Júlio Fonseca Marques

Palaeogeographical Evolution of the Lusitanian Basin (Portugal) During the Jurassic. Part I: The Tectonic Constraints and Sedimentary Response

In this paper, we present the general tectonic framework that conditioned the evolution of the Lusitanian Basin during the Jurassic, when most of the filling of the basin was accumulated. The rifting episodes and the evolution of the basin’s geometry are presented and their close relationship with the main basin-wide unconformities is discussed. The unconformity-bounded sequences are briefly presented as a basis for understanding the evolution of the sedimentary environments. This constitutes the basic geological information to construct the palaeogeographical maps presented in Part II of this paper (this volume).

Palaeogeographical Evolution of the Lusitanian Basin (Portugal) During the Jurassic. Part II: The Slow-to-Fast Transformations of Sedimentary Infilling

In this paper we present the first palaeogeographical maps of the Lusitanian Basin during the Jurassic. We also present the methodology used to produce these maps and discuss the close relationship of the temporal and spatial distributions of facies with the sequence of tectonic events in the basin (already discussed in Part I of this study, this volume). One of the main conclusions is that the main bordering N–S-trending faults were the main tectonic structures that conditioned the facies geometry but only during paroxysmal events; during those short intervals, “instant” modifications of the facies geometry occurred. The other main conclusion is that in the time intervals between the paroxysmal events, the structures that conditioned the facies distribution were the main transfer faults, oriented ENE–WSW, and the sedimentary environments gradually rotated from N–S to ENE–WSW.