Na-alkaline rocks

Sicily (7 Ma to Present) Etna (0.5-Present), Iblei (7-1.5), U-stica (0.75-0.13), Pantelleria (0.3-0.005), Linosa (1-0.5), Sicily Channel seamounts - Stratovolcanoes, diatremes, small plateaux, etc. formed of tholeiitic and Na-alkaline rocks (basanite, hawaiite, trachyte, peralkaline trachyte and rhyolite). 

Sardinia (5.3 to 0.1) Capo Ferrato (—5), Montiferro (4-2), Orosei-Dorgali (4-2), Monte Ar-ci (3.7-2.3), Logudoro (3-0.1) - Stratovolcanoes, basaltic plateaux and monogenetic centres composed of subalkaline and Na-alkaline rocks, sometimes with a K-affinity. 

This province consists of central volcanoes, basaltic plateaux and monoge-netic centres composed of tholeiitic to Na-alkaline rocks (basalt to rhyolite, basanite and trachybasalt to phonolite and trachyte). It overlies calc-alkaline rocks of Oligo-Miocene age. 

Sr-Nd-Pb isotope variation along the Aeolian arc represents a part of a larger hyperbolic array connecting the Na-alkaline rocks of Etna-Iblei-Ustica and Tuscany (Figs. 7.6, 7.17). Most of the western and central Aeolian islands plot near to the low-Sr, high-Nd-Pb end-member, whereas the Stromboli volcanics plot away from Etna together with Campanian volcanoes and Emici-Roccamonfina KS rocks. However, the isotopically most primitive rocks from Alicudi have low Sr-isotopic ratios that fall outside the trend (Fig. 7.17). 

Etna About 0.6 Ma to present - Several coalescing and superimposed stratovolca-noes mostly formed of lavas, spotted with hundreds of cinder cones, cut by three rift zones and by the Valle del Bove depression. Rocks include tholeiitic basalts followed by Na-alkaline rocks (trachybasalts, hawaiites and minor benmoreites and trachytes). 

Figure 1.167. Sulfur content vs. value for Quaternary volcanic rocks of Japan. Field bounded by solid lines show two volcanoes (AK and HK), two volcanic zones (NA and CH) in Northeast Japan, three volcanic belts (IM, SW and RY), alkaline rocks (AL) and volcanic rocks of unusually high values (HI) in Ryukyu belt. Symbols surrounded by small circles show S S values of Satsuma-Iwojima volcanic rocks in West Japan (Ueda and Sakai, 1984).

Recalculation of whole-rock geochemical data to normative corundum represents a particularly useful geochemical tool that can point to hydrothermal alteration zones. Normative corundum represents alkali imbalance in sub-alkaline rocks which is generally an indicator of Na depletion and K... 

The volcanoes in the Campania Province, Pontine Islands and Vulture are composed of a wide variety of magma types. Silica undersaturated ultrapo-tassic volcanism is restricted to Somma-Vesuvio, whereas mildly undersaturated to oversaturated potassic rocks occur at Campi Flegrei, Ischia, Procida and Ventotene. In the latter two islands, low potassium compositions close to calc-alkaline basalts are found among lavas and lithic ejecta. Pliocene calc-alkaline rocks are found as rhyolites at Ponza and as basalts and basaltic andesites beneath the Campanian Plain. At Vulture, volcanism is highly enriched in both Na and K, a composition that is distinct from any other volcano in the Italian peninsula. 

REE patterns are fractionated for all the rocks, but tholeiites show lower La/Yb ratios than alkaline products (Fig. 8.5a). Incompatible element patterns normalised to primordial mantle compositions for mafic rocks are very different from the Aeolian arc and central-southern Italian peninsula. Both tholeiitic and alkaline basalts show a marked upward convexity, with negative spikes of K (Fig. 8.5b). Note, however, that there are also negative anomalies for Hf and Ti, which are uncommon in most Na-alkaline basalts from intraplate settings (e.g. Wilson 1989). Overall, the Etna magmas have been found to be more enriched in volatile components than common intraplate magmas, and water contents up to 3-4 wt % have been found by melt inclusion studies (Corsaro and Pompilio 2004 Pompilio, personal communication). 

The Ustica rocks range from mildly Na-alkaline basalt to trachyte on the TAS classification diagram, with a gap in intermediate compositions between about 55-60 wt % SiC>2 (Fig. 8.19). The mafic rocks straddle the boundary between the subalkaline and the alkaline fields, displaying a... 

The Sicily Province consists of tholeiitic to Na-alkaline magmas. Most rocks are mafic in composition, ranging from basalt to hawaiite and nephelinite, except at Pantelleria where peralkaline acid volcanics (pantellerites) dominate. A few trachytic rocks occur at Etna, Ustica and as lithic ejecta at Linosa. 

A strongly silica undersaturated Na-alkaline series ranging in composition from basanite-tephrite to phonolite, with some of the most evolved rocks reaching a peralkaline composition. This is best represented by volcanic rocks from Montiferro. 

Prometeo. This lava field site is located southeast of Island of Ustica. The recovered lavas have mafic to intermediate Na-alkaline composition, close to the equivalent rocks from Ustica. 

The Sardinia Province contains a wide variety of rocks, ranging from subalkaline to Na alkaline and nephelinitic, and from mafic to felsic. Most rocks have relatively unradiogenic Sr and Pb isotopic signatures, resembling EMI mantle compositions. A few outcrops from southern Sardinia have isotopic and trace element signatures very close to the rocks of the Sicily Province. Plio-Quatemary volcanism in Sardinia overlies Oligo-cene-Miocene arc-type tholeiitic to calc-alkaline volcanism. 

The isotopic similarity of some Italian volcanoes, such as Mt. Etna and Iblei, with Na-alkaline and tholeiitic rocks from central and west-... 

Rey C, Collins B, Goehl T, Dickson IR, Glimcher MJ (1989) The carbonate enviromnent in bone mineral A resolution-enhanced Fourier transform infrared spectroscopy study. Calcif Tissue Inti 45 157-164 Roeder PL, MacArthur D, Ma XP, Palmer GR (1987) Cathodoluminescence and microprobe study of rare-earth elements in apatites. Am Mineral 72 801-811 Ronsbo JG (1989) Coupled substitution involving REEs and Na and Si in apatites in alkaline rocks from the Illimaussaq intmsions. South Greenland, and the petrological implications. Am Mineral 74 896-901 Rouse RC, Dunn PJ (1982) A contribution to the crystal chemistry of ellestadite and the sihcate srrlfate apatites. Am Mineral 67 90-96... 

The spring waters of the Sierra Nevada result from the attack of high C02 soil waters on typical igneous rocks and hence can be regarded as nearly ideal samples of a major water type. Their compositions are consistent with a model in which the primary rock-forming silicates are altered in a closed system to soil minerals plus a solution in steady-state equilibrium with these minerals. Isolation of Sierra waters from the solid alteration products followed by isothermal evaporation in equilibrium with the eartKs atmosphere should produce a highly alkaline Na-HCO.rCOA water a soda lake with calcium carbonate, magnesium hydroxy-silicate, and amorphous silica as precipitates. 

Tyrrhenian Sea Floor (12 Ma to Present) Comacya (12), Magnaghi (3), Mar-sili (1.8-0), Vavilov, Aceste, Anchi-se, Lametini, Palinuro, older Ponza, etc. - Coexisting intraplate (oceanic tholeiites, Na-transitional and alkaline) and arc-type (arc-tholeiitic, calc-alkaline, potassic) rocks. 

Cinder and spatter cones and associated lava fields formed predominantly of alkaline mafic rocks with both Na and K affinity, and of minor tholeiites. 

A mildly silica undersaturated to saturated series (trachybasalt to trachyte) with a moderate alkali content and a Na- to mildly K-alkaline affinity. This comprises most of the Plio-Quatemary rocks, including some lavas from Monte Arci. 

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