Elena Marrocchino

Chemical-mineralogical characterization of historical bricks from Ferrara: an integrated bulk and micro-analytical approach

Abstract In this paper we present bulk X-ray fluorescence-X-ray diffraction (XRF/XRD) and microanalytical scanning electron microscope-electron microprobe analysis (SEM-EMPA) data on historical bricks from Medieval or Renaissance buildings of Ferrara (NE Italy) to provide insights into the nature and provenance of the raw material as well as clues on the sintering techniques. Chemical data indicate that the starting materials were obtained by mixing high Cr-Ni clay and subordinate sand (both quarried from the Po river alluvial deposits) with the possible introduction of a Na-rich flux component. Thin-section observation, XRD and micro-analytical data indicate the presence of key accessory phases such as pyroxene, amphibole, epidote and rare olivine in the pre-fired mineral assemblage, confirming the utilization of the Po river sediments. Recognition of neo-formation firing phases (e.g. melilite, wollastonite), together with composition of micas, amphiboles and interstitial glasses, indicate kiln temperatures between c. 800 and 1000 °C. This provides guidelines for making new compatible and durable bricks to be utilized for restoration, and contributes to the preservation of historical masonry.

Petrological evolution of the Middle Triassic Predazzo Intrusive Complex, Italian Alps

ABSTRACT The Predazzo Intrusive Complex (PIC), a Ladinian plutonic body located in the Southern Alps (NE Italy), is made up of a 4.5 km3 gabbroic to syenitic and syenogranitic intrusion, basaltic to latitic volcanic products (about 6 km3 in volume) and by an extended dike swarm intruding both intrusive and volcanic rocks. An extensive field survey of the complex, followed by detailed petrographic and geochemical analyses, allowed the identification of three different magmatic units: a Shoshonitic Silica Saturated Unit (SS), 3.1 km3 in volume, a Shoshonitic Silica Undersaturated Unit (SU), 0.3 km3 in volume, and a Granitic Unit (GU), 1.1 km3 in volume. K-affinity, marked Nb and Ti negative anomalies and a strong Pb enrichment are distinctive markers for all PIC lithotypes. A general HFSE (Th, U, Pb), LREE (La, Ce, Pr, Nd) and Na enrichment characterizes the SU suite with respect to the SS series. Mass balance calculations, based on major and trace element whole rock and mineral compositions, have been used to simulate the fractionation process of SS and SU suites, showing (i) the complexity of the evolutionary stages of the PIC and (ii) the analogy between the calculated subtracted solid assemblages and the natural cumulitic lithotypes outcropping in the area. The field relationships between the various portions of the intrusive complex, the volcanic products and the dike swarm define the temporal evolution of the PIC, in which the SS magma batch was followed by the GU and later on by the SU intrusion. The presence, in both eastern and western portions of the complex, of a transitional magmatic contact between the intrusive rocks of the SS suite and the volcanics is not in favour of the hypothesis of a caldera collapse to explain the ring-like shape of the PIC.

The Coastal Sediment Provenance and Their Distribution in the Mediterranean Beaches of NW Morocco

This work deals with the granulometric and geochemical features of sediments collected at the foreshore of Tetouan beaches (NW Morocco) and at the mouth of the local five main watercourses in order to establish the links between the continental and coastal areas. The littoral, which underwent a great increase of human pressure in past decades, records great erosion rates that menace different human settlements and natural features of great environmental importance such as dune ridges, fossil cliffs and coastal lagoon. Specifically, the analysis of sediment samples collected along the Tetouan littoral made possible the characterization of the transport and depositional environments as well as the determination of sediment characteristics that are closely related to the geology and hydrology of adjacent basin areas and the relationship among long shore transport and the influence of human activities and natural coastal features that influence the geochemical composition of coastal sediments. The sedimentological studies support coastal monitoring programs for suitable coastal protection and beach nourishment projects. Analyzed beach sediments are essentially composed by quartz-rich sand and can be clearly distinguished two different sectors: (i) the first one, between Ras Mazari and Cabo Negro headlands, is characterized by medium sand, from well to very well-sorted, main sedimentary supplies to the littoral being provided by Martil River; (ii) the second one, between Cabo Negro and Ceuta headlands, consists of coarse to very coarse sediments, poorly sorted, main sedimentary inputs being related to biogenic sources and to the erosion of metamorphic rocks from Cabo Negro headland.