Abstract The Ofanto River drains volcanic rocks from the Monte Vulture, lacustrine–fluviolacustrine deposits associated with the same volcano and sedimentary deposits of the Southern Apennines and the Bradanic foredeep sequences. Comparing the modal composition of river sands and the outcrop area of different lithologies in the different sub-basins, an over-concentration of the volcaniclastic fraction, mainly represented by loose crystals of clinopyroxene, garnet and amphibole, is shown. This has been related to the preferential erosion of pyroclastic deposits, characterized by high production of sand-sized loose minerals, together with the carbonate lability and the low sand-sized detritus production from claystones and marls. The occurrence of volcaniclastic components upstream of Monte Vulture can be explained as a contribution from the lacustrine–fluviolacustrine deposits cropping out in the upstream sector or from pyroclastic fall deposits of Monte Vulture and/or Campanian volcanoes. This research shows that the volcanic record in the fluvial sands of the Ofanto River comes from weathering and sorting processes of volcaniclastic deposits rather than of the lavas building the main edifice. Therefore, caution must be taken during palaeoenvironmental and palaeoclimatic reconstructions when relating the type and abundance of the volcanic component in sediments to the weathering stage and evolutionary history of the volcano.

ABSTRACT Mount Diablo State Park exemplifies many other conservation areas where managers balance the dual missions of protecting natural resources while providing public access. Roads and trails that crisscross the park are etched into the geomorphic surface, capturing and redirecting storm runoff, and presenting both a challenge for soil conservation and a consequence of construction and maintenance. We used field mapping, remote sensing, and modeling to assess erosion along the roads and trails in Mount Diablo State Park, which encompasses the headwaters of several urbanized watersheds. The field mapping in 2011 determined that 56% of the assessed roads and trails required either repair or reconstruction to control erosion and that ~67% of the culverts in the park required either repair or replacement. Aerial photography and modeling showed that other erosion (unrelated to roads or trails) preferentially occurred during wet periods, in specific lithologies, and on convergent slopes. Although lithology and climate drive slope-forming geomorphic processes, we found that the road and trail system (1) expanded the stream network with a capillary-like system of rills, (2) catalyzed prolonged erosion, and (3) altered the timing and pattern of sediment yield. In addition to water-driven erosion during wet periods, road and trail surfaces were subject to mechanical and wind erosion during dry periods. Spatially, dry erosion and runoff both conformed with and crossed topographic gradients by following the road and trail network. Road- and trail-induced erosion occurred across a wider range of rock properties and slope geometries than is typical for other erosion. Hence, the roads and trails have expanded the spatial and temporal boundary conditions over which geomorphic processes operate and, due to continual soil disturbance, have accelerated erosion rates. Although road density is a commonly used metric to rank road-related impacts at watershed scales, it misses both spatial variability and the opportunity to identify specific road and trail segments for remediation. We developed a spatially explicit scoring scheme based on actual erosion and the potential for sedimentation of discrete waterbodies. The data were incorporated into the park’s road and trail management plan in 2016.

Abstract The Oligocene–Early Miocene Maykop depositional system of the Western Black Sea Basin is investigated in terms of sediment supply and provenance. Potential sediment source regions and conduits for sediment supply into the deep-water portion of the basin are evaluated based on the tectonic history and framework of the region, and are supported by observations from published well, reflection seismic and isopach data. The outcrop geology of the present-day land areas adjacent to the basin is used as a guide to the likely provenance and, hence, quality of potential siliciclastic reservoirs. Reservoir presence and reservoir quality are key subsurface risks for exploration in deep-water plays involving Maykop turbidite sandstones and charge from the well-known Maykop organic carbon-rich mudstones that are widespread across the basin. Sediments sourced from the NE Moesian Platform and Dobrogea, channelled into the offshore Black Sea via the Histria Trough, are considered moderate risk in terms of primary reservoir quality, as evidenced by thick packages of fine-grained sediment. In contrast, sediments derived from the southern Strandja Massif fed into the Burgas Basin, and potentially into the deeper-water Turkish Black Sea, are relatively low risk in terms of reservoir quality, given the abundance of acidic intrusions within the massif. Sediment derived from parts of the northern Strandja Massif, especially the volcaniclastics of the Srednogornie region, are likely to have poorer reservoir quality characteristics. Sediments derived from the granitic Bolu Massif within the Pontides might be of good reservoir quality but are likely to be ponded behind the offshore Kozlu Ridge. An important sediment source-to-sink system was derived from the Balkanides and entered the deeper-water western Black Sea via the Kamchia Trough. The present-day Kamchia river is a relatively minor sediment supplier to the Black Sea, but the palaeo-Kamchia river of the Oligocene–Early Miocene would have exploited a much greater drainage area consisting of an axial trunk stream, occupying the newly formed Kamchia Foredeep to the north of the Balkanides, and transverse rivers sourcing sediment from the granitic and gneissic bodies of the Balkan Mountains and from Early Cretaceous and Palaeogene sandstones. These would provide reasonable reservoir quality, and it is estimated from reference source-to-sink relationships that offshore sediment flux via this system was probably at least eight times greater than at present. Known shelf-edge canyons in offshore Bulgaria facilitated this sediment reaching the deep water offshore, where a sedimentary fan with a length in excess of 150 km is likely to have developed. This suggests that the potential is good for encountering good-quality reservoir sands in the Maykop succession deep water of the western Black Sea, and this aspect of regional play risk could be of less concern than was previously considered.

Abstract The role of climate change in driving alluvial-fan sedimentation is hard to assess in pre-Quaternary successions, for which detailed chronologies and climate-proxy records cannot be easily established. In the Teruel Basin (Spain), high-resolution (10 4 –10 5 years) chronological and palaeoclimatic information was derived by orbital tuning of Late Miocene mudflat to ephemeral-lake deposits. The semi-arid palaeoclimate made this low-gradient, basinal environment sensitive to thresholds in the local hydrological balance. Basic facies rhythms are attributed to alternating, relatively humid/arid phases controlled by the climatic precession cycle. The lower stratigraphic interval of this reference section interfingers with distal, coarse-clastic beds from a coeval alluvial fan. The consistent interdigitation of debris-flow deposits with distal strata indicative of arid-to-humid climate transitions shows that fan sedimentation was regulated by climate cyclicity. In particular, the largest volumes of terrigenous debris were shed from the fan onto adjacent mudflats during transitions to relatively humid periods with pronounced seasonality, during precession minima. Distal to medial sections within alluvial-fan outcrops also feature prominent, laterally continuous alternations of coarse- and fine-clastic packages. This high degree of architectural organization, uncommon in fan successions, and stratigraphic relationships with the reference section suggest orbitally controlled climate change to have been the forcing mechanism.