Crustal structure and tectonic setting of the south central Andes from gravimetric analysis

Based on terrestrial gravity data, in this paper we prepared a map of Bouguer anomalies, which was filtered to separate shallow and deep gravity sources. Based on a density model and gravimetric inversion techniques, the discontinuous crust-mantle boundary and the top of crystalline basement were modeled. Subsequently, the equivalent elastic thickness (Te) was evaluated, considering information from the crust-mantle discontinuity and topographic load, finding high Te values in the eastern Andean foothills and west of the Velasco range. These results are consistent with the positive isostatic and residual Bouguer anomaly values, which suggest the presence of high-density rocks in the mid-to upper crust. In addition, petrographic and geochemical analysis conducted in surface outcrops suggest a mantle origin.     

Proglacial erosion rates and processes in a glacierized catchment in the Swiss Alps

In the Swiss Alps, climatic changes have not only caused glacier retreat, but also likely increased sedimentation downstream of glaciers. This material either originates from below the glacier or from periglacial environments, which are exposed as glaciers retreat, and often consist of easily erodible sediment. Griesgletscher's catchment in the Swiss Alps was examined to quantify erosion in the proglacial area, possible hydrological drivers and contributions of the sub‐ and periglacial sources. Digital elevation models, created from annual aerial photographs, were subtracted to determine annual volume changes in the proglacial area from 1986 to 2014. These data show a strong increase in proglacial erosion in the decade prior to 2012, coincident with increasing proglacial area size. However, examination of the gradient between discharge and sediment evacuation, and modeled sediment transport, could suggest that the proglacial area began to stabilize and sediment supply is limited. The large influx of sediment into the proglacial reservoir, which is roughly 2.5 times greater than the amount of sediment eroded from the proglacial area, demonstrates the importance of subglacial erosion to the catchment's sediment budget. Although far more sediment originates subglacially, erosion rates in the proglacial area are over 50 times greater than the rest of the catchment. In turn, both sub‐ and periglacial processes, in addition to constraining sediment supply, must be considered for assessing future sediment dynamics as glacier area shrinks and proglacial areas grow. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

A diverse rodent fauna from the middle Bartonian (Eocene) of Les Alleveys,Switzerland: snapshot of the early theridomyid radiation

A fossiliferous fissure filling at Les Alleveys, Mormont (Canton de Vaud, Switzerland), sampled in 1986 and representing part of the same fissure system as that excavated by Chavannes and Morlot in 1852, contains an Eocene mammal fauna of 27 species-group taxa, dominated by micromammals. Unlike the 1852 collection, thanks to screenwashing techniques, there is an abundance of rodents, especially theridomyids, which provide new information on the early radiation of the family. The homogeneity of the new assemblage suggests that the Les Alleveys fauna is entirely Bartonian in age and not as previously thought mixed with Priabonian elements. Bartonian faunas rich in a diversity of micromammals are relatively uncommon in Europe outside the Quercy region of France and this is the first such fauna from Mormont and from Switzerland. The rodents are here treated systematically and a new species of Elfomys, E. engesseri sp. nov. is described. A few teeth of an undescribed species tentatively referred to ‘Protadelomys’ provide an archaic element, whereas a single milk premolar of Patriotheridomys? suggests a considerable range for the genus prior to the middle Priabonian. The Les Alleveys theridomyids, together with a range of other early family members are analysed cladistically. The analysis confirms both the distinctness of the subfamily Remyinae and that the genus Estellomys is a primitive theridomyine; it shows Paradelomys to be a primitive member of the Columbomyinae, but finds no dental synapomorphies to support the Issiodoromyinae as represented by Elfomys and Pseudoltinomys.     

Soil stabilization with microbially induced desaturation and precipitation (MIDP) by denitrification: a field study

Acta Geotechnica - A field trial was performed to test the feasibility of microbially induced desaturation and precipitation (MIDP) by denitrification for the stabilization of a silty soil....