Basement-cover interaction in the mountain front of the Northern Neuquén fold and thrust belt (37°10’ – 37°40’ S), Argentina

TURIENZO, MARTÍN; SÁNCHEZ, NATALIA; LEBINSON, FERNANDO; PERALTA, FLORENCIA; ARAUJO, VANESA; IRASTORZA, AINARA; DIMIERI, LUIS

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 100

0895-9811

The deformation front of the Neuquén fold and thrust belt (~37°30?S) comprises25 kilometer-scale basement-involved anticlines, related to development of the Las Yeseras26 and Pampa Tril thrust systems, connected with a wide frontal syncline. The27 interpretation of more than 70 seismic lines led to the construction of a time-structure28 map at top of the Cuyo Group (Middle Jurassic), which shows a structural high east of29 the Tromen volcano produced by the superposition of thick-skinned structures.30 Moreover, data from 35 oil wells constrain the along-strike variations in structural31 reliefs. The structural relief of the Las Yeseras anticline increase from north to south,32 between ~1000 m and 2000 m, while the structural relief of the Pampa Tril anticline 33 reaches its maximum height of 3700 m in the north and decreases southwards to only34 1600 m height and then disappears. Three structural cross-sections based on surface and35 subsurface information show the overall structural style dominated by north-trending36 basement-involved anticlines, with subhorizontal backlimbs and maximum structural37 reliefs around 3-4 km, associated with thick-skinned thrust systems and without38 significant participation of inverted normal faults. Calculated thick-skinned shortenings39 are ~8.3 km (14.8%) in the north and ~4 km (7.8%) in the south, which principally40 reflects the decreasing displacement of the Pampa Tril thrust system. Along-strike41 structural changes were locally controlled by WNW transfer zones that can be42 interpreted as SSW-dipping preexisting normal faults with minor positive inversion.43 Thin-skinned structures that form oil fields at depth are genetically associated with the44 thick-skinned thrust systems, thus the understanding of basement-cover interaction in45 the mountain fronts will aid to future hydrocarbon explorations and to comprehend the46 mechanisms of Andean mountain building.