In the last couple of years Scientists discovered a new suture zone in the northern part of Madagascar, which indicates a former Subduction zone that was active around 600 Ma ago. Most major tectonic and continental crust forming events over the history of the Earth, and therefore also the event in Madagascar, are associated with middle to high-grade metamorphism and plutonism. The rocks may retain a memory of the time-scale of temperature relaxation, following peak PT conditions. A knowledge of these relationships of time with respect to P and T are crucial to our understanding of the magnitude and rate of change of dynamic processes operating in orogenic belts as well as offering an insight into the fundamental processes of the Earth s crust. A wide variety of geochronological methods can be employed to estimate quantitative and qualitative dating of rocks and sediments.
Techniques exist to date all geological materials, from billions of years to historical records.
Quaternary dating provides a record of climate change and geologically recent changes in environment. U-Pb ages of metamorphic minerals, such as zircon, sphene and monazite are used to date thermal events, including terrestrial meteoritic impacts, and to determine thermochronologic histories of terranes. U-Pb ages of zircon in sediments are used to determine the provenance of the sediments. This technique can also be used to determine ages for other geologic processes, such as dolomitization. Tephrochronology dates volcanic ash and tuff, with a range of the last 15 million years.