Comparison of Fennoscandian Archean terrains with Indian Himalayas: Is the present key to the past? (Academy of Finland/DST India mobility grant)

Kuvaus

General description

The formation of Earth’s continents is a consequence of lithospheric plate movements called plate tectonics. The question when and how plate tectonics started and evolved to its modern style is unresolved and vigorously debated in the scientific community. It is still unclear how the oldest parts of the continents - the 4.0–2.5 billion years old fragments of Archean cratons - were formed. The continental crust is mainly composed of granitoid rocks, whose geochemical characteristics are a function of their formation mechanisms as well as the components and physical conditions of their source. Revealing ancient crust-formation mechanisms and tectonic processes at collisional zones requires a profound understanding of geochemical differences between Archean granitoids and granitoids occurring at modern-style tectonic settings such as Himalayas.
At present, Archean crust is exposed to various degrees on all continents (Fig. 2). Some of the most comprehensively studied Archean domains are located in Fennoscandia; in Finland and northwestern Russia. Structural, geophysical and geochemical as well as isotope geological studies have revealed a multitude of tectonic events during an almost one billion year period in this area.

Objectives

The main objective of the proposed project is to understand the differences between Archean (>2.5 Ga) and modern plate tectonic processes. The project compares the petrogenesis and tectonic setting of granitoid rocks and other lithologies from the Archean Fennoscandian terrains with those found in the Indian Himalayas representing a present-day continental collision. An extensive body of data will be acquired through petrographic, geochemical, thermobarometrical and isotopic (U-Pb, Pb-Pb, Lu-Hf, Sm-Nd and O) studies on the various rock types found in Fennoscandia and Himalayas. The results will be compared, and from these correlations we hope to draw conclusions on the tectonic evolution and possible parallels within these areas. The ultimate goal is to give constraints on the onset of modern-style plate tectonics.
TilaPäättynyt
Todellinen alku/loppupvm01/01/201501/01/2017