MTNet EMinars
Integrated multi-disciplinary mapping of the Global Lithospheric Architecture Mapping Project (GLAM) aims to create the world’s first map of the architecture and tectonothermal and geodynamic history of the entire continental lithosphere.
We can report that a) Continental Lithospheric Mantle (CLM) is segmented, with individual domains generally in the region of 100-400 km across, clustered into cratonic blocks and microcontinents, and assembled into continental amalgams by orogenic processes; b) the CLM is dominantly (greater than 60%) of Archean origin (mostly 3.6-3.0 Ga), broadly in line with isotope-derived estimates of net crustal growth (Dhuime et al., 2017, and references therein); c) the Archean CLM has been extensively modified (refertilisation, thinning), mostly by arc-related magmatism; d) the structure of the CLM imposes a fundamental control on many types of ore systems.
The boundaries of discrete CLM blocks, mapped at a nominal 80-100 km depth, are identified by direct and indirect indicators (patterns and responses) in geological, geophysical, geochemical, and topographic data. Higher confidence is assigned to potential boundaries that have geological support, and/or are present in multiple datasets. Hidden Archean lithosphere is revealed by isotopic methods (Re-Os, Hf, Nd, U-Pb) and high velocities in benchmarked Vs bodywave data at about 130km depth (Begg et al., 2009).
Our findings reveal that (1) tectonothermal reworking of CLM via plate tectonics and mantle convection (including mantle plume interaction) is the dominant process affecting continents; (2) individual continents have swapped microcontinental swaths of lithosphere during supercontinent cycles via the agency of plate tectonics; (3) the architecture and tectonothermal history of the CLM imparts a fundamental control on the spatial distribution of many types of ore deposit (e.g. Griffin et al., 2013).