The Preandean geological confguration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis.The positive gravity anomalies located near the Atlantic coast are due to535 and 540 Ma old rocks belonging to the Pampean Orogeny(Precambrianemiddle Cambrian),which are widely recognized in central and northern Argentina.The Famatinian Cycle(OrdovicianeDevonian)is represented by a SilurianeDevonian marine basin equivalent to those of eastern-central Argentina and South Africa,and which was deformed at the end of the Devonian by an wEeW to WNWeESE compressional event,part of the Famatinian Orogeny.Containing strong gravity gradients,the NWeSE belt is coincident with fault zones which were originated during the Gondwanide Orogeny.This event also produced NWeSE overthrusting of the SilurianeDevonian sequences and strike-slip faults that displaced blocks in the same direction.This deformation event belongs to the Gondwanide Orogeny that includes movements related to a counterclockwise rotation of blocks in northern Patagonia.The strong negative anomalies located in the western part of the area stem from the presence of rocks of the Jurassic Ca adón Asfalto basin interbedded in the Marifl Complex.These volcaniclastic sequences show mild deformation of accommodation zones in a pre-Jurassic paleorelief. The Preandean geological confguration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis. The positive gravity anomalies located near the Atlantic coast are due to535 and 540 Ma old rocks belonging to the Pampean Orogeny (Precambrianemiddle Cambrian), which are widely recognized in central and northern Argentina. The Famatinian Cycle (OrdovicianeDevonian) is represented by a SilurianeDevonian marine basin equivalent to those of eastern-central Argentina and South Africa, and which was deformed at the end of the Devonian by an wEeW to WNWeESE compressional event , part of the Famatinian Orogeny. Contact strong gravity gradients, the NWeSE belt is coincident with fault zones which were originated during the Gondwanide Orogeny. This event also produces NWeSE overthrusting the SiluriaDevonian sequences and strike-slip faults that displaced blocks in the same direction .This deformation event belongs to the Gondwanide Orogeny that include s movements related to a counterclockwise rotation of blocks in northern Patagonia. The strong negative anomalies located in the western part of the area stem from the presence of rocks of the Jurassic Ca adón Asfalto basin interbedded in the Marifl Complex. the volcaniclastic sequences show mild deformation. of accommodation zones in a pre-Jurassic paleorelief.