Mafic rock

This is divided into a western, a central and an eastern sector. The western Aeolian arc (Alicudi, Filicudi, Salina) consists of calc-alkaline rocks with typical island arc signatures. Mafic and intermediate rocks dominate the volcanic sequence, with minor silicic volcanics. The central islands (Vul-cano and Lipari) are dominated by calc-alkaline to shoshonitic mafic to silicic rocks mafic rocks from this sector show isotopic compositions and incompatible trace element ratios similar to the western islands. The eastern arc (Panarea and Stromboli) consists of calc-alkaline to potassic alkaline rocks. Stromboli shows geochemical and isotopic signatures akin to the Neapolitan volcanoes. The Island of Panarea, located between Stromboli and Lipari, has intermediate characteristics between these two volcanoes (Calanchi et al. 2002a). 

Distinctions between glauconite and celadonite may be vague in the area of approximately 0.2% tetrahedral Al. Celadonite is found as an alteration mineral in mafic volcanic rocks (127). 

Most copper deposits are (/) porphyry deposits and vein replacement deposits, (2) strata-bound deposits in sedimentary rocks, (J) massive sulfide deposits in volcanic rocks, (4) magmatic segregates associated with nickel in mafic intmsives, or (5) native copper, typified by the lava-associated deposits of the Keweenaw Peninsula, Michigan. 

Feux, A. N. and Baker, D. R. (1973). Stable carbon isotopes in selected granitic, mafic, and ultramafic igneous rocks. Geochim. Cosmochim. Acta 37, 2509-2521. 

Blundy JD, Brooker RA (2003) Trace element partitioning during melting and ciystalhzation of mafic rocks in the lower crust. Contrib Mineral Petrol (submitted). 

Valuable mineral deposits which form by residual concentration pertain to iron, manganese, aluminum, nickel, clays, tin and gold. Aluminum comes almost exclusively from residual concentrations of bauxite, which result from the laterihsation of alumina rich igneous rocks like syenites under tropical and subtropical climatic conditions. Laterites also contribute nearly 80% of the world s reserves of nickel at grades better than 1% Ni. They form by residual concentrations as a result of weathering of mafic and ultramafic igneous rocks, which are relatively enriched in nickel. 

The Archaean Yilgarn Craton is composed mainly of granite, with mafic, volcanic and sedimentary greenstone rocks. It is one of the world s principal mineral provinces, with considerable resources of primary and supergene Au, sulfide-hosted and lateritic nickel, bauxite, as well as a wide range of other commodities. 

Figure 5 presents Ni in 0-5-cm soils. There are no notable elevated concentrations of Ni in the region, with the exception of northern Maine and north-central New Brunswick. Figure 6 displays Ni in the C-horizon where there is a distinctive elevated Ni signature spatially correlative with the mafic rocks of northern New Brunswick that host mineralization at the Bathurst mining camp. 

Detectior limits Acidic rock Inter- mediate rook Basic rook Ultra- mafic rook Sand- stone Shale Carbo- nate Gneiss Leptite Amphi- bolite Meta- pelite Vlarble Alluvial plain soils Soils Stream Sedi- ments Shallo w sea Sed- iments... 

Acidic rock Inter- mediat e rock Basic rock Ultra- mafic rock Sand- stone Shale Carbo nate Gneis s Leptit e Amphi bolite Meta- pelite Marbl e Alluvia I plain soil Soil Stream sedimen t shallow sea edimen t... 

Bulk rock geochemistry of the Lac Cinquante deposit shows that the Archean volcanic rocks (both the mafic volcanic flows and the bimodal volcanic suite) are dominantly tholeiitic high-Fe basalts and basaltic andesites. The alternating felsic units in the bimodal suite are dacitic and rhyolitic in composition (Fig. 2). 

ABSTRACT A geochemical analysis of major, trace and rare earth elements was carried out in beach sands collected from the Northeastern coast of Mexico in order to observe the spatial trends along three different beaches. Results show that major elements patterns along the beaches are controlled by heavy minerals and plutonic and sedimentary input towards the coast. In addition, trace elements tendencies indicate that the beach sands are influenced by the presence of magnetite. Finally, the differences in Eu anomalies indicate a mix of felsic to mafic and intermediate rocks and feldspar weathering. 

Rare earth elements trends show a negative and positive Eu anomalies in some samples studied from the Northeastern beaches suggesting a mix of felsic and mafic source rocks and feldspar weathering. 

The geology of Cyprus is dominated by four distinct terranes - the Troodos Ophiolite Complex composed of mafic and ultramafic rocks, the Circum-Troodos Sedimentary Sequence containing calcarenites, siltstones and carbonates, the Mamonia Complex composed of igneous, sedimentary and metamorphic rocks and the Kyrenia Terrain containing a series of allochthonous massive and recrystallised limestones dolomites and marbles. These terranes generate highly varied landscapes (Fig 1). 

The Stillwater Complex consists of a sequence of differential layers of mafic and ultramafic rocks, which extend for a strike length of up to 40 km and has a maximum exposed thickness of about 7.4 m [3], There are several mineralization zones at the Stillwater Complex, including a PGM-rich zone and a low-grade zone. The Stillwater ore that is processed nowadays contains olivine, plagioclase, as well as plagioclase-brauzite, all of which are naturally hydrophobic gangue minerals. 

Crocket, J.H., Platinum Group Elements in Mafic and Ultrafamic Rocks A Survey, Canadian Minerals, Vol. 17, pp. 391-403, 1979. 

Heinrich CA (1986) Eclogite facies regional metamorphism of hydrous mafic rocks in the Central alpine Adula nappe. J Petrol 27 123-154... 

Alteration in Allende chondmle C6 is concentrated at the margins where 5 Mg values are low (Fig. 17). Evaluation of the likelihood that low 8 Mg values could be the result of aqueous alteration will require studies of Mg isotope fractionation during low-T alteration of terrestrial mafic rocks. An alternative explanation is that low 8 Mg and alteration resulted from condensation (collision frequency of gaseous Mg is greater for the lighter isotopes). 

Hatton CJ, Sharpe MR (1989) Significance and origin of boninite-like rocks associated wifii file Bushveld Complex. In Boninite Crawford AJ (ed) Unwin Hyman, Boston, p 174-207 Helz RT (1985) Compositions of fine-grained mafic rocks from sills and dikes associated wifii the Stillwater complex. In Stillwater complex, geology and guide. Special Pub 92. Czamanske GK, Zientek ML (eds) Montana Bureau of Mines and Geology, p 97-117... 

Chromium is a compatible element in the Earth s mantle, and tends be present in much greater concentrations in mafic igneous rocks than in felsic ones (Faure 1991). Ultramafic rocks often contain over 1,000 ppm Cr and can generate environmental problems when they weather (Robertson 1975 Robles and Armienta 2000). Granites may contain less than 20 ppm Cr, whereas shales contain roughly 90 ppm. 

The mafic to intermediate and tholeiitic to transitional rocks of the Bousquet Formation are characterized by moderately enriched chondrite-normalized LREE and MREE patterns, flat HREE profiles and negative Nb, Ta, Zr, and Hf... 

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