The synrift of theHuincul High, Neuquén Basin: Evolution and control on the stratigraphy andstructure of the area

Abstract

The Huincul High constitutes an outstanding E-Wmorpho-structural feature that splits the Neuquén Basin into two, it spans formore than 250 km from the Andean orogenic front, eastwards to the General Rocaarea. It is composed by a trend of E-W oriented, strongly asymmetric and southverging anticlines with a vertical throw exceeding 1.5 km. The evolution of theHuincul High began with the development of a series of NW orientedhalf-grabens, typically with the downthrown block to the north; this tendencyshifts in the eastern end to more WNW-ENE oriented half grabens. They arenormally 10 to 20 km long in strike direction with a 1.5 to 5 km thick infillof Upper Triassic to Lower Toarcian deposits. The morphology previous to thefirst marine transgressions during Early Jurassic times was of a series ofhalf-grabens whose relief had been partly leveled by the volcanic and clasticdeposits of the Precuyano; besides prominent basement highs and volcanicedifices controlled the distribution of the Jurassic marine sediments. Theinfluence of the rift subsidence is well documented until Early Toarcian times;afterwards the area went through a period of relative tectonic quiescenceaccompanied by the progradation of the depositional systems from the southregardless of the underlying structural features. The development of acompressive system spanning from the Upper Jurassic to the Upper Cretaceousgave the Huincul High its present day configuration.