Geodynamics and sea-level changes in the Meso-Cenozoic:

from the global evolution to the Lisbon Metropolitan Area

Abstract

This article presents an evolution of geodynamics and eustatic sea-level changes in the
Meso-Cenozoic and relates global events to the formation of Iberia and the Lisbon Metropolitan
Area (LMA). The distensive tectonic regime resulted in the breakup of Pangea, the separation
between the North American and Eurasian plates and the individualization of the Iberian
microplate in the Lower Cretaceous. Rift basins were developed until the formation of oceanic
crust in the Atlantic. The Lusitanian Basin is linked to the genesis of the Meso-Cenozoic Western
Portuguese Border, where a large part of the Northern LMA is included. The compressive
regime from the end of Cretaceous gave rise to mountain ranges in the Iberian Peninsula and
to the reactivation of late-hercinian faults responsible for the formation and subsidence of a
tectonic depression (Cenozoic Basin of the Tagus-Sado), where most of the Southern LMA is
included. It was in this tectonic framework that the subvolcanic massif of Sintra was formed at
the end of the Upper Cretaceous or the Arrábida chain during the Miocene. The transition to
the compressive regime marked the maximum sea-level in the Meso-Cenozoic (170 to 250m
above the current level). The variations in sea-level explain the LMA’s lithological diversity. The
formations of the Northern LMA date mostly from Cretaceous (prevalence of limestones and
marls), while more recent formations are prevailing in the Southern LMA (Pliocene and Pleistocene),
which justifies its detrital character.