The Sierra Nevada de Santa Marta (Santa Marta) in Colombia and Nevado del Famatina (Famatina) in Argentina are two isolated peaks within the Andes of South America, having elevations of about 5,500 and 6,000 m, respectively. Both massifs are bounded by major wrench faults of opposite kinematics but comparable magnitude in their lateral displacement. Despite the volumes of research available, little has been said in the literature about the tectonics surrounding these particular systems. In this context, digital terrain elevation (DEM), regional geology, satellite imagery and geophysical data were analysed to illustrate how a network of transcurrent faults uplifted the peaks. We propose a model to account for topography by the opposed movement of faults operating in two compartments: internal (acute) and external (obtuse). Fault motion caused uplift of the internal compartments: a) the Santa Marta tectonic syntaxis is generated by the sinistral Santa Marta-Bucaramanga Fault on the west and the dextral Oca-Pilar Fault to the north whilst, b) the Famatina tectonic syntaxis is caused by the Valle F´ertil sinistral fault on the western side and the dextral Tucum´an lineament to the north. Elevation maps documenting the lateral displacement of modern alluvial fans provide evidence of the existence and kinematics of these faults. Active since the Neogene, the transcurrent faults resulted in displacements in the order of 25–60 km, with velocities of approximately 1–2 cm/year. Seismic records suggest that the syntaxis occurred after reactivation of oblique discontinuities in the basement due to the convergence of the Nazca, Caribbean, and South American plates. This tectonic framework led to the formation of a remarkable positive relief and the development of internal positive compartments subject to onstrictive forces. Simultaneously, external distensive and negative compartments controlled the syntectonic deposition of thick sedimentary sequences. The significant topographic difference between the internal positive compartments and their external negative counterparts triggered high rates of erosion, transport, and ultimately sedimentation. Regional subsurface surveys indicate strong anomalies of the underlying bedrock influenced by tectonic syntaxis.

Geology and exploratory potential of the Cerro Cuadrado and El Bagual polymetallic epithermal manifestations (Santa Cruz, Argentina). The geology and exploratory potential of the polymetallic (Ag-Zn rich) epithermal manifestations of Cerro Cuadrado and El Bagual, located in the northwestern corner of the Santa Cruz province, in southern Patagonia, are described. Both manifestations are temporal and spatially associated with the emplacement of a dome and pyroclastic eruptive felsic units of the El Quemado Formation, related to the Jurassic plateau of the Deseado Massif. The main mineralization at Cerro Cuadrado and El Bagual occurs in veins, veinlets and brecciated areas along N-S trending fault corridors associated with apical portions and in the peripheries of domic structures with several hundred meters in diameter. In the Cerro Cuadrado, the mineralization is preferentially arranged in narrow vein corridors and banded areas rich in Ag and Zn that increase their thickness in dilating jogs of faults in the central portions of the dome. In the El Bagual, gold-silver veins and the presence of a subvertical cylindrical late intrusive body of a few dozen meters in diameter, called the Central Chimney, this structure represents a diatreme filled with volcanic agglomerates with metamorphic subangular lithic fragments of the underlying the Late Paleozoic Rio Lácteo Formation. Both polymetallic manifestations present a very interesting exploratory potential related to the outer areas of a Jurassic rhyolitic dome-complex model.

Satellite gravity datasets have been widely used in understanding of the Earth's internal structure and processes. These datasets are effective in providing insights into the lithospheric structure of the Earth. Gravity data from the satellite products CryoSat-2 and Jason-1 have been used to investigate the Gulf of Guinea sedimentary basins and structural lineaments in this under-explored marginal sea region through the application of various edge filters. Present-day filtering methods such as the analytical signal, tilt angle of the gradient amplitude, NTilt gradient amplitude and softsign function were evaluated for their performance on synthetic gravity anomalies with and without noise prior to their application to gravity data covering the Gulf of Guinea. The softsign filter outputs obtained from synthetic examples result in higher resolution and more explicit edges while preventing fictitious edges production in the findings. The results of the data interpretation disclosed deep-seated and shallow structural features within the Gulf of Guinea oriented mainly in the WNW-ESE, NW-SE, NE-SW and NNE-SSW directions and seen to be concentrated in the upper slope domain. This observation is in good agreement with the occurrence of drag folds and the apparent concentration of wrench faulting features across the ridge top and bordering the upper slope. These results bring new facts ruling our understanding of this atypical regional tectonic setting in close agreement with the NE–SW-striking Pelusium Megashear Zone.

We here review in terms of tectono-magmatic setting and Quaternary landscape dynamics what is known about
the provenance of Argentine dune fields and their fluvial feeder systems draining the Andean Cordillera. The
detrital signatures of these eolian sediments were previously investigated based on either framework petrography and heavy minerals or detrital-zircon geochronology, and their peculiar volcaniclastic nature was long
recognized. Compositional variability, however, was only broadly evaluated, and quantitative provenance
analysis based on a systematic multimethod approach across the entire region was not carried out so far. For this
reason, here we integrate original and previously obtained petrographic, heavy-mineral, and detrital-zircon
geochronology data to present the first comprehensive provenance study of dune fields stretching for 1000
km across central Argentina from the Andean piedmont to the Atlantic Ocean.
In dune fields along the Andean retroarc basin, sediment composition defines a steady northward decrease in
volcanic detritus. This reflects active magmatism in the Southern Volcanic Zone and Payenia province (38◦-
34◦S), in contrast with the ~600-km-long Pliocene-Quaternary magmatic gap in the Pampean flat-slab segment
(33◦-27◦S), where sediment is derived from deeper-seated tectono-stratigraphic levels of the continental arc and
uplifted blocks of retroarc-basin basement. In distal Pampean lowlands extending across the bulge and backbulge
depozones, instead, sand dunes display notably homogeneous compositional signatures, indicating that detritus
was mostly generated north of 34◦S and transported by a paleo-Desaguadero trunk river that formed during
southward-progressing diachronous uplift of the Sierras Pampeanas since the late Miocene. In contrast with huge
African and Arabian deserts that contain multiply recycled quartzose to pure quartzose sand, even very fragile
volcanic clasts, plagioclase feldspar, and unstable ferromagnesian minerals are widespread, testifying to largely
first-cycle volcanic provenance and only minor effects of mechanical breakdown and chemical weathering in the
Pampean Sand Sea.
During the Late Pleistocene, after a first southward shift of the Desaguadero trunk river possibly induced by
increased water and sediment discharge at the end of the penultimate glacial maximum, tectonic uplift eventually outpaced stream power during the last glacial period. Paleo-rivers were thus forced to shift farther
southwards, leading to the formation of an integrated paleo-Desaguadero+Colorado drainage system. During the
latest Pleistocene-early Holocene, such a large trunk river fostered the rapid progradation of a wide delta and
littoral sand transport all along the shores of the Buenos Aires Province. Climate change and repeated waxing and
waning of glaciers through the Quaternary have left a prominent mark on sediment distribution, dominated by
fluvial processes during periods of high fluvial discharge but alternating with arid phases characterized by
limited transport capacity and vegetation cover, extensive wind deflation of floodplains, and sand accumulation
in the dune fields.

The Mid Permian San Pedro porphyry deposit in the San Rafael Massif (central-western Argentina) offers a valuable opportunity to contribute in the understanding of ore concentration mechanisms operating during the phyllic alteration stage. In this deposit, two generations of low-temperature D-veins (D1 and D2) formed during the phyllic alteration stage. The D2-type veins show an atypical Cu-Ag sulfide paragenesis consisting mainly of galena, chalcocite, native silver, chalcopyrite and bornite, which can not be explained using the traditional cooling model. Based on previous research and own data, we test Reverse Osmosis as a possible mechanism contributing to D2-vein ore deposition. Reverse Osmosis is a pressure-driven retention-selective membrane filtration process resulting in solute/ion retention on the high-pressure side of the membrane. D2-veins from San Pedro porphyry formed at 211◦–176 ◦C during transient fluid overpressures produced by the hydrothermal sealing that followed the earlier D1-vein formation. Besides the temperature range and the declining orogeny, physico-chemical conditions were optimal for Reverse Osmosis to activate because the presence of a semi-permeable phyllic membrane and a transmembrane pressure gradient with hydrothermal fluid pressure exceeding the relatively low stress normal to the fracture walls (σn). This particular condition activated Reverse Osmosis, allowing to get similar membrane rejection values for Cu and Ag chloride complexes at lower fluid temperatures, causing the decrease of the osmotic differentiation performance, and the consequent coeval precipitation of Cu and Ag sulfide minerals.