Significance of the project
Source: IGCP 649   Publish Time: 2015-04-28 19:41   2989 Views   Size:  16px  14px  12px

Using the newly discovered occurrence of natural diamonds and UHP minerals in ophioliticperidotitesandchromitites, and the geochemical compositions of these unusual minerals and their host rocks, we will test in this project some of the fundamental questions about mantle compositional heterogeneity, crust-mantle recycling, and petrogenetic evolution of the mantle lithosphere based on a global study of ophiolites - the only readily available samples of mantle rocks on Earth.  The findings of this project have the potential to change many of the currently held models of how the Earth works, as we address the following major questions: what happens to subducted slabs near the Transition Zone and how is the subducted material mixed into the mantle? What is the redox state of the upper mantle and how can we explain the presence of highly reduced phases in oxidized minerals such as chromites? To what extent and how can subduction zone processes modify mantle domains formed beneath mid-ocean ridges? What carbon reservoirs exist in the mantle and what is the source(s) of the carbon? How are the highly reduced phases and diamonds brought from the mantle Transition Zone to shallower levels? Do chromitites have distinctly different life cycles in different domains in the mantle before they become incorporated into ophioliticperidotites, and if so what does that mean for the partial melting processes that occur during ophiolitepetrogenesis?  We may not be able to answer all of these questions fully, but our results will provide new data and insights that will shed light on many aspects of oceanic lithosphere formation and recycling through plate tectonics. Hence, we anticipate making significant contributions to scientific advancement in the broad field of geodynamics through this IGCP project.

One of the unique aspects of this project is that it is based on systematic fieldwork in ophiolites in different orogenic belts in different continents, and thus it will be carried out by active participation and collaboration of many ophiolite scientists in the world.  This requires international cooperation and the involvement of many academic, industry and governmental organizations in a large number of countries in synergistic ways. The members of our research team have been engaged in such collaborative efforts in their ophiolite studies over the years, and are hence highly experienced. In particular, we have already carried out pilot studies of ophiolite-hosted diamonds in China (including Tibet), Russia, Myanmar, Albania, Turkey, Oman and Cyprus, and therefore we are well aware of the feasibilities of our project.

During the course of our IGCP project we will coordinate and run field-based meetings, workshops and training courses for graduate students, young scientists and mid-career researchers from developing countries in order to provide them with contemporary information on field techniques and sampling protocols for systematic studies in mantle peridotites, chromitites and oceanic upper crustal rocks. These rock types have complex mineral assemblages, superimposed igneous and metamorphic structures, and deformation textures that require an integrated, multi-disciplinary approach and background to study effectively in the field. Similarly,isotopic dating and geochemical fingerprinting of peridotitic rocks, ophiolitic diamonds, UHP minerals, and chromites requires special instrumentation and analyses, and our collaborators and the project leaders collectively have the in-house facilities and technical support (see the attached collaboration letters) to carry out these analyses expeditiously and at much cheaper rates than commercial laboratories. We will make these facilities accessible to the project participants, graduate students and young researchers to analyse their rock samples and to learn how to obtain, reduce and interpret quantitative data through workshops and individually scheduled time frames. This objective of the project is extremely important for us, to ensure that the young researchers and graduate students will acquire quantitative skills in addition to gaining learned information and knowledge. Collectively, the field workshops, training courses for instrumentation and laboratory techniques, and thematic meetings will serve as a two-way pathway for knowledge transfer and capacity building mechanisms, particularly for all scientists from developing countries and nations. These project activities will be a catalyst for establishing strong professional and social bonds among the participants and for networking.