Geochronology of subduction-related metamorphic rocks from the Central Indonesian Accretionary Collision Complex

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This proposal seeks funding for field-based research activities that aim at establishing a solid geochronologic foundation for in-depth understanding of subduction- and collision-related metamorphic processes in the Central Indonesian Accretionary Collision Complex (CIACC). Previous studies have outlined the essential field, petrological and geochemical context of the metamorphic rocks from the CIACC. However, the knowledge about the timing and geodynamic significance of regional metamorphic processes is fragmentary and needs further attention. Relative to its geographic extent, the regional coverage with isotopic age data is insufficient under both quantitative and qualitative aspects for meaningful interpretation of the geologic history. Such data are crucial for a correct interpretation of the geologic histories and have the potential to significantly advance the understanding of the subduction–exhumation events recorded in the CIACC. New age data produced in a previous study focusing on metamorphic rocks from Bantimala (Sulawesi) and Luk Ulo (Java) revealed distinct age differences for the HP/LT stage that had previously not been recognized, due to the poor precision of an earlier K–Ar data set. The new geochronologic evidence has opened up new perspectives for an in-depth understanding of diverse metamorphic histories in different segments of the CIACC. More research is needed to fully understand the P–T–D–t evolution of the processes operating along the CIACC and to fully resolve the geotectonic context. A more comprehensive regional coverage is a prerequisite for an improved understanding of the geodynamic processes that have led to the formation of the pre-Tertiary accretionary complexes of the larger study area. For this purpose it will necessary to complement the existing data with age and P–T information for other occurrences, and to improve the knowledge of already studied locations by additional petrologic and age data. In order to establish a more comprehensive regional coverage with isotopic ages the logical next step is to focus on the metamorphic rocks from other parts of the CIACC. In this context the Meratus complex (south Kali-mantan) is of special importance for geodynamic considerations. New age data will help resolving spatial and temporal patterns in the geodynamic evolution on a broader regional scale, and will provide new insights into the development of the crustal architecture of Indonesia. The newly gained knowledge will provide a solid and robust foundation for refinement of palinspastic reconstructions, regional correlations and an improved interpretation of large-scale geodynamic processes in the central Indonesian region.