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See detailCycles of humid-dry climate conditions around the P/E boundary: New stable isotope data from terrestrial organic matter in Vasterival section (NW France)
Storme, Jean-Yves ULg; Dupuis, C.; Schnyder, J. et al

in Terra Nova (2012), 24(2), 114-122

The Palaeocene/Eocene boundary (P/EB) and the Palaeocene-Eocene Thermal Maximum (55.8Ma) are defined stratigraphically based on carbon isotope ratios of various materials. Here, the position of the P/EB ... [more ▼]

The Palaeocene/Eocene boundary (P/EB) and the Palaeocene-Eocene Thermal Maximum (55.8Ma) are defined stratigraphically based on carbon isotope ratios of various materials. Here, the position of the P/EB is refined in the terrestrial-lacustrine and swampy Vasterival section (Upper Normandy coast, France) by using carbon isotopes measured on dispersed organic matter (δ 13C org). Moreover, nitrogen isotopes on dispersed organic matter (δ 15N org) are, for the first time in the Palaeogene record, associated with carbon isotope and lithological data to constrain palaeoclimatic and environmental changes around the P/EB in a terrestrial environment. Humid-dry fluctuations before and during this key interval in Earth history are suggested. © 2012 Blackwell Publishing Ltd. [less ▲]

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See detailThe Palaeocene/Eocene boundary section at Zumaia (Basque-Cantabric Basin) revisited: New insights from high-resolution magnetic susceptibility and carbon isotope chemostratigraphy on organic matter (δ 13C org)
Storme, Jean-Yves ULg; Devleeschouwer, X.; Schnyder, J. et al

in Terra Nova (2012), 24(4), 310-317

The Zumaia section, the most complete and representative section of the early Palaeogene (hemi)-pelagic succession of the Pyrenees, is widely acknowledged as a key reference for the Palaeocene-Eocene ... [more ▼]

The Zumaia section, the most complete and representative section of the early Palaeogene (hemi)-pelagic succession of the Pyrenees, is widely acknowledged as a key reference for the Palaeocene-Eocene boundary. New high-resolution δ 13C org of the Zumaia section (-23.8 to -28.8‰) confirms the position of the Carbon Isotope Excursion and enhances the distinction between the different steps of the CIE/PETM event. According to new magnetic susceptibility data and detailed cycle counting, the entire duration of the CIE/PETM in Zumaia is estimated in ∼168±16ka. Moreover, the investigation of palynofacies and low-field magnetic susceptibility reveal significant detrital influx during the interval. Several magnetic susceptibility phases and trends are recognised and are interpreted in terms of sea-level fluctuations before, during and after the PETM. Coupled with results from other sections, our data reveal the presence of an unconformity followed by an eustatic sea-level rise (TST) in the latest Palaeocene. © 2012 Blackwell Publishing Ltd. [less ▲]

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See detailMonitoring and mapping landslide displacements: a combined DGPS-stereophotogrammetric approach for detailed short- and long-term rate estimates
Demoulin, Alain ULg

in Terra Nova (2006), 18(4), 290-298

Although desirable for a reliable hazard assessment, rate estimates of landslide motion rarely combine a good time resolution and a sufficiently long time of observation. Here, both angles are tackled for ... [more ▼]

Although desirable for a reliable hazard assessment, rate estimates of landslide motion rarely combine a good time resolution and a sufficiently long time of observation. Here, both angles are tackled for the Manaihan landslide (East Belgium), dramatically reactivated in September 1998. I monitored the landslide displacements by repeated Global Positioning System (GPS) surveys from 1999 to 2005. Two digital elevation models were also produced, one of the landslide topography in 1999 by GPS and a second by stereophotogrammetry from aerial photographs of 1953. Subtracting one model from the other, I mapped the height changes within the landslide over the 1953-1999 period. All measurements consistently showed that, beyond the sudden similar to 1.5 m slip of September 1998, the landslide moved at a mean rate of c. 20 cm yr(-1) since 1980. Most displacements occurred around the winter's end, when long-lasting precipitation combined with minimal evaporation and occasional intense daily rainfall. The motions are spatially determined by seepage from a broken sewage pipe inducing local high pore pressures. [less ▲]

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See detailThe north-eastern Polish anorthosite massifs: petrological, geochemical and isotopic evidence for a crustal derivation
Wiszniewska, Janina; Claesson, Stefan; Stein, Holly et al

in Terra Nova (2002), 14(6), 451-460

Deeply buried 1.5 Ga Polish anorthosites, accessible only by bore holes, reveal diagnostic features of some massif-type anorthosites (polybarism, jotunitic parent magma), diapirically emplaced in the mid ... [more ▼]

Deeply buried 1.5 Ga Polish anorthosites, accessible only by bore holes, reveal diagnostic features of some massif-type anorthosites (polybarism, jotunitic parent magma), diapirically emplaced in the mid crust together with the rapakivi granites of the EW-trending Mazury complex, intruded along a major crustal discontinuity. Geochemical modelling and isotope data corroborate recent experimental work on the basaltic system in dry conditions: the source rock of the parental magma is a gabbronorite, necessarily lying in the lower crust. Since no Archaean crust is known in the region, high initial Os-188/Os-187 ratios for sulphide-oxide isochrons and negative epsilon(Nd) values are best accounted for by melting a similar to 2.0 Ga mafic crust. [less ▲]

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See detailKarst in granitic rocks, South Cameroon: cave genesis and silica and taranakite speleothems
Willems, Luc ULg; Compère, Philippe ULg; Hatert, Frédéric ULg et al

in Terra Nova (2002), 14(5), 355-362

A cave in granitic rocks was studied in Mezesse, South Cameroon. Coralloid speleothems, draperies and dissolution traces on the cave walls attest to its truly karstic nature. The speleothems consist of ... [more ▼]

A cave in granitic rocks was studied in Mezesse, South Cameroon. Coralloid speleothems, draperies and dissolution traces on the cave walls attest to its truly karstic nature. The speleothems consist of microlayers of opal and taranakite (K,NH4)Al-3(PO4)(3)(OH).9H(2)O. They indicate a significant mobilization of silica, Al and K from granite during the formation of the cave. Identification of silicified bacteria in the speleothems layers suggests a possible role of these micro-organisms in silica deposition. The presence of taranakite and of silicified organic remains within the speleothems lead to a better understanding of the genesis of the cave. [less ▲]

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See detailImaging downward granitic magma transport in the Rogaland Igneous Complex, SW norway
Bolle, Olivier ULg; Trindade, Ricardo I.F.; Bouchez, Jean-Luc et al

in Terra Nova (2002), 14(2), 87-92

Combining geological mapping and petrological, structural and geophysical (gravity and seismic) data already available for the late Proterozoic Rogaland Igneous Complex of Norway allows the 3D shape of ... [more ▼]

Combining geological mapping and petrological, structural and geophysical (gravity and seismic) data already available for the late Proterozoic Rogaland Igneous Complex of Norway allows the 3D shape of the Bjerkreim-Sokndal layered intrusion to be modelled as a thick cumulate series capped by massive granitic rocks. Using the latter data, along with the spectacular convergent linear flow pattern that covers both the cumulates and the felsic rocks of this chamber, evidence is presented to show that the granitic material was down-dragged through the sinking of its high-density mafic floor into lower density anorthosites and granulitic gneisses. This example illustrates that downward gravity-driven flows of rocks were active, in addition to upward flows, in the building of the early crust up to late-Proterozoic times, helping to explain the geochemical and structural complexities of the old crust. [less ▲]

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See detailWhy is stromatactis so rare in Mesozoic carbonate mud mounds?
Neuweiler, F.; Bourque, P. A.; Boulvain, Frédéric ULg

in Terra Nova (2001), 13(5), 338-346

The sedimentary-diagenetic structure stromatactis is wide-spread in Palaeozoic spiculitic carbonate mud mounds, but occurs only sporadically in Mesozoic sponge carbonate mud mounds. Comparative analysis ... [more ▼]

The sedimentary-diagenetic structure stromatactis is wide-spread in Palaeozoic spiculitic carbonate mud mounds, but occurs only sporadically in Mesozoic sponge carbonate mud mounds. Comparative analysis of Palaeozoic and Mesozoic stromatactis limestones suggests that this variation results from the degree of siliceous sponge skeletal rigidity and the amount of internal sediment accumulation in the original cavity network. Partial to entire filling by internal sediment resulted in a continuum, from a small amount of internal sediment and large amount of cement (stromatactis, common in the Palaeozoic), to only internal sediments (aborted stromatactis, common in the Mesozoic). These observations match independent lines of evidence concerning the siliceous sponge evolution and sediment recycling (e.g. bioerosion) across the Palaeozoic to Mesozoic biotic revolution. [less ▲]

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See detailThe crustal tongue melting model and the origin of massive anorthosites
Duchesne, Jean-Clair ULg; Liégeois, Jean-Paul ULg; Vander Auwera, Jacqueline ULg et al

in Terra Nova (1999), 11

Recent detailed field studies in several anorthosite complexes have shown that anorthosites are frequently linked with weakness zones in the crust which favour their emplacement at mid-crust levels ... [more ▼]

Recent detailed field studies in several anorthosite complexes have shown that anorthosites are frequently linked with weakness zones in the crust which favour their emplacement at mid-crust levels. Recent experimental data have also shown that the parent magma compositions of various anorthosite massifs lie on thermal highs in the relevant phase diagrams, indicating that these magmas cannot be derived by fractionation of peridotitic mantle melts but rather are produced by melting of gabbronoritic sources. In the Sveconorwegian province terrane boundaries have been traced in deep seismic profiles to Moho offsets or to tongues of lower crustal material underthrust to depths of 40-50 km. We therefore suggest that the parent magmas of anorthosite massifs are produced by melting of gabbronoritic rocks from the lower crust that had been thrust into the mantle by collision of terranes. [less ▲]

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See detailTransformations of biotite and smectite into Al-rich chlorites: an HRTEM-AEM study
Amouric, Marc; Olives, Jean; Anceau, Annick ULg

in Terra Nova (1997), 9

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See detailHistorical seismicity of the Strait of Dover–Pas de Calais
Melville, Charles; Levret, Agnès; Alexandre, Pierre ULg et al

in Terra Nova (1996), 8

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