From peridotite to fuchsite bearing quartzite via carbonation and weathering: with implications for the Pb budget of continental crust

Abstract Extensive carbonation of peridotite results in listvenite, a rock composed magnesite and quartz. At Gråberget, Røros, SE-Norway, variably serpentinized body, surrounded by the Røros schists, former abyssal sediment displays all stages transformation to quartzite. In this paper we record sequence steps process combining observation mineral assemblages, textural relationships geochemistry, variations Pb isotopic compositions. Initial serpentinization, stage that also involved an enrichment fluid-mobile elements (Pb, Sb As), was followed through CO 2 fluids formed soapstone, eventually listvenite. The listvenite grades decreasing amounts carbonates into fuchsite bearing dissolved during supergene alteration pores coated with oxides Fe, Mn Ni resulting brown color. quartzite porous stylolites enriched Pb, As chromite grains as only relicts original mineralogy peridotite. dissolution carbonate occurred at oxidizing conditions temperatures below 150 °C, where solubility is higher than Formation from supported low REE contents lack zircons two types. coupled elimination Mg Si. This chemical fractionation selective transfer continents important mechanism needs be taken account models continental evolution.