D. Nuwan Sanjaya Wanniarachchi (Sri Lanka)

Email: nuwan0sanjaya @gmail.com

Thesis title:  Internal textures and chemical properties of zircon and garnet in metamorphic rocks from the southwestern part of Sri Lanka.

Supervisor:  Prof Masahide Akasaka (2011-2012).

Sri Lanka is a high-grade metamorphic terrain, and about 90% of the land is underlain by metamorphic rocks. According to geochronological evidence, the country is divided into three major crustal blocks known as the Wanni, Highland, and Vijayan complexes. My study area is situated in the southwestern part of Sri Lanka, and lies within the Highland Complex. On the basis of the chemical and mineralogical variations which have been reported by several geologists, the southwestern part of the Highland Complex is distinguished as a separate unit known as the Southwestern Group.

The main target of my research is to identify characteristic assemblages, textures and chemical compositions of constituent metamorphic minerals, internal textures, and chemical properties especially of zircon and garnet, and to propose a genetic model for the Southwestern Group. To achieve this goal, rock samples were collected from outcrops of several different metamorphic lithotypes, including quartzite, garnet biotite gneiss, and charnockitic gneiss. These samples will be examined using petrographic and EPMA methods to elaborate chemical zoning (and enrichment of REE), the mineral assemblages present, petrographic characteristics, and chemical variations of the minerals. Those variations can be related to the sample locations, and contradictory views of origin of the Southwestern Group would be more reliably based.