Search results for "BASAL"
showing 10 items of 920 documents
The Late Cretaceous Klepa basalts in Macedonia (FYROM) – Constraints on the final stage of Tethys closure in the Balkans
2017
The waning stage(s) of the Tethyan ocean(s) in the Balkans are not well understood. Controversy centres on the origin and life-span of the Cretaceous Sava Zone, which is allegedly a remnant of the last oceanic domain in the Balkan Peninsula, defining the youngest suture between Eurasia- and Adria-derived plates. In order to investigate to what extent late-Cretaceous volcanism within the Sava zone is consistent with this model, we present new age data together with trace-element and Sr–Nd–Pb isotope data for the Klepa basaltic lavas from the central Balkan Peninsula. Our new geochemical data show marked differences between the Cretaceous Klepa basalts (Sava Zone) and the rocks of other volca…
Investigation of Li/Ca variations in aragonitic shells of the ocean quahogArctica islandica, northeast Iceland
2009
Interannual and intra-annual variations in lithium-to-calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile Arctica islandica (Mollusca; Bivalvia) collected alive in 2006 off northeast Iceland. Li/Ca shell ranged between 7.00 and 11.12 µmol mol -1 and presented well-marked seasonal cycles with minimum values recorded at the annual growth lines; a general pattern was a progressive increase in Li/Ca shell from March to May, followed by a plateau in June and a decrease down to minimum values in July-August. Li/Ca shell was correlated with d 18 O shell -derived temperature, but the strength of this relationship was weak ( r 2 p shell in A.…
Trade me an axe? Interpretive challenges of the distribution and provenance of Neolithic basaltic bifacial tools in Israel
2016
The discovery of a Neolithic quarry and production site for basanite bifacial tools at Giv�at Kipod in Israel has provided new insights into these socially significant artefacts. Geochemical analysis of material from the quarry distinguishes it from other basaltic rock sources in Israel, allowing stone tools from a variety of sites and dated contexts to be assigned a provenance. Results suggest that Giv�at Kipod was an important production centre for over several millennia. It operated primarily on a local, regional level and independently of the parallel manufacture-and-distribution mechanisms of flint bifacials. While flint tools developed in response to the practical requirements of the …
The Geochemistry of Basalt Handaxes from the Lower Palaeolithic Site of Ma‛ayan Baruch, Israel-A Perspective on Raw Material Selection
2014
The Upper Acheulian site of Ma‛ayan Baruch, northern Israel, is primarily known for its exceptionally large assemblage of thousands of flint handaxes. Within this assemblage, a minute collection of basalt handaxes was retrieved as well, representing particular technological choice within the Upper Acheulian. Using geochemistry, we were able to determine that these basalt handaxes were not made from local basalt, but from different sources. Thus, the use of basalt at the site does not represent an ad hoc choice of using local raw material but, rather, a more complex technological choice pertaining to variability in raw material selection in the Lower Palaeolithic Levant.
Evidence of deep magma degassing and ascent by geochemistry of peripheral gas emissions at Mount Etna (Italy): Assessment of the magmatic reservoir p…
2003
[1] Five gas discharges in the area of Mount Etna volcano (Italy) and in the near Hyblean plateau have been monitored since 1996. All the emissions displayed low contributions from crustal fluids, whereas magmatic gases were the main component. Selective dissolution of these gases into hydrothermal aquifers has been recognized and modeled, allowing us to calculate the original composition of the magma-released gases. The inferred composition of the magmatic gases exhibits synchronous variations of He/Ne and He/CO2 ratios, which are coherent with the magma degassing process. On the basis of numerical simulations of volatile degassing from Etnean basalts we have computed the initial and final…
The origin and evolution of breakouts in a cooling-limited rhyolite lava flow
2018
Understanding lava flow processes is important for interpreting existing lavas and for hazard assessments. Although substantial progress has been made for basaltic lavas our understanding of silicic lava flows has seen limited recent advance. In particular, the formation of lava flow breakouts, which represent a characteristic process in cooling-limited basaltic lavas, but has not been described in established models of rhyolite emplacement. Using data from the 2011–2012 rhyolite eruption of Puyehue-Cordón Caulle, Chile, we develop the first conceptual framework to classify breakout types in silicic lavas, and to describe the processes involved in their progressive growth, inflation, and mo…
Hydrothermal macroscopic Fe-sepiolite from Oujda Mounts (Middle Atlas, Eastern Morocco)
2008
The Triassic-Jurassic series in the Oujda Mounts (Middle Atlas, NE Morocco) includes two basaltic units. The whole sequence is crosscut by veins filled with Fe-sepiolite + chalcedony + calcite + smectite and mixed layer talc-saponite. Fe-sepiolite occurs as macroscopic fibres and is one of the latest mineral phases in the filling sequence of the veins. The compositional relationships and crystallographic parameters obtained on carefully selected samples of sepiolite are compared with previous data, and support the actual development of Mg-Fe substitution in this clay mineral, given the adequate hydrothermal conditions. Genesis of this uncommon variety of sepiolite in veins is interpreted as…
Geochemical constraints on basalt petrogenesis in the Strait of Sicily Rift Zone (Italy): Insights into the importance of short lengthscale mantle he…
2020
Igneous activity from the late Miocene to historic time (most recently 1891 CE) in the Strait of Sicily has created two volcanic islands (Pantelleria and Linosa) and several seamounts. These volcanoes are dominated by transitional (ol + hy-normative) to alkaline (ne-normative) basaltic lavas and scoriae; volcanic felsic rocks (peralkaline trachyte-rhyolite) crop out only on Pantelleria. Although most likely erupted through continental crust, basalts demonstrate no evidence of crustal contamination and are geochemically similar to oceanic island basalts (OIB). Despite their isotopic similarities, there are considerable compositional differences with respect to major and trace element geochem…
Some aspects regarding the static behavior of basalt in the machine building industry
2017
Basalt is a material available in big quantities in nature. It has a low price and can be used in various domains. It can be relatively easily extracted from natural deposits and processed by means of melting. Melted and recrystallized basalt has demonstrated promising behavior with regards of its use in manufacturing, as reported in the literature. This work aims to present some aspects regarding the opportunity of using basalt in manufacturing the subassemblies of machine-tools. The research was made using grey cast iron and steel parts as reference for a comparative study. The researches presented in this work were focused on analyzing the behavior of basalt parts submitted to static str…
Study on Experimental Determination of the Elasticity Modulus of Casted Basalt
2020
Basalt is a material available in big quantities in nature. It has a low price and can be used in various domains. It can be relatively easily extracted from natural deposits and processed by means of melting. Melted and recrystallized basalt has demonstrated promising behavior with regards of its use in manufacturing, as reported in the literature. This paper presents the results of an experimental study on the determination of the modulus of elasticity of molten and recrystallized basalt by the method of resistive electrical tensometry and to validate the result and by simulation using finite elements method. Testing methodology, experimental test, data records, data processing and result…