23 24 Large rounded pyrite grains (>1 mm), commonly referred to as ‘buckshot’ pyrites, are a characteristic feature of 25 the auriferous conglomerates (reefs) in the Witwatersrand and Ventersdorp supergroups. Detailed petrographic 26 analyses of the reefs indicated that the vast majority of the buckshot pyrites are of reworked sedimentary origin, 27 i.e., that the pyrite originally formed in th...

We report herein the first description of the physical structure of the aquatic habitats of the Lower Paraguay River along 390 km from Asunción city (Paraguay) to the confluence with the Paraná River. The hierarchical ordination of the Fluvial Hydrosystem Approach (FHA) allowed us to classify the Lower Paraguay as a meandering functional sector where five functional sets were identified: (a) ma...

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore, been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase extraction from fluvial bi...

[1] We compare morphologies of drainage basins on Mars and Earth in order to confine the formation process ofMartian valley networks. Basins on both planets are computationally extracted from digital topography. Integral-geometry methods are used to represent each basin by a circularity function that encapsulates its internal structure. The shape of such a function is an indicator of the style ...

The purpose of this paper is to first show how an Euler-Lagrange theorem can be applied to the steady-state fluvial landscape model, thereby allowing the geomorphic solution surfaces to be understood as those that globally optimize the difference between kinetic and potential energy dissipation (Hamilton’s Principle) while conserving mass. It is then shown how this variational formulation of th...

Introduction: Tyrrhena Terra is located in cratered and dissected Noachian terrains in the southern hemisphere [1] south of Isidia Planitia and north of Hellas basin. Tyrrhena Terra contains both highlands and a series of intercrater plains. In this region, many outcrops of phyllosilicates are observed by OMEGA spectrometer on many craters walls or ejecta [2, 3]. Several plains in Tyrrhena Terr...

Measurements of nutrient and suspended matter concentrations and loads entering and leaving the Castanhão reservoir during the rainy season were carried out to assess the influence of this large reservoir on land-sea fluvial transport in the ephemeral Jaguaribe river basin. Spatial variation indicated statistically significant attenuation of concentrations only for total phosphorous and suspend...

The theories of critical orogenic wedges and fluvial erosion are combined to explore the interactions between tectonics, erosion, and climate. A model framework is developed which allows the derivation of an exact analytical scaling relationship for how orogen width, height, and rock uplift rate vary as a function of accretionary flux and precipitation rate. Compared to a model with prescribed ...

Introduction: Impact crater degradation provides a powerful tool to analyze past Martian hydrological evolution. Previous studies concluded that large impact craters were strongly degraded during early Martian history, whereas younger craters are only weakly degraded [1]. Degraded craters are therefore one of the main lines of evidence for a warmer climate on early Mars. Global altimetry and re...

Fish passes facilitate fish movement in fragmented river systems, yet they can also provide important habitat functions. This study investigated the community composition of different constructed types (fluvial habitats, floodplain ponds) within relation to characteristics order deduce recommendations for fish-friendly designs such structures. structures differed significantly from those main r...