SPP 1833 - Subproject: Elucidating Eoarchean geodynamic processes by multiple sulfur isotopes

Basic data for this project

Description

The style of Archean geodynamic processes as well as the geodynamic setting of early continental crust formation are currently highly debated. Based on a well-characterized set of Eoarchean samples from the > 3.7 Ga Isua Supracrustal Belt and adjacent areas in Greenland, we will investigate how crustal recycling processes operated in the early Archean. We use bulk rock and in situ multiple sulfur isotope compositions of Eoarchean oceanic crust, mantle peridotites and continental crust to trace recycling of material, which interacted with the ocean-atmosphere system, into the mantle and by melting processes into early continental crust. By performing bulk rock and in situ sulfur isotope compositions of sulfides together with petrographic observations, we test if mass-independent fractionated sulfur (MIF-S) was incorporated in hydrothermally altered oceanic crust, then transferred into the mantle and subsequently incorporated in the early continental crust that possibly sourced from thickened proto-arc crust. Thus, we place constraints on the early Archean magmatic and hydrothermal sulfur cycle and investigate, if crustal recycling processes comparable to present-day subduction were operating.