22 research outputs found
An efficient admission control model based on dynamic link scheduling in wireless mesh networks
Denial of service (DoS) attacks detection in MANETs using Bayesian classifiers
International audienc
Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation
New field data demonstrate that during the Late Ordovician (Hirnantian) glaciation, an ice sheet expanding northwestwards over the Anti-Atlas range reached into the southern Meseta of northern Morocco. Its growth to a glacial maximum position resulted in extensive subglacial erosion and deformation including the development of soft-sediment striated surfaces and streamlined subglacial bedforms preserved between the High Atlas of Marrakech and Rehamna. These features imply that this ice mass extended >200 km further than previously thought, and increase its size by at least ca. 190, 000 km2 (comparable in area to the UK). Correlation between a measured section in the High Atlas of Marrakech and that of the southern Meseta identifies sedimentary evolution within an ice-contact system common to both. These findings imply that the West African Craton and northern Morocco were in full glaciological communication during the latest Ordovician. Palaeogeographic reconstruction shows that beyond the ice sheet, south and southeastward palaeoslopes persisted on the shelf. A palaeohigh beyond the main ice sheet was a major source for sand, feeding delta systems that grew along the
shelf as far as the shelf break. This palaeohigh probably formed as a result of rift shoulder uplift and supported a satellite ice mass. In the eastern Meseta, a thick (350 m) underflow-dominated deep-marine fan was fed both from this shelf delta system and from glaciogenic debris derived fromthe main ice sheet. The occurrence of this unexpected deep-marine area in northern Morocco implies that continued
northward advance of the ice sheet was hampered by a dramatic break in bathymetry. Two depositional units are recognised across the Meseta, containing four distinct sedimentary cycles, each recognised as a glacioeustatic response to the waxing and waning of ice masses elsewhere in West Gondwana
On the use of IoT and big data technologies for real-time monitoring and data processing
Towards an IoT and big data analytics platform for the definition of diabetes telecare services
The impact of the end-Ordovician glaciation on sediment routing systems: A case study from the Meseta (northern Morocco)
Assessment of sediment redistribution by end-Ordovician ice sheets is crucial for the reconstruction of Lower Paleozoic source-to-sink patterns. Focusing on the ice-distal, deepwater Tazekka depocenter (Moroccan Meseta), we performed a provenance study that combined whole-rock geochemistry, petrography and insights from high-resolution detrital zircon ages. The results show that the glacigenic sediments are compositionally â mineralogically and geochemically â more mature than preglacial strata. This observation points to a preferential cannibalization of the âgreat Lower Paleozoic quartz-rich sandstone sheetâ, with a limited input of first-cycle, far-travelled clastic sediments. Differentiation of glacial units is not straightforward, yet the glaciation acme istypified by a highly mature sedimentary source and an age spectrum lacking Mesoproterozoic zircon grains, both features strongly indicating derivation from the CambrianâLower Ordovician cover of the Tuareg Shield. More regional sources are expressed during the earlier glaciation stages, during which lowstand remobilizations unrelated to subglacial erosion are also suspected. Subordinate but notable late Tonian (âŒ0.8 Ga) and latest Stenian to early Tonian (âŒ1 Ga) zircon populations are also evidenced inMorocco, which may have implications for future paleogeographic reconstructions