Regional geology-_________________________ Granitic rocks and gneisses-____________ Mafic and ultramafic rocks____________ Mafic rocks.______________________ Ultramafic rocks_______-__-_____-_. Absolute age determinations____-_-_______. Analytical techniques ______________________ Northwestern part of the Quadrila'tero Ferrif ero___ Special studies.-__________________________ Age determinations-___________________ Alkali feldspars________________________ Minor elements in biotite_______________ Older granodiorite and gneiss_______________ Younger granites and gneiss ________________ Souza Noschese Gneiss-_._______-____. Granite gneiss at Marzagao-____________ Granite at Morro da Pedra_-_____-____ Younger granite dikes._________________ Petrogenesis. ______________________________ Older gneisses.-_-____-__-___________. Younger granites and gneisses.__________ Ultramafic and mafic rocks_ _______________ West-central part of the Quadrila'tero Ferrifero___. Special studies.-__________________________ Age determinations-___________________ Alkali feldspars..______________________ Porphyritic granodiorite____________________ Granite gneiss.____________________________ Contact between the Minas Series and border gneiss._________________________________ Mafic rocks_______________________________ Summary and history of the Moeda complex. _ Bagao complex._______________________________ Special studies.___________________________ Age determinations.___________________ Alkali feldspars._______________________ Minor elements in biotite.______________

An isotopic data base of δ13C and δ18O analyses of 528 samples collected from 39 classical Greek and Roman quarries of Turkey, Greece, Italy and Tunisia has been accumulated. The discriminative possibilities of the data base vary from quarry to quarry. Most quarries have a distinctive pattern for either or both variables, but some have more than one grouping. The data also overlap for many quarries preventing a unique provenance assignment. If the alternatives are known so that the total pool of possible sources is reduced, the data base can then discriminate and assign a provenance for most classical marble artifacts.

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Two stable isotopic data bases for ∂13C and ∂18O values of marble have been accumulated: (1) 590 analyses from 42 Classical quarries of Greece, western Turkey, Tunisia, and Carrara, Italy, and (2) potential Early Bronze Age (EBA) marble sources in the central Cyclades, comprising 192 analyses from 16 sites on the islands of Paros, Naxos, Ios, and Keros. The data bases include the most important marble occurrences in the eastern Mediterranean and so can be used to source artefacts of any age. Neolithic artefacts found at Franchthi Cave, where no marble occurs locally, have been attributed to the Peloponnese and the Cyclades, direct evidence for early trade. In the Cycladic EBA, Naxos and Keros were the principal marble sources for the abundant artefacts found at Keros. The commercial marble trade in Archaic Greece began in the central Cyclades where the tradition apparently went back some 5000 years, to the Neolithic. Classical Greece and especially Rome expanded the number and locations of commercial marble sources throughout the Mediterranean.

The Roseland district of Nelson and Amherst Counties, Va., is centered on an intermontane basin along the southeastern margin of the Blue Ridge. The Grenville-age igneous rocks in this area are less altered than elsewhere in the Blue Ridge, and exposure is sufficient to map their relations. The district was formerly an important producer of titanium minerals and still contains over 5 percent of U.S. identified resources of those minerals. The valuable minerals, rutile and ilmenite, formed in two stages which largely correlate with anorthosite and ferrodiorite, respectively.The oldest rocks (apparently pre-Grenville) are garnet-graphitepyroxene-blue quartz granulites and quartz mangerites. Platytextured leucocratic charnockites are associated with these rocks but are probably a younger neosome.The Roseland Anorthosite (about 1,050 Ma) intrudes these older rocks as a largely concordant basal sheet. Crosscutting relations with country rock are abundant, however. The anorthosite consists of andesine-antiperthite megacrysts in a granulated oligoclase-potassium feldspar matrix. Its margins contain pyroxene and blue quartz megacrysts, probably as a result of high-temperature reaction between anorthosite melt and country rocks. The unusually alkalic nature of the anorthosite has led to unusual rutile mineralization in this contaminated marginal facies and its immediate country rocks, especially in swarms of anorthosite sills in mangeritic rocks forming the anorthosite roof along the eastern side of the body.The Shaeffer Hollow Granite (about 990 Ma) is a coarse leucocratic blue quartz granite, porphyritic with tabular feldspars. It cuts granulite but is present largely as roof pendants and screens in the younger ferrodioritic plutons, except in a wide deformation zone where it appears to be the dominant protolith of mylonitic rocks.The Roses Mill and Turkey Mountain ferrodiorite-charnockite plutons (about 970 Ma) together form a largely concordant upper intrusive sheet. Intrusive relations with older units, however, are abundant. These rocks have high ilmenite-apatite-(zircon) contents that reflect distinctively high values of Ti, P, Zr, Fe/Mg, and K/Si. Blue quartz is present only as abundant xenocrysts. Much of these plutons is isochemically altered to biotitic augen gneiss. Layered concordant impure nelsonite (ilmenite-apatite rock) is locally found along the bases of these plutons, and nelsonite forms discordant bodies in the immediately underlying country rock. These lithologies probably formed by liquid immiscibility. Nelsonites and ilmenite-rich ferrodiorite constitute the main ilmenite resources of the district.The anorthosite and ferrodiorite-charnockite plutons are apparently not comagmatic but probably cogenetic. The anorthosite formed in a deeper crustal environment than ferrodiorite and probably was emplaced as a diapir into the higher crustal level.In the northwestern side of the district are ferrodioritic charnockitic rocks of the Pedlar massif. They are about 1,040 m.y. old but are separated from all othe...