Search results for "Salt"
showing 10 items of 1157 documents
Late Cretaceous lithospheric extension in SE China: Constraints from volcanic rocks in Hainan Island
2015
Abstract Petrological, geochemical and in-situ zircon U–Pb dating and Hf-isotope analyses have been carried out on a suite of basalt–andesite–rhyolite volcanic rocks exposed in the Liuluocun area, Hainan Island, SE China. Zircon analyses show that these volcanic rocks crystallized in the Early Cretaceous (ca. 102 Ma). The basalts are characterized by low MgO contents and mg-numbers but high rare earth element, high field strength element and large ion lithophile element contents and Nb–Ta negative anomalies. They have relatively uniform Sr–Nd isotope compositions with e Nd (t) values of − 4.09 to − 3.63. The andesites show enrichment of high field strength element and rare earth element wit…
Lower Cretaceous tholeiitic dyke swarms from the Ponta Grossa Arch (southeast Brazil): Petrology, Sr-Nd isotopes and genetic relationships with the P…
1990
The Lower Cretaceous dykes of the Ponta Grossa Arch, the most important dyke swarms in Brazil, are associated with the flood basalts and rare acid flows of the northern Parana basin. The Ponta Grossa (PG) dykes are formed by two-pyroxene tholeiites and rare acid rocks. The basaltic dykes may be distinguished into two main groups: a dominant, high-TiO2 (> 2 wt.%; HTi) group and a subordinate, low-TiO2 (< 2 wt.%; LTi) group, characterized, for similar MgO content, by high and low incompatible-element contents, respectively. Most PG dykes do not show chemical and isotope evidence supporting important crustal contamination. PG dykes with (87Sr86Sr)0 < 0.7060 plot in the mantle array (ϵSr ≈ + 17…
Basalt magmatism along the passive continental margin of SE Brazil (Campos basin)
1992
The SE-Brazil passive continental margin is characterized by tholeiitic magmatism that is particularly widespread in the marginal Campos basin, facing the inland flood basalts of the adjacent Parana basin. Campos magmatism is represented by Early Cretaceous (EC; 134–122 Ma) flood basalts and minor Upper Cretaceous-Early Tertiary basalt flows and intrusives, which were emplaced in a basin with attenuated crustal thickness (20 km). Petrography, mineral chemistry, wholerock geochemistry and Sr−Nd isotope composition emphasize that the EC-Campos basalts have suffered extensive seawater interaction which caused enrichment in MgO, FeO total, K2O, Rb and Ba, and depletion in SiO2 and CaO, while Zr…
Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation – Part 2: A…
2012
Abstract. For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120–9336 μg g−1) as well as for Sr (9–21…
Mauna Kea, Hawaii, as an Analog Site for Future Planetary Resource Exploration: Results from the 2010 ILSO-ISRU Field-Testing Campaign
2013
Within the framework of the International Lunar Surface Operation - In-Situ Resource Utilization Analogue Test held on January 27 - February 11, 2010 on the Mauna Kea volcano in Hawaii, a number of scientific instrument teams collaborated to characterize the field site and test instrument capabilities outside laboratory environments. In this paper, we provide a geological setting for this new field-test site, a description of the instruments that were tested during the 2010 ILSO-ISRU field campaign, and a short discussion for each instrument about the validity and use of the results obtained during the test. These results will form a catalogue that may serve as reference for future test cam…
Steam and gas emission rate from La Soufriere volcano, Guadeloupe (Lesser Antilles): Implications for the magmatic supply during degassing unrest
2014
Abstract Since its last magmatic eruption in 1530 AD, La Soufriere andesitic volcano in Guadeloupe has displayed intense hydrothermal activity and six phreatic eruptive crises. Here we report on the first direct quantification of gas plume emissions from its summit vents, which gradually intensified during the past 20 years. Gas fluxes were determined in March 2006 and March 2012 by measuring the horizontal and vertical distributions of volcanic gas concentrations in the air-diluted plume and scaling to the speed of plume transport. Fluxes in 2006 combine real-time measurements of volcanic H2S concentrations and plume parameters with the composition of the hot (108.5 °C) fumarolic fluid at …
Brittle reactivation of ductile shear zones in NW Namibia in relation to South Atlantic rifting
2015
Rifting has occurred worldwide along preexisting mobile belts, which are therefore thought to control rift orientation on a large scale. On a smaller scale, shear zones within mobile belts are reactivated as rift faults. In NW Namibia, shear zones of the Neoproterozoic Kaoko Belt run subparallel to the present-day continental passive margin and are inferred to have been reactivated during the opening of the South Atlantic Ocean. However, the extent of this reactivation and the influence of the reactivated shear zones on South Atlantic rifting are largely unknown. A combined remote sensing and field study was conducted to quantify offsets that are a direct function of shear zone reactivation…
The White Stone of South-Eastern Sicily: Urban and Territorial Identity
2017
La Sicilia è un territorio fortemente "segnato" dall'impiego massiccio della ricca varietà di materiali lapidei che la natura ha messo a disposizione: materia prima dalle differenti qualità petrografiche, colore, caratteristiche tecniche e con una vasta possibilità di impiego, sia come elemento costruttivo sia come pietra ornamentale. La "pietra bianca" di Siracusa, il basalto dell'Etna, la "pietra forte" del ragusano, la pietra di Sabucina di Caltanissetta e Niscemi, le calcareniti e le rocce tufacee delle cave di Carini e Aspra, il calcare grigio di billiemi nel palermitano e il tufo calcareo di Agrigento, caratterizzano gran parte degli insediamenti antropici dell'isola, espressione di u…
Mobility and fluxes of major, minor and trace metals during basalt weathering and groundwater transport at Mt. Etna volcano (Sicily)
2000
Abstract The concentrations and fluxes of major, minor and trace metals were determined in 53 samples of groundwaters from around Mt Etna, in order to evaluate the conditions and extent of alkali basalt weathering by waters enriched in magma-derived CO 2 and the contribution of aqueous transport to the overall metal discharge of the volcano. We show that gaseous input of magmatic volatile metals into the Etnean aquifer is small or negligible, being limited by cooling of the rising fluids. Basalt leaching by weakly acidic, CO 2 -charged water is the overwhelming source of metals and appears to be more extensive in two sectors of the S-SW (Paterno) and E (Zafferana) volcano flanks, where out …
Geochemical mapping of magmatic gas–water–rock interactions in the aquifer of Mount Etna volcano
2001
Abstract Systematic analysis of major and minor elements in groundwaters from springs and wells on the slopes of Mt. Etna in 1995–1998 provides a detailed geochemical mapping of the aquifer of the volcano and of the interactions between magmatic gas, water bodies and their host rocks. Strong spatial correlations between the largest anomalies in pCO2 (pH and alkalinity) K, Rb, Mg, Ca and Sr suggest a dominating control by magmatic gas (CO2) and consequent basalt leaching by acidified waters of the shallow (meteoric) Etnean aquifer. Most groundwaters displaying this magmatic-type interaction discharge within active faulted zones on the S–SW and E lower flanks of the volcanic pile, but also in…