Trace-element signatures of kyanite-eclogites from a southern Indian kimberlite

Anand, M.; Misra, K. C.; Paul, D. K.; Ishikawa, A. and Pearson, D. G. (2008). Trace-element signatures of kyanite-eclogites from a southern Indian kimberlite. In: 9th International Kimberlite Conference, 10-15 Aug 2008, Frankfurt.



Eclogite xenoliths found in kimberlites provide important information about geodynamic processes that were involved in the cratonic evolution of a region. Most eclogite xenoliths are demonstrably Precambrian in age and have equilibrated over a range of temperature and pressures throughout the subcratonic mantle (Jacob, 2004). Many eclogite xenoliths are diamondiferous (e.g., Anand et al., 2004) and thus they are not only of economic significance but they also provide information on the chemical and isotopic nature of deeper parts of Earth’s mantle (> 150 km), which is otherwise directly inaccessible. Although eclogite is apparently a minor component of the Earth’s mantle, it plays an important role in mantle geodynamics by facilitating subduction of the oceanic crust and imparting chemical heterogeneity to the mantle. Nevertheless, there has been some debate about the origin of eclogite xenoliths as to whether they are high-pressure cumulates from mantle melts or remnants of subducted ancient oceanic crust (e.g., see Jacob, 2004). Eclogite xenoliths from a number of locations worldwide have been studied for their detailed geochemical and isotopic characteristics, except those from India. Very little data exist on lithospheric materials of any nature for the cratonic roots in this region and the aim of this study is to redress this situation. Here we report on trace-element signatures of minerals and bulk-rock rhenium-osmium (Re-Os) isotope systematics of eclogite xenoliths recovered from the KL-2 kimberlite pipe in the Kalyandurg cluster of the Proterozoic Wajrakarur kimberlite field (WKF) of southern India. A detailed textural and mineralogical description of these samples can be found in an accompanying abstract (Misra et al., this volume).

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