Geological evidence for fluid overpressure, hydraulic fracturing and strong heating during maturation and migration of hydrocarbons in Mesozoic rocks of the northern Neuquén Basin, Mendoza Province, Argentina. (October 2015)

• Record Type: Journal Article
• Authors: Zanella, Alain; Cobbold, Peter R.; Ruffet, Gilles; Leanza, Hector A.
• Is Part Of: Journal of South American earth sciences. Volume 62(2015:Oct.)
• Page Start: 229
• Page End: 242
• Publication Date: 2015-10
• Subjects: Neuquén basin -- Mendoza province -- 'Beef' -- bitumen veins -- Hydrocarbon migration -- Fluid overpressure -- 39Ar-40Ar; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2015.06.006
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: In the northern Neuquén Basin of Argentina (especially in Mendoza Province), there is strong geological evidence for fluid overpressure in the past. The evidence takes the form of bitumen veins and bedding-parallel veins of fibrous calcite ('beef'). Such veins are widespread in the fold-and-thrust belt of the Malargűe area, where bitumen mining has been active for a century or so. So as to collect information on the development of fluid overpressure in this part of the Neuquén Basin, several old mines were visited and studied in the Malargűe area. Here the bitumen veins have intruded mainly the Late Jurassic to Early Cretaceous Mendoza Group, but also the Late Cretaceous Neuquén Group. The veins have the forms of bedding-parallel sills or dykes and they are especially thick within anticlines, forming saddle-reefs in several places. Beef veins are also numerous in the Malargűe area. They contain bitumen and therefore seem to have formed at the same time as the bitumen veins. Near many outcrops of bitumen and beef, we have found fine-grained volcanic intrusive bodies. The best examples are from the La Valenciana syncline. According to 39 Ar- 40 Ar dating, these bodies are mainly of Mid-Miocene age. More generally, volcanism, deformation and maturation of source rocks seem to have reached a climax in Miocene times, when the subducting Pacific slab became relatively flat. Highlights: Beef and bitumen veins are widespread in the northern part of the Neuquén Basin. Beef and bitumen veins provide geological evidence for hydraulic fracturing. Hydrocarbon generation led to fluid overpressure and hydraulic fracturing. Volcanic activity has contributed to maturation of the source rock.