Neodymium isotope mapping a polygenetic TTG batholith: Failed back-arc rifting in the Central Metasedimentary Belt, SW Grenville Province

Fifty-five new Nd isotope analyses are presented for plutonic orthogneisses from the Grimsthorpe domain in the marble-rich segment of the Grenvillian Central Metasedimentary Belt (CMB) to test the back-arc aulacogen model for its origin. Nd isotope analyses from the Weslemkoon batholith, Elzevir batholith, Lingham Lake complex and Canniff tonalite are used to probe the crustal formation age of their source rocks. Despite its concentric foliation, the Weslemkoon batholith displays a complex geochemical pattern consisting of several NE trending domains with older TDM ages, surrounded by juvenile crustal material. The new Nd isotope results, coupled with geochemistry for the Weslemkoon and Elzevir batholiths depict the fragmentation of a block of old crust that formed a screen between en echelon segments of a mid-Mesoproterozoic back-arc rift zone. The isotope boundaries identified within the Weslemkoon batholith delineate magma pulses sampling two distinct sources, interpreted as Laurentian basement and juvenile basaltic underplate. Underplating could be attributed to slab rollback under the pre-Grenvillian continental margin arc. The intensification of rift-related magmatism in the CMB is demonstrated by its bimodal petrological character. A modern analogue for the tectonic context of the CMB is the Gulf of California, where subduction-related magmatism has transitioned to rift-related magmatism. However, the Gulf of California exhibits more transcurrent motion than is evidenced by the geometry of the CMB rift. A geometrical analogue for the break-up of the Elzevir block between two rift segments is provided by the Danakil block of the Red Sea, which is currently undergoing similar tectonic fragmentation.

Rare Earth Elements distribution in grapevine varieties grown on different types of soils: examples from Mount Etna and from the Hyblean Plateau (Sicily, Italy)

<p>The present contribution reports the results from a geochemical and statistical study aimed to identify in the Rare Earth Elements (REEs) absorption a good fingerprinting marks for determining the territoriality and the provenance of Vitis vinifera L. into two different geological contexts in Sicily: the volcanic district of Mount Etna and the carbonate platform of the Hyblean Plateau (Sicily, southern Italy). Our aim was to: i) define if the REEs  distribution in plants may reflect the composition of the provenance soil under similar climate conditions; ii) highlight differences, if any, in REE absorption within the various parts of the plants; and  iii) propose, for selected cultivar of Vitis vinifera L., a REE fingerprint in the Etna Volcano and Hyblean carbonate soils as well as to recognize characteristic REEs pattern.</p><p>To this aim, REE content has been determined by ICP-MS investigation in the soils and in the selected grapevine varieties for all the following parts: leaves, seeds, juice, skin and berries. Geochemical data have also been approached by a multivariate statistical analysis of the Principal Component Analysis (PCA), together with the Linear Discriminant Analysis (LDA).</p><p>The work permitted to highlight various REE distribution within the various parts of the plant and assessed as each grape variety presents a characteristic geochemical pattern in the absorption of REEs in relationship with the geochemical features of the type of soil on which the grapes grew.</p>

Evidence of Low-Habitat Contamination Using Feathers of Three Heron Species as a Biomonitor of Inorganic Elemental Pollution

The concentration of 12 elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) has been investigated in the feathers of three species of Ardeidae, namely the Grey Heron Ardea cinerea, the Little Egret Egretta garzetta, and the Cattle Egret Bubulcus ibis, all breeding at a colony located in the southern Padana Plain (NW Italy). This study is a first step for an evaluation of possible direct effects of these elements on chicks’ survival and growth rate. Fe, Zn, Cu, and Mn were in the range 7–69 mg Kg−1, while lower levels of Pb, Ni, As, and Se (0.27–1.45 mg Kg−1) were measured. Co, Cd, and Cr were close to the method detection limits (MDLs) in all the species. The measured concentrations of the most abundant trace elements, such as Zn and Cu, seem to reflect the geochemical pattern of the background (running water and soil), while Hg concentration is lower and it appears to be biomagnified, particularly in Grey Heron feathers. Its concentration is higher in adults than in chicks, and it differs among the three species, as it is closely related to the fish-based dietary pattern. The measured trace elements’ concentrations are below the threshold levels in all the heron species, and consequently, harmful and acute effects on the local population are unlikely; the conservation status of herons populations in northern Italy is probably more affected by other factors, such as climate changes, altered aquatic environment, and, consequently, food quality.

Hydrogeological and hydrogeochemical characterization of the unconfined aquifer in the fluvio-eolian plain of Cordoba (Argentina)

The studied area, a vast plain located in the South of Córdoba (Argentina), presents a relief resulting from the juxtaposition of an eolian and a fluvial system. The objective of this work was to characterize the unconfined aquifer from a dynamic and a geochemical point of view, establishing relationships with lithological and geomorphological features and validating with statistical multivariate analysis (Q mode) of the geochemical data. The unconfined aquifer presents variable hydraulic gradients and groundwater velocity, both conditioned by the local relief and lithology. The aquifer showed a varied spatial geochemical pattern with fresh to salty water (0.4–10.0 g/L) and sodium bicarbonate to sodium chloride geochemical types, in some places of mixed anionic type. The statistical analysis showed two groups: Group 1 links salty-brackish groundwater of sulfate and chloride type with longitudinal dunes and lowlands with locally outcropping water. It represents evolved groundwater coming from intermediate and regional flows. Group 2 links fresh groundwater of bicarbonate type with active dunes and paleochannels. In these sites, where coarser sediments prevail, local groundwater flow cells develop as a result of recent recharge, leading to greater groundwater velocity and decreasing the transference of ions to solution. These results allow us to identify the most promising areas for freshwater abstraction.