile in Amphibolite Facies Metamorphic Rocks: A Rare Example from the East Qinling Orogen, China

Abstract

Rutile is an important ore mineral to meet the increasing demand of critical metal Ti in various sectors. Here we report a rare example of rutile deposits hosted within the Baishugang–Wujianfang amphibolite-facies metamorphic rocks in the East Qinling Orogen, central China. The rutiles are mostly located within or along the margins of biotite and show 94.6 to 99 wt% TiO2. Rutiles occur as chains, thin layers along the foliation, and dense clusters. The grains are coexisted with magnetite. Based on Zr-in-rutile thermometer the estimated crystallisation temperature is at 630 °C at 7.0 kba. Based on Cr/Nb ratio, the source of the rutile is correlated with Ti-bearing silicate minerals such as biotite from aluminous sedimentary protoliths. The rutile deposit formed during lower amphibolite-facies metamorphism, and is distinct from the eclogite- and granulite-related types elsewhere in the orogen. The LA-ICP-MS U–Pb analyses of rutiles from the deposit yield lower intercept 238U/206Pb ages of 386 ± 16 Ma at the Baishugang–Wujianfang district. These ages correspond to a Devonian arc–continent collisional event between the South and North Qinling domains in the East Qinling Orogen.

Genesis of the Baiyangping Cu–Co and Pb–Zn Mineralizations in Lanping Basin, SW China

“…The classification of sediment-hosted Pb-Zn deposits consists of Mississippi Valleytype (MVT), vein-type, or clastic-dominated deposits. Sediment-hosted Pb-Zn deposits are major sources of Pb and Zn and significant sources of Ag and Ge, whereas Cu mineralization is generally rare yet economically important [1][2][3][4][5]. Such Pb-Zn deposits rich in Cu-Co and hosted in siliciclastic and dolomitic rocks often have mixed mineralizing fluid sources, such as basinal brines relating to magmatic-hydrothermal or metamorphic fluids [6][7][8][9][10].…”