Metamorphism and continental growth: Introduction

摘要

The growth of continents in orogenic belts has always been a key factor in understanding the interaction and co-evolution of Earth's crust and mantle in time and space. The cyclic process of plate tectonics has been continuously operating throughout much of the Earth's history, and the continental crust has an important role in evaluating this because the materials accumulated in the continental crust are retained for geologically long durations compared to the oceanic crust. The formation of continental crust is associated with large-scale tectonic processes, and the geological processes involved in its preservation in orogenic belts are therefore important. Because of its close relation with orogeny, continent formation has been episodic and often related to high-temperature (T), and medium to high-pressure (P) metamorphic processes (Brown, 2006). Therefore, a clear understanding of the temporal (?) and spatial evolution (P-T-t evolution) of metamorphic belts is central to the formulation of testable tectonic models. A key turning point in this field of geological sciences has been the progress achieved in micro-analytical techniques used in geochronology during the past two decades. Coupled with developments in phase equilibria modeling using internally consistent thermodynamic datasets, this has been instrumental in advancing our understanding of orogeny. By combining these two approaches together, we are now able to provide tight constraints on the time- and length-scales of metamorphism in the order of less than few millions of years within the orogenic cycle.