From a tectonic and structural standpoint, the Montejunto area is divided in two parts by a transversal group of errors. The EINE zone is restricted, in the east side, simply by fault with an orientation NE-SW as well as the contact involving the Meso-Cenozoic composition is more or perhaps less vertical. The zone SW of Montejunto area is characterized by the presence of a lot of faults of NE-SW orientation.
The Montejunto anticline resulted in the Cenozoic alpine compression and uplift. Basement faults and salt movement controlled that uplift nevertheless also managed the Mesozoic differential subsidence as might be seen in the variable thicknesses of Upper Jurassic rift-related sequences. Three sub-basins could possibly be defined surrounding the Montejunto anticline: Bombarral, Arruda and Turcifal.
One of many big geometrical transformations of the LB container is this partage in sub-basins, especially in the Central sector. The first time the effect of Torres Vedras-Montejunto fault is visible, which is the main contributor for the segmentation on this area in the LB from a tectonic perspective. Torres Vedras-Montejunto wrong doing (FTVM) corresponds to a sequence of united flaws by soft-links, with normal movement. During Upper Jurassic and Decrease Cretaceous, it really is responsible by the differentiation among Bombarral pot, in the subsident block, and Arruda and Turcifal basins to southern region. This mistake has an important role in the geological development of the location. With a great orientation NE-SW it formed in 3 rd rifting stage of the Lusitanian basin.
This basin’s separation of tectonic characteristics works during sedimentation as a paleogeographical hurdle, differentiating sedimentation environments. Turcifal and Arruda sub-basin happen to be divided simply by an average of 20km long north to North-Northeast striking Runa Fault Sophisticated, and Turcifal and Arruda half grabens are separated from Bombarral-AlcobaÃ§a sub-basin by 70km long northeast to east trending structural lineament, the Torres Vedras-Montejunto lineament (Figure 4). The development of intricate fault- and diapir-bound sub-basins resulted by the presence of halite for depth (latest Triassic-Hettangian era, Dagorda Formation) limited and modified the propagation of basement flaws into the post-salt overburden, contributing to the development of sodium pillows as it can be seen in seismic data, and extensionally-forced retracts during the Jurassic extensional phasesÑŽ This development resulted in the separation the southern component into two half-grabens resulting in Arruda and Turcifal sub-basins with the accompanying salt shifting from the Arruda sub-basin in the Montejunto Anticline separated the Arruda and Bombarral sub-basins.
The Arruda sub-basin corresponds to a half-graben produced during the Midsection Oxfordian-Late Oxfordian as a consequence of transtensional rifting attacks that have influenced the Estremadura Basin. This kind of sub-basin symbolizes an intra-continental pull-apart pot with a rhomb-like shape.