Grenville Province and Monteregian carbonatite and nepheline syenite distribution related to rifting, collision, and plume passage

Abstract

Stimulated by the recognition of a rifted continental margin to pre-Grenville Laurentia, we interpret the deformed alkaline igneous rocks and carbonatites (DARCs) adjacent to that margin in the Bancroft domain of Ontario, Canada, to be rocks initially erupted as alkaline rocks and carbonatites (ARCs) in an intra-continental rift. When an ocean began to form, rupturing Laurentia on the site of that rift, the newly formed Laurentian rifted continental margin contained ARCs that had erupted into the intra-continental rift. Later in a Wilson cycle of ocean opening and closing, those ARCs became DARCs during a collision that sutured the Grenville province composite arc belt and Bancroft domain rocks against the margin of Laurentia on the Central Meta-sedimentary Belt boundary thrust zone. Using this interpretation we show that DARCs of the down-dip Bancroft domain suture zone in the mantle at a depth of ~100 km are likely sources of the Early Cretaceous ARC rocks in the Monteregian province.on June 9, 2015 geology.gsapubs.org Downloaded from

A model for carbonatite hosted REE mineralisation — the Mianning–Dechang REE belt, Western Sichuan Province, China

“…They can also form in continental collision zones (e.g. India-Asia collision zone, Hou et al, 2009) and on rifted continental margin (Burke et al, 2008).…”

Proterozoic Alkaline rocks and Carbonatites of Peninsular India: A review

“…Note that the carbonatite is volumetrically insignificant to the associated alkaline rocks (Ashwal et al, 2016). The ARCs have been reported from three dominant tectonic settings: continental rifts, stable intraplate setting, and collisional or suture zones in subduction settings (Woolley, 2001;Burke et al, 2003Burke et al, , 2008Leelanandam et al, 2006;Vijaya Kumar et al, 2007;Upadhyay, 2008;Woolley and Kjarsgaard, 2008;Ashwal et al, 2016;Ackerman et al, 2017;Ranjan et al, 2018). In general, majority of the alkaline rocks occur in or near the continental rifts and ocean islands.…”

Plate Tectonics, the Wilson Cycle, and Mantle Plumes: Geodynamics from the Top

“…In Malawi, Ashwal acquired an ∼750-Mya date for initial eruption, presumably in a rift, of a nepheline syenite and an ∼525-Ma age for gneissification of that nepheline syenite body in a Pan-African suturing event (Ashwal et al 2007). Recently, we demonstrated the rift and suture relationships of the classic Grenville Province nepheline syenite gneisses and carbonatites of Ontario, Canada, and also established their relationship to the Monteregian Hills nepheline syenites and carbonatites of neighboring Quebec (Burke et al 2008a).…”