Physical mechanical consolidation and protection of Miocenic limestone used on Mediterranean historical monuments: the case study of Pietra Cantone (southern Sardinia, Italy)

The present work aims to study the consolidating and protective chemical treatments of the Pietra Cantone, a Miocenic (lower Tortonian) limestone widely used in important monuments and historical buildings of Cagliari (southern Sardinia, Italy). Similar limestones of the same geological period have also been used in several important monuments of Mediterranean area, i.e., Malta and Gozo Islands, Matera (central Basilicata, Italy), Lecce (southern Puglia, Italy) and Balearic Islands (Spain). The Pietra Cantone limestone shows problems of chemical–physical decay, due to their petrophysical and compositional char- acteristics: high porosity (on average 28–36 vol%), low cemented muddy-carbonate matrix, presence of phyllosil- icates and sindepositional sea salts (\3%). So, after placed in the monument, this stone is easily alterable by weath- ering chemical processes (e.g., carbonate dissolution and sulfation) and also by cyclic mechanisms of crystalliza- tion/solubilization of salts and hydration/dehydration of hygroscopic phases of the clay component. To define the mineralogical-petrographic features (composition, texture) of limestone, the clay and salt crystalline phases, the optical microscope in polarized light and diffraction anal- ysis were used. To define the petrophysical characteristics (i.e., shape and size distribution of porosity, surface area(SBET), matrix microstructures, rock composition) and interactions of chemical treatments with rock, SEM–EDS analysis and N2 porosimetry with BET and BJH methods were used. To evaluate the efficacy of Na/K-silicates, ethyl silicate consolidants and protective nano-molecular silane monomer water repellent, the mechanical strengths (uni- axial compressive strength, point load and flexural resis- tance), water/helium open porosity, water absorption and vapour permeability data determined before and after the chemical treatments of the Pietra Cantone samples from monument were compared

Cross-Location Analysis of the Impact of Household Socioeconomic Status on Participation in Urban and Peri-Urban Agriculture in West Africa

This study explores the relation between household socioeconomic status (SES) and participation in urban and periurban agriculture (UPA) in three West African cities. We used a structured questionnaire to survey 700 randomly selected households: 250 in Kano, Nigeria, 250 in Bobo Dioulasso, Burkina Faso, and 200 in Sikasso, Mali. Multiple correspondence analysis was applied on household asset variables to create an index of assets which was used as a proxy for household SES. The results showed no significant differences in households’ rate of participation in UPA across socioeconomic groups. Participation in UPA was rather significantly (P < 0.001) and positively related to household size. Interestingly, the analysis revealed that field crop cultivation and gardening were more common among households in the low and medium SES groups while those in the high SES group were more likely to keep livestock

Le manifestazioni filoniane quarzitiche del complesso magmatico tardo-ercinico nel settore occidentale sud-alpino

Un relativo addensamento di masse filoniane quarzitiche si manifesta nell’area Biellese-bassa Val Sesia del settore occidentale sudalpino. Esse sono localizzate nelle zone periferiche prospicienti dei corpi magmatici tardo-ercinici intrusivi ed estrusivi e rivelano un andamento preferenziale NNE-SSW cd ENE-WSW sotto forma di filoni sub-verticali potenti sino a 6-:-7 m e sviluppati in direzione anche per alcune centinaia di metri. I rapporti stratigrafici già definiti per le quarziti nel settore orientale della bassa Val Sesia indicano una loro connessione al magmatismo tardo-ercinico. I caratteri petrografia e geochimici, in particolare la distribuzione e i bassissimi tenori di terre rare (14,8-^19,9 ppm), evidenziano la contemporaneità genetica delle diverse masse considerate. A spread swarm of quartzite dikes outcrops in the western district of the Southern Alps, particularly in the « Biellese-bassa Val Sesia » area. The dikes are situated on the overlooking peripheral portions of intrusive and extrusive late-Hercynian magmatic bodies and show mostly NNE-SSW and ENE-WSW strike, even for several hundred meters, subvertical attitude and 6-J-7 m thickness. The stratigraphical relations previously defined for quartzites in eastern area of « bassa Val Sesia » show they are connected with to late-Hercynian magmatism. The petrographic and geochemical characters, specially the distribution and the very low contents in rare earth elements (14.8-19.9 ppm), point out the genetic contemporaneity of the considered various quartzites

Rare-earth and large-ion-lithophile elements fractionation in late hercynian granite massif of the Biellese area (Southern Alps, Italy)”

Rare-earth, large-ion-lithophile and Zr-Hf element distributions confirm that the Biel-lese late-Hercynian granite massif is a zoned complex with W-E differentiated trend, produced by only one intrusive event at meso-epiplutonic setting. The main gradual variations from mesoplutonic monzo- and syenogranites to epiplutonic syeno-granites are: a) the decrease of the total REE content (correlated to considerable systematic light REE impoverishment) and also of Ba, Sr, Zr and Hf contents; b) the increase of the Rb and Cs amounts; :) the U-impoverishment, which denotes the intense weathering process in the massif. The origin of the relatively b- and ¿¡-type granites is explained by fractional crystallization of a calc-alkaline granitic magma, which results by the partial melting of the late-Ordovician granitoid masses of the « Lakes series » zone. The depth at which the granitic magma is generated from the melting of cintinental crust is greater than the different levels of intrusion. The high crust thickness (> 30 km), deduced by Rb and Sr correlated contents, agrees with late-orogenic setting of the Biellese granite massif. Il massiccio granitico del Biellese manifesta un graduale frazionamento nella distribuzione delle terre rare, degli elementi a largo raggio ionico, di Zi e Hf, che appare essere in diretta relazione con la evoluzione W-E della differenziazione dei litotipi fondamentali e dei diversi livelli di loro messa in posto. Le principali variazioni notate dai monzo-sieno-graniti mesoplutonici ai sienograniti epiplutonici sono: a) diminuzione del contenuto totale di terre rare (correlata al sistematico impoverimento delle terre rare leggere) e dei tenori di Ba, Sr, Zr, e Hf; b) aumento dei tenori di Rb e Cs; c) impoverimento di U per mobilizzazione, che denota l’grado di alterazione superficiale del corpo granitico esposto. L’origine dei diversi tipi granitici, formatisi in conseguenza di un unico evento intrusivo, è ricondotta a cristallizzazione frazionata di un magma per-siliceo e calc-alcalino, derivato in età tardo-ercinica dalla fusione parziale di granitoidi tardo-Ordovi-ciani nei terreni della « Serie dei Laghi ». La profondità a cui il magma si è generato per fusione di crosta continentale è più elevata di quella dei livelli di intrusione granitica. L’alto spessore crostale (> 30 km), dedotto dai correlati contenuti di Rb e Sr, è in accordo con una messa in posto tardo-orogenetica del corpo granitico del Biellese