Trace fossils from the Desejosa Formation (Schist and Greywacke Complex, Douro Group, NE Portugal):

Abstract

Trace fossils from a new locality in the Desejosa Formation, Freixo de Espada à Cinta area, northeast Portugal, are described, including Teichichnus rectus and the first Cambrian record from Iberia of the ichnogenus Rosselia, identified as R. cf. socialis. A literary review of the Cambrian record of Rosselia reveals no occurrences older than Cambrian Age 3. The occurrence of Rosselia in the Desejosa Formation therefore adds evidence to that of earlier reports on trilobite remains from the upper part of the Desejosa Formation for a Cambrian age of this unit. Both Rosselia and Teichichnus are zindicative of the Cruziana ichnofacies, which is representative of a shallow-marine depositional environment, consistent with earlier interpretations for the depositional conditions of the upper part of the Desejosa Formation in this sector, and in the equivalent Cambrian units in Spain.. Trace fossils. Rosselia socialis. Teichichnus rectus. Early Cambrian. Iberian Massif. Douro Group. KEYWORDS InTRoduCTIon Previous stratigraphic and paleontological studies (trace and body fossils) on the Spanish pre-Ordovician record of the Central Iberian Zone (CIZ) demonstrate that the age of the sequence is latest Ediacaran (

A first estimation of the contraction related to vertical axis rotation: the case of the Ibero-Armorican Arc formation

“…Díez Fernández et al, 2011). The lowermost tectonic unit of the GTMZ, the Parautochthon (Dias da Silva et al, 2014a, 2015, 2020) also called the Schistose Domain (Farias et al, 1987) or the Parautochthonous Thrust Complex (Ribeiro et al, 1990), can be divided into Upper Parautochthon, made up of a Cambrian-Silurian stratigraphic sequence comparable to the CIZ (Dias da Silva et al, 2014a, 2015; and the Lower Parautochthon comprised of synorogenic early Carboniferous marine strata imbricated in a piggy-back thrust sequence (Rodrigues et al, 2013;Dias da Silva et al, 2015;Martínez Catalán et al, 2016).…”

“…Around 340 Ma (Dallmeyer et al, 1997), the Upper Parautochthon was tectonically imbricated at the base of the unrooted allochthonous complexes (Martínez Catalán et al, 2009) and both were tectonically transported towards present-day southeast (Dias da Silva, 2014;Dias da Silva et al, 2020). The Upper Parautochthon was thrust onto its foreland basin (Lower Parautochthon) (Dias da Silva et al, 2014a, 2015. This stage (C 2 after Martínez Catalán et al, 2014) was responsible for the underthrusting of the underlying autochthon, leading to the regional Barrovian metamorphism peak (M 1 ).…”