The best worldwide examples of obducted ophiolite sequences occur along the Alpine-Himalayan belt in Italy (Northern Apennines), in Cyprus (Troodos ophiolite) and in Oman (Semail ophiolite). Despite the fact that these Ophiolite sheets belong to the same orogenic belt, they were not so far compared. We propose to compare quantitatively for the first time these three areas concerning the following aspects: thickness of obducted ophiolite sheets; thermal evolution of sub-ophiolite rocks; structural level at which obduction processes occurred; tectonic structures that accommodated ophiolite obduction and unroofing of sub-ophiolite rocks; nature and temperature of fluids involved during faulting; timing and duration of obduction and exhumation processes.
To do this, we propose a multidisciplinary study based on stratigraphic and structural field geology, geochemical laboratory analyses (clumped isotopes), fluid inclusions on calcite veins, mixed layers illite-smectite (I-S) paleothermal indicators, paleomagnetic analyses and U-Pb datings.
The following research objectives will be pursued:
1) the lateral variation of the thickness of ophiolite sheets will be constrained by paleothermal analysis of sub-ophiolite rocks;
2) the structural level at which obduction processes occurred will be constrained via paleothermal analysis of sub-ophiolite rocks and via analysis (clumped isotopes and fluid inclusions on syn-kinematic calcite veins associated with faults) of fossil fluids which permeated fault zones;
3) the tectonic structures that accommodated ophiolite obduction and exhumation of sub-ophiolite rocks will be constrained by field and laboratory structural analyses and by paleomagnetic analysis on sub-ophiolite rocks;
4) the age and duration of obduction and exhumation processes will be constrained by U-Pb datings of syn-tectonic calcite veins;
5) we will finally propose evolutionary models for ophiolite obduction in the investigated areas.
The best worldwide examples of obducted ophiolite sequences occur along the Alpine-Himalayan belt in Italy (Northern Apennines), in Cyprus (Troodos ophiolite) and in Oman (Semail ophiolite). Several studies were dedicated in the literature to ophiolitic rocks, but less interest has been dedicated to the sub-ophiolite rocks and to the processes that led to ophiolite obduction, to their erosion and to the exhumation of sub-ophiolite rocks. Despite the fact that Ophiolite sheets in Northern Apennines, Cyprus and Oman belong to the same orogenic belt, a thorough comparison of their characteristics still lacks. With this project, we propose to compare quantitatively for the first time these three areas concerning the following aspects: thickness of obducted ophiolite sheets; thermal evolution of sub-ophiolite rocks; structural level at which obduction processes occurred; tectonic structures that accommodated ophiolite obduction and unroofing of sub-ophiolite rocks; nature and temperature of fluids involved during faulting; timing and duration of obduction and exhumation processes. To do so we aim at developing a coherent understanding of the geometry and evolution of the three regions via a multidisciplinary study based on stratigraphic and structural field geology, geochemical laboratory analyses, mixed layers illite-smectite (I-S) paleothermal indicators, paleomagnetic analyses and U-Pb datings of syn-tectonic calcite veins. The multidisciplinary nature of our approach is innovative and will add valuable quantitative information to the state of the art.
A wider and very ambitious goal of the proposed research is the development of a general model for the obduction of large ophiolite sheets. This model may be validated against the characteristics and evolution of other obducted ophiolites worldwide (e.g., Klamath ophiolite, Boudier et al. 1989; Sarmiento ophiolite, Stern and De Wit 2003, Karmoy, Solund, and Leka ophiolites, Furnes et al. 1988; Vourinos, Mirdita, Othrys, and other Balkan Jurassic ophiolites; Phillips-Lander and Dilek 2009, Robertson et al. 2009). We are confident that our studies will improve significantly the understanding of ophiolite obduction, one of the most enigmatic processes of plate tectonics.
Boudier et al., 1989, Bulletin of the Geological Society of America, 101, 820¿833
Furnes et al., 1988, Journal of the Geological Society of London, 145, 401¿412
Phillips-Lander and Dilek, 2009, Lithos 106, 192¿206
Robertson et al., 2009, Lithos, 106, 1¿36
Stern and De Wit, 2003, Geological Society of London Special Publication, 218, 665¿683