The Late Ordovician (Hirnantian) glaciation is examined through the North Gondwana record. This domain extended from southern high palaeo-latitudes (southeastern Mauritania, Niger) to northern lower (Morocco, Turkey) and covered a more than 4000 km-wide section perpendicular ice-flow lines. A major mid-Hirnantian deglaciation event subdividing Hirnantian in two first-order cycles recognised. As best illustrated by glacial record western Libya, each cycle comprises 2–3 phases separated...

ABSTRACT Rocks of Late Ordovician to Silurian age are well exposed on the western rim Murzuq Basin (Ghat‐Tikiumit area, Libya) where seismic‐scale exposures allow spectacular insights into growth and decay (Hirnantian) ice sheet. The final deglaciation left a complex topography with combination subglacial morphologies proglacial depositional systems. This paper documents glacial palaeo‐topography that controls accumulation postglacial transgressive system Rhuddanian (Early Silurian) shales....

Abstract The southern North Sea is a shallow epicontinental sea that was glaciated several times during the Quaternary. area known for its remarkable record of tunnel valleys, age and origin which are debated. recent availability continuous three-dimensional seismic data between coasts Britain Netherlands provides opportunity to establish new interpretation workflow adapted intracratonic glaciogenic successions. By analysing geomorphology buried basal unconformity, four distinct major ice...

Cadmium (Cd) isotope signatures (δ114Cd) deduced from modern and ancient marine deposits are often used as a proxy for bioproductivity micronutrient cycling, whereas chromium (Cr) (δ53Cr) potential oxygenation. The Cretaceous—Paleogene (K/Pg) boundary records one of Earth's five big mass extinctions, which contains geochemical fingerprints the Chixculub asteroid impact is coeval with Deccan Trap volcanism. Here we present first time combined record Cd Cr isotopes Danish Basin to interrogate...

Climbing dune-scale cross-statification is described from Late Ordovician paraglacial successions of the Murzuq Basin (SW Libya). This depositional facies comprised medium-grained to coarse-grained sandstones that typically involve 0·3 1 m high, 3 5 in wavelength, asymmetrical laminations. Most often stoss-depositional structures have been generated, with preservation topographies formative bedforms. Climbing-dune cross-stratification related migration lower-flow regime dune trains thus...

The southern termination of the Middle and Late Pleistocene Scandinavian ice sheets was repeatedly located in North Sea (sNS) adjacent, north‐sloping land areas. Giant meltwater‐excavated valleys (tunnel valleys) formed at contain a hitherto enigmatic succession northward prograding clinoforms, comprising 1000s km 3 sediment. This study analyses 3D seismic data, covering entire sNS, demonstrates for first time that formation these tunnel separate from their infill. infill constitutes...

Research Article| September 01, 2005 440 Ma ice stream in North Africa Julien Moreau; Moreau 1Ecole et Observatoire des Sciences de la Terre, Centre Géochimie Surface, 1 rue Blessig, 67084 Strasbourg cedex, France Search for other works by this author on: GSW Google Scholar Jean-François Ghienne; Ghienne Daniel Paul Le Heron; Heron 2CASP, Department of Earth Sciences, 181A Huntingdon Road, Cambridge CB3 0DH, UK Jean-Loup Rubino; Rubino 3Centre Scientifique Technique Jean Feger (CSTJF),...

Abstract The processes and the structures within middle lower crust are intimately related to evolution of orogenies, but more detailed knowledge is needed these deep crustal processes. Seismic reflection data, chiefly displayed in amplitude, commonly used interpret structures. strongest amplitude events probably lithological changes do not necessarily correspond geological structures, tectonic boundaries, or deformation fabrics. Furthermore, strain distribution between interpreted...

Abstract Mount Telout, situated at the edge of Murzuq Basin, is a 325 m high conical hill within circular collapse structure that records 0·5 km 3 sand intrusion into Silurian shales. Based on comparison with other similar structures around it argued injection in form pipes occurred during Devonian. The overpressures triggering process are inferred to result from combination of: (i) tectonic uplift basin scale initially focused regional ground water flows; and (ii) igneous sand‐rich...

Abstract Deep, elongated incisions, often referred to as tunnel valleys, are among the most characteristic landforms of formerly glaciated terrains. It is commonly thought that valleys were formed by meltwater flowing underneath large ice sheets. The sedimentary infill these features highly intricate and therefore difficult predict. This study intends improve comprehension sedimentology establish a conceptual model tunnel‐valley infill, which can be used predictive tool. To this end, densely...

F innish L apland is known as an area where numerous sites with sediments from P leistocene glacial and interglacial periods occur. Recent sedimentological observations dating call for reinterpretation of the record, which shows a complicated M id‐ W eichselian ice‐sheet evolution within ice‐divide zone. Here, large, previously unstudied section former H annukainen iron mine was investigated sedimentologically dated optically stimulated luminescence ( OSL ). Ten sedimentary units were...

Abstract Detailed facies analysis of a 350 m long core upper Campanian–Maastrichtian chalk at Stevns Peninsula, eastern Denmark, shows that four mudstone and wackestone account for close to 95% the succession, bioturbated alone accounts nearly 55% sediment. Sedimentation took place in deep water, below photic zone storm‐wave base, is characterized by decimetre metre‐scale variations trace fossil assemblages indicating repeated shifts depositional environment. Integration with published data...

In the Murzuq Basin, Late Ordovician glaciogenic succession forms a very complex clastic reservoir system. Although structural setting is simple, architecture of stratigraphic particularly intricate, and conventional wireline logs display rather homogeneous signatures. However, when exposed, sedimentary indicates large range depositional environments clear changes. Based on high-quality processing interpretation microresistivity image over single well, our method allows precise recognition...

Abstract The Late Palaeozoic glaciation was the longest of Phanerozoic era. It is recorded in numerous Gondwanan basins, with some, such as Chaco Basin, having a high petroleum potential. In this basin, quality available seismic, well and outcrop data permits us to characterize glacial record. Palaeovalleys that are c . 500 m deep 7 km wide have been analysed here. Focusing on glaciogenic Carboniferous deposits, seismic ties analogues provide new sedimentological insights. palaeovalley...

Abstract The genesis of polygonal faults is an intriguing diagenetic phenomenon. This study discusses their origin in carbonate mudstones together with other associated features. In the eastern Danish Basin, at fringe Baltic Sea, Stevns peninsula offers a unique opportunity to early diagenesis Upper Cretaceous Chalk deposits, buried between 500 m and 1400 m. paper combines data from onshore offshore high‐resolution seismic reflection profiles, fully cored borehole wireline logs quarry...

We present data for 31 kilometre-scale hydrothermal vent complexes and associated sand remobilization that have formed as a consequence of magmatic intrusions within salt strata (southern North Sea, Dutch Sector). This study uses 3D seismic tied to three wells artificial neural networks describe conical cylindrical structures located in the NE part Broad Fourteens Basin. The are composites 58 subvertical pipes form complexes, 951 ± 364 m height 487 426 diameter. Interactions magma fluids at...

Attenuated and highly elongate glacial lineations, known as mega-scale lineations (MSGLs), are produced on the deforming bed of fast-flowing modern palaeo-ice streams (Canals et al. 2000; Stokes & Clark 2001; King 2009). Large cross-shelf troughs, often containing also diagnostic past activity. MSGLs widespread exposures western Murzuq Basin in Libya (Moreau 2005); examples these other streamlined landforms, together with converging patterns ice flow evidence deformable-bed conditions, have...

Analysis of offshore glacial geomorphology is becoming a popular topic since the massive release industrial seismic data in North Sea. As well, glaciogenic sediments are involved several petroleum systems (Permo-Carboniferous, Ordovician rocks).

Abstract Lake margin sedimentary systems have been the subject of only limited study. The cyclic Middle Devonian lacustrine succession Northern Scotland contains repeated developments shore zone sandstones and thus provides an ideal location for study these units. cycles comprise deep lake, shallow playa facies. Detailed field observations are presented alongside ground penetrating radar data which has aided large‐scale three‐dimensional characterization sand bodies. Loading discrete channel...