Arathy Ravindran

ETH Zurich | ETH Zürich · Department of Earth Sciences

Radiogenic isotopes provide an important means towards elucidating Archean crustal evolution. The global Hf and Nd isotope record of Archean crustal fragments has been instrumental to unveiling the history of ancient crustal growth and differentiation. The Rb-Sr system could provide valuable complementary constraints in this regard, as this system...

The scarcity of well-preserved, exposed, ancient rocks has introduced controversies about how to obtain primary isotope compositions suitable to constrain the early silicate differentiation of the Earth. The 146Sm-142Nd chronometer is a powerful tracer of Hadean silicate differentiation that has the potential to overcome challenges related to post-...

Both primary mantle differentiation and early extraction of oceanic and continental crust can have resulted in a chemically heterogeneous Archaean mantle. Evidence for heterogeneity of the Archaean mantle is preserved in the correlated Hf and Nd isotopes in mafic (basaltic) magmatic rocks and their ‘decoupling’ in ultramafic rocks, especially in ko...

Knowledge on the origin and evolution of the Archaean continental crust is limited due to the scarcity of pristine and exposed old crustal rock sequences. Due to the limitation imposed by metamorphosed rocks in preserving their primary geochemical signatures, it is relevant to study ancient grains of zircon that can provide valuable constraints on...

The composition of the primordial mantle has a primary influence on the amount and composition of Earth’s early continental crust. Studying the processes associated with ancient crust formation is complicated due to the limited exposure of Hadean-Archaean (>3.2 Ga) rocks. The western Dharwar Craton, India, (dominantly ~3.4 Ga) is one of the few wel...

The small extend of exposed Hadean-Paleoarchaean (>3.2 Ga) rocks in the global record poses a major challenge in interpreting Earth’s early crust-mantle evolution. This results in major uncertainty in the degree and extent of heterogeneity of the Archaean mantle (e.g. Nebel et al., 2014). Isotope systems like 176Lu-176Hf and 147Sm-143Nd are powerfu...

Crustal evolution models are primarily based on radiogenic isotope systematics with some preferential bias towards rocks formed after 3.0 Ga. The key problem is the lack of exposure of rocks older than 3.0 Ga and their common overprint by metamorphism and extensive deformation that obscure primary features including mineralogy and isotope systemati...

Determining the initial 87 Sr/ 86 Sr ratios of Archean rocks is quite challenging due to the high Rb/Sr ratios of most rocks that require large corrections for in-situ produced 87 Sr. Added to this is the high susceptibility of Rb-Sr system to alteration. However, the minerals barite (sediments, hydrothermal deposits) and apatite (igneous rocks) ge...

Determining the initial 87 Sr/ 86 Sr ratios of Archean rocks is quite challenging due to the high Rb/Sr ratios of most rocks that require large corrections for in-situ produced 87 Sr. However, the minerals barite (sediments, hydrothermal deposits) and apatite (igneous rocks) generally have near zero Rb/Sr and thus corrections for the decay of 87 Rb...

Barite, formed in some Archaean marine settings, is less susceptible to later alteration than carbonates and thus is more reliable in reconstructing the isotope composition of Archaean seawater. Due to the long residence times and redox insensitivity in the oceans, the Sr isotopes can be used to link the Sr-seawater trend with crustal evolution. St...

Strontium-rich Archaean barites can potentially preserve primary 87Sr/86Sr ratios and thereby give information on the extent and timing of crust-mantle evolution during Earth’s earliest preserved history. The barite-bearing zone in the Ghattihosahalli Schist Belt (GHSB), part of the Western Dharwar Craton, India, are studied in detail to better dis...