Project Details
Projekt
Understanding the crust-mantle transition from fast-spreading mid-ocean ridges: experiments and analytical studies using ICDP OmanDP drill core samples
Applicants
Dr. Carl-Dieter Garbe-Schönberg; Professor Dr. Francois Holtz; Professor Dr. Jürgen Koepke
Subject Area
Palaeontology
Mineralogy, Petrology and Geochemistry
Mineralogy, Petrology and Geochemistry
Term
from 2020 to 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 439183043
In winter 2017/18, the ICDP drilling initiative "Oman Drilling Project" (OmanDP) successfully penetrated the paleo-crust-mantle transition of the Oman ophiolite, which is regarded as the world’s largest, best-exposed, and most-studied section of subaerially exposed oceanic lithosphere. The cores are 400 m (CM1) and 300 m (CM2) long and were recovered with a nearly 100 % success rate, making them a uniquely valuable resource for petrographical, petrological, and geochemical study and ensuring access to coherent sections throughout the enigmatic transition between the uppermost mantle and the lowermost crust of fast-spreading ridge systems. The drilled transects through the crust-mantle transition of the Oman paleo-crust, provide coherent long sections of the lowermost layered gabbros, massive dunites, troctolites, and wehrlites without any gaps, and can be regarded as a Rosetta Stone for understanding the magmatic processes and the mode of deep crustal accretion, in a depth window that was not accessible in recent oceans so far. The proposed project focuses on several scientific targets following two different methodological approaches: (1) In an experimental study we aim to simulate equilibrium and fractional crystallization in a parental MORB-type system relevant for a setting of initiation of a subduction zone at the transition between "dry" (like East Pacific Rise) and "wet" conditions (Izu-Bonin-Mariana arc-type crust). In a subproject we aim to quantify the trace element distribution between spinel/chromite and MORB melt. (2) The second approach focus on petrological and geochemical investigations on the rocks from the CM1 and CM2 drill cores in order to clarify the mechanism of massive dunite formation in the crust-mantle transition, and establish the exact mode of differentiation/fractionation within the lowermost crust. The results of both complementary approaches will provide a basis for a deep understanding of the magmatic processes at the base of fast-spreading crust in an environment of initial subduction, and will provide fundamental knowledge about the geodynamics of accretion of fast-spreading oceanic crust.
DFG Programme
Infrastructure Priority Programmes
International Connection
Australia
Cooperation Partner
Dr. Sandrin Feig
