Clinoform growth in a Miocene,Para‐tethyan deep lake basin: thin topsets,irregular foresets and thick bottomsets

Late Miocene lacustrine clinoforms of up to 400 m high are mapped using a 1700 km² 3‐D seismic data set in the Dacian foreland basin, Romania. Eight Meotian clinoforms, constructed by sediment from the South Carpathians, prograded around 25 km towards southwest. The individual clinothems show thin (10–60 m thick), if any, topsets, disrupted foresets and highly aggradational bottomsets. Basin‐margin accretion occurred in three stages with changing of clinoform heights and foreset gradients. The deltaic system prograded into an early‐stage deep depocenter and contributed to high gradient clinoforms whose foresets were dominated by closely (100–200 m) spaced 1.5–2 km wide V‐shaped sub‐lacustrine canyons. During intermediate‐stage growth, 2–4 km wide canyons were dominant on the clinoform foresets. From the early to intermediate stages, the lacustrine shelf edges were consistently indented. The late‐stage outbuilding was characterised by smaller clinoforms with smoother foresets and less indentation along the shelf edge. Truncated and thin topsets persisted through all three stages of clinoform evolution. Nevertheless, the resulting long‐term flat trajectory shows alternating segments of forced and low‐amplitude normal regressions. The relatively flat trajectory implies a constant base level over time and was due to the presence of the Dacian–Black Sea barrier that limited water level rise by spilling to the Black Sea. Besides the characteristic shelf‐edge incision of the thin clinoform topsets and the resultant sediment bypass at the shelf edge, the prolonged regressions of the shelf margin promoted steady sediment supply to the basin. The high sediment supply at the shelf edges generated long‐lived slope sediment conduits that provided sustained sediment transport to the basin floor. Clinothem isochore maps show that large volumes of sediment were partitioned into the clinoform foresets, and especially the bottomsets. Sediment predominantly derived from frequent hyperpycnal flows contributed to very thick, ca. 300–400 m in total, bottomsets. Decreasing subsidence over time from the foredeep resulted in diminishing accommodation and clinoform height, reduced slope channelization and smoother slope morphology.     

Evaluation and archaeological potential of geophysical investigations of the Roman fort and baths in Northern Muntenia,România

The Roman fort from Sfârleanca is one of the most representative archaeological sites dating from the Roman period (2nd century A.D.) in Northern Muntenia. The existing natural and anthropic features of the environment required the application of geophysical methods in order to outline the spatial pattern of the buried remains, to define the geometry of the anthropogenic settlements and to obtain detailed information about different archaeological materials without digging. During the survey, two different geophysical methods have been employed: total magnetic field measurements and electrical resistance mapping using Twin-probe array. The instrument consists of GSM19W Overhauser magnetometers with GPS, in base-rover system, and a twin-probe array LGM 4-Point light hp. The measurements were used to draw primary maps of the physical parameters (total magnetic field strength/intensity, electrical resistance), and also processed maps (filtering, derivative). The magnetic results obtained by interpreting the anomalies yielded information about the limits of the fort, about the internal organization of the military structure (its axial road, partially its secondary road, the localization and the shape of its constructions) and at the bath and heating installation. A previously unknown element is the possible water supply pipe made of ceramic material highlighted by the mathematical modelling of the data obtained by the magnetic investigations. Electrical resistance results provide complementary information to the magnetic survey concerning the limits of the baths and the remains of the fort structure. This paper brings to light geophysical investigations into this Roman fort and baths, extending the picture produced by previous archaeological excavations that only dealt with a small part of the site. It indicates the importance of using geophysical methods in preliminary archaeological research and the advantages of combining total magnetic field measurements and electrical resistance mapping when investigating an archaeological site characterized by a number of environmental difficulties.     

Facies and architectural variability of sub-seismic slope-channel fills in prograding clinoforms,Mid-Jurassic Neuquén Basin,Argentina

Most slope-channel outcrop studies have been conducted at continental margin-scale on seismic data. However, in foreland and back-arc deepwater settings, sub-seismic scale slope channels hold equally important information on deepwater sediment delivery, often in hydrocarbon-bearing provinces. One such slope-channel system is examined in Lower Jurassic prograding shelf-margin clinoforms in Bey Malec Estancia, La Jardinera area, southern Neuquén Basin, Argentina. In a 4 km wide, 300 m tall, slightly oblique- to depositional-dip section of Jurassic Los Molles Formation deepwater slope deposits, seven clinoform timelines were identified by isolated slope-channel fills with thicknesses less than 50 m. Sedimentary logs, satellite images, a digital elevation model and drone photogrammetry were used to map variations in downslope channel geometry and infill facies. The slope channels are filled with sediment density flow deposits: poorly sorted conglomeratic debrites, structureless sandy high-density turbidites and well-sorted, fine-grained, graded low-density turbidites. The debrite portion decreases downslope, whereas high- and low-density turbidites increase. A grain-size analysis reveals a broad downslope fining trend of turbidite and debrite beds within slope channels with increasing water depth, and some notable bypass of conglomeratic facies to the lowermost slope channels and basin floor fans. The architecture of the slope channels changes from lateral to aggradational infill downstream. The Bey Malec clinoforms and its slope channels add new knowledge on downslope changes for sediment delivery in relatively shallow (<500 m water depth), prograding-dominant deepwater basins. They also highlight one of very few outcropping examples of oblique-type clinoforms.