Search results for "EarthArXiv|Physical Sciences and Mathematics|Earth Sciences"

Using machine learning on tree-ring data to determine the geographical provenance of historical construction timbers

2023

Funder: Bavarian Climate Research Network (BayKliF)

Spatial and temporal variability of rainfall over the Republic of Djibouti from 1946 to 2017.

2021

20 pages; International audience; For the first time, the spatial and temporal variability of rainfall in the Republic of Djibouti is investigated using data from 14 weather stations over the period 1946–2017. Due to limited data availability, high-resolution long-term satellite rainfall products (CHIRPS, PERSIANN-CDR, TAMSATv3, ARC2) and ERA5 reanalysis also contribute to document time–space rainfall variability at monthly, seasonal and annual scales. Principal component analysis identifies two spatially coherent regions of rainfall variability in the east (coastal zone) and the west (inland zone) of the country. Annual rainfall amounts are everywhere very low (60–300 mm), but with contras…

Experimental Constraints on the Deep Magma Feeding System at StromboliVolcano, Italy

2009

International audience; New experiments have been performed on a high-K basalt (PST-9) from Stromboli volcano, Italy, to constrain the physical conditions of golden pumice magmas at their storage level and discuss their petrogenesis. Fluid-present, H2O- and CO2-bearing, near-liquidus experiments were performed at 11508C between 100 and 400MPa and under oxidizing conditions. Glasses were analyzed by Fourier transform IR spectroscopy and their H2O and CO2 concentrations compared with those in glass inclusions.Most glass inclusions cluster near the 200MPa isobar, suggesting entrapment at a depth of ~8 km. Golden pumice magmas have viscosities of 7.9 Pa s and densities of 2.48-2.57 g/cm3. Compo…

Ultra-high temperature metamorphism recorded in Fe-rich olivine-bearing migmatite from the Khondalite Belt, North China Craton

2018

International audience; We document the first occurrence of Fe‐rich olivine‐bearing migmatitic metapelite in the Khondalite Belt, North China Craton. Petrological analyses revealed two exotic assemblages of orthopyroxene+spinel+olivine and orthopyroxene+spinel+cordierite. Phase relation modelling suggests that these assemblages are diagnostic of ultra‐high temperature (UHT) metamorphism in the Fe‐rich system, with temperatures from 1,000 to 1,050°C at 0.6 GPa. U–Th–Pb SIMS analyses on zircon reveal a similar age of c. 1.92 Ga for the olivine‐bearing migmatite and an adjacent gabbronoritic intrusion that is therefore identified as the heat source for the UHT metamorphism. These results, coup…

Alteration-Induced Volcano Instability at La Soufrière de Guadeloupe (Eastern Caribbean)

2021

International audience; Volcanoes are unstable structures that deform laterally and frequently experience mass wasting events. Hydrothermal alteration is often invoked as a mechanism that contributes significantly to volcano instability. We present a study that combines laboratory experiments, geophysical data, and large-scale numerical modeling to better understand the influence of alteration on volcano stability, using La Soufrière de Guadeloupe (Eastern Caribbean) as a case study. Laboratory experiments on variably altered (advanced argillic alteration) blocks show that uniaxial compressive strength, Young's modulus, and cohesion decrease as a function of increasing alteration, but that …

Étude des traces de pas de vertébrés du Permien et du Trias d'Ardèche. Enjeux et perspectives.

2022

Le département de l'Ardèche estremarquable car il offre un accès privilégié auxroches sédimentaires permiennes et triasiques danslesquelles abondent les traces de vertébrés fossiles.Une vingtaine de localités et plus de 1500empreintes de pas ont déjà été recensées le longd'une succession sédimentaire affleurant entrePrivas et Les Vans. Ce patrimoine ichnologique,reconnu internationalement, documente le passagede grands groupes de reptiles en terres ardéchoises,incluant essentiellement des représentants basauxde la lignée des crocodiles (pseudosuchiens) et de lalignée des oiseaux (dinosauriformes et dinosaures),ainsi que quelques membres de la lignée des lézards/serpents (lépidosauromorphes)…

Talant vineyards and wines: 800 years of history in Burgundy

2021

The Climats in Burgundy: issues and developments in a winegrowing landscape that has become cultural heritage

2020

Quantification de la dynamique sédimentaire en contexte anthropisé. L'érosion des versants viticoles de Côte d'Or.

2007

The wine slopes of Côte d'Or (Burgundy, France) are subject to the combined effects of runoff/erosion processes and intense cultivation practices. The purpose of this study is to characterize the erosion processes, and to quantify the sedimentary dynamics over different time scales and spatial scales. Sedimentary budgets show that the studied slopes, with grounds that are made very sensitive to the runoff phenomena by intensive mechanisation, are subject to erosion rates of several millimetres per year. Overflow triggering and its extension, which determine sediment transfer distances, are dependent on a runoff threshold. The existence of this threshold is observed through the analysis of t…

Dyvalocca : un projet pour l'étude des nuages bas de saison sèche sur la façade atlantique de l'Afrique centrale et de leur impact bioclimatique sur …

2020

Low-level clouds are key components of the climate but are not well represented in weather and climate models. Recently it has been shown that an extensive low-level cloud cover develops during the June-September main dry season in western equatorial Africa, from the coastal plains of Gabon and Congo-Brazzaville to the inland plateaus downstream of the low-mountain crests. Such a cloudy main dry season is unique in the moist Tropics and is likely to explain the presence of the densest and evergreen forests of Central Africa as evapotranspiration is low and the quality of light is high. The ANR-DFG funded “DYVALOCCA” project will conduct from 2020 to 2022 a field campaign, raise existing in-…