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Jaouadi S.,UMR | Lebreton V.,UMR | Bout-Roumazeilles V.,Lille University of Science and Technology | Siani G.,University Paris - Sud | And 6 more authors.
Climate of the Past | Year: 2016

Pollen and clay mineralogical analyses of a Holocene sequence from Sebkha Boujmel (southern Tunisia) trace the climatic and environmental dynamics in the lower arid bioclimatic zone over the last 8000 years. During the mid-to late Holocene transition, between ca. 8 and 3 ka BP, a succession of five wet-dry oscillations is recorded. An intense arid event occurs between ca. 5.7 and 4.6 ka BP. 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 BP. 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 BP. The event at 4.2 ka BP is not evidenced and the link between events recorded in Sebkha Boujmel and the North Atlantic cooling events is clearer from ca. 3 ka BP 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 ca. 3 ka BP 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 ca. 1.1 and 0.8 ka BP (850-1150 AD) is linked to intensive pastoral activity, associated with heightened interannual and/or seasonal climatic instability. A complete reshaping 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. © 2016 Author(s).

Lebreton V.,French Natural History Museum | Jaouadi S.,French Natural History Museum | Mulazzani S.,Aix - Marseille University | Boujelben A.,University of Tunis | And 6 more authors.
Environmental Archaeology | Year: 2015

Pollen analyses from the sebkha-lagoon Halk El Menjel document the vegetation history in Central Tunisia, linked to climate change since the Middle Holocene. Steppes are the main biomes developed under semi-arid conditions between 4965 ± 35 and 3410 ± 40 BP. At 4365 ± 50 BP Pistacia is replaced by Olea and high representation of Olea pollen grains are reported between 4365 ± 50 and 3410 ± 40 BP, illustrating a humid episode at the Mid-to-Late Holocene transition. Thus, the semi-arid area of Central Tunisia could correspond to the native biome for oleasters at the beginning of the Late Holocene. Early olive cultivation is not yet evidenced in the Neolithic sites of the eastern Maghreb, and the Phoenicians are assumed to have introduced olive cultivars in Tunisia. However, an early cultivation of Olea from local native oleaster and dissemination of native cultivars in Central Tunisia can be hypothesised even if it has to be still demonstrated with further archaeological and archaeobotanical evidences. © 2015 Association for Environmental Archaeology.

Baklouti S.,Tunis el Manar University | Maritan L.,University of Padua | Casas L.,Autonomous University of Barcelona | Laridhi Ouazaa N.,Tunis el Manar University | And 6 more authors.
Applied Clay Science | Year: 2016

This paper presents the results of the archaeometric study of African Keay 25.2 amphorae from the archaeological site of Sidi Zahruni (Beni Khiar, NE Tunisia), where this pottery was massively produced. A set of 43 amphorae was analysed with a combined approach consisting of thin-section petrography, X-ray powder diffraction (XRPD) and X-ray fluorescence (XRF), to establish a homogeneous reference group for this production. Although all the amphorae are petrographically very similar, three petro-fabrics were identified in terms of grain-size distribution and abundance of inclusions. Detailed digital image analysis, carried out on SEM-BSE images of some representative samples of each petro-fabric, was used to quantify the differences among them. Cluster analysis of XRPD data patterns also revealed groups of samples for which similar raw materials/paste and firing conditions were used, contributing to better assessment of information on the production process. Statistical multivariate treatment (principal component and cluster analyses) of chemical data and comparisons with 10 samples previously attributed to the Sidi Zahruni potteries show that the potsherds analysed here are similar from the geochemical viewpoint. Similar trends in the abundance and ratio of some trace and rare earth elements (REE) also indicate that the Sidi Zahruni amphorae were produced from a local clayey material collected from nearby outcrops of Upper Miocene deposits. © 2016.

Belhouchet L.,Institute National du Patrimoine | Mulazzani S.,21 Allee Of Luniversite | Pelegrin J.,21 Allee Of Luniversite
Quaternary International | Year: 2014

The Upper Capsian is an Epipalaeolithic techno-complex occurring in the Maghreb between the 9th and the 8th millennium cal BP, generally associated with the appearance of pressure-knapping bladelet production. The chronology of Capsian sequences based on earlier excavations is uncertain, and studies of lithic industries based on a technological approach are relatively scarce. The site of SHM-1 (Hergla) in east coastal Tunisia has been recently excavated with a stratigraphic protocol. A sequence of seven main layers was detected, all radiocarbon dated. The technological and petrological study applied to the lithic production established on a diachronic basis allowed identification of the main chaînes opératoires involved in bladelet and flake production. The first was obtained through three main schemes, with the pressure bladelet production starting in the first occupational layer, at the first half of the 9th millennium cal BP. Some changes appear between the older layers and recent ones, including the introduction of a more sophisticated pressure mode in the last layers. Detailed examination of the pressure production modes reveals distinctive platform preparation, opening different questions. The pressure bladelets are mainly transformed into backed bladelets, geometric microliths and notches and denticulates. The typological analysis of the armatures reveals an evolution in the raw material selected for some specific tools as well as some changes in the tool types produced. © 2013 Elsevier Ltd and INQUA.

Bowen J.W.,University of Reading | Owen T.,Culham Center for Fusion Energy | Jackson J.B.,University of Reading | Walker G.C.,University of Reading | And 6 more authors.
IEEE Transactions on Terahertz Science and Technology | Year: 2015

This paper presents measurements of the terahertz properties of the art conservation substance cyclododecane, demonstrating that it can act as a contrast improving agent in the terahertz imaging of concealed wall paintings. Results are presented which show that the terahertz optical properties of cyclododecane are dependent on the rate at which it has cooled from the melt. Based on the results, a theoretical explanation of the contrast enhancement mechanism is postulated. The findings presented here may lead to the development of novel coating materials that could improve the quality of terahertz images in a variety of fields and not just in art conservation. © 2011-2012 IEEE.

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