Hydrocarbon generation and migration from Barremian – Aptian source rocks, Northern Orange Basin, offshore Western South Africa: A 3d numerical modelling study

A 3D numerical modelling workflow was applied to the Barremian—Aptian source rock interval in a shelfal to lower slope area of the northern Orange Basin, offshore western South Africa. The main objective was to investigate the timing of hydrocarbon generation and migration. Hydrocarbon migration has previously been investigated in the south of the basin by relating gas escape features with structural elements as seen on seismic sections, but migration pathways are still poorly understood. The modelling study was based on data from three exploration wells (AO-1, AE-1 and AF-1) together with 42 2D seismic sections totalling 3537 km in length, and a 3D seismic cube covering an area of 750 sq. km. Modelled formation temperatures increase from north to south in the study area and were consistent with downhole temperatures at well locations. However, there is variation between measured and modelled values of vitrinite reflectance (VR), especially in the Turonian and Cenomanian intervals. The measured VR is lower than the modelled VR within the Turonian section in the north of the study area, suggesting that erosion has affected the thermal maturity of the sediments. However, in the Cenomanian interval, the measured VR is higher than the modelled VR. Uplift, increased erosion in the hinterland and sediment transport to the coastal areas resulted in Cenomanian progradation of the Orange Basin fill

Introduction or reintroduction? Last resorts for the latest bird to become extinct in Europe, the Andalusian hemipode Turnix sylvatica sylvatica

The Andalusian hemipode (Turnix sylvatica sylvatica) (Order: Turniciformes, Family: Turnicidae), formerly distributed in several Mediterranean countries, is a critically endangered bird, if not already extinct. Subspecies of the T. sylvatica complex, in turn composed by nine subspecies are widely distributed in Africa and southern Asia. The last free-ranging Andalusian hemipodes were shot by hunters near Donana National Park (Spain) in 1981. Therefore, this species could be the last bird species getting extinct in Iberia and Europe in the XXth century. This investigation deals with the phylogenetic relationships of the Andalusian hemipode with the sup- posedly congeneric T. varia, T. tanki, T. suscitator and T. pyrrhothorax, and with the supposedly conspecific T. sylvatica lepurana, which is the geographically nearest buttonquail population (occurring in central and southern Africa). A 606 bp long fragment of the cytochrome b gene (approx. 1140 bp) of the mitochondrial DNA was sequenced, using both museum skins (the only available source for T. s. sylvatica) or blood/tissue samples from contemporary individuals (remaining species and subspecies). Seven haplotypes were found: two each for T. varia and T. s. lepurana, and one each for T. tanki, T. suscitator, T. pyrrhothorax, and T. s. sylvatica. Sequence divergence values obtained from pairwise distances between the T. sylvatica group haplotypes and the other species, ranged from 19.4 to 25.9%. The low genetic divergence between T. s. sylvatica and T. s. lepurana (0.00–0.01%) confirmed that the current classification based on morphological characters is correct, and that these two taxa may should be considered as subspecies. This close relationship would permit an introduction T. sylvatica where the species was last seen in Spain (i.e., Donana National Park). This area is now strictly protected and human persecution is no longer a problem.Peer reviewe