Room Number: 5015
Thesis Title: The 1.4-1.2 Ga tectonic setting of the SE Laurentian margin and its evolution as a hot mid-crust during the Grenville Orogeny: An example from the central Grenville Province
Supervisor: Dr. Aphrodite Indares
Current Research Interests:
> Orogenic evolution of continental crust
> Granulite facies metamorphism of mafic rocks
> Hydrothermal alteration of mafic tuffs in volcanosedimentary environments
> Phase equilibria modelling of mafic rocks
> Zircon and monazite geochronology
> Trace element and isotope geochemistry
The Grenville Province: The Mesoproterozoic Grenville Province is a Himalayan-scale eroded orogen that offers insights into mountain building processes operating at depth (Dunning & Indares, 2010). The Grenville Province of the Canadian Shield evolved mainly in two phases: (i) Mesoproterozoic growth of the active Laurentian continental margin during various subduction- accretionary events (~1.7 - 1.2 Ga) and (ii) subsequent continental collision during Grenvillian orogeny (1.09- 0.98 Ga, Rivers, 1997). During subsequent collision, this continental margin was subjected to burial at great depth, high P-T metamorphism and subsequent exhumation at upper crustal levels (Hynes & Rivers, 2010). Tectonic erosion also played important role facilitating exhumation of mid and lower crustal portions, and their preservation with juxtaposed upper crustal parts on the surface (Rivers, 2012). This gives us a unique opportunity to study the tectonothermal evolution of a continental margin crust in the form of preserved core of a protracted, large hot long-lived orogenic belt (Rivers, 2008, 2009; Hynes & Rivers, 2010).
Current Research Project:
My current research focuses on studying MP-HT granulites from central Grenville province in the eastern Canadian shield. These rocks are thought to have originated in an active continental margin arc- island arc accretionary system (~1.4 Ga) followed by rifting of the arc crust (~1.3- 1.2 Ga). Subsequently, these rocks underwent Grenvillian Orogenic event under deep crustal conditions and evolved as a hot mid-lower crust producing a vast area of HT granulite (high grade gneiss) terrane. In central Grenville we can identify all the different crustal levels ranging from lower crust (HP rocks) to those high level ones that escaped Grenvillian events (orogenic lid) exposed on both sides of Manicouagan Impact Crater and along a N-S transect of Manic-Baie Comeau transect.
There are different approaches of studying these high grade rocks:
1. Petrography of mafic granulites. This includes optical and SEM-MLA study of metamorphic textures, mineral chemistry, mineral and textural evolution in response to polyphase metamorphism.
2. Forward modelling of P-T pseudosections (in Thermocalc) coupled with conventional thermobarometry that can provide useful informations about the type/ shape of the P-T paths of prograde, peak and retrograde evolutions.
3. Major, trace element and REE geochemistry and various isotope systematics in mafic rocks and minerals to identify pre-Grenvillian nature of the Laurentian crust and the role of SCLM in it.
4. Zircon and monazite geochronology (U-Pb) and trace element geochemistry in LA-ICP-MS/ ion microprobe.
5. Synthesizing informations from different studies in order to construct a consistent tectonic model of Grenville.
My previous interest was on Neoproterozoic mafic dyke swarms from Singhbhum Craton in Eastern Indian Shield. Dyke swarms indicate periods of significant crustal extensions and are therefore, linked to supercontinent formations and breakups, crust-mantle interaction and crustal evolution.
1. Maity B., Ray J., Chattopadhyay B., Sengupta S., Nandy S. and Saha A. (2008): Contrasting Petrological Variants in Newer Dolerite Dyke Swarm Around Bisoi, Eastern Indian Shield: Insights from Petrography and Mineral Chemistry, In Srivastava R. K., Ch. Sivaji and Chalapathi Rao N. V. (ed.), Indian Dykes (Narosa Publishers, New Delhi), pp.447-470.
Poster presentation in Granulites & Granulites, 2013 held in Hyderabad, India from 16-20th January, 2013.
Poster title: Metamorphic textures of mafic granulites from two contrasting pressure domains in central Grenville Province.