Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4688235 | Journal of Geodynamics | 2013 | 25 Pages |
Analysis of regional gravity data over the Grenville Province of SW Québec, Canada, has identified hitherto unrecognized transverse deep-crustal structures, in addition to lineaments that correspond to mapped upper crustal, orogen-parallel tectonic boundaries. Lineaments that trend NW–SE, i.e. transverse to the orogen, are interpreted as reactivated Palaeoproterozoic faults in Archaean basement that are controlled by structures in Archaean sub-crustal lithospheric mantle (SCLM). A prominent lineament (the Mont-Laurier lineament) that extends from the SE Superior Province across the SW Grenville Province is identified on both gravity and seismic tomographic imagery, the latter confirming it represents a lithospheric-scale structure. Baltica is placed at the Laurentian margin in tectonic reconstructions, and the Mont-Laurier lineament correlates with the extension towards the Superior Craton of the Belomorian Province between the Karelia and Kola cratons. It is proposed that this structure developed as a normal fault zone, and was subsequently reactivated as a transfer fault, during two orthogonal Palaeoproterozoic rifting events. The ensuing irregular basement geometry subsequently influenced sedimentation and deformation during the Grenvillian orogenic cycle and the Mont-Laurier lineament again acted as a transfer fault zone during Grenvillian orogenesis and post-orogenic collapse. Identification of tranverse structures has implications in understanding the architecture of this part of the Grenville Province. The role of pre-existing basement structures and rigid SCLM on the formation and preservation of long, linear structures transverse to an orogen throughout a complex sequence of rifting, back-arc basin formation, collisional orogenesis, and post-orogenic collapse in the Grenville Province of SW Quebec is also documented in New Guinea, with which comparisons are made.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Transverse lineaments are identified from Quebec Grenville Province gravity data. ► Gravity lineaments reflect reactivated Palaeoproterozoic basement faults. ► 100 km tomographic data show the NW–SE Mont-Laurier lineament affects the mantle. ► The Mont-Laurier lineament may be an extension of the Karelia–Kola craton boundary. ► The Grenville parautochthon promontory reflects Laurentia-Baltica rift geometry.