A pedo-geomorphological classification and map of the Holocene sediments in the coastal plain of the three Guianas

Stiboka onderzoe

Fossil and recent soil formation in Late Pleistocene sand deposits in the eastern part of the Netherlands.

Along the Slinge Brook near Winterswijk, a profile was investigated which is assumed to consist of two aeolian deposits: Old Coversand I at the bottom and Old Coversand II at the top, between which a fluvioglacial deposit occurs, the Beuningen Complex. The profile, which now is well-drained, was poorly drained from the beginning of the Holocene up to some centuries ago. The following soil forming processes were recognized micromorphologically: decarbonation, biological activity, clay illuviation, decomposition of illuviated clay and one or two cycles of gleying. It was concluded that: (1) during the deposition of the Beuningen Complex a hydromorphic cycle may have occurred in this profile; (2) between the beginning of the Bolling interstadial and the rise of the watertable at the beginning of the Holocene, biological activity and clay illuviation occurred and possibly some decarbonation; (3) between the beginning of the Holocene and recent times a hydromorphic cycle (possibly the second) took place; (4) finally in recent times biological activity and decarbonation occur. (Abstract retrieved from CAB Abstracts by CABI’s permission

Fossil and recent soil formation in lateleistocene loess deposits in the southern part of the Netherlands.

In the younger, Weichselian (Wurm, Wisconsin) loess deposits in the south of the Netherlands there is a horizon with fossil pedotubules (filled animal burrows). These pedotubules, 3 mm ( plus or minus 1 mm) in diameter, unbranched, without preferential orientation, are most abundant in the zone extending from about 30 cm above the decalcification boundary (situated 2-3 m below the soil surface) to some decimeters below it. They are rare in the B3t horizon of the overlying Hapludalf. Their lower extension boundary occurs some 2 m below the decalcification boundary. These tubules result from fossil animal activity followed by decalcification, mainly of a Boelling soil surface. A loess layer some 2 m thick was probably deposited in the post-Boelling period; the lower part of this layer has a lamellae spot zone. Micromorphological evidence shows that the lamellae spot zone was originally at the actual soil surface. Consequently a geogenic origin of the lamellae spot zone rather than a pedogenic origin seems likely. Soil formation subsequently intensified the textural differences. It is suggested that the post-Boelling loess was free of calcium carbonate at the beginning of the Holocene and was deposited non-calcareously or was decalcified synsedimentarily. In Western Europe, loess soils formed from Pleistocene deposits probably matured earlier in the Holocene than has been assumed hitherto. (Abstract retrieved from CAB Abstracts by CABI’s permission

Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype