Cantabrian Thrust Belt: basin history of the North Gondwana passive margin – rifting, glaciations? More rifting and collision.

Doherty, Helen; Ferriday, Tim; Kelly, Michael; Montenari, Michael; Rogers, Steven; Williams, Graham

Abstract

The Variscan thrust belt of the Cantabrian Mountains in NW Spain preserves a Palaeozoic stratigraphy that developed during the evolution of the north Gondwana passive margin through multiple rift
phases, drifting and eventual collision and collapse of the margin during the Variscan Orogeny. Plate tectonic reconstructions show that the initial rifting that separated Avalonia from northern
Gondwana commenced during the early Ordovician at polar latitudes and this gave rise to the Palaeozoic Rheic Ocean. Closure of the Rheic Ocean and collision occurred through the mid and late
Carboniferous at equatorial latitudes. The stratigraphy of the Gondwana passive margin generally comprises a sequence of carbonate and siliciclastic sediments with two significant hiatuses.
In this integrated basin analysis project, palaeontological determinations have assisted in refining the chronostratigraphy and palaeobathymetric estimates have been made for the whole Palaeozoic sequence. The stratigraphy has been sub-divided into mega-sequences related to basin forming events
with two pronounced rift events plus a thrust-related basin forming event. Using information on stratigraphy thickness, palaeontology, chronostratigraphy and palaeobathymetry burial history curves
clarify the details of basin evolution related to major tectonic events.
A NNE-SSW trending cross section through the southern part of the Somiedo-Correcillas (SCZ) thrust unit shows the tectonic style, back steepening and northward vergence of the thrust system which
exhibits horizontal shortening of some 60%+. Evidence of Variscan contraction is abundant in small scale structures and there are many minor rotated extensional faults, often conjugate that show a
consistent stretching vector of NNE-SSW. An E-W correlation panel along the SCZ illustrates the detail of thickness changes within the syn-rift sequence and this has been used as the basis for the construction of a chronostratigraphic diagram. A detailed basin history model for the northern Gondwana to Rheic Ocean passive margin in the Palaeozoic is presented.

Citation

Doherty, H., Ferriday, T., Kelly, M., Montenari, M., Rogers, S., & Williams, G. (2010). Cantabrian Thrust Belt: basin history of the North Gondwana passive margin – rifting, glaciations? More rifting and collision.

• Conference Name: Tectonic Studies Group Annual Meeting
• Conference Location: Birmingham
• Start Date: Jan 6, 2010
• End Date: Jan 8, 2010
• Online Publication Date: Sep 16, 2010
• Publication Date: Sep 16, 2010
• Deposit Date: Jun 12, 2023