Weakening processes in thrust faults: insights from the Monte Perdido thrust fault (southern Pyrenees,Spain)

The Monte Perdido thrust fault (southern Pyrenees) consists of a 6‐m‐thick interval of intensely deformed clay‐bearing rocks. The fault zone is affected by a pervasive pressure solution seam and numerous shear surfaces. Calcite extensional‐shear veins are present along the shear surfaces. The angular relationships between the two structures indicate that shear surfaces developed at a high angle (70°) to the local principal maximum stress axis σ₁. Two main stages of deformation are present. The first stage corresponds to the development of calcite shear veins by a combination of shear surface reactivation and extensional mode I rupture. The second stage of deformation corresponds to chlorite precipitation along the previously reactivated shear surfaces. The pore fluid factor λ computed for the two deformation episodes indicates high fluid pressures during the Monte Perdido thrust activity. During the first stage of deformation, the reactivation of the shear surface was facilitated by a suprahydrostatic fluid pressure with a pore fluid factor λ equal to 0.89. For the second stage, the fluid pressure remained still high (with a λ value ranging between 0.77 and 0.84) even with the presence of weak chlorite along the shear surfaces. Furthermore, evidence of hydrostatic fluid pressure during calcite cement precipitation supports that incremental shear surface reactivations are correlated with cyclic fluid pressure fluctuations consistent with a fault‐valve model.     

Gazetteer of small‐scale monuments in prehistoric Hadramawt,Yemen: a radiocarbon chronology from the RASA‐AHSD Project research 1996–2008

This paper provides a new, interpretive gazetteer and chronology of Hadramawt’s highland monuments based on results from archaeological survey and test excavations by the RASA‐AHSD (Roots of Agriculture in southern Arabia‐Arabian Human Social Dynamics) Project. With the exception of a few incidental sightings and an unpublished pipeline survey, the prehistoric record of southern Yemen’s highland plateau has been largely unknown. There are few settlements, so that understanding human landscape history must begin with the numerous small‐scale stone monuments left by mobile people. With examples representing monuments from the fifth, fourth, third and first millennia BC, the corpus of small excavations and radiocarbon dates reported here provides the first guide to the monument types of South Arabian highlands. Monument building began under more moist conditions and appears to have commemorated animal sacrifices long before commemorating mortuary rites and interment. There appears to be a temporal break of 1000 years before the widespread and varied practices of Bronze Age tomb construction, which lasted through the third millennium BC. After another break in monument construction, tombs were reused in the first millennium BC, sometimes with successive ritual visits. The data presented offer new material for the interpretation of the lives and activities of prehistoric pastoralists throughout the Holocene.     

Ancient Egyptian Pottery from the Subsurface Floodplain of the Saqqara–Memphis Area: Its Mineralogical and Geochemical Implications*

Potsherds recovered from the Saqqara–Memphis floodplain in Egypt, dated according to their typology and radiocarbon dating of the included sediments, are analysed geochemically and mineralogically to identify source materials and fabrication characteristics. Pottery layers were identified and potsherds were recovered from several settlement levels. Sherd typology was used to identify sherds from four periods (the Old and New Kingdoms, and from the Late Period to the Ptolemaic). The Pharaonic pieces were found at depths of between 8 and 12 m and the later material was between 6 and 3 m. Chemical analyses of the potsherds revealed three main source materials: local Nile silt, marl clay and mixed Nile silt–marl. Two marl clay types were recognized: marl clay from Upper Cretaceous marine sediment and another one from Late Pliocene deltaic sediments. The mineralogical composition of the pottery samples shows that the estimated firing temperature was about 850–900°C. No consistent differences in sherd mineralogy and geochemistry were found according to pottery types, so that the ancient Egyptian potters used essentially the same materials throughout the Pharaonic period. However, this initial study has revealed the existence of extensive pottery‐rich occupation sites buried within the Nile floodplain deposits between Memphis and Saqqara.     

La genèse des concepts mathématiques

Counter to the standard viewpoint which tends to dismiss history and intersubjectivity when dealing with mathematical cognition, the article shows that taking them into account is the only way to overcome a certain number of aporias related to mathematical objectivity, especially psychologism and relativism. Resting upon the conceptual framework devised by Ernst Cassirer under the name «symbolic form», the article shows that the fictional and the scientific stance must be located along the same meaning continuum and that it is only the collective elaboration of individual representations which can account for cultural productions.     

The mortgage crisis and evictions in Barcelona: identifying the determinants of the spatial clustering of foreclosures

The article identifies the determinants of the uneven spatial distribution of housing accumulated by banks via foreclosures in the city of Barcelona. Working with a new data source, we geolocalised foreclosed housing and analysed its tendency to spatially cluster. Using the bivariate version of the Local Moran Indicator, we confirmed the spatial correlation between the concentration of foreclosed housing and indicators of the socio-economic vulnerability of the neighbourhoods containing it. We also applied an OLS model to identify and weight the determinants of this clustering at the neighbourhood level. Our findings revealed that the growth of unemployment, the concentration of (non-EU) immigrant population and a greater presence of residents with low levels of studies were the key variables that explain the uneven geography of foreclosures in Barcelona. The results obtained also allowed us to characterize the spatial distribution of the housing accumulated by the banks during the mortgage crisis. As a result of the massive wave of evictions, banks have emerged as large-scale property owners in Spain and key agents for present and future housing policies.