Extrait de : Les Colonies françaises, petite encyclopédie coloniale (p. 489)
Résumé : Explorateur et géographe spécialiste du Sahara, il part pour l'Algérie en 1859 et va jusqu'à Ghardaïa, Tougourt, le Tassili des Ajers et Ghat. Médaille d'or de la Société de géographie en 1864, il servira de modèle à de nombreux explorateurs du Sahara : Foucauld, Dournaux-Duperé, Flatters.
Siècle(s) traité(s) : 19
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/images/MMC16023-1-0522i1
MMC16023-1-0522i1

Extrait de : Les Colonies françaises, petite encyclopédie coloniale (p. 482)
Résumé : Portrait d'un targui, personne du peuple nomade du Sahara, appelée aussi Touareg.
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/images/MMC16023-1-0515i1
MMC16023-1-0515i1

Extrait de : La carte de l'empire colonial français (Entre p.16 et p.17)
Siècle(s) traité(s) : 20
Droits : Domaine public
Permalien : http://www.manioc.org/images/FRA120670002i2
FRA120670002i2

Extrait de : Les Colonies françaises, petite encyclopédie coloniale (p. 482)
Résumé : Portrait d'un targui, personne du peuple nomade du Sahara, appelée aussi Touareg.
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/images/MMC16023-1-0515i2
MMC16023-1-0515i2

Extrait de : La carte de l'empire colonial français (Entre p.46 et p.47)
Siècle(s) traité(s) : 20
Droits : Domaine public
Permalien : http://www.manioc.org/images/FRA120670008i1
FRA120670008i1

Extrait de : Les Colonies françaises, petite encyclopédie coloniale (p. 596)
Résumé : Explorateur du Sahara occidental
Siècle(s) traité(s) : 19
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/images/MMC16023-1-0629i1
MMC16023-1-0629i1

Extrait de : La carte de l'empire colonial français (Entre p.16 et p.17)
Siècle(s) traité(s) : 20
Droits : Domaine public
Permalien : http://www.manioc.org/images/FRA120670002i1
FRA120670002i1

Extrait de : Les Colonies françaises, petite encyclopédie coloniale (p. 481)
Description : Portrait d'un targui, personne du peuple nomade du Sahara, appelée aussi Touareg.
Siècle(s) traité(s) : 19
Droits : Domaine public
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/images/MMC16023-1-0514i1
MMC16023-1-0514i1

Extrait de : Les Colonies françaises, petite encyclopédie coloniale (p. 491)
Résumé : Explorateur du Sahara.
Siècle(s) traité(s) : 19
Provenance : Communauté d'agglomération de La Rochelle. Médiathèque Michel-Crépeau
Permalien : http://www.manioc.org/images/MMC16023-1-0524i1
MMC16023-1-0524i1

Éditeur(s) : [S.l. : s.n.]
Extrait de : La traite des nègres et la croisade africaine comprenant la lettre encyclique de Léon XIII sur l'esclavage, le discours du cardinal Lavigerie à Paris, les témoignages des grands explorateurs : Livingstone, Cameron, Stanley, des missionnaires français, etc., ainsi que l'organisation des sociétés antiesclavagistes en France et en Europe (entre p. 30 et p. 32)
Résumé : Charles-Martial Allemand-Lavigerie, né à Bayonne (Basses-Pyrénées) le 31 octobre 1825, sacré évêque de Nancy le 22 mars 1863, nommé archevêque d'Alger par décret du 12 janvier 1867, préconisé le 27 mars suivant ; archevêque de Carthage en 1884, délégué apostolique pour les Missions du Sahara, du Soudan, de l'Afrique équatoriale, de Ste Anne de Jérusalem ; crée Cardinal-prêtre du titre de Ste Agnès-hors-les-murs, dans le consistoire du 27 mars 1882.
Siècle(s) traité(s) : 19
Permalien : http://www.manioc.org/images/LAM17014-0033i1
LAM17014-0033i1

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
PURPOSE: Dairy farming is a risk factor for the development of chronic obstructive pulmonary disease (COPD). We assessed the prevalence of farming-induced COPD (FI-COPD) using a new screening device, and we analyzed symptoms and occupational risk factors. METHODS: We performed on-site screening study of bronchial obstruction using an electronic mini-spirometer (EMS) on an entire population of dairy farmers (n = 147) from two villages in Brittany, France. Suspected bronchial obstruction (FEV1/FEV6 <0.8) was confirmed with standardized lung function tests (FEV1/FVC ≤0.7). We assessed past medical histories, respiratory symptoms, and occupational tasks of subjects with bronchial obstruction; asthmatics were defined as atopic and/or reversible; smoking-induced COPD patients were defined as non-reversible, non-atopic with smoking histories (≥5 PY); and FI-COPD patients were defined as non-reversible, non-atopic, and non-smokers. RESULTS: Using the EMS, 30.6% (n = 45) of dairy farmers were suspected of bronchial obstruction and underwent standardized spirometry. The FEV1/FEV6 ratio and FEV1/FVC ratio were in good agreement (r² = 0.66, P < 0.0001). The prevalence of confirmed bronchial obstruction was 9.5% (n = 14), which included 4 asthmatics, 3 smoking-induced COPD subjects, and 7 FI-COPD subjects. All the COPD patients were GOLD Stage II, and none were aware of their respiratory disease. Foddering duration was significantly higher in FI-COPD subjects compared with non-obstructive subjects, with 44 versus 17 min/day, respectively. CONCLUSIONS: The EMS was a convenient mean of screening for bronchial obstruction, especially in on-site settings, and allowed us to diagnose FI-COPD in a non-spontaneously complaining dairy farmer population. Foddering was considered a significant risk factor.
ISSN: 0340-0131

hal-00872929
https://hal.archives-ouvertes.fr/hal-00872929
DOI : 10.1007/s00420-011-0708-6
PUBMED : 21986906

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The In-Ezzane volcanic district (EZD), located at the triple junction of Algeria, Niger and Libya belongs to the Eastern Hoggar, covers 350 km2 and includes 9 volcanic edifices that are probably aligned along NW-SE faults, parallel to the Tafassasset valley. The low volume (0.7 and 1 km3) of emitted lavas, the similar morphology of the monogenic cones and the lack of differentiated rocks indicate that the volcanic activity of the EZD was restricted in time and volume. The new K-Ar age (i.e. 2.86 ± 0.07 Ma) indicates that the EZD is contemporaneous with the last alkali volcanism paroxysm in Hoggar and with the nearby Libyan volcanics. The EZD alkali basalts (mainly basanite) show a remarkable homogeneous compositions both in major elements (44.8 ⩽ SiO2 ⩽ 45.8 wt.%; 5.2 ⩽ (Na2O + K2O) ⩽ 6.2 wt.%), trace elements (4.3 ⩽ Th ⩽ 5.5 ppm; 34.7 ⩽ La ⩽ 44.7 ppm; 16.1 < La/Yb(N) < 21.6) and radiogenic isotopes (0.70285 < 87Sr/86Sr < 0.70303; 0.51298 < 143Nd/144Nd < 0.51301; (19.212 < 206Pb/204Pb < 19.340, 15.589 < 207Pb/204Pb < 15.602 and 38.834 < 208Pb/204Pb < 38.903). Relative to the Hoggar alkaly basalts the EZD basalts appear systematically impoverished in incompatible elements and show a depleted signature both in Sr and Nd isotopes (almost MORB-like). The Pb isotopes are relatively enriched and intermediate between tholeiites and alkali basalts of the Hoggar. This unusual geochemical signature, is uneasy to reconcile with the known characteristics of the Hoggar swell, and would rather fingerprint a circum cratonic mantle lying beneath the west border of the Murzuq craton (Libya).
ISSN: 0899-5362

hal-01054340
https://hal.archives-ouvertes.fr/hal-01054340
DOI : 10.1016/j.jafrearsci.2013.12.001

Éditeur(s) : HAL CCSD European Geosciences Union (EGU)
Résumé : International audience
Pollen and clay mineralogical analyses of a Holocene sequence from Sebkha Boujmel (southern Tunisia) traces the climatic and environmental dynamics in the lower arid bioclimatic zone over the last 8000 years. During the Mid- to Late Holocene transition, between 8 and 3 ka, a succession of five wet/dry oscillations is recorded. An intense arid event occurs between 5.7 and 4.6 ka. This episode marks the onset of a long-term aridification trend with a progressive retreat of Mediterranean woody xerophytic vegetation and of grass steppes. It ends with the establishment of pre-desert ecosystems around 3 ka. The millennial-scale climate change recorded in the data from Sebkha Boujmel is consistent with records from the south and east Mediterranean, as well as with climatic records from the desert region for the end of the African Humid Period (AHP). Eight centennial climatic events are recorded at Sebkha Boujmel and these are contemporary with those recorded in the Mediterranean and in the Sahara. They indicate a clear coupling between the southern Mediterranean and the Sahara before 3 ka. The event at 4.2 ka is not evidenced and the link between events recorded in Sebkha Boujmel and the North Atlantic Cooling events is clearer from 3 ka onwards. These variations indicate the importance of climatic determinism in the structuring of landscapes, with the establishment of the arid climatic conditions of the Late Holocene. It is only from 3 ka onwards that the dynamic of plant associations is modified by both human activity and climatic variability. The climatic episodes identified during the historic period indicate strong regionalisation related to the differential impact of the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) on the Mediterranean basin. The local human impact on regional ecosystems is recorded in the form of episodes of intensification of pastoral and/or agricultural activities. The development of olive production and of several taxa associated with agriculture attest to increasing sedentism among human populations during Classical Antiquity. The significant increase in Artemisia (wormwood) between 1.1 and 0.8 ka (850–1150 AD) is linked to intensive pastoral activity, associated with heightened interannual and/or seasonal climatic instability. A complete re-shaping of the landscape is recorded during the 20th century. The remarkable expansion of the olive tree, and the deterioration of regional ecosystems with the spread of desert species, is linked to recent local socio-economic changes in Tunisia.
ISSN: 1814-9324

hal-01319967
https://hal.archives-ouvertes.fr/hal-01319967
https://hal.archives-ouvertes.fr/hal-01319967/document
https://hal.archives-ouvertes.fr/hal-01319967/file/cp-12-1339-2016.pdf
DOI : 10.5194/cp-12-1339-2016

Éditeur(s) : Copernicus Gesellschaft Mbh
Résumé : Relict dune fields that are found as far south as 14 N in the modern-day African Sahel are testament to equatorward expansions of the Sahara desert during the Late Pleistocene. However, the discontinuous nature of dune records means that abrupt millennial-timescale climate events are not always resolved. High-resolution marine core studies have identified Heinrich stadials as the dustiest periods of the last glacial in West Africa although the spatial evolution of dust export on millennial timescales has so far not been investigated. We use the major-element composition of four high-resolution marine sediment cores to reconstruct the spatial extent of Saharan-dust versus river-sediment input to the continental margin from West Africa over the last 60 ka. This allows us to map the position of the sediment composition corresponding to the Sahara Sahel boundary. Our records indicate that the Sahara Sahel boundary reached its most southerly position (13 N) during Heinrich stadials and hence suggest that these were the periods when the sand dunes formed at 14 N on the continent. Heinrich stadials are associated with cold North Atlantic sea surface temperatures which appear to have triggered abrupt increases of aridity and wind strength in the Sahel. Our study illustrates the influence of the Atlantic meridional overturning circulation on the position of the Sahara Sahel boundary and on global atmospheric dust loading.
Climate Of The Past (1814-9324) (Copernicus Gesellschaft Mbh), 2013 , Vol. 9 , N. 3 , P. 1181-1191

Droits : Author(s) 2013. CC Attribution 3.0 License. Access Climate of
http://archimer.ifremer.fr/doc/00181/29240/27635.pdf
DOI:10.5194/cp-9-1181-2013
http://archimer.ifremer.fr/doc/00181/29240/

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
We show here that the Amalaoulaou complex, in the Pan-African belt of West Africa (Gourma, Mali), corresponds to the lower and middle sections of a Neoproterozoic intra-oceanic arc. This complex records a 90-130-Ma-long evolution of magmatic inputs and differentiation above a subducting oceanic slab. Early c. 793 Ma-old metagabbros crystallised at lower crustal or uppermost mantle depths (25-30 km) and have geochemical characteristic of high-alumina basalts extracted from a depleted mantle source slightly enriched by slab-derived sedimentary components ((La/Sm)(N) < 1; epsilon(Nd): +5.4-6.2; Sr-87/Sr-86: 0.7027-0.7029). In response to crustal thickening, these mafic rocks were recrystallised into garnet-granulites (850-1,000A degrees C; 10-12 kbar) and subject to local dehydration-melting reactions, forming trondhjemititic leucosomes with garnet-clinopyroxene-rutile residues. Slightly after the granulitic event, the arc root was subject to strong HT shearing during partial exhumation (detachment faults/rifting or thrusting), coeval with the emplacement of spinel- and garnet-pyroxenite dykes crystallised from a high-Mg andesitic parental magma. Quartz and hornblende-gabbros (700-660 Ma) with composition typical of hydrous volcanic rocks from mature arcs ((La/Sm)(N): 0.9-1.8; epsilon(Nd): +4.6 to +5.2; Sr-87/Sr-86: 0.7028-0.7031) were subsequently emplaced at mid-arc crust levels (similar to 15 km). Trace element and isotopic data indicate that magmas tapped a depleted mantle source significantly more enriched in oceanic sedimentary components (0.2%). Exhumation occurred either in two stages (700-660 and 623 Ma) or in one stage (623 Ma) with a final exhumation of the arc root along cold P-T path (550A degrees C, 6-9 kbar; epidote-amphibolite and greenschist facies conditions) during the main Pan-African collision event (620-580 Ma). The composition of magmas forming the Cryogenian Amalaoulaou arc and the processes leading to intra-arc differentiation are strikingly comparable to those observed in the deep section of exposed Mezosoic oceanic arcs, namely the Kohistan and Talkeetna complex. This evolution of the Amalaoulaou oceanic arc and its accretion towards the West African craton belong to the life and closure of the Pharusian Ocean that eventually led to the formation of the Greater Gondwana supercontinent, a similar story having occurred on the other side of the Sahara with the Mozambique Ocean.
ISSN: 0010-7999

hal-00639447
https://hal.archives-ouvertes.fr/hal-00639447
DOI : 10.1007/s00410-011-0624-5

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : Reconstruction of Northern African monsoon between 6.2 and 4.9 Ma and possible relationships with Late Miocene events. Mineralogical and geochemical investigations have been realized on ODP Site 659 in order to better understand the detrital sedimentation of the Cap Verde plateau and to reconstruct African monsoon intensity variations between 6.2 and 4.9 Ma. Time intervals corresponding to an intensification of the summer African monsoon rainfall are associated to a reduction of eolian input from the Sahara and an intensification of the African river input. The reflooding of the Mediterranean Sea at the end of the Messinian salinity crisis (MSC) (5.33 Ma) is correlated to a greater aridity in the Sahara.
ISSN: 1631-0713

hal-00412151
https://hal.archives-ouvertes.fr/hal-00412151
DOI : 10.1016/j.crte.2008.07.005

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Holocene Lake Mega-Chad (LMC) was the largest late Quaternary water-body in Africa. The development of this giant paleo-lake is related to a northward shift of the isohyetes interpreted as evidence for an enhanced Monsoon (African Humid Period). Numerous preserved coastal features have been described all around the LMC shore. Such features reveal the main paleo-hydrodynamical tendencies. In the context of a closed water-body like LMC, hydrodynamics are forced mainly by winds. We use a three-dimensional numerical model (SYMPHONIE) to simulate the mean hydrodynamics in LMC under both Harmattan-like (northeasterly trade winds) and Monsoon-like (southwesterly winds) forcings. The northern part of LMC displays coastal features, such as sand spits, that are consistent with the simulations forced by Harmattan-like winds. Geomorphic features related to Monsoon-driven hydrodynamics are not clearly expressed. They could have developed during the early stage of LMC but subsequently reworked. At the time of sand-spit building, Harmattan-like driven hydrodynamics prevailed and related coastal features were preferentially preserved in the sedimentary record.
ISSN: 0033-5894

hal-00475633
https://hal.archives-ouvertes.fr/hal-00475633
DOI : 10.1016/j.yqres.2009.10.010

Éditeur(s) : HAL CCSD Cambridge University Press (CUP)
Résumé : International audience
The Ben Zireg anticline NW of Bechar yields the currently most-important Frasnian succession on the northern margin of the Algerian Sahara. It represents 26.5 m of calcilutites which are attributed to the middle–late Frasnian. As the early Frasnian is not represented, the succession rests conformably on undifferentiated, probably late Givetian, substrate. Fine-scaled conodont biostratigraphy reveals a continuous sequence of Montagne Noire Zones 5–13, superseded by the earliest Famennian Lower triangularis Zone. The deposits are organized into 15 sedimentary cycles that are initially condensed and become dilated upwards. Conodont biofacies indicate an overall deepening towards the top of the section with an episode of slight shallowing at the MN11/12 transition marked by an increase of ancyrodellids, which is also seen in the Marhouma section of the Ougarta region (SW Algeria). Homogeneous calcareous microfacies with only a few shaly intercalations determine a predominantly oxygenated depositional environment on an outer platform, submarine rise or ramp setting. This is also indicated by relatively low sedimentation rates which are similar in selected sections from the Tafilalt platform, and contrast with those from the Marhouma trough and the Maider basin. Unlike other Frasnian successions south of the Atlas Fault, but similar to the Moroccan Meseta, the Upper Kellwasser horizon is clearly discriminated at Ben Zireg by an outstanding occurrence of black shales on top of the oxygenated latest Frasnian deposits.
ISSN: 0016-7568

hal-01217151
https://hal.archives-ouvertes.fr/hal-01217151
DOI : 10.1017/S0016756814000715

Éditeur(s) : HAL CCSD Elsevier
Résumé : This paper is the first presentation of a project called GHYRAF (Gravity and Hydrology in Africa) devoted to the detailed comparison between models and multidisciplinary observations (ground and satellite gravity, geodesy, hydrology, meteorology) of the variations of water storage in Africa from the Sahara and part to the monsoon equatorial part. We describe the various actions planned in this project. We first detail the actions planned in gravimetry which consist in two main surface gravity experiments: on the one hand the periodic repetition of absolute gravity measurements along a north-south monsoonal gradient of rainfall in West Africa, going from Tamanrasset (20 mm/year) in southern Algeria to Djougou (1200 mm/year) in central Benin; on the other hand the continuous measurements at Djougou (Benin) with a superconducting gravimeter to monitor with a higher sampling rate the gravity changes related to an extreme hydrological cycle. Another section describes the actions planned in GPS which will maintain and develop the present-day existing network in West Africa. The third type of actions deals with hydrology and we review the three sites that will be investigated in this joint hydrogeophysics project namely Wankama (near Niamey) and Bagara (near Diffa) in the Niger Sahelian zone and Nalohou (near Djougou) in the Benin monsoon zone. We also address the question of the ground truth of satellite-derived missions: in this context the GHYRAF project will lead to test the hydrology models by comparison both with in situ and satellite data such as GRACE, as well as to an important increase of our knowledge of the seasonal water cycle in Africa. We finally present preliminary results in GPS based on the analysis of the vertical motion of the Djougou site. The resulting absolute gravity changes related to the 2008 monsoon are finally given.
ISSN: 0264-3707

hal-00475660
https://hal.archives-ouvertes.fr/hal-00475660
DOI : 10.1016/j.jog.2009.09.014

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0031-0182

hal-00720714
https://hal.archives-ouvertes.fr/hal-00720714