{{Short description|Fault that extends from the Neuquén Basin eastwards into the Argentine Shelf}} {{distinguish|Huincul Formation}} [[File:EIA_Neuquen_Basin.png|thumb|250px|Map of Vaca Muerta Formation in Neuquén Basin. The formations extent mimics that of the basin. Colors indicate hydrocarbon maturity as measured by vitrinite reflectance. Huincul basement high is shown in grey.]]
The '''Huincul Fault''' or '''Huincul Fault Zone''' ({{langx|es|Falla de Huincul, Zona de falla Huincul}}) is an east-to-west-oriented, continental-scale fault that extends from the Neuquén Basin eastwards into the Argentine Shelf, passing near the cities of Plaza Huincul and Cutral Có, in central Neuquén Province (approximately {{coord|-38.65|-69.20|region:AR|display=inline}}).<ref name=Ramosetal2004>{{cite journal|last1=Ramos|first1=V.A.|last2=Riccardi|first2=A.C.|last3=Rolleri|first3=E.O.|date=2004|title=Límites naturales del norte de la Patagonia|url=http://www.scielo.org.ar/scielo.php?pid=S0004-48222004000400024&script=sci_arttext&tlng=en|journal=Revista de la Asociación Geológica Argentina|volume=59|issue=4|language=es}}</ref><ref name=Mosqueraetal2011>{{cite conference|url=https://www.researchgate.net/publication/284701478|title=La estructura de la dorsal de Huincul|last1=Mosqueira|first1=Alfonso|last2=Silvestro|first2=José|author-link3=Víctor Alberto Ramos|last3=Ramos|first3=Víctor A.|last4=Alarcón|first4=Martín|last5=Zubiri|first5=Martín|date=2011|book-title=Relatorio del XVIII Congreso Geológico Argentino, Neuquén, 2011|pages=385–397|language=es}}</ref> To the west, it has been proposed that the fault extends across the Andes to the Chilean Coast Range.<ref name=Mosqueraetal2011/>
In the Neuquén Basin, the fault exhibits a slightly curved path, being convex to the north.<ref name=Kostadinoffetal2005>{{cite journal|last1=Kostadinoff|first1=José|last2=Gregori|first2=Daniel A.|last3=Raniolo|first3=Daniel A.|date=2005|title=Configuración geofísica-geológica del sector norte de la provincia de Río Negro|url=http://www.scielo.org.ar/pdf/raga/v60n2/v60n2a11.pdf|journal=Revista de la Asociación Geológica Argentina|volume=60|issue=2|pages=368–376|access-date=May 14, 2017|language=es}}</ref> It is a major geological discontinuity and it truncates the north-to-south-oriented Pampean orogen, among other structures. Because of this, it has been proposed to represent the northern geological limit of Patagonia.<ref name=Ramosetal2004/>
==Origin and development== The fault develops on the suture zone between the Patagonian terranes and western Gondwana.<ref name=MosqueraRamos2006/> In a broader sense, the Huincul Fault Zone is a belt of deformation, thus it is the suture zone itself. The first and main deformation phase along the fault zone began in the Toarcian age continued through the Valanginian age before vanishing in Albian times.<ref name=Mosqueraetal2011/> Strike-slip movement along the fault began in the Toarcian.<ref name=MosqueraRamos2006/> The main stress vector (i.e. direction of compression) was originally northwest-oriented but shifted over time to the north-northwest. In the Late Miocene, the last phase of deformation began with east–west compression followed by tectonic extension in Pliocene times.<ref name=Mosqueraetal2011/>
The different stages of deformation were a consequence of the successive subduction of the Aluk, Farallon, and Nazca plates beneath the plates of Gondwana and then South America.<ref name=Mosqueraetal2011/>
==Geological structures== A structure associated with the fault, the Huincul basement high or Huincul Ridge ({{langx|es|Dorsal de Huincul}}) divides the Neuquén Basin in two parts.<ref name=MosqueraRamos2006>{{cite journal|last1=Mosquera|first1=Alfonso|last2=Ramos|first2=Víctor A.|author-link2=Víctor Alberto Ramos|date=2006|title=Intraplate Deformation in the Neuquén Embayment|journal=Geological Society of America Special Papers|volume=407|pages=97–123}}</ref><ref name=Pangaroetal2009>{{cite journal|last1=Pángaro|first1=Francisco|last2=Pereira|first2=Diego Martín|last3=Micucci|first3=Eduardo|date=2009|title=El sinrift de la dorsal de Huincul, Cuenca Neuquina: evolución y control sobre la estratigrafía y estructura del área|url=http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0004-48222009000600004|journal=Revista de la Asociación Geológica Argentina|volume=65|issue=2|language=es}}</ref> The basement high is one of the most studied features of the Neuquén Basin, given its importance for hydrocarbon exploration and production.<ref name=Pangaroetal2009/> The basement high has an approximate length of {{convert|250|to|300|km|mi|abbr=on}}.<ref name=Pangaroetal2009/><ref name=Mosqueraetal2011/> Various ideas have been expressed concerning the nature of this structure. In the 1970s and 1980s, it was proposed to be a transpressive fault zone.<ref name=MosqueraRamos2006/><ref name=Pangaroetal2009/> Later, Pángaro ''et al.''. described it as being made up of inverted half-grabens.<ref name=Pangaroetal2009/> East of city of Neuquén, the fault roughly follows the path of the upper course of Río Negro. In this region, a series of basement highs and small pull-apart basins has formed along the fault, reflecting a clockwise movement.<ref name=Kostadinoffetal2005/>
==References== {{reflist}}
{{Major South American geological formations}}
Category:Seismic faults of Chile Category:Seismic faults of Argentina Category:Strike-slip faults Category:Suture zones Category:Geology of Araucanía Region Category:Geology of Buenos Aires Province Category:Geology of La Pampa Province Category:Geology of Neuquén Province Category:Geology of Río Negro Province Faults