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Sample records for alkaline pluton kola

  1. Spinel-group minerals in rocks of the Khibiny alkaline pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Ivanyuk, G. Yu.; Pakhomovsky, Ya. A.; Konopleva, N. G.; Yakovenchuk, V. N.; Men'shikov, Yu. P.; Mikhailova, Yu. A.

    2007-12-01

    Seven spinel-group minerals in various geological settings have been revealed in the rocks of the Khibiny pluton. Hercynite, gahnite, and vuorelainenite occur only in xenoliths of hornfels after volcanic and sedimentary rocks, whereas spinel and magnesiochromite occur in alkaline ultramafic rocks of dike series. Franklinite has been discovered in a low-temperature hydrothermal vein. Ubiquitous magnetite is abundant in foyaite, foidolites, alkaline ultrabasic rocks, and pegmatite and hydrothermal veins and may even be the main mineral in some foidolite varieties. The spinel-group minerals are characterized by various chemical compositions due to the fractionation of nepheline syenites resulting in formation of the Main ring of foidolites and apatite-nepheline ore. Like most other minerals found throughout the pluton, magnetite is characterized by variation in the chemical composition along the radial line from the contact with country Proterozoic volcanic rocks to the geometric center of the pluton. Toward the center, the total Ti and Mn contents in magnetite increase from 5 15 up to 40 at %.

  2. Typochemistry of rinkite and products of its alteration in the Khibiny Alkaline pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Konopleva, N. G.; Ivanyuk, G. Yu.; Pakhomovsky, Ya. A.; Yakovenchuk, V. N.; Mikhailova, Yu. A.; Selivanova, E. A.

    2015-12-01

    The occurrence, morphology, and composition of rinkite are considered against the background of zoning in the Khibiny pluton. Accessory rinkite is mostly characteristic of foyaite in the outer part of pluton, occurs somewhat less frequently in foyaite and rischorrite in the central part of pluton, even more sparsely in foidolites and apatite-nepheline rocks, and sporadically in fenitized xenoliths of the Lovozero Formation. The largest, up to economic, accumulations of rinkite are related to the pegmatite and hydrothermal veins, which occur in nepheline syenite on both sides of the Main foidolite ring. The composition of rinkite varies throughout the pluton. The Ca, Na, and F contents in accessory rinkite and amorphous products of its alteration progressively increase from foyaite and fenitized basalt of the Lovozero Formation to foidolite, rischorrite, apatite-nepheline rocks, and pegmatite-hydrothermal veins.

  3. Rock-Forming feldspars of the Khibiny alkaline pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Ivanyuk, G. Yu.; Pakhomovsky, Ya. A.; Konopleva, N. G.; Kalashnikov, A. O.; Korchak, Yu. A.; Selivanova, E. A.; Yakovenchuk, V. N.

    2010-12-01

    This paper describes the structural-compositional zoning of the well-known Khibiny pluton in regard to rock-forming feldspars. The content of K-Na-feldspars increases inward and outward from the Main foidolite ring. The degree of coorientation of tabular K-Na-feldspar crystals sharply increases in the Main ring zone, and microcline-dominant foyaite turns into orthoclase-dominant foyaite. The composition of K-Na-feldspars in the center of the pluton and the Main ring zone is characterized by an enrichment in Al. This shift is compensated by a substitution of some K and Na with Ba (the Main ring zone) or by an addition of K and Na cations to the initially cation-deficient microcline (the central part of the pluton). Feldspars of volcanosedimentary rocks occurring as xenoliths in foyaite primarily corresponded to plagioclase An15-40, but high-temperature fenitization and formation of hornfels in the Main ring zone gave rise to the crystallization of anorthoclase subsequently transformed into orthoclase and albite due to cooling and further fenitization. Such a zoning is the result of filling the Main ring fault zone within the homogeneous foyaite pluton with a foidolite melt, which provided the heating and potassium metasomatism of foyaite and xenoliths of volcanosedimentary rocks therein. The process eventually led to the transformation of foyaite into rischorrite-lyavochorrite, while xenoliths were transformed into aluminum hornfels with anorthoclase, annite, andalusite, topaz, and sekaninaite.

  4. Kyanoxalite, a new cancrinite-group mineral species with extraframework oxalate anion from the Lovozero alkaline pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Pekov, I. V.; Olysych, L. V.; Massa, W.; Yakubovich, O. V.; Zadov, A. E.; Rastsvetaeva, R. K.; Vigasina, M. F.

    2010-12-01

    Kyanoxalite, a new member of the cancrinite group, has been identified in hydrothermally altered hyperalkaline rocks and pegmatites of the Lovozero alkaline pluton, Kola Peninsula, Russia. It was found at Mount Karnasurt (holotype) in association with nepheline, aegirine, sodalite, nosean, albite, lomonosovite, murmanite, fluorapatite, loparite, and natrolite and at Mt. Alluaiv. Kyanoxalite is transparent, ranging in color from bright light blue, greenish light blue and grayish light blue to colorless. The new mineral is brittle, with a perfect cleavage parallel to (100). Mohs hardness is 5-5.5. The measured and calculated densitiesare 2.30(1) and 2.327 g/cm3, respectively. Kyanoxalite is uniaxial, negative, ω = 1.794(1), ɛ = 1.491(1). It is pleochroic from colorless along E to light blue along O. The IR spectrum indicates the presence of oxalate anions C2O{4/2-} and water molecules in the absence of CO{3/2-} Oxalate ions are confirmed by anion chromatography. The chemical composition (electron microprobe; water was determined by a modified Penfield method and carbon was determined by selective sorption from annealing products) is as follows, wt %: 19.70 Na2O, 1.92 K2O, 0.17 CaO, 27.41 Al2O3, 38.68 SiO2, 0.64 P2O5, 1.05 SO3, 3.23 C2O3, 8.42 H2O; the total is 101.18. The empirical formula (Z = 1) is (Na6.45K0.41Ca0.03)Σ6.89(Si6.53Al5.46O24)[(C2O4)0.455(SO4)0.13(PO4)0.09(OH)0.01]Σ0.68 · 4.74H2O. The idealized formula is Na7(Al5-6Si6-7O24)(C2O4)0.5-1 · 5H2O. Kyanoxalite is hexagonal, the space group is P63, a = 12.744(8), c = 5.213(6) -ray powder diffraction pattern are as follows, [ d, [A] ( I, %)( hkl)]: 6.39(44) (110), 4.73 (92) (101), 3.679 (72) (300), 3.264 (100) (211, 121), 2.760 (29) (400), 2.618 (36) (002), 2.216, (29) (302, 330). According to the X-ray single crystal study ( R = 0.033), two independent C2O4 groups statistically occupy the sites on the axis 63. The new mineral is the first natural silicate with an additional organic anion and is the most

  5. Yegorovite, Na4[Si4O8(OH)4]·7H2O, a new mineral from the Lovozero alkaline pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Zubkova, N. V.; Chukanov, N. V.; Zadov, A. E.; Grishin, V. G.; Pushcharovsky, D. Yu.

    2010-12-01

    A new mineral, yegorovite, has been identified in the late hydrothermal, low-temperature assemblage of the Palitra hyperalkaline pegmatite at Mt. Kedykverpakhk, Lovozero alkaline pluton, Kola Peninsula, Russia. The mineral is intimately associated with revdite and megacyclite, earlier natrosilite, microcline, and villiaumite. Yegorovite occurs as coarse, usually split prismatic (up to 0.05 × 0.15 × 1 mm) or lamellar (up to 0.05 × 0.7 × 0.8 mm) crystals. Polysynthetic twins and parallel intergrowths are typical. Mineral individuals are combined in bunches or chaotic groups (up to 2 mm); radial-lamellar clusters are less frequent. Yegorovite is colorless, transparent with vitreous luster. Cleavage is perfect parallel to (010) and (001). Fracture is splintery; crystals are readily split into acicular fragments. The Mohs hardness is ˜2. Density is 1.90(2) g/cm3 (meas) and 1.92 g/cm3 (calc). Yegorovite is biaxial (-), with α = 1.474(2), β = 1.479(2), and γ = 1.482(2), 2 V meas > 70°, 2 V calc = 75°. The optical orientation is X ∧ a ˜ 15°, Y = c, Z = b. The IR spectrum is given. The chemical composition determined using an electron microprobe (H2O determined from total deficiency) is (wt %): 23.28 Na2O, 45.45 SiO2, 31.27 H2Ocalc; the total is 100.00. The empirical formula is Na3.98Si4.01O8.02(OH)3.98 · 7.205H2O. The idealized formula is Na4[Si4O8(OH)4] · 7H2O. Yegorovite is monoclinic, space group P21/ c. The unit-cell dimensions are a = 9.874, b= 12.398, c = 14.897 Å, β = 104.68°, V = 1764.3 Å3, Z = 4. The strongest reflections in the X-ray powder pattern ( d, Å ( I, %)([ hkl]) are 7.21(70)[002], 6.21(72)[012, 020], 4.696(44)[022], 4.003(49)[211], 3.734(46)[ bar 2 13], 3.116(100)[024, 040], 2.463(38)[ bar 4 02, bar 2 43]. The crystal structure was studied by single-crystal method, R hkl = 0.0745. Yegorovite is a representative of a new structural type. Its structure consists of single chains of Si tetrahedrons [Si4O8(OH)4]∞ and sixfold polyhedrons

  6. Shlykovite KCa[Si4O9(OH)] · 3H2O and cryptophyllite K2Ca[Si4O10] · 5H2O, new mineral species from the Khibiny alkaline pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Zubkova, N. V.; Filinchuk, Ya. E.; Chukanov, N. V.; Zadov, A. E.; Pushcharovsky, D. Yu.; Gobechiya, E. R.

    2010-12-01

    New minerals, shlykovite and cryptophyllite, hydrous Ca and K phyllosilicates, have been identified in hyperalkaline pegmatite at Mount Rasvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia. They are the products of low-temperature hydrothermal activity and are associated with aegirine, potassium feldspar, nepheline, lamprophyllite, eudialyte, lomonosovite, lovozerite, tisinalite, shcherbakovite, shafranovskite, ershovite, and megacyclite. Shlykovite occurs as lamellae up to 0.02 × 0.02 × 0.5 mm in size or fibers up to 0.5 mm in length usually combined in aggregates up to 3 mm in size, crusts, and parallel-columnar veinlets. Cryptophyllite occurs as lamellae up to 0.02 × 0.1 × 0.2 mm in size intergrown with shlykovite being oriented parallel to {001} or chaotically arranged. Separate crystals of the new minerals are transparent and colorless; the aggregates are beige, brownish, light cream, and pale yellowish-grayish. The cleavage is parallel to (001) perfect. The Mohs hardness of shlykovite is 2.5-3. The calculated densities of shlykovite and cryptophyllite are 2.444 and 2.185 g/cm3, respectively. Both minerals are biaxial; shlykovite: 2 V meas = -60(20)°; cryptophyllite: 2 V meas > 70°. The refractive indices are: shlykovite: α = 1.500(3), β = 1.509(2), γ = 1.515(2); cryptophyllite: α = 1.520(2), β = 1.523(2), γ = 1.527(2). The chemical composition of shlykovite determined by an electron microprobe (H2O determined from total deficiency) is as follows, wt %: 0.68 Na2O, 11.03 K2O, 13.70 CaO, 59.86 SiO2, 14.73 H2O; the total is 100.00. The empirical formula calculated on the basis of 13 O atoms (OH/H2O calculated from the charge balance) is (K0.96Na0.09)Σ1.05Ca1.00Si4.07O9.32(OH)0.68 · 3H2O. The idealized formula is KCa[Si4O9(OH)] · 3H2O. The chemical composition of cryptophyllite determined by an electron microprobe (H2O determined from the total deficiency) is as follows, wt %: 1.12 Na2O, 17.73 K2O, 11.59 CaO, 0.08 Al2O3, 50.24 SiO2, 19.24 H2

  7. Davinciite, Na12K3Ca6Fe{3/2+}Zr3(Si26O73OH)Cl2, a New K,Na-Ordered mineral of the eudialyte group from the Khibiny Alkaline Pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.; Rozenberg, K. A.

    2013-12-01

    This paper presents a description of a new zirconosilicate of the eudialyte group, which was named davinciite in honor of Leonardo da Vinci (1452-1519), a famous Italian scientist, painter, sculptor and architect. The new mineral has been found in hyperagpaitic pegmatite at the Rasvumchorr Mountain, Khibiny Pluton, Kola Peninsula, as relict inclusions, up to 1-2 mm in size in a rastsvetaevite matrix. It is associated with nepheline, sodalite, potassium feldspar, delhayelite, aegirine, shcherbakovite, villiaumite, nitrite, nacaphite, rasvumite, and djerfisherite. Davinciite is dark lavender and transparent, with a vitreous luster and white streak. The new mineral is brittle, with conchoidal fracture; the Mohs' hardness is 5. No indications of cleavage or parting were observed. The measured density is 2.82(2) g/cm3 (volumetric method); the calculated density is 2.848 g/cm3. Davinciite is optically uniaxial, positive; ω = 1.603(2), ɛ = 1.605(2). It is nonpleochroic and nonfluorescent in UV light. The new mineral slowly breaks down and gelates in 50% HCl and HNO3. It is trigonal, space group R3m. The unit-cell dimensions are a = 14.2956(2), c = 30.0228(5) Å, V=5313.6(2) Å3. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %) ( hkl)] are as follows: 2.981(100)(315), 2.860(96)(404), 4.309(66)(205), 3.207(63)(208), 6.415(54)(104), 3.162(43)(217). The chemical composition (electron microprobe, H2O calculated from X-ray diffraction data) is as follows, wt %: 12.69 Na2O, 3.53 K2O, 11.02 CaO, 0.98 SrO, 0.15 BaO, 5.33 FeO, 0.37 MnO, 0.07 Al2O3, 51.20 SiO2, 0.39 TiO2, 11.33 ZrO2, 0.21HfO2, 0.09 Nb2O5, 1.89 Cl, 0.93H2O, -O = Cl2 0.43; total is 99.75. The empirical formula calculated on the basis of Si + Al + Zr + Hf + Ti + Nb = 29 ( Z = 3) is (Na1l.75Sr0.29Ba0.03)Σ12.07(K2.28Na0.72)Σ3Ca5.99(Fe2.26Mn0.16)Σ2.42(Zr2.80Ti0.15Hf0.03Nb0.02) Σ3(Si1.96Al0.04)Σ2[Si3O9]2 [Si9O27]2[(OH)1.42O0.58]Σ2[Cl1.62(H2O)0.38]Σ2 · 0.48H2O. The simplified

  8. Voronkovite, Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH,O)4Cl · H2O, a new mineral species of the eudialyte group from the Lovozero alkaline pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.

    2009-12-01

    This paper describes a new member of the eudialyte group named in honor of Alexander Alexandrovich Voronkov (1928-1982), the prominent Russian crystallographer. The new mineral has been found in the Shkatulka hyperalkaline pegmatite body at Mt. Alluaiv, Lovozero alkaline pluton, Kola Peninsula, Russia. The mineral is associated with microcline, sodalite, nepheline, aegirine, terskite, lomonosovite, vuonnemite, shkatulkalite, manganoneptunite, and sphalerite. Voronkovite occurs as rounded, poorly faced crystals up to 2-5 mm across. The new mineral is light brown, with vitreous luster and conchoidal fracture. The streak is white. Voronkovite is transparent and brittle; the Mohs hardness is 5; cleavage or parting is not observed. D(meas) = 2.97(2) g/cm3 (volumetric method); D(calc) = 2.95 g/cm3. The new mineral is uniaxial, positive, pleochroic from lemon yellow along X to brownish pink along Y, and is not luminescent in UV light. Voronkovite easily dissolves and gelates in acid at room temperature. The new mineral is trigonal, space group R3, a = 14.205(7), c = 30.265(15) Å, V = 5289(8) Å3, Z = 3. The strongest reflections in the X-ray diffraction pattern [ d, Å ( I)( hkl)] are 2.970(100)(315), 4.316(85)(205), 2.848(84)(404), 3.221(43)(208), 3.536(41)(027), 3.039(41)(119). The chemical composition (electron microprobe, H2O determined with chemical analysis) is as follows, wt %: 15.84 Na2O, 0.28 K2O, 3.08 CaO, 1.76 SrO, 4.65 MnO, 3.53 FeO, 0.93 La2O3, 1.36 Ce2O3, 0.68 Nd2O3, 0.15 Al2O3, 49.48 SiO2, 0.33 TiO2, 14.11 ZrO2, 0.23 HfO2, 0.91 Nb2O5, 0.44 Cl, 0.21 F, 1.56 H2O, 0.19 -O = (Cl,F)2; total is 99.34. The empirical formula calculated on the basis of Si + Al = 26 ( Z = 3) is as follows: (Na13.96Sr0.54K0.19)Σ14.69(Na1.64Ca0.92Ce0.26 La0.18)Σ3.00(Mn2.06Ca0.81Nd0.13)Σ3.00(F1.54Zr0.60Na0.48Nb0.21Ti0.13Hf0.04)Σ3.00Zr3.00(Si1.91Al0.09)Σ2.00(Si24O72)[(OH)2.98 O1.02]Σ4(Cl0.39F0.35)Σ0.74 · 1.23H2O. The simplified formula is Na15(Na,Ca,Ce)3(Mn,Ca)3Fe3Zr3Si26O72(OH

  9. Dualite, Na30(Ca,Na,Ce,Sr)12(Na,Mn,Fe,Ti)6Zr3Ti3MnSi51O144(OH,H2O,Cl)9, a new zircono-titanosilicate with a modular eudialyte-like structure from the Lovozero alkaline Pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.

    2008-12-01

    Dualite has been found at Mount Alluaiv, the Lovozero Pluton, the Kola Peninsula in peralkaline pegmatoid as sporadic, irregularly shaped grains up to 0.3-0.5 mm across. K-Na feldspar, nepheline, sodalite, cancrinite, aegirine, alkaline amphibole, eudialyte, lovozerite, lomonosovite, vuonnemite, lamprophyllite, sphalerite, and villiaumite are associated minerals. Dualite is yellow, transparent or translucent, with conchoidal fracture. The new mineral is brittle, with vitreous luster and white streaks. The Mohs hardness is 5. The measured density is 2.84(3) g/cm3 (volumetric method); the calculated density is 2.814 g/cm3. Dualite dissolves and gelates in acid at room temperature. It is nonfluorescent. The new mineral is optically uniaxial and positive; ω = 1.610(1), ɛ = 1.613(1). Dualite is trigonal, space group R3 m. The unit cell dimensions are a = 14.153(9), c = 60.72(5) Å, V = 10533(22) Å, Z = 3. The strongest reflections in the X-ray powder pattern [ d, Å ( I,%)( hkl)] are as follows: 7.11(40)(110), 4.31(50)(0.2.10), 2.964(100)(1.3.10), 2.839(90)(048), 2.159(60)(2.4.10, 0.4.20), 1.770(60)(2.4.22, 4.0.28, 440), 1362(50)(5.5.12, 3.0.42). The chemical composition (electron microprobe, H2O calculated from X-ray diffraction data) is as follows, wt %: 17.74 Na2O, 0.08 K2O, 8.03 CaO, 1.37 SrO, 0.29 BaO, 2.58 MnO, 1.04 FeO, 0.79 La2O3, 1.84 C2O3, 0.88 Nd2O3, 0.20 Al2O3, 51.26 SiO2, 4.40 TiO2, 5.39 ZrO2, 1.94 Nb2O5, 0.58 Cl, 1.39 H2O,-O = 0.13 Cl2; they total is 99.67. The empirical formula calculated on the basis of 106 cations as determined by crystal structure is (Na29.79Ba0.1K0.10)Σ30(Ca8.55Na1.39REE1.27Sr0.79)Σ12 · (Na3.01Mn1.35Fe{0.87/2+}Ti0.77)Σ6(Zr2.61Nb0.39)Σ3 (Ti2.52Nb0.48)Σ3(Mn0.82Si0.18)Σ1(Si50.77Al0.23)Σ51 O144[(OH)6.54(H2O)1.34·Cl0.98]Σ8.86). The simplified formula is Na30(Ca,Na,Ce,Sr)12(Na,Mn,Fe,Ti)6Zr3Ti3 MnSi51O144 (OH,H2O,Cl)9). The name dualite is derived from Latin dualis (dual) alluding to the dual taxonomic membership of this mineral

  10. Uranium-lead dating of perovskite from the Afrikanda plutonic complex (Kola Peninsula, Russia) using LA-ICP-MS.

    NASA Astrophysics Data System (ADS)

    Reguir, E.; Camacho, A.; Yang, P.; Chakhmouradian, A. R.; Halden, N. M.

    2009-04-01

    Perovskite (CaTiO3) is a common early crystallizing accessory phase in a variety of alkaline rocks, and has been shown to contain enough U and Th for U-Pb dating. U and Pb analysis of perovskite has been primarily carried out using the SHRIMP or ID-TIMS techniques, and the resulting U-Pb dates commonly yield the emplacement age of the host rock. To our knowledge, only one U-Pb study of perovskite has been done using the LA-ICP-MS (Cox and Wilton, 2006). Some of the advantages of this method over the SHRIMP and ID-TIMS techniques include greater speed and lower cost of analysis. In this work, the U-Pb ages of perovskite from the Afrikanda plutonic complex (Russia) were obtained in situ using the LA-ICP-MS. The measured 238U/206Pb and 207Pb/206Pb ratios were corrected for time-dependent mass-bias using the well-calibrated zircon standard GJ-1 (608.5 ± 0.4 Ma; Jackson et al., 2004). On a Tera-Wasserburg diagram (Tera and Wasserburg, 1972) the analyses of perovskite from two magmatic phases (clinopyroxenite and carbonatite) plot in separate clusters. Although the variations in the 238U/206Pb and 207Pb/206Pb ratios within each group are small, there is enough dispersion between the two clusters to obtain a reasonably precise age of 375 ± 13 Ma (2; MSWD = 0.23), which strongly suggests that the carbonatitic rocks are broadly coeval with the clinopyroxenite. The only other isotopic study on the Afrikanda Complex was done on a clinopyroxenite using the Rb-Sr method and yielded a whole rock-mineral (perovskite, biotite, augite and apatite) isochron age of 364.0 ± 3.1 Ma (2; MSWD = 0.72). This age is within error of our U-Pb date, which demonstrates that LA-ICP-MS-based U-Pb dating of perovskite can serve as a reliable geochronological tool. References Cox, R.A. and Wilton, D.H.C. (2006) U-Pb dating of perovskite by LA-ICP-MS: An example from the Oka carbonatite, Quebec, Canada. Chem. Geol., 235, 21-32. Jackson, S.E., Pearson, N.J., Griffin, W.L. and Belousova, E.A. (2004

  11. Archaean multiphase Porosozero sanukitoid pluton of the Kola region: petrological, geochronological and geochemical data

    NASA Astrophysics Data System (ADS)

    Kudryashov, Nikolai; Mokrushin, Artem; Petrovsky, Michail; Elizarov, Dmitry

    2013-04-01

    The Porosozero sanukitoid intrusion is located in the greenstone belt of the Kolmozero-Voronja, north-eastern part Fennoscandian (Baltic) Shield. The Porosozero multiphase pluton was formed as a result of the 4 magmatic phases during the period ca. 60 million years. The main phase is represented by a differentiated series of gabbro-diorite - quartz monzodiorite - granodiorite - granite. The zircon TIMS ages of granodiorite and quartz monzodiorites are 2733±6 Ma and 2734±4 Ma, respectively. The second phase is composed of leucogranites formed during intrusion of the residual melt portion from intracrustal source. The age of zircon from leucogranite is 2712±6 Ma. The third phase is represented by the lamprophyre dykes with the zircon age 2680±8 Ma. The late pegmatite veins were formed during the fourth final phase. The volume relationships between the gabbro-diorite, quartz monzodiorites, granodiorites and granites are 5:55:27:13, respectively. The medium weighted composition of the initial melt, calculated from the rock compositions of the first phase is andesite (wt.%): SiO2 = 61.53, TiO2 = 0.58, Al2O3 = 15.74, Fe2O3 = 3.75, FeO = 3.07, MnO = 0.10, MgO = 3.06, CaO = 5.83, Na2O = 3.78, K2O = 2.37. The compositional variation is the result of fractional crystallization. The last magmas may have experienced some crustal contamination. All rocks of the first phase are enriched in Ba (500-800 ppm), Sr (450-700 ppm), K2O (1.8-3.2 wt. %), P2O5 (0.15-0.35), LREE [(La/Yb)N=15-23] and contain high concentrations of Cr (150-400 ppm) and Ni (60-140 ppm), possess high mg# values (0.45-0.65), and show a negative Nb-Ta anomaly. Sm-Nd isotopic data for sanukitoids indicate their formation from a mantle source enriched in LILE and LREE with ɛNd (2740) = +1.02 - +0.36, T(DM)=2.9-2.8 Ga. The Porosozero polyphasic pluton is similar to worldwide Archaean and Phanerozoic magmatic sanukitoide series. The Porosozero pluton formation is determined by the processes of mantle

  12. Zvyaginite, NaZnNb2Ti[Si2O7]2O(OH,F)3(H2O)4 + x ( x < 1), a new mineral of the epistolite group from the Lovozero Alkaline Pluton, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Lykova, I. S.; Chukanov, N. V.; Yapaskurt, V. O.; Belakovskiy, D. I.; Zolotarev, A. A.; Zubkova, N. V.

    2014-12-01

    A new mineral, zvyaginite, a member of the epistolite group, has been found at Mt. Malyi Punkaruaiv, Lovozero Alkaline Complex, Kola Peninsula, Russia. It occurs in a hydrothermally altered peralkaline pegmatite and is associated with ussingite, microcline, aegirine, sphalerite, vigrishinite, and sauconite. Zvyaginite forms rectangular or irregular-shaped lamellae up to 0.1 × 1 × 2 cm in size when flattened [001]. The mineral is translucent to transparent and colorless, pearly-white, yellowish brownish, pale pink, or violet pink. The luster is nacreous on crystal faces and greasy on broken surfaces. Its Mohs' hardness is 2.5-3. Zvyaginite is brittle. The cleavage parallel to {001} is perfect. D meas = 2.88(3), D calc = 2.94 g/cm3. The mineral is optically biaxial (-), α = 1.626(5), β = 1.714(3), γ = 1.740(5), 2 V meas = 45(15)°, 2 V calc = 55°. The IR spectrum is given. Chemical composition is as follows (wt %; average of five point analyses; H2O was determined using the modified Penfield method): 4.74 Na2O, 0.22 K2O, 0.77 CaO, 1.36 MnO, 0.24 FeO, 9.61 ZnO, 0.19 Al2O3, 29.42 SiO2, 12.33 TiO2, 27.22 Nb2O5, 1.94 F, 12.65 H2O, -0.82 -O = F2, for a total of 99.87. The empirical formula calculated on the basis of Si + Al = 4 is: Na1.24K0.04Ca0.11Mn0.16Fe0.03Zn0.96Nb1.66Ti1.25(Si3.97Al0.03)Σ4O15.07(OH)2.10F0.83(H2O)4.64. The simplified formula is: NaZnNb2Ti[Si2O7]2O(OH,F)3(H2O)4 + x ( x < 1), Zvyaginite is triclinic, , a = 8.975(3), b = 8.979(3), c = 12.135(4) Å, α = 74.328(9)°, β = 80.651(8)°, γ = 73.959(8)°, V = 900.8(6) Å3, Z = 2. The strongest reflections in the X-ray powder pattern ( d, Å- I[ hkl]) are: 11.72-100[001], 5.83-40[002], 5.28-53[-1-11, 112], 4.289-86[200, 021], 3.896-36[-1-12, -201, 003, 022, 113], 2.916-57[310, 132, 004], 2.862-72[130, 312]. The model of the crystal structure was obtained on a single crystal, R = 0.159. Zvyaginite and epistolite are similar in the structure of the NbTiSiO motif, but differ from each other in composition

  13. Late Proterozoic and Silurian alkaline plutons within the southeastern New England Avalon zone

    SciTech Connect

    Hermes, O.D. ); Zartman, R.E. )

    1992-07-01

    Distinct pulses of quartz-bearing, alkaline plutonism and volcanism are known to have occurred in the Avalon zone of southeastern New England during the Late Ordovician, Early Silurian, Devonian, and Carboniferous. Zircon separates from the Franklin and Dartmouth plutons demonstrate that two additional, previously unrecognized periods of alkaline magmatism occurred. The Franklin pluton yields an age of 417 {plus minus} 6 Ma (Late Silurian), whereas the Dartmouth pluton is Late Proterozoic (595 {plus minus} 5 Ma) and markedly older than the other plutons of alkaline affinity. The new ages further emphasize the episodic nature and long-term duration of such alkaline igneous events within the southeastern New England Avalon zone. The Dartmouth pluton may represent a post-collisional alkaline granite emplaced in the Late Proterozoic, almost immediately after a major period of calcalkaline igneous activity that accompanied plate convergence and continental accretion. The abrupt change from orogenic calcalkaline igneous activity to post-collisional alkaline granite, followed by younger episodes of anorogenic emplacement, is remarkably similar to igneous events reported from pan-African mobile belts widespread throughout Africa. In addition, parts of the Dartmouth pluton exhibit features indicative of mixing and commingling of felsic and mafic melts that are associated with coevally formed mylonitic fabrics. Because these fabrics are conformable to those in adjacent gneisses, but discordant with Alleghanian fabrics in the nearby Carboniferous Narragansett basin, they represent some of the best candidates for pre-Alleghanian structures thus far identified in the southeastern New England Avalon zone.

  14. Paleoproterozoic layered PGE-bearing Monchetundra pluton, Kola Peninsula: Sm-Nd age of metamorphic alteration of mafic rocks

    NASA Astrophysics Data System (ADS)

    Kunakkuzin, E. L.; Serov, P. A.; Bayanova, T. B.; Nerovich, L. I.; Borisenko, E. S.

    2015-09-01

    The aim of this work is Sm-Nd study of metamorphic alteration of massive gabbronorites from the Monchetundra pluton. The mafic rocks of the pluton are unevenly metamorphosed up to amphibolite facies with the formation of garnet, hornblende, and other minerals. The presence of garnet is a distinctive feature of this pluton in comparison with other Paleoproterozoic PGE-bearing plutons of the eastern part of the Baltic shield: Mt. General'skaya, Fedorovo-Pana, Imandra lopolith, and Monchepluton [9]. The degree of metamorphic alteration of rocks increases near the faults, the largest of which is Monchetundra fault separating the studied pluton from the Monchepluton. This fault was formed about 1.9-2.0 Ga ago according to Sm-Nd and Rb-Sr mineral isochrons for minerals from metagabbro-anorthosites of the M1 well.

  15. Rare gas isotopes and parent trace elements in ultrabasic-alkaline-carbonatite complexes, Kola Peninsula: identification of lower mantle plume component

    NASA Astrophysics Data System (ADS)

    Tolstikhin, I. N.; Kamensky, I. L.; Marty, B.; Nivin, V. A.; Vetrin, V. R.; Balaganskaya, E. G.; Ikorsky, S. V.; Gannibal, M. A.; Weiss, D.; Verhulst, A.; Demaiffe, D.

    2002-03-01

    During the Devonian magmatism (370 Ma ago) ˜20 ultrabasic-alkaline-carbonatite complexes (UACC) were formed in the Kola Peninsula (north-east of the Baltic Shield). In order to understand mantle and crust sources and processes having set these complexes, rare gases were studied in ˜300 rocks and mineral separates from 9 UACC, and concentrations of parent Li, K, U, and Th were measured in ˜70 samples. 4He/ 3He ratios in He released by fusion vary from pure radiogenic values ˜10 8 down to 6 × 10 4. The cosmogenic and extraterrestrial sources as well as the radiogenic production are unable to account for the extremely high abundances of 3He, up to 4 × 10 -9 cc/g, indicating a mantle-derived fluid in the Kola rocks. In some samples helium extracted by crushing shows quite low 4He/ 3He = 3 × 10 4, well below the mean ratio in mid ocean ridge basalts (MORB), (8.9 ± 1.0) × 10 4, indicating the contribution of 3He-rich plume component. Magnetites are principal carriers of this component. Trapped 3He is extracted from these minerals at high temperatures 1100°C to 1600°C which may correspond to decrepitation or annealing primary fluid inclusions, whereas radiogenic 4He is manly released at a temperature range of 500°C to 1200°C, probably corresponding to activation of 4He sites degraded by U, Th decay. Similar 4He/ 3He ratios were observed in Oligocene flood basalts from the Ethiopian plume. According to a paleo-plate-tectonic reconstruction, 450 Ma ago the Baltica (including the Kola Peninsula) continent drifted not far from the present-day site of that plume. It appears that both magmatic provinces could relate to one and the same deep-seated mantle source. The neon isotopic compositions confirm the occurrence of a plume component since, within a conventional 20Ne/ 22Ne versus 21Ne/ 22Ne diagram, the regression line for Kola samples is indistinguishable from those typical of plumes, such as Loihi (Hawaii). 20Ne/ 22Ne ratios (up to 12.1) correlate well with 40

  16. Minerals of zirconolite group from fenitized xenoliths in nepheline syenites of Khibiny and Lovozero plutons, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Menshikov, Yu. P.; Mikhailova, Yu. A.; Pakhomovsky, Ya. A.; Yakovenchuk, V. N.; Ivanyuk, G. Yu.

    2015-12-01

    Zirconolite, its Ce-, Nd-, and Y-analogs, and laachite, another member of the zirconolite group, are typomorphic minerals of the fenitized xenoliths in nepheline syenite and foidolite of the Khibiny-Lovozero Complex, Kola Peninsula, Russia. All these minerals are formed at the late stage of fenitization as products of ilmentie alteration under the effect of Zr-bearing fluids. The diversity of these minerals is caused by the chemical substitutions of Na and Ca for REE, Th, and U compensated by substitution of Ti and Zr for Nb, Fe and Ta, as well as by the redistribution of REE between varieties enriched in Ti (HREE) or Nb (LREE). The results obtained can be used in the synthesis of Synroc-type titanate ceramics assigned for the immobilization of actinides.

  17. 1.1 Ga K-rich alkaline plutonism in the SW Grenville Province

    NASA Astrophysics Data System (ADS)

    Corriveau, Louise; Heaman, Larry M.; Marcantonio, Franco; van Breemen, Otto

    1990-09-01

    U-Pb zircon and baddeleyite dating of six syenitic stocks establishes that the ultrapotassic, potassic alkaline and shoshonitic magmatism with island-arc affinities in the Central Metasedimentary Belt (CMB) of the southwestern Grenville Province, Canada took place between 1089 and 1076 Ma, along a 400-km-long, northeast-trending plutonic belt. These ages indicate that ultrapotassic rocks with arc affinities are not unique to the Phanerozoic. West to east emplacement ages along a northern and southern cross-section of this belt range from 1083±2 Ma (Kensington), through 1081±2 Ma (Lac Rouge) to 1076{-1/+3}Ma (Loranger) in the north, and from 1089{-3/+4}Ma (loon Lake) and 1088±2 Ma (Calabogie), to 1076±2 Ma (Westport) in the south. Although closely spaced in time, in detail these ages suggest a slight younging of this magmatic activity to the southeast. Integration of the geochronological data with the spatial extent and potassic character of the plutons shows that the K-rich alkaline suite is distinct from the nepheline-syenite belt of the Bancroft terrane and from the syenite-monzonite suite of the Frontenac terrane of the CMB, and it is considered to be a magmatic episode unique to the Elzevir terrane and its Gatineau segment. The timing and the postmetamorphic emplacement of these plutons indicate that the regional greenschist to granulite-facies metamorphism of the country rock (precise age unknown) is older than 1089 Ma throughout the entire Elzevir terrane. The potassic magmatism is interpreted as the initiation of the 1090 1050 Ma Ottawan Orogeny in the Elzevir terrane; thus, the regional metamorphism in this terrane, previously assigned to the Ottawan Orogeny, is an earlier event. The contemporaneous emplacement of this postmetamorphic plutonic belt with Keweenawan volcanism is at variance with current tectonic models which consider the Keweenawan rift to be formed at the same time as regional metamorphism in the CMB.

  18. Trace-element study and uranium-lead dating of perovskite from the Afrikanda plutonic complex, Kola Peninsula (Russia) using LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Reguir, Ekaterina P.; Camacho, Alfredo; Yang, Panseok; Chakhmouradian, Anton R.; Kamenetsky, Vadim S.; Halden, Norman M.

    2010-11-01

    The U-Pb geochronology of perovskite is a powerful tool in constraining the emplacement age of silica-undersaturated rocks. The trace-element and U-Pb isotopic compositions of perovskite from clinopyroxenite and silicocarbonatite from the Afrikanda plutonic complex (Kola, Russia) were determined by laser-ablation inductively-coupled mass-spectrometry (LA-ICP-MS). In addition, the Sr isotopic composition of perovskite was measured by isotope-dilution mass-spectrometry to better constrain the relations between its host rocks. Perovskite from the two rock types shows a different degree of enrichment in Na, Mg, Mn, Pb, Fe, Al, V, rare-earth elements, Zr, Hf, Th, U and Ta. The perovskite 87Sr/86Sr values are within analytical uncertainty of one another and fall within the range of mantle values. The 206Pb/238U ages (corrected for common lead using 207Pb-method) of perovskite from silicocarbonatite statistically yield a single population with a weighted mean of 371 ± 8 Ma (2σ; MSWD = 0.071). This age is indistinguishable, within uncertainty, to the clinopyroxenite weighted mean 206Pb/238U age of 374 ± 10 Ma (2σ; MSWD = 0.18). Our data are in good agreement with the previous geochronological study of the Afrikanda complex. The observed variations in trace-element composition of perovskite from silicocarbonatite and clinopyroxenite indicate that these rocks are not related by crystal fractionation. The Sr isotopic ratios and the fact that the two rocks are coeval suggest that they were either produced from a single parental melt by liquid immiscibility, or from two separate magmas derived at different degrees of partial melting from an isotopically equilibrated, but modally complex mantle source.

  19. The rare-metal ore potential of the Proterozoic alkaline ultramafic massifs from eastern part of the Baltic Shield in the Kola alkaline province.

    NASA Astrophysics Data System (ADS)

    Sorokhtina, Natalia; Kogarko, Lia

    2014-05-01

    The Kola Alkaline Province consists of intrusions of two main stages of the intraplate alkaline magmatism. The early stage of igneous activity occurred in Proterozoic 1.9 billion years ago, the next in Paleozoic at 380 million years. The Proterozoic alkaline magmatism produced Gremyakha-Vyrmes and Elet'ozero large alkaline-ultrabasic massifs, Tiksheozero carbonatite massif and numerous small syenite complexes. Paleozoic magmatism on Baltic Shield exhibited more widely, than Proterozoic. The world largest Khibiny and Lovozero alkaline intrusions, numerous alkaline-ultrabasic massifs with carbonanites, alkaline dike swarms and diatremes were formed. It is well known that carbonatites of Paleozoic alkaline-ultrabasic massifs contain large-scale deposits of rare-metal ores (Afanasiev et al., 1998). The metasomatic rocks on foidolites and carbonatites of Gremyakha-Vyrmes are final products of differentiation of Proterozoic alkaline-ultrabasic magma enriched in incompatible elements, including Nb and Zr similar to Paleozoic carbonatites. The massif Gremyakha-Vyrmes is one of the largest titanomagnetite-ilmenite deposits in Russia associated with ultrabasites. Our investigation showed that albite-microcline and aegirine-albite metasomatites formed rich rare-metal ores consisting of 3.2 wt. % Nb2O5 and 0.7 ZrO2. Zircon and pyrochlore-group minerals represent the main minerals of rare-metal ores. The following evolutionary sequences of pyrochlore group minerals has been observed: betafite or U pyrochlore - Na-Ca pyrochlore - Ba-Sr pyrochlore - "silicified" pyrochlore - Fe-Nb, Al-Nb silicates. Such evolution from primary Nb oxides to secondary silicates under low temperature hydrothermal conditions is similar to the evolution of rare metal phases in Paleozoic alkaline massifs analogous to Lovozero syenites and in carbonatites. The rare metal minerals of Gremyakha-Vyrmes crystallized in high alkaline hydrothermal environment at increased activity of Nb, Ta, Zr, U, Th and at

  20. Magma genesis and evolution in the Kola alkaline-carbonatitic province. A Pb-Sr-Nd isotope study.

    NASA Astrophysics Data System (ADS)

    Brassinnes, S.; Balaganskaya, E.; Demaiffe, D.

    2003-04-01

    The Kola Peninsula (NW Russia) is well known for its late Devonian (380-360Ma) ultramafic, alkaline and carbonatitic magmatic province, that comprises more than 20 intrusions including the two giant massifs of agpaitic nepheline syenite of Khibina and Lovozero and numerous smaller annular differentiated complexes (i.e. : Kovdor, Vuorijarvi, …). These massifs intrude the Archean to Proterozoic crustal terranes. Whole rock Pb isotope data are reported for the first time on these intrusions. Representative samples of the Kovdor massif (carbonatites, ultramafic cumulates, ijolites-melteigites) have been analysed. Two U-rich pyrochlore-bearing carbonatites have extremely high measured 206Pb/204Pb and 207Pb/204Pb ratios (94.1 to 253.6 and to 19.6 to 28.2 respectively). Together with 5 other samples, these carbonatites plot along a linear array in the 207Pb/204Pb-206Pb/204Pb diagram. Interpreted as a secondary isochron, this array gives an age indication of 392+/-15 Ma (MSWD = 22), in agreement with the U-Pb baddeleyite age of 380+/-4 Ma. Crustal contamination or source heterogeneity are hardly detectable with such radiogenic Pb composition. Some samples of other massifs of the Kola region (Khibina, Lovozero, Sebljavr and Ozernaya Varaka) have also been analysed, they plot reasonably close to the Kovdor Pb-Pb isochron, confirming that all the complexes of the province are grossly contemporaneous. Although most rocks plot in the depleted mantle quadrant of the Sr-Nd diagram, the data show some dispersion. The Kovdor ultramafic cumulates and carbonatites have overlapping compositions (epsNd(t): +0.5 to +6 ; (87Sr/86Sr)I: 0.7031 to 0.7039) while the ijolites-melteigites tend to have lower epsNd(t) (+0.5 to -3.4) and higher (87Sr/86Sr)I (0.7035 to 0.7047) values. This dispersion can be explained either by heterogeneities of the mantle (or mixing between different geochemical reservoirs) or by open system behaviour during complex emplacement history and hydrothermalism

  1. Magmatic evolution of the differentiated ultramafic, alkaline and carbonatite intrusion of Vuoriyarvi (Kola Peninsula, Russia). A LA-ICP-MS study of apatite

    NASA Astrophysics Data System (ADS)

    Brassinnes, S.; Balaganskaya, E.; Demaiffe, D.

    2005-11-01

    The nature of the petrogenetic links between carbonatites and associated silicate rocks is still under discussion (i.e., [ Gittins J., Harmer R.E., 2003. Myth and reality of the carbonatite-silicate rock "association". Period di Mineral. 72, 19-26.]). In the Paleozoic Kola alkaline province (NW Russia), the carbonatites are spatially and temporally associated to ultramafic cumulates (clinopyroxenite, wehrlite and dunite) and alkaline silicate rocks of the ijolite-melteigite series [ Kogarko, L.N., 1987. Alkaline rocks of the eastern part of the Baltic Shield (Kola Peninsula). In: Fitton, J.G., and Upton, B.G.J. (eds). Alkaline igneous rocks. Geol. Soc. Special Publication 30, 531-544; Kogarko, L.N., Kononova, V.A., Orlova, M.P., Woolley, A.R., 1995. Alkaline rocks and carbonatites of the world. Part 2. Former USSR. Chapman and Hall, London, 225 pp; Verhulst, A., Balaganskya, E., Kirnarsky, Y., Demaiffe, D., 2000. Petrological and geochemical (trace elements and Sr-Nd isotopes) characteristics of the Paleozoic Kovdor ultramafic, alkaline and carbonatite intrusion (Kola Peninsula, NW Russia). Lithos 51, 1-25; Dunworth, E.A., Bell, K., 2001. The Turiy Massif, Kola Peninsula, Russia; isotopic and geochemical evidence for a multi-source evolution. J. Petrol. 42, 377-405; Woolley, A.R., 2003. Igneous silicate rocks associated with carbonatites: their diversity, relative abundances and implications for carbonatite genesis. Period. di Mineral. 72, 9-17)]. In the small (≈ 20 km 2) Vuoriyarvi massif, apatite is typically a liquidus phase during the magmatic evolution and so it can be used to test genetic relationships. Trace elements contents have been obtained for both whole rocks and apatite (by LA-ICP-MS). The apatites define a single continuous chemical evolution marked by an increase in REE and Na (belovite-type of substitution, i.e., 2Ca 2+ = Na + + REE 3+). This evolution possibly reflects a fractional crystallisation process of a single batch of isotopically

  2. Unusual rocks and mineralisation in a new carbonatite complex at Kandaguba, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pilipiuk, A. N.; Ivanikov, V. V.; Bulakh, A. G.

    2001-04-01

    The paper presents the results from a reconnaissance investigation of carbonatites in a newly discovered alkaline complex in the Kola peninsula, Russia. The Kandaguba complex differs from other carbonatite plutons of the Kola alkaline province by (a) the absence of ultrabasic rocks, (b) widespread occurrence of nepheline-, cancrinite- and nepheline-cancrinite syenites and carbonatites and (c) presence of apatite-calcite ijolites and feldspar ijolites as separate intrusive phase. The Kandaguba carbonatites are notable for the predominance of late ferromagnesian varieties together with quartz and numerous accessory mineral species. The association of phosphates (monazite, gorseixite, goyazite, apatite), sulphides and tellurides (pyrite, sphalerite, galena, hessite), ilmenorutile, barite with quartz and ankerite is a remarkable feature of these carbonatites. The Kandaguba carbonatites are inferred to have been generated as the products of liquid immiscibility followed by differentiation of the carbonatite melt.

  3. Igneous banding, schlieren and mafic enclaves in calc-alkaline granites: The Budduso pluton (Sardinia)

    NASA Astrophysics Data System (ADS)

    Barbey, P.; Gasquet, D.; Pin, C.; Bourgeix, A. L.

    2008-08-01

    This study deals with the origin of igneous layering in plutons, and, especially, the extent layering is related to mafic-silicic magma interactions. The Budduso pluton (Sardinia) shows three main scales of organization. (i) Large scale lithological variations correspond to three main magmatic units, with differentiation increasing from the Outer (hornblende-bearing biotite granodiorite/monzogranite) to the Middle (biotite monzogranite) and the Inner (leucomonzogranite) units. The striking homogeneity of 87Sr/ 86Sr initial ratios (0.7090 ± 4) and ɛNd(t) values (- 5.6 ± 0.1) strongly suggests that magma isotopic equilibration was achieved prior to emplacement, whereas mixing/mingling structures observed within the pluton reflect second-stage processes involving broadly cogenetic components. (ii) Metre to decametre-scale igneous layering may be isomodal or modally-graded, locally with cross-layering. Biotite and plagioclase compositions are similar in both biotite-rich and quartzofeldspathic layers, as are the trace-element patterns which differ only by relative abundances. This precludes an origin by fractional crystallization. A penetrative submagmatic fabric superimposed on the layering and corresponding mainly to flattening can be ascribed to interference between pluton growth and regional deformation. (iii) Composite layering and schlieren are commonly associated to mafic microgranular enclaves, locally within synmagmatic shear zones or disrupted synplutonic dykes. In that case, there is a progressive shift in biotite XFe values from the core of enclave (˜ 0.65) to the host monzogranite (˜ 0.72): schlieren in the monzogranite show biotite XFe values similar to that of the host rock, whereas schlieren close to mafic enclaves show lower XFe values (˜ 0.69) towards those of enclave rims. These features can be ascribed to three main processes: (i) assembly of differentiated (± mixed/mingled) magmatic pulses; (ii) local hydrodynamic sorting related to density

  4. Britholite-group minerals as sensitive indicators of changing fluid composition during pegmatite formation: evidence from the Keivy alkaline province, Kola peninsula, NW Russia

    NASA Astrophysics Data System (ADS)

    Zozulya, Dmitry R.; Lyalina, Lyudmila M.; Savchenko, Yevgeny E.

    2017-09-01

    The Keivy alkaline province, Kola Peninsula, NW Russia, consists of vast alkali granite massifs and several dike-like nepheline syenite bodies. It contains numerous rare-metal occurrences, formed by a complex sequence of magmatic, late-magmatic and post-magmatic (including pegmatitic) processes. The Sakharjok nepheline syenite pegmatite contains a remarkably diverse number of britholite group minerals, pointing to different physico-chemical conditions in the fluid. REE and actinides distribution in the host rock indicates that the late-magmatic (and pegmatitic) fluids were alkaline, with significant amounts of F and CO2. From REE and F variations of the britholite group minerals possible fluid compositions at different stages are suggested. The earliest fluorbritholite-(Ce) formed locally from a late magmatic, high temperature F-rich fluid. Fluorbritholite-(Y) presumably crystallized from a F-bearing and CO2-rich fluid; marked F saturation resulted in precipitation of abundant fluorite due to a temperature drop. Variations in REE and F contents in the most abundant fluorcalciobritholite indicate a successive decrease of F in the fluid during its evolution. The relationship between intergrown fluorapatite and fluorcalciobritholite and the presence of zones with a REE-rich fluorapatite between them indicate a continuous to sudden crystallization in this mineral sequence. The crystallization of the latest "calciobritholite" is related to the input into the fluid of CO2 and/or H2O.

  5. Britholite-group minerals as sensitive indicators of changing fluid composition during pegmatite formation: evidence from the Keivy alkaline province, Kola peninsula, NW Russia

    NASA Astrophysics Data System (ADS)

    Zozulya, Dmitry R.; Lyalina, Lyudmila M.; Savchenko, Yevgeny E.

    2017-01-01

    The Keivy alkaline province, Kola Peninsula, NW Russia, consists of vast alkali granite massifs and several dike-like nepheline syenite bodies. It contains numerous rare-metal occurrences, formed by a complex sequence of magmatic, late-magmatic and post-magmatic (including pegmatitic) processes. The Sakharjok nepheline syenite pegmatite contains a remarkably diverse number of britholite group minerals, pointing to different physico-chemical conditions in the fluid. REE and actinides distribution in the host rock indicates that the late-magmatic (and pegmatitic) fluids were alkaline, with significant amounts of F and CO2. From REE and F variations of the britholite group minerals possible fluid compositions at different stages are suggested. The earliest fluorbritholite-(Ce) formed locally from a late magmatic, high temperature F-rich fluid. Fluorbritholite-(Y) presumably crystallized from a F-bearing and CO2-rich fluid; marked F saturation resulted in precipitation of abundant fluorite due to a temperature drop. Variations in REE and F contents in the most abundant fluorcalciobritholite indicate a successive decrease of F in the fluid during its evolution. The relationship between intergrown fluorapatite and fluorcalciobritholite and the presence of zones with a REE-rich fluorapatite between them indicate a continuous to sudden crystallization in this mineral sequence. The crystallization of the latest "calciobritholite" is related to the input into the fluid of CO2 and/or H2O.

  6. Evolution and geochemistry of the Tertiary calc-alkaline plutons in the Adak Island region of the central Aleutian oceanic island arc

    NASA Astrophysics Data System (ADS)

    Kay, Suzanne; Citron, Gary P.; Kay, Robert W.; Jicha, Brian; Tibbetts, Ashley

    2014-05-01

    Calc-alkaline plutons are major crustal building blocks of continental margin mountain belts like the Mesozoic to Tertiary Andes and the Sierra Nevada, but are rare in oceanic island arcs. Some of the most calc-alkaline I-type island arc plutons are in the Central Aleutians with the most extreme signatures, as indicated by FeO/MgO ratios of < ~2 at 48-70% wt. % SiO2, in the ~10 km wide Oligocene Hidden Bay pluton on southern Adak Island and the 10 km wide Miocene Kagalaska pluton to the north on eastern Adak and the adjacent Kagalaska Island. Although small compared to most continental plutons, similarities in intrusive units, mineralogy and chemistry suggest common formation processes. The Aleutian calc-alkaline plutonic rocks mainly differ from continental plutons in having more oceanic like isotopic (87Sr/86Sr = 0.703-0.7033; Epsilon Nd = 9-7.8) and LIL (e.g., higher K/Rb) ratios. The Adak region plutons differ from Tertiary plutons on Unalaska Island further east in being more K-rich and in having a more oxidized and lower-temperature mineralogy. From a regional perspective, the Adak area plutons intrude Eocene/Oligocene Finger Bay Formation mafic volcanic and sedimentary rocks and postdate the small ~38 Ma tholeiitic Finger Bay pluton. The chemistry of these older magmatic rocks is basically similar to that of young Central Aleutian magmatic rocks with boninites and arc tholeiitic magmas seemingly being absent. The formation of the calc-alkaline plutons seems to require a sufficient crustal thickness, fluid concentration and contractional stress such that magma chambers can stabilize significant amounts of pargasitic hornblende. Seismic receiver function analyses (Janiszewski et al., 2013) indicate the modern Adak crust is ~ 37 km thick. Existing and new hornblende, plagioclase and biotite Ar/Ar ages from 16 Hidden Bay pluton and Gannet Lake stock gabbro, porphyritic diorite, diorite, granodiorite, leucogranodiorite and aplite samples range from 34.6 to 30

  7. Phosphoinnelite, Ba4Na3Ti3Si4O14(PO4,SO4)2(O,F)3, a new mineral species from peralkaline pegmatite of the Kovdor pluton, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Chukanov, N. V.; Kulikova, I. M.; Belakovsky, D. I.

    2007-12-01

    Phosphoinnelite, an analogue of innelite with P > S, has been found in a peralkaline pegmatite vein crosscutting calcite carbonatite at the phlogopite deposit, Kovdor pluton, Kola Peninsula. Cancrinite (partly replaced with thomsonite-Ca), orthoclase, aegirine-augite, pectolite, magnesioarfvedsonite, golyshevite, and fluorapatite are associated minerals. Phosphoinnelite occurs as lath-shaped crystals up to 0.2 × 1 × 6 mm in size, which are combined typically in bunch-, sheaf-, and rosettelike segregations. The color is yellow-brown, with vitreous luster on crystal faces and greasy luster on broken surfaces. The mineral is transparent. The streak is pale yellowish. Phosphoinnelite is brittle, with perfect cleavage parallel to the {010} and good cleavage parallel to the {100}; the fracture is stepped. The Mohs hardness is 4.5 to 5. Density is 3.82 g/cm3 (meas.) and 3.92 g/cm3 (calc.). Phosphoinnelite is biaxial (+), α = 1.730, β = 1.745, and γ = 1.764, 2V (meas.) is close to 90°. Optical orientation is Z^c ˜ 5°. Chemical composition determined by electron microprobe is as follows (wt %): 6.06 Na2O, 0.04 K2O, 0.15 CaO, 0.99 SrO, 41.60 BaO, 0.64 MgO, 1.07 MnO, 1.55 Fe2O3, 0.27 Al2O3, 17.83 SiO2, 16.88 TiO2, 0.74 Nb2O5, 5.93 P2O5, 5.29 SO3, 0.14 F, -O=F2 = -0.06, total is 99.12. The empirical formula calculated on the basis of (Si,Al)4O14 is (Ba3.59Sr0.13K0.01)Σ3.73(Na2.59Mg0.21Ca0.04)Σ3.04(Ti2.80Fe{0.26/3+}Nb0.07)Σ3.13[(Si3.93Al0.07)Σ4O14(P1.11S0.87)Σ1.98O7.96](O2.975F0.10)Σ3.075. The simplified formula is Ba4Na3Ti3Si4O14(PO4,SO4)2(O,F)3. The mineral is triclinic, space group P overline 1 or P1. The unit cell dimensions are a = 5.38, b = 7.10, c = 14.76 Å; α = 99.00°, β = 94.94°, γ = 90.14°; and V = 555 Å3, Z = 1. The strongest lines of the X-ray powder pattern [ d, Å in ( I)( hkl)] are: 14.5(100)(001), 3.455(40)(103), 3.382(35)(0overline 2 2), 2.921(35)(005), 2.810(40)(1overline 1 4), 2.683(90)(200, overline 2 01), 2.133(80)(overline 2 overline

  8. Differing responses of zircon, chevkinite-(Ce), monazite-(Ce) and fergusonite-(Y) to hydrothermal alteration: Evidence from the Keivy alkaline province, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Macdonald, Ray; Bagiński, Bogusław; Zozulya, Dmitry

    2017-09-01

    A quartzolite from the Rova occurrence, Keivy alkali granite province, Kola Peninsula, Russia, is used to examine the differing responses of certain rare-metal minerals during interaction with hydrothermal fluids. The minerals are two silicates [chevkinite-(Ce) and zircon], a phosphate [monazite-(Ce)] and an oxide [fergusonite-(Y)]. Textural evidence is taken to show that the dominant alteration mechanism was interface-coupled dissolution-reprecipitation. Zircon was the most pervasively altered, possibly by broadening of cleavage planes or fractures; the other minerals were altered mainly on their rims and along cracks. The importance of cracks in promoting fluid access is stressed. The compositional effects of the alteration of each phase are documented. The hydrothermal fluids carried few ligands capable of transporting significant amounts of rare-earth elements (REE), high field strength elements (HFSE) and actinides; alteration is inferred to have been promoted by mildly alkaline, Ca-bearing fluids. Expansion cracks emanating from fergusonite-(Y) are filled with unidentified material containing up to 35 wt% UO2 and 25 wt% REE2O3, indicating late-stage, short-distance mobility of these elements. Electron microprobe chemical dating of monazite yielded an age of 1665 ± 22 Ma, much younger than the formation age of the Keivy province (2.65-2.67 Ga) but comparable to that of the Svecofennian metamorphic event which affected the area (1.9-1.7 Ga) or during fluid-thermal activation of the region during rapakivi granite magmatism (1.66-1.56 Ga). Dates for altered monazite range from 2592 ± 244 Ma to 773 ± 88 Ma and reflect disturbance of the U-Th-Pb system during alteration.

  9. Differing responses of zircon, chevkinite-(Ce), monazite-(Ce) and fergusonite-(Y) to hydrothermal alteration: Evidence from the Keivy alkaline province, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Macdonald, Ray; Bagiński, Bogusław; Zozulya, Dmitry

    2017-03-01

    A quartzolite from the Rova occurrence, Keivy alkali granite province, Kola Peninsula, Russia, is used to examine the differing responses of certain rare-metal minerals during interaction with hydrothermal fluids. The minerals are two silicates [chevkinite-(Ce) and zircon], a phosphate [monazite-(Ce)] and an oxide [fergusonite-(Y)]. Textural evidence is taken to show that the dominant alteration mechanism was interface-coupled dissolution-reprecipitation. Zircon was the most pervasively altered, possibly by broadening of cleavage planes or fractures; the other minerals were altered mainly on their rims and along cracks. The importance of cracks in promoting fluid access is stressed. The compositional effects of the alteration of each phase are documented. The hydrothermal fluids carried few ligands capable of transporting significant amounts of rare-earth elements (REE), high field strength elements (HFSE) and actinides; alteration is inferred to have been promoted by mildly alkaline, Ca-bearing fluids. Expansion cracks emanating from fergusonite-(Y) are filled with unidentified material containing up to 35 wt% UO2 and 25 wt% REE2O3, indicating late-stage, short-distance mobility of these elements. Electron microprobe chemical dating of monazite yielded an age of 1665 ± 22 Ma, much younger than the formation age of the Keivy province (2.65-2.67 Ga) but comparable to that of the Svecofennian metamorphic event which affected the area (1.9-1.7 Ga) or during fluid-thermal activation of the region during rapakivi granite magmatism (1.66-1.56 Ga). Dates for altered monazite range from 2592 ± 244 Ma to 773 ± 88 Ma and reflect disturbance of the U-Th-Pb system during alteration.

  10. A New Occurrence of Alkaline Magmatism on the Kola Peninsula: An Agpaitic Dyke in the Kandalaksha Region.

    NASA Astrophysics Data System (ADS)

    Akimenko, Mariya; Kogarko, Lia; Sorokhtina, Natalia; Kononkova, Natalia; Mamontov, Vladimir

    2015-04-01

    A new occurrence of alkaline dyke magmatism was discovered in 2010 during the geological works performed by the Murmansk Geological Prospecting Expedition in the "Mokhnatye Roga" area located 55 km to the southeast of the Kovdor massif (67°15' N, 31°30' E). The "Mokhnatye Roga" area is located in the Ensk segment of the northwestern part of the Belomorian mobile belt. We performed a complete petrological and geochemical description of the sections in Holes 19 and 24, which reveal one of the largest dykes in the area. The dyke, with a length of ≈4 km and a width of ≈160 m, has an eastern orientation with steep dipping (60°-90°) to the north. The thickness of Quaternary deposits ranges from 0.8 to 4.0 m; alkaline rocks occur in the range of 4.0-93.9 m being followed by host amphibole-biotite gneiss with interbeds of plagioamphibolite (AR2 mt) along the section. Among the major minerals of the dyke are the minerals of the lamprophyllite group (20-25 vol %), aegirine-augite (10-15 vol %), enigmatite (10-15 vol %), nepheline (10-15 vol %), orthoclase (15-20 vol %), alkaline amphibole (5-10 vol %), and astrophyllite (up to 5 vol %). The minor minerals are represented by shcherbakovite, sodalite, natrolite, barite, Mn carbonate, ilmenite, rutile, sphalerite, and goethite. The texture of the rock is porphyric: the groundmass is composed of finegranular nepheline and orthoclase, which are observed as individual large euhedral crystals as well. In addition, large phenocrysts are represented by the minerals of the lamprophyllite, enigmatite, pyroxene, and alkaline amphibole groups. Based on the generally accepted classifications [1], the studied agpaitic rock may be related to nepheline syenite; according to the mineral and chemical compositions, it is close to syenite of the Niva massif [2] located 35 km to the northeast from the "Mokhnatye Roga" area. Agpaitic syenite of the "Mokhnatye Roga" area is extremely enriched in dispersed and rare lithophile elements. The

  11. Mid-Neoproterozoic ridge subduction and magmatic evolution in the northeastern margin of the Indochina block: Evidence from geochronology and geochemistry of calc-alkaline plutons

    NASA Astrophysics Data System (ADS)

    Qi, Xuexiang; Santosh, M.; Zhao, Yuhao; Hu, Zhaocuo; Zhang, Chao; Ji, Fengbao; Wei, Cheng

    2016-04-01

    The mid-Neoproterozoic medium- to high-K calc-alkaline magmatic rocks in the northeastern margin of the Indochina block, SW China, provide important insights into the relationship of the Indochina block with the Gondwana supercontinent. Here we report zircon LA-ICP-MS U-Pb data from the early and late stage plutons which yield weighted mean 206Pb/238U ages of 765 Ma and 732-739 Ma suggesting mid-Neoproterozoic emplacement. The zircon εHf(t) values show a range of - 3.2 to + 2.4 (average + 0.1 ± 0.9) with TDMC of 1510 to 1870 Ma for the early plutons, and - 5.4 to + 5.1 (average + 2.1 to - 3.9) with TDMC of 1366 to 1985 Ma for late plutons. Both groups show similar geochemical characteristics including high Mg#, enrichment of LILE and LREE, slight negative Eu anomalies, and strongly negative Nb, Ta and Ti anomalies, with all the samples falling within the continental/island arc field in tectonic discrimination diagrams. These features suggest that the early and late stage magmas were produced by the mixing of mantle-derived magma and crust-derived magma in different proportion within an active continental margin, in subduction-related continental-arc tectonic setting. The linear zoning and roughly parallel distribution of the two generations of intrusions with a hiatus of 20 Ma might suggest an episode of ridge subduction with asthenosphere upwelling through the slab window that generated the second phase of plutons.

  12. Low-Sulfide PGE ores in paleoproterozoic Monchegorsk pluton and massifs of its southern framing, Kola Peninsula, Russia: Geological characteristic and isotopic geochronological evidence of polychronous ore-magmatic systems

    NASA Astrophysics Data System (ADS)

    Chashchin, V. V.; Bayanova, T. B.; Mitrofanov, F. P.; Serov, P. A.

    2016-01-01

    New U-Pb and Sm-Nd isotopic geochronological data are reported for rocks of the Monchegorsk pluton and massifs of its southern framing, which contain low-sulfide PGE ores. U-Pb zircon ages have been determined for orthopyroxenite (2506 ± 3 Ma) and mineralized norite (2503 ± 8 Ma) from critical units of Monchepluton at the Nyud-II deposit, metaplagioclasite (2496 ± 4 Ma) from PGE-bearing reef at the Vurechuaivench deposit, and host metagabbronorite (2504.3 ± 2.2. Ma); the latter is the youngest in Monchepluton. In the southern framing of Monchepluton, the following new datings are now available: U-Pb zircon ages of mineralized metanorite from the lower marginal zone (2504 ± 1 Ma) and metagabbro from the upper zone (2478 ± 20 Ma) of the South Sopcha PGE deposit, as well as metanorite from the Lake Moroshkovoe massif (2463.1 ± 2.7 Ma). The Sm-Nd isochron (rock-forming minerals, sulfides, whole-rock samples) age of orthopyroxenite from the Nyud-II deposit (2497 ± 36 Ma) is close to results obtained using the U-Pb method. The age of harzburgite from PGE-bearing 330 horizon reef of the Sopcha massif related to Monchepluton is 2451 ± 64 Ma at initial ɛNd =-6.0. The latter value agrees with geological data indicating that this reef was formed due to the injection of an additional portion of high-temperature ultramafic magma, which experienced significant crustal contamination. The results of Sm-Nd isotopic geochronological study of ore-bearing metaplagioclasite from PGE reef of the Vurechuaivench deposit (2410 ± 58 Ma at ɛNd =-2.4) provide evidence for the appreciable effect of metamorphic and hydrothermal metasomatic alterations on PGE ore formation. The Sm-Nd age of mineralized norite from the Nyud-II deposit is 1940 ± 32 Ma at initial ɛNd =-7.8. This estimate reflects the influence of the Svecofennian metamorphism on the Monchepluton ore-magmatic system, which resulted in the rearrangement of the Sm-Nd system and its incomplete closure. Thus, the new

  13. Aqualite, a new mineral species of the eudialyte group from the Inagli alkaline pluton, Sakha-Yakutia, Russia, and the problem of oxonium in hydrated eudialytes

    NASA Astrophysics Data System (ADS)

    Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.

    2007-12-01

    Aqualite, a new eudialyte-group mineral from hydrothermally altered peralkaline pegmatites of the Inagli alkaline pluton (Sakha-Yakutia, Russia) is described in this paper. Natrolite, microcline, eckermanite, aegirine, batisite, innelite, lorezenite, thorite, and galena are associated minerals. Aqualite occurs as isometric crystals up to 3-cm across. The color is pale pink, with a white streak and vitreous luster. The mineral is transparent. The fracture is conchoidal. The mineral is brittle; no cleavage or parting is observed. The Mohs’ hardness is 4 to 5. The density is 2.58(2) g/cm3 (measured by the volumetric method) and 2.66 g/cm3 (calculated). Aqualite is optically uniaxial (+), α = 1.569(1) and β = 1.571(1). The mineral is pleochroic from colorless to pale pink on X and pink on Y, α < β. Aqualite is weakly fluorescent with a dull yellow color under ultraviolet light. The mineral is stable in 50% HCl and HNO3 at room temperature. Weight loss after ignition at 500°C is 9.8%. Aqualite is monoclinic, and the space group is R3. The unit-cell dimensions are a = 14.078(3) Å, c = 31.24(1) Å, V = 5362 Å3, and Z = 3. The strongest reflections in the X-ray powder pattern [ d, Å ( I)( hkl)] are: 4.39(100)(2005), 2.987(100)(315), 2.850(79)(404), 10.50(44)(003), 6.63(43)(104), 7.06(42)(110), 3.624(41)(027), and 11.43(39)(101). The chemical composition (electron microprobe, H2O determined with the Penfield method) is as follows (wt %): 2.91 Na2O, 1.93 K2O, 11.14 CaO, 1.75 SrO, 2.41 BaO, 0.56 FeO, 0.30 MnO, 0.17 La2O3, 0.54 Ce2O3, 0.36 Nd2O3, 0.34 Al2O3, 52.70 SiO2, 12.33 ZrO2, O.78 TiO2, 0.15 Nb2O5; 1.50 Cl, 9.93 H2O,-O=Cl2 0.34; where the total is 99.46. The empirical formula calculated on the basis of Si + Zr + Ti + Al + Nb = 29 apfu is as follows: [(H3O)7.94Na2.74K1.20Sr0.49Ba0.46Fe0.23Mn0.12]Σ13.18(Ca5.79REE0.19)Σ5.98 (Zr2.92Ti0.08)Σ3.0(Si25.57Ti0.21Al0.19Nb0.03)S26.0[O66.46(OH)5.54]Σ72.0 [(OH)2.77Cl1.23]Σ4.0. The simplified formula is (H3O)8(Na,K,Sr)5

  14. Vigrishinite, Zn2Ti4 - x Si4O14(OH,H2O,□)8, a new mineral from the Lovozero alkaline complex, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Pekov, I. V.; Britvin, S. N.; Zubkova, N. V.; Chukanov, N. V.; Bryzgalov, I. A.; Lykova, I. S.; Belakovskiy, D. I.; Pushcharovsky, D. Yu.

    2013-12-01

    A new mineral vigrishinite, epistolite-group member and first layer titanosilicate with species-defining Zn, was found at Mt. Malyi Punkaruaiv, in the Lovozero alkaline complex, Kola Peninsula, Russia. It occurs in a hydrothermally altered peralkaline pegmatite and is associated with microcline, ussingite, aegirine, analcime, gmelinite-Na, and chabazite-Ca. Vigrishinite forms rectangular or irregularly shaped lamellae up to 0.05 × 2 × 3 cm flattened on [001]. They are typically slightly split and show blocky character. The mineral is translucent to transparent and pale pink, yellowish-pinkish or colorless. The luster is vitreous. The Mohs' hardness is 2.5-3. Vigrishinite is brittle. Cleavage is {001} perfect. D meas = 3.03(2), D calc = 2.97 g/cm3. The mineral is optically biaxial (-), α = 1.755(5), β = 1.82(1), γ = 1.835(8), 2 V meas = 45(10)°, 2 V calc = 50°. IR spectrum is given. The chemical composition (wt %; average of 9 point analyses, H2O is determined by modified Penfield method) is as follows: 0.98 Na2O, 0.30 K2O, 0.56 CaO, 0.05 SrO, 0.44 BaO, 0.36 MgO, 2.09 MnO, 14.39 ZnO, 2.00 Fe2O3, 0.36 Al2O3, 32.29 SiO2, 29.14 TiO2, 2.08 ZrO2, 7.34 Nb2O5, 0.46 F, 9.1 H2O, -0.19 O=F2, total is 101.75. The empirical formula calculated on the basis of Si + Al = 4 is: H7.42(Zn1.30Na0.23Mn0.22Ca0.07Mg0.07K0.05Ba0.02)Σ1.96(Ti2.68Nb0.41Fe{0.18/3+}Zr0.12)Σ3.39(Si3.95Al0.05)Σ4 20.31F0.18. The simplified formula is: Zn2Ti4- x Si4O14(OH,H2O,□)8 ( x < 1). Vigrishinite is triclinic, space group P , a = 8.743(9), b = 8.698(9), c = 11.581(11)Å, α = 91.54(8)°, β = 98.29(8)°, γ = 105.65(8)°, V = 837.2(1.5) Å3, Z = 2. The strongest reflections in the X-ray powder pattern ( d, Å, - I[ hkl]) are: 11.7-67[001], 8.27-50[100], 6.94-43[01, 10], 5.73-54[11, 002], 4.17-65[020, 2, 200], and 2.861-100[30, 22, 004, 11]. The crystal structure model was obtained on a single crystal, R = 0.171. Vigrishinite and murmanite are close in the structure of the TiSiO motif, but

  15. High-K calc-alkaline magmatism at the Archaean-Proterozoic boundary: implications for mantle metasomatism and continental crust petrogenesis. Example of the Bulai pluton (Central Limpopo Belt, South Africa)

    NASA Astrophysics Data System (ADS)

    Laurent, Oscar; Martin, Hervé; Doucelance, Régis; Moyen, Jean-François; Paquette, Jean-Louis

    2010-05-01

    The Neoarchaean Bulai pluton, intrusive within the supracrustal granulites of the Central Limpopo Belt (Limpopo Province, South Africa) is made up of large volumes of porphyritic granodiorites with subordinate enclaves and dykes which have monzodioritic and charno-enderbitic compositions. New U-Pb LA-ICP-MS dating on separated zircons yielded pluton emplacement ages ranging between 2.60 and 2.63 Ga, which are slightly older than previous proposed ages (~ 2.57-2.61 Ga). The whole-rock major- and trace-element composition of the Bulai pluton evidences unequivocal affinities with "high-Ti" late-Archaean sanukitoids. It belongs to a high-K calc-alkaline differentiation suite, with metaluminous affinities (0.7 < A/CNK < 1) and relatively high Mg# (0.4-0.6). These rocks have "juvenile" affinities, such as eNd ranging between -0.5 and 0.5, and in addition, are very rich in all incompatible trace elements, which is particularly obvious in monzodioritic enclaves and enderbites where primitive mantle-normalized LILE and LREE contents are up to 300. These characteristics point to an enriched mantle source for the Bulai batholith. Chondrite normalized, REE patterns are strongly fractionated ([La/Yb]N ~ 25-80), mainly due to high LREE contents (LaN ~ 250-630), and chiefly high HFSE contents (Nb ~ 15-45 ppm ; up to 770 ppm Zr) indicate that the metasomatic agent is a silicic melt rather than a hydrous fluid. Moreover, based on high Nb/Ta, Th/Rb, La/Rb and low Sr/Nd and Ba/La, we suggest that the metasomatic agent is a granitic melt generated by melting of terrigenous sediments. Interactions of this melt with mantle peridotites implies that sediments are located under a mantle slice; geometry which is easily achieved in subduction zone settings. This conclusion is supported by the fact that Bulai trace element patterns are very similar to those of sub-actual potassic magmas generated in magmatic arc environments by interactions between mantle and terrigenous sediments (e.g. Sunda

  16. Early Paleozoic alkalic and calc-alkalic plutonism and associated contact metamorphism, central Virginia Piedmont

    USGS Publications Warehouse

    Pavlides, Louis; Arth, Joseph G.; Sutter, J.F.; Stern, T.W.; Cortesini, Henry

    1994-01-01

    Early Paleozoic plutonism in the central Virginia Piedmont consists of the igneous Lahore Complex and Ellisville Pluton. The Lahore Complex consists of a small altered mafic pluton intruded by the shoshonitic, alkalic monzonites of the Lahore Pluton (-450 Ma) that, in turn, is intruded by the calc-alkaline, granodioritic Ellisville Pluton (-440 Ma). These plutons were emplaced at about 760aC at a depth of 12 to 18 km within greenschist-facies rocks and are enclosed by contact-metamorphosed rocks.

  17. PRECIPITATION OF PLUTONOUS PEROXIDE

    DOEpatents

    Barrick, J.G.; Manion, J.P.

    1961-08-15

    A precipitation process for recovering plutonium values contained in an aqueous solution is described. In the process for precipitating plutonium as plutonous peroxide, hydroxylamine or hydrazine is added to the plutoniumcontaining solution prior to the addition of peroxide to precipitate plutonium. The addition of hydroxylamine or hydrazine increases the amount of plutonium precipitated as plutonous peroxide. (AEC)

  18. Mechanics of Triangle Plutons

    NASA Astrophysics Data System (ADS)

    Parker, G. A.; Yin, A.

    2013-12-01

    Although most plutons around the world display circular or elliptic geometry in map view, some crop out with distinctive triangle geometry. The most prominent examples of the latter types of plutons are those exposed in the White-Inyo Mountains of eastern California. They include the Cretaceous Birch Creek pluton and Jurassic Beer Creek pluton. The triangle plutons are commonly bounded by overturned folds on all three sides, suggesting that the emplacement was mostly accommodated by magmatic expansion. Here, we present a mechanical model to explain the formation of triangle plutons. First, a rising pluton expands in the brittle upper crust, causing its overlain strain to expand uniformly in all directions. Such uniform expansion leads to the formation of a triple-junction like crack system, with three arms oriented at about 120 degrees from one another. Second, the rising and expanding magmatic body intrudes into the three extensional fracture zones and pushes the wall rocks of the cracks laterally as they fill and expand the cracks. Third, the three triangular domains bounded by the triple-junction like extensional cracks become folded as a result of uniform expansion of the magma. Our mechanical models are currently being evaluated against field observations using balanced cross sections around the rims of the Birch Creek pluton, and simulation of the mechanics and kinematic evolution of its country rocks using scaled analogue experiments.

  19. Alkaline igneous rocks

    SciTech Connect

    Fitton, J.G.; Upton, B.G.J.

    1987-01-01

    In this volume, an international team of scientists provides an up-to-date overview of the nature, origin, and evolution of alkaline magmas. Particular attention is paid to carbonatites, lamprophyres, and lamproites which are rock suites of current interest not recently reviewed elsewhere. Recent work on the classical alkaline provinces of East Africa, South Greenland, and the Kola Peninsula is included together with reviews of other areas of alkaline magmatism in North and South America, East Greenland, Europe, West Africa, and the ocean basins. Other papers discuss the impact of experimental isotopic and geochemical studies of the petrogenesis of alkaline rocks. This book will be of interest to petrologists and geochemists studying alkaline igneous rocks, and to other earth scientists as a reference on the rapidly expanding field of igneous petrology.

  20. Magma-mixing in the genesis of Hercynian calc-alkaline granitoids: an integrated petrographic and geochemical study of the Sázava intrusion, Central Bohemian Pluton, Czech Republic

    NASA Astrophysics Data System (ADS)

    Janoušek, Vojtěch; Braithwaite, Colin J. R.; Bowes, D. R.; Gerdes, Axel

    2004-10-01

    The Devonian-early Carboniferous (354.1±3.5 Ma: conventional zircon U-Pb age) Sázava intrusion (biotite-amphibole quartz diorite, tonalite and granodiorite) of the Central Bohemian Pluton (CBP) associated with bodies of (olivine, pyroxene-) amphibole gabbro, gabbrodiorite, (quartz) diorite and rare hornblendite, gives an opportunity for a comparative study of a rather shallow, calc-alkaline magma-mixing zone at two levels, separated by a vertical difference of approximately 1 km. The deeper section (Příbram) displays the direct evidence for the existence of a long-lived, periodically tapped and replenished, floored magma chamber (MASLI). The contacts between the subhorizontal sheet-like basic bodies and the surrounding, commonly cumulus-rich, Sázava granitoid, are arcuate, and cut by a series of veins and ascending pipes. Shallow-dipping swarms of strongly elongated and flow-aligned mafic microgranular enclaves (MME), concordant with the contacts of the basic bodies, are commonplace. The higher level (Teletín) section shows relatively independent basic intrusions, some of them distinctly hybrid in character and mainly of quartz dioritic composition, surrounded by relatively homogeneous, nearly cumulus-free Sázava tonalite rich in texturally variable MME. Larger quartz microdiorite bodies and the MME, both interpreted as hybrids, contain varying proportions of highly heterogeneous plagioclase megacrysts with complex zoning, particularly well shown by cathodoluminescence (CL). Most often the megacrysts have cores of labradorite-anorthite, partly resorbed and overgrown by andesine rims but some are strongly brecciated and fragments have been annealed by rim growth. Also characteristic are long prisms of apatite, oikocrysts of quartz and K-feldspar and zoned amphibole. The latter has brown pargasite and magnesiohastingsite cores, resorbed and overgrown by magnesiohornblende, compositionally similar to the amphibole in the Sázava tonalite. The brown cores are

  1. Petrology of the Plutonic Rocks of west-central Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    1970-01-01

    A series of plutons in west-central Alaska defines the Hogatza plutonic belt which extends for about 200 miles in an east-west direction from the northeastern Seward Peninsula to the Koyukuk River. The plutonic rocks have an aggregate area of about 1,200 square miles and their composition, distribution, and possible petrogenesis are discussed for the first time in this report. Field, petrographic and chemical data supported by K/Ar age dating indicate the plutonic rocks are divisible into two suites differing in age, location, and composition. The western plutons are mid-Cretaceous (~100 m.y.) in age and consist of a heterogeneous assemblage of monzonite, syenite, quartz monzonite. Associated with these granitic rocks is a group of alkaline sub-silicic rocks that forma belt of intrusive complexes extending for a distance of at least 180 miles from west-central Alaska to the Bering Sea. The complex at Granite Mountain shows a rare example of zoning from an alkaline rim to a quartz-bearing core. The occurrence of a similar complex at Cape Dezhnev on the easternmost tip of Siberia suggests the alkaline province may extend into Siberia. The easternmost plutons are Late Cretaceous (180 m.y.) in age and composed primarily of granodiorite and quartz monzonite similar to calc-alkaline plutons found throughout the North America Cordillera. The plutons are epizonal and intrude deformed but unmetamorphosed Lower Cretaceous andesitic volcanics and volcanic graywacke which constitute the highly mobile Yukon-Koyukuk volcanogenic province of west-central Alaska. No older rocks have been found within the confines of this vast tract; the occurrence of a bounding ophiolite sequence has lead to the suggestion that the province was formed by large-scale rifting and is underlain by oceanic crust. The possibility of no juvenile sialic crust over much of the area suggests that the potassium-rich magma now represented by the alkaline rocks originated in the mantle. The distribution of the

  2. Microbiology of the Gut of the Kola Nut Weevil, Balanogastris kolae

    PubMed Central

    Femi-Ola, T. O.; Babalola, A. G.

    2012-01-01

    Reports have shown that many insects have microbes in their gut system. Gut microbes are very important for insect vitality and much of their nutrition is derived from products of microbial metabolism. The habitat of Balanogastris kolae (Desbrocher des Loges) (Coleoptera: Curculionidae) suggests that they possess the ability to digest varieties of sugars particularly starch and protein materials present in the kola nut, Cola nitida Schott & Endlicher (Malvales: Malvaceae). The aim of this study was to characterize the gut bacterial communities of the kola weevil, B. kolae. To ascertain this, the gut bacterial community of a kola nut-feeding weevil, B. kolae was characterized using culture-dependent methods. The bacterial counts in the foregut, midgut and hindgut were 7.14 ± 0.11 × 106cfu ml-1, 2.68 ± 0.13 × 107 cfu ml-1 and 1.43 ± 0.20 × 106 cfu ml-1 respectively. There were no significant differences in the total bacterial count of the foregut, midgut and hindgut. The bacterial species were identified to be Fusobacterium nucleatum, Staphylococcus aureus, Bacillus subtilis, Corynebacterium fascians, Arthrobacter globiformis, Serratia marcescens, Bacillus brevis, Vibrio haemolyticus and Flavobacterium breve. The majority of these isolates were demonstrated to have both proteolytic and amylolytic activities. PMID:23421598

  3. Late Jurassic plutonism in the southwest U.S. Cordillera

    USGS Publications Warehouse

    Barth, A.P.; Wooden, J.L.; Howard, K.A.; Richards, J.L.

    2008-01-01

    Although plate reconstructions suggest that subduction was an approximately steady-state process from the mid-Mesozoic through the early Tertiary, recent precise geochronologic studies suggest highly episodic emplacement of voluminous continental-margin batholiths in the U.S. Cordillera. In central and southern California and western Arizona, major episodes of batholithic magmatism are known to have occurred in Permian-Triassic, Middle Jurassic, and late Early to Late Cretaceous time. However, recent studies of forearc-basin and continental-interior sediments suggest that Late Jurassic time was probably also a period of significant magmatism, although few dated plutons of this age have been recognized. We describe a belt of Late Jurassic plutonic and hypabyssal rocks at least 200 km in length that extends from the northwestern Mojave Desert through the Transverse Ranges. The belt lies outboard of both the voluminous Middle Jurassic arc and the ca. 148 Ma Independence dike swarm at these latitudes. The plutons include two intrusive suites emplaced between 157 and 149 Ma: a calc-alkaline suite compositionally unlike Permian-Triassic and Middle Jurassic mon-zonitic suites but similar to Late Cretaceous arc plutons emplaced across this region, and a contemporaneous but not comagmatic alkaline suite. The Late Jurassic was thus a time of both tectonic and magmatic transitions in the southern Cordillera. ?? 2008 The Geological Society of America.

  4. Late Silurian plutons in Yucatan

    NASA Astrophysics Data System (ADS)

    Steiner, M. B.; Walker, J. Douglas

    1996-08-01

    U-Pb measurements of zircons from two composite plutons in the Maya Mountains of the Yucatan Block (Belize) give Late Silurian ages. Zircons from one of the five compositional phases of the Mountain Pine Ridge pluton yield an age of 418±3.6 Ma. A second compositional phase gives a minimum age of 404 Ma, and zircons from a third phase, although plagued with high common Pb, yield ages consistent with the other two. Zircons from one compositional phase of the Hummingbird-Mullins River pluton indicate an age of about 410-420 Ma. These data demonstrate that two of the three Maya Mountains plutons residing among the strata of the Late Pennsylvanian through Permian Santa Rosa Group are older than that sedimentation. Although the third pluton was not dated, both the similarity of sedimentary facies patterns adjacent to it to those adjacent to one of the plutons dated as Late Silurian and a published single Rb-Sr age of 428 ± 41 Ma suggest this third pluton also was emergent during Santa Rosa deposition. Thus the new U/Pb dates and other data suggest that all three Maya Mountains plutons pre-date Late Carboniferous sedimentation and that none intrude the Santa Rosa Group. Although very uniform ages of about 230 Ma amongst all plutons, derived from abundant earlier dating by the K-Ar system, led to the conclusion that intrusion mostly had occurred in the Late Triassic, the U-Pb ages (obtained from the same sites as the K-Ar dates) demonstrate that the K-Ar ages do not derive from a Late Triassic intrusive episode. The K-Ar dates probably are a signature of the rifting associated with Pangean breakup and formation of the Gulf of Mexico. In a reconstructed Pangea, the position of the Maya Mountains Late Silurian plutons suggests that the Late Silurian Acadian-Caledonian orogen of eastern North America extended through the region of the future Gulf of Mexico. Finally, the U-Pb ages of the Maya Mountains plutons are the same as those of a group of shocked zircons found in the

  5. Late-stage sinking of plutons

    USGS Publications Warehouse

    Glazner, A.F.; Miller, D.M.

    1997-01-01

    Many granodiorite to diorite plutons in the Great Basin of western North America are surrounded by rim monoclines or anticlines that suggest relative downward movement of the plutons while wall rocks were hot and ductile. We propose that such plutons rise to a level of approximately neutral buoyancy and then founder as their densities increase ??? 40% during crystallization. Late-stage sinking of intermediate to mafic plutons should be common when wall rocks are rich in weak, low-density minerals such as quartz and calcite. Structures related to sinking will overprint those related to initial pluton emplacement and may be mistaken for regional tectonic structures.

  6. Microbiological exploitation of cardiac glycosides and alkaloids from Garcinia kola, Borreria ocymoides, Kola nitida and Citrus aurantifolia.

    PubMed

    Ebana, R U; Madunagu, B E; Ekpe, E D; Otung, I N

    1991-11-01

    The four medicinal plants, Garcinia kola (roots), Borreria ocymoides (leaves), Kola nitida (bark) and Citrus aurantifolia (roots) were screened for phytochemical components. They were found to contain tannins, phlobatannins, polyphenols, hydroxymethyl anthraquinones, glucides, saponins, alkaloids, cardiac glycosides, flavanoids and reducing compounds. The aqueous and alcoholic extracts as well as alkaloids and cardiac glycosides of the medicinal plants were tested on various pathogenic bacteria. They were found to inhibit such organisms as Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, beta-haemolytic streptococci, Escherichia coli and Neisseria gonorrhoeae. The usefulness of the phytochemical bases of these plants as potential sources of pharmaceutical drug preparation is discussed.

  7. A comparative study of two rear-arc plutons and implications for the Fuegian Andes tectonic evolution: Mount Kranck Pluton and Jeu-Jepén Monzonite, Argentina

    NASA Astrophysics Data System (ADS)

    González-Guillot, M.; Prezzi, C.; Acevedo, R. D.; Escayola, M.

    2012-10-01

    A petrologic, geochemical and geophysical study of two Late Cretaceous plutons of the Fuegian Andes is carried out: the Jeu-Jepén Monzonite (JJM) and the Mt. Kranck Pluton (MKP). The plutons show a wide lithological spectrum from ultramafic lithologies (clinopyroxenites and hornblendites), gabbros, diorites to late stage K-feldspar syenite veins. They represent the top of magmatic chambers exposed at or close to the roof level. Mode and chemistry indicate a monzonitic-mildly alkaline trend with high K2O content, equivalent to shoshonitic series. Trace element composition is typical of arc magmas. These features plus their high LILE content (Ba 320-1600 ppm, Sr 475-1560 ppm), high LILE/HFSE ratio (Rb/Zr 0.6-1.6) and age confirm they belong to a rear-arc, monzonitic to mildly alkaline suite (the Fuegian Potassic Magmatism). Therefore, they represent the farthest-from-the-trench plutons in the suite. The petrographical and chemical characteristics of the plutons suggest the lithological spectrum is the result of magmatic differentiation. The process involved crystal accumulation and magma mingling at the early stages, favored either by injections of fresh magma from deeper reservoirs and/or the action of convective currents within the chamber. Country rock assimilation also took part simultaneously with crystallization. The JJM and MKP lie along the trace of a Cenozoic left-lateral strike-slip fault (Magallanes-Fagnano fault system), on opposite blocks. However, lithological, chemical and geophysical subtle differences between these two plutons suggest they evolved in individual magmatic chambers and therefore the distance between them cannot be used as an estimation of total offset along the fault, as was indicated in previous studies.

  8. Emplacement of the Solarya Pluton (NW Turkey)

    NASA Astrophysics Data System (ADS)

    Ünal, Alp; Altunkaynak, Şafak

    2017-04-01

    The Solarya pluton is one of the major plutons located in NW Anatolia. It consists of three plutonic rock groups: K-feldspar megacrystalline granodiorite (KFMG), microgranite-granodiorite (MGG) and haplogranite (HG). Also mafic dikes and mafic microgranular enclaves (MME) are common within the plutonic body. The northern and southern parts of the pluton present different textural properties. At the northern part of the pluton, K-feldspar megacrystalline granodiorite with porphyritic texture is dominant while southern part of the pluton is formed from microgranite-granodiorite with microgranular texture. Haplogranite, which is typical with its graphic/granophyric texture, outcrops between KFMG and country rocks as a thin aureole. The emplacement of the Solarya pluton began forcefully at the deeper levels of the epizone and then reached to shallow levels in the crust. The northern and southern part of the pluton displays textural and structural indicators of this different emplacement levels. At the northern part, between KFMG and the country rocks, pluton developed a narrow contact metamorphic zone characterized by the hornblend-hornfels facies. Additively, through the northern and eastern margin, the structural properties of the regional metamorphic rocks have changed depending on the emplacement of pluton indicating a forceful emplacement. The basement rocks at the southern boundary represent a "roof pendant" on the MGG. In some places of southern margin, MGG gradually passes into the subvolcanic rocks (microgranodiorite-quartzdiorite porphyries) which were emplaced into the ring and radial faults connected to pluton emplacement. The amphibole-plagioclase geothermobarometer results of Solarya pluton indicate that, for MGG 0.8-1.0 kb and 626-678 C and for K-feldspar megacrystalline granodiorite 1.8-2.3 kbar and 737-752 C pressure and temperature emplacement conditions are calculated. This data suggest that while the southern part of the pluton were emplaced into

  9. Potential use ofGarcinia kola as hop substitute in lager beer brewing.

    PubMed

    Aniche, G N; Uwakwe, G U

    1990-09-01

    The chemical, brewing and anti-microbial properties of a tropical seed,Garcinia kola, were compared with traditional hops. Treatment ofGarcinia kola with methanolic lead acetate produced a yellow precipitate from which organic acids (alpha acids) were contirmed to be present by thin-layer chromatography. Hops, however, had a higher concentration of organic acids thanGarcinia kola. Laboratory brewing trials withGarcinia kola and hops gave beers with simillar chemical properties. Organoleptically,Garcinia kola beer was as acceptable to tasters as hopped beer except that it had an improved bitterness.Garcinia kola and hop extracts exerted similar anti-microbial effects on two beer spollage micro-organisms (Lactobacillus delbruckii andCandida vini).

  10. Technology for NPP decantate treatment realized at Kola NPP

    SciTech Connect

    Stakhiv, Michael; Avezniyazov, Slava; Savkin, Alexander; Fedorov, Denis; Dmitriev, Sergei; Kornev, Vladimir

    2007-07-01

    At Moscow SIA 'Radon' jointly with JSC 'Alliance Gamma', the technology for NPP Decantate Treatment was developed, tested and realized at Kola NPP. This technology consists of dissolving the salt residue and subsequent treatment by ozonization, separation of the deposits formed from ozonization and selective cleaning by ferro-cyanide sorbents. The nonactive salt solution goes to an industrial waste disposal site or a repository specially developed at NPP sites for 'exempt waste' products by IAEA classification. This technology was realized at Kola NPP in December 2006 year. At this time more than 1000 m{sup 3} of decantates log time stored are treated. It allows solving very old problem to empty decantates' tanks at NPPs in environmentally safe manner and with high volume reduction factor. (authors)

  11. Helminths of brown bears (Ursus arctos) in the Kola Peninsula.

    PubMed

    Bugmyrin, S V; Tirronen, K F; Panchenko, D V; Kopatz, A; Hagen, S B; Eiken, H G; Kuznetsova, A S

    2017-06-01

    We present data on the species composition of helminths in brown bears (Ursus arctos) from the Murmansk Region, Russia. The absence of any information about helminths of brown bear in the region necessitated the conduct of these studies. Samples were collected in 2014 and 2015 in the southern part of the Kola Peninsula from the White Sea coastal habitats. Annually, in the study area, 1-3 bears are legally hunted and biological samples for examination are very difficult to obtain. Therefore, we used fecal samples. We studied 93 feces and identified parasite eggs identified in 43 of them by morphometric criteria. The surveys revealed eggs of the following helminths: Dicrocoelium sp., Diphyllobothrium sp., Anoplocephalidae, Capillariidae, Baylisascaris sp., Strongylida 1, and Strongylida 2. These results represent the first reconnaissance stage, which allowed characterizing the taxonomic diversity and prevalence of parasites of brown bears of the Kola Peninsula.

  12. Petrography and geochemistry of Ilıca-Şamlı Pluton, NW Turkey

    NASA Astrophysics Data System (ADS)

    Aydın, Halil Can; Özdamar, Şenel

    2017-04-01

    The major and trace elements of the plutonic rocks from the Ilıca-Şamlı Pluton, Northwest of Turkey, were studied to understand petrogenesis. The plutonic rocks consist of a variety of rock types ranging from diorite to granodiorite. Diorites and granodiorite contain large, massive alkali feldspar crystals which are porphyritic textures. These plutonic rocks have SiO2=62-65, Al2O3=14,55-15,74, Fe2O3=4,03-5,85, MgO=1,85-2,80, CaO=4,83-5,96, Na2O=3,14-3.58, K2O=3,04-4,16 major oxide percentages. All of the rocks show a calc-alkaline afinity. Chondrite-normalized REE patterns are moderately fractionated and relatively flat. They display small negative Eu anomalies with enrichment of LILE and less amount of depletion of HFSE. The 40Ar/39Ar ages ˜21-22 Ma. These ages are interpreted as crystalliczation ages of the plutonic rocks and also these ages imply collision of the Intra-Pontide Suture and Anatolide-Tauride platform.

  13. Anticariogenic potentials of clove, tobacco and bitter kola.

    PubMed

    Uju, Dibua Esther; Obioma, Nnamani Petra

    2011-10-01

    To investigate three tropical plant materials - clove seeds [Syzygium aromaticum (S. aromaticum)], bitter kola fruits [Garcinia kola (G. kola)] and tobacco leaves (Nicotiana species) as potential targeted killers of Streptococcus mutans (S. mutans), a cavity-causing bacterium (gram-positive, facultative anaerobe) that resides in a multispecies microbial community (dental plaque) for the treatment of dental caries (tooth decay). Thirty one (31) teeth samples were collected from patients with obvious signs of tooth decay (swollen gum, weak or fallen tooth, etc.) using sterile swab sticks. These samples were collected from two major dental clinics in Nsukka, Enugu State, Nigeria and investigated by spread inoculation onto sterile blood agar and Mueller Hinton agar (MHA) respectively and incubated at 37 °C for 24 h. The discrete colonies obtained were further re-inoculated onto sterile Mitis salivarius agar (MSA) plates and incubated as above. The isolates were characterized by gram staining and catalase test. Tobacco leaves, clove seeds and bitter kola fruits were ground into powder, extracted with three different solvents (n-hexane, hot water and ethanol), filtered, dried and stored in clean containers, corked and kept until used. The plant extracts were investigated for phytochemistry, minimum inhibitory concentration (MIC), minimum cidal concentration (MCC) and compared with some conventional antibiotics commonly used against tooth decay. Antibiotic sensitivity test was also carried out. The results were statistically analyzed. The extracts showed varied phytochemical composition but most abundantly the flavonoids. Our result also shows that females (16) have more tooth decay than males (15) and that 16 samples were very bloody while 15 were slightly bloody. The microbial characterization showed that 18 samples were catalase-positive indicating the presence of S. mutans while 13 were catalase-negative suspected to be Staphylococcus spp. The Gram reaction confirmed

  14. Dichotomy of The Messada Pluton, Serbo-Macedonian Massif, Greece: From Rifting to Subduction

    NASA Astrophysics Data System (ADS)

    Vasilatos, Charalampos

    2016-10-01

    The Messada pluton is a mafic intrusion that is located about 12 km SW of Serres town, (Macedonia Greece) that intrudes the two mica, biotite and the augen gneisses of the Vertiskos formation (Serbo-Macedonian massif). The aim of this study is to investigate, define and evaluate the geochemical characteristics of the pluton in order to determine the geotectonic environment in which the parental magma has been formed. The Mesada pluton is a mid to coarse grained intrusion presenting petrographic variety from diorite and quartz diorite to tonalite and granodiorite. The variety in petrography reflects its chemical inhomogeneity in major and trace elements. It is suggested that parts of pluton have been formed by distinctly different types of magmas originated in diverse geotectonic settings. Those parts of quartz diorite and tonalite composition, present similar geochemical characteristics, LILE/HFSE ratios and negative Nb, but no Ti anomalies in their primitive mantle normalized trace elements spider grams. They exhibit higher HFS values than those of granodioritic composition. Moreover, their ORG normalized spider grams not only suggest that they have been evolved by a common parental magma, but also present the typical characteristics of a “crust dominated” within plate pluton that may have been formed in an early stage during rifting, prior to a subsequent subduction episode. This interpretation may be in accordance with the suggestion for the Gondwanian origin of the more silicic Triassic rift related meta-granites (e.g. Arnea plutonic complex) of the Serbo-Macedonian massif. In contrary; the parts of Mesada pluton of granodioritic composition, exhibit a calc-alkaline to high K calc-alkaline magmatic suite and present higher LILE/HFSE and LREE/HREE ratios, related to a higher crustal component contribution for the magma genesis. Furthermore, their primitive mantle normalized spider grams’ present negative anomalies at Nb and Ti. These characteristics

  15. Plutonic rock types series: discrimination of various granitoid series and related rocks

    NASA Astrophysics Data System (ADS)

    Lameyre, Jean; Bowden, Peter

    1982-10-01

    The Streckeisen QAP diagram discriminates four characteristic type series among the large variety of granitoids associated in intrusions. Three of them integrate varied compositions from basic to acid terms: (1) the calcalkaline series with its low K (or trondhiemite), medium K (or granodioritic), high K (or monzonitic) variants; (2) the alkaline series with its characteristic syenitic members; (3) the tholeiitic series, deprived of K feldspars. The fourth (4) corresponds to mobilizates associated with migmatites of varied composition but always quartz rich. The generalization in the QAPF system, allowing the plotting of undersaturated alkaline series, provides an excellent visual display of the major associations and trends for the plutonic rocks.

  16. Time of formation and genesis of yttrium-zirconium mineralization in the Sakharjok massif, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Vetrin, V. R.; Skublov, S. G.; Balashov, Yu. A.; Lyalina, L. M.; Rodionov, N. V.

    2014-12-01

    The Kola geotectonic province in the northeastern Fennoscandian Shield accommodates a significant number of alkaline rock massifs differing in age. They are of mantle and mantle-crustal origin (alkali and nepheline syenites, carbonatites) and related to crustal sources (Neoarchean alkali granites). Among them, the Neoarchean Sakharjok nepheline syenite massif is related to the oldest intrusions of this kind bearing yttrium-zirconium mineralization. The crystallization of alkali syenite pertaining to the first intrusive phase of the intrusive Sakharjok massif is dated to 2645 ± 7 Ma, and this implies that this syenite postdated alkali granites (2.66-2.67 Ga). To date the yttrium-zirconium ore, we applied the local U-Pb method to zircon crystals occurring in the mineralized block hosted in nepheline syenite. The earliest fragments of zircon crystallized 1832 ± 7 Ma ago; the age of metamorphism is estimated at 1784 ± 13 Ma. These dates indicate the Paleoproterozoic age of the yttrium-zirconium mineralization, which was formed as a product of fluid reworking of the Neoarchean nepheline syenite of the Sakharjok massif.

  17. Crystal mush flow in a small concentrically expanded pluton (Castle Crags pluton; Klamath Mountains, CA, USA)

    NASA Astrophysics Data System (ADS)

    Machek, Matej; Závada, Prokop; Petrovský, Eduard; Roxerová, Zuzana; Špičák, Aleš

    2017-04-01

    By means of an example of small concentrically-zoned Castle Crags pluton in the Klamath Mountains (USA), we decipher origin of granite rock fabrics, emplacement mode, and evolution of internal architecture of the pluton, which have been mostly in the crystal mush state during fabric development and solidification. Through the detailed microstructural and magnetic study we discuss the pluton fabric formation and emplacement. The study combines the field-based structural measurements, anisotropy of magnetic susceptibility analyses, and rock magnetic properties with detailed quantitative and qualitative microstructural analysis. The pluton structure with the marginal strain gradient is interpreted as a result of compaction, melt segregation and cumulate formation in the granodiorite caused by the intrusion of the throndhjemite magma to the core of the already emplaced granodiorite. The lateral flow of the magma from the central region formed lobe, the existence of which aphiliates the Castle Crags pluton to concentrically expanded plutons, which grew in at least two increments. The AMS results put forward the presence of anomalously high intensive magnetic fabric, (high P values, P > 1.2) and evolution of the T parameter through the pluton. We interpret the high P values as a result of variable microstructural position and crystal plastic deformation of a part of the magnetite crystals due to magma flow in submagmatic state. The AMS ellipsoid shape evolution is explained by fabric intensification in earlier magma pulses due to the intrusion of the throndhjemite magma to the core of the evolving pluton.

  18. Distinctly different parental magmas for plutons and lavas in the central Aleutian arc

    NASA Astrophysics Data System (ADS)

    Cai, Y.; Rioux, M. E.; Kelemen, P. B.; Goldstein, S. L.; Bolge, L.; Kylander-Clark, A. R.

    2014-12-01

    While it is generally agreed that continental crust is generated by arc magmatism, average arc lavas are basaltic while the bulk continental crust is andesitic, and this has led to many models for secondary reprocessing of the arc crust in order to form continental crust. We report new data on calc-alkaline plutons in the central Aleutians showing that they have distinctly different sources compared to Holocene tholeiitic lavas. Therefore the lavas are not representative of the net magmatic transfer from the mantle into the arc crust. Eocene to Miocene (9-39 Ma) intermediate to felsic plutonic rocks from the central Aleutian arc show higher SiO2 at a given Mg#, higher ɛNd- and ɛHf-values, and lower Pb isotope ratios than Holocene volcanic rocks from the same region. Instead, the plutonic rocks resemble volcanics from the western Aleutians isotopically, and have chemical compositions similar to bulk continental crust. These data could reflect temporal variation of Aleutian magma source compositions, from Eocene-Miocene "isotopically depleted" and predominantly calc-alkaline to Holocene "isotopically enriched" and predominantly tholeiitic. Alternatively, they may reflect different transport and emplacement processes for the magmas that form plutons and lavas: calc-alkaline magmas with higher Si content and high viscosity may preferentially form plutons, perhaps after extensive mid-crustal degassing of initially high water contents. The latter case implies that the upper and middle arc crust is more like the calc-alkaline bulk composition of the continental crust than the lavas alone. Crustal reprocessing mechanisms that preserve upper and middle arc crust, while removing lower arc crust, can account for the genesis and evolution of continental crust. Since gabbroic lower arc crust extends from ca 20-40 km depth, and is density stable over most of this depth range, "delamination" of dense lithologies [1] may not be sufficient to accomplish this. Alternatively

  19. Origin of adakite-like plutons in southern Korea

    NASA Astrophysics Data System (ADS)

    Oh, Jeong-Im; Choi, Sung Hi; Yi, Keewook

    2016-10-01

    We present Sr-Nd-Pb isotopic compositions for two adakite-like intrusions in southern Korea (Jindong and Bongnae), including major and trace element concentrations, and the sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb age. Our aim is to constrain the origin and tectonomagmatic processes that gave rise to the plutons. A SHRIMP U-Pb zircon age of 88.7 ± 0.7 Ma was obtained from a Jindong granodiorite sample. The Jindong plutons belong to the medium-K calc-alkaline series, and have an overall enrichment in large ion lithophile elements (LILE), such as K, Rb, Ba, and Pb, and a relative depletion in high field strength elements, such as Nb, Ta, and Ti, compared with the neighboring elements in the primitive mantle-normalized multi-trace element variation diagram. It was found that (87Sr/86Sr)i = 0.70475-0.70596, (143Nd/144Nd)i = 0.512547-0.512604, [(εNd)i = + 0.4 to 2.2], and (206Pb/204Pb)i = 18.19-18.37, which fall within the field of the arc-type Cretaceous to Tertiary Bulguksa intrusive rocks in the Sr-Nd and Pb-Pb isotopic correlation diagrams. The elevated Sr/Y (17-40), but low La/Yb (3.7-8.8) ratios of the Jindong plutons, together with their coherent geochemical trends and U-shaped rare earth element (REE) patterns, indicate that they were not formed by slab melting, but by amphibole-dominated fractional crystallization of the Bulguksa-like arc magma. A SHRIMP U-Pb zircon age of 226.5 ± 2.5 Ma was obtained from a Bongnae tonalite sample. The Bongnae plutons belong to the shoshonitic series. Their trace element patterns resemble the Jindong samples, but are characterized by significantly negative U anomalies in mafic rocks. They also have elevated MgO, Ni, Co, Cr, Rb, Ba, Sr, and low Al2O3 and Na2O contents at a given SiO2 concentration compared with the Jindong plutons, and are typified by highly radiogenic Sr and unradiogenic Nd and Pb isotopic compositions: [(87Sr/86Sr)i = 0.71096-0.71290, (143Nd/144Nd)i = 0.511641-0.511681, (εNd)i = - 13

  20. Nature of Phyllosilicates and Magma Types in the Plutonic Complexes of NE Egypt

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, A.

    2007-05-01

    The Late Proterozoic plutonic complexes of northeastern Egypt belong to a number of magma types of variable tectonic regimes, and exhibit a variety of phyllosilicate minerals. The results show that the phyllosilicates define three compositionally distinct groups. Phyllosilicates in the anorogenic peralkaline granites, which were developed from a hypersolvus felsic melt, are restricted to iron-rich siliceous annites and belong to type A-biotite (referring to biotite in anorogenic alkaline A-type suites). Such Fe-enriched, Al-depleted mica compositions suggest that the substitutions Fe3+ = Al, 3Fe2+ = 2Al, Fe2+ = Mg and (Fe2+ + Si) = 2Al are vital in producing annitic compositions in the peralkaline granites. In sharp contrast, phyllosilicates in the trondhjemitic pluton that crystallized from a peraluminous felsic melt, are siderophyllitic in composition and belong to type P-biotite (referring to biotite in peraluminous, including S-type suites). The substitutions Fe2+ = Mg, along with the Tschermaks substitution (Fe2+, Mg) + Si = 2Al are vital in producing siderophyllitic compositions in the trondhjemite pluton. The substitution 2Al = 3Mg (or Fe2+) also plays a role when referring to a possible solid solution between phlogopite (or annite) end-member and muscovite end-member. This pluton also contains late- to post-magmatic muscovite. Phyllosilicates in the diorite-tonalite and the voluminous granodiorite-adamellite orogenic complexes (crystallized from calcic to calc-alkaline subsolvus magmas), cover a wide range of composition, and belong to type C-biotite (referring to biotite in calcic and calc- alkaline, mostly I-type suites). The nature of micas and the magmatic stages of their development were controlled by the various physiochemical conditions (including the behavior of volatiles) prevailed during the crystallization of these hypersolvus, dry, anorogenic magmas versus subsolvus, wet, orogenic magmatic systems.

  1. Plutonic rocks in the Mineoka-Setogawa ophiolitic mélange, central Japan: Fragments of middle to lower crust of the Izu-Bonin-Mariana Arc?

    NASA Astrophysics Data System (ADS)

    Ichiyama, Yuji; Ito, Hisatoshi; Hokanishi, Natsumi; Tamura, Akihiro; Arai, Shoji

    2017-06-01

    A Paleogene accretionary complex, the Mineoka-Setogawa Belt, is distributed around the Izu Collision Zone, central Japan. Plutonic rocks of gabbro, diorite and tonalite compositions are included as fragments and dykes in an ophiolitic mélange in this belt. Zircon U-Pb dating of the plutonic rocks indicates that they were formed at ca. 35 Ma simultaneously. These ages are consistent with Eocene-Oligocene tholeiite and calc-alkaline arc magmatism in the Izu-Bonin-Mariana (IBM) Arc and exclude several previous models for the origin of the Mineoka-Setogawa ophiolitic rocks. The geochemical characteristics of these plutonic rocks are similar to those of the Eocene-Oligocene IBM tholeiite and calc-alkaline volcanic rocks as well as to the accreted middle crust of the IBM Arc, the Tanzawa Plutonic Complex. Moreover, their lithology is consistent with those of the middle and lower crust of the IBM Arc estimated from the seismic velocity structure. These lines of evidence strongly indicate that the plutonic rocks in the Mineoka-Setogawa ophiolitic mélange are fragments of the middle to lower crust of the IBM Arc. Additionally, the presence of the Mineoka-Setogawa intermediate to felsic plutonic rocks supports the hypothesis that intermediate magma can form continental crust in intra-oceanic arcs.

  2. Petrology and radiogeology of the Stripa pluton

    SciTech Connect

    Wollenberg, H.; Flexser, S.; Andersson, L.

    1980-12-01

    Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monozite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region, biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the the leptite and other plutons in the region. Uranium and thorium abundances are both approx. 30 ppM, considerably higher than in normal granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat productivity considerations show that although Stripa quartz monzonite contains high abundances of radioelements, the pluton has little efect on the regional heat flow. If it occurs in a layered plutonic setting, it is not more than 1.5 km thick; otherwise it may comprise a stock, dike, or border phase that is relatively small compared with the large granitic plutons exposed in the region.

  3. Apatite Fission Track Thermochronology of Khibina Massif (Kola Peninsula, Russia): Implications for post-Devonian Tectonics of the NE Fennoscandia

    NASA Astrophysics Data System (ADS)

    Veselovskiy, R. V.; Thomson, S. N.; Arzamastsev, A.

    2015-12-01

    The thermal history of the Kola Peninsula area of NE Fennoscandia remains almost fully unknown because of absence of any thermochronological data such as apatite and/or zircon fission track or (U-Th)/He ages. In order to fill this gap and to constrain the post-Devonian erosion and exhumation history of this region, we present the results of apatite fission track (AFT) dating of eleven samples selected from the cores taken from different depths of the northern part of the Khibina intrusive massif. This alkaline magmatic complex is located at the center of Kola Peninsula and formed at about 370 Ma (Kramm and Kogarko, 1994). Samples were analyzed from depths between +520 to -950 meters and yielded AFT ages between 290-268 Ma with an average age uncertainty (1σ) of ±30 Ma. Mean track lengths (MTL) lie between 12.5-14.4 μm. We used the most reliable AFT ages and distribution of MTL in two samples, corresponding to depths of +280 and -920 m, to conduct inverse time-temperature modelling of the Khibina massif. Thermal histories that best predict the measured data show three stages: (1) 290-250 Ma - rapid cooling from >110°C to 70°C/50°C for lower/upper sample correspondingly; (2) 250-50 Ma - a stable temperature stage; (3) 50-0 Ma - slightly increased cooling rates down to modern temperatures. We propose that the first cooling stage is related to late-Hercynian orogenesis; the second cooling stage may be associated with tectonics accompanying with opening of Arctic oceanic basin. The obtained data show that geothermal gradient at the center of Kola Peninsula has remained close to the modern value of 20°C/km for at least the last 250 Myr. AFT data show that the Khibina massif has been exhumed not more then 5-6 km in the last 290 Myr. This study was funded by grants 15-35-20599, 15-05-02116, 15-05-01860 and 13-05-01033 from the Russian Foundation of Basic Research, grant 3.38.224.2015 from the St. Petersburg State University, grant 14.Z50.31.0017 from the Government

  4. Bullialdus - Strengthening the case for lunar plutons

    NASA Astrophysics Data System (ADS)

    Pieters, Carle M.

    1991-11-01

    Although many craters expose materials of a composition different from that of the local surroundings, Bullialdus has excavated material representing three distinct stratigraphic zones that occur in the upper 6 km of crust, the top two of which are gabbroic and the deepest of which is noritic. This three-component stratigraphy at Bullialdus provides strong evidence that the lunar crust includes pockets of compositionally layered material reminiscent of mafic layered plutons. When combined with previous information on the compositional diversity at other large craters, these remote analyses obtained in a geologic context substantially strengthen the hypothesis suggested from lunar samples that plutons play an integral role in lunar crustal evolution.

  5. Mineralization related to Alvand pluton in the Hamadan, western Iran

    NASA Astrophysics Data System (ADS)

    Salehi, M. H.; Doosti, E. A.; Ahadnejad, V.

    2009-04-01

    The Alvand (Hamadan) plutonic batholith is one of the largest plutonic bodies in the Sanandaj-Sirjan metamorphic belt. This complex is consist of mafic part (gabbro-diorite-tonalite), intermediate (granite-granodiorite porphyroids), and hololeucocratic granitoids. Previous studies have shown that S-type granite-granodiorites are mostly peraluminous and calc-alkaline; the gabbro-diorite-tonalite suite is mostly metaluminous and tholeiitic to calc-alkaline (Sepahi, 2008). High initial 87Sr-86Sr ratios (0.7081 to 0.7115), low epsilon Nd values (-1.0 to -3.3), and peraluminous character reflects a different origin for the granites, possibly crustal sources (Ghalamghash et al, 2007). Aplite-pegmatite dikes are intruded in granitoide rocks, metamorphic rocks and the contact of Alvand granite with metamorphic rocks. The contact of Alvand granite with metamorphic rocks is sharp. By using heavy mineral studies on the alluvium of Alvand complex, it is recognized 28 minerals amongst Scheelite, Cassiterite, Ilmenite, Zircon and Garnet. Different geostatistical studies such as variant, bivariant and multivariant studies have been done on rough data of heavy minerals. They showed normal concentration of gold in studied rocks and low enrichment of tin and tungsten. The index of the ore elements average, frequeney distribution criteria of elements, the ratio of elements index and multielements show that Alvand granite is barren. Mineralography studies did not recognized any tin and tungsten minerals. The grains of gold was recognized in some of the microscopic thin sections. Calcopyrotite is the most important ore mineral that is accompanied with oxides and iron carbonates. The contacts of aplite-pegmatite dikes with granitoide rocks mostly are not prolific. For recognizing Scheelite, some samples of rocks studied by ultraviolet and few Scheelite is recognized in the samples. Some alteration zone observed in this area but they are not accompany with main mineralization. Although

  6. Multiphase groundwater flow near cooling plutons

    USGS Publications Warehouse

    Hayba, D.O.; Ingebritsen, S.E.

    1997-01-01

    We investigate groundwater flow near cooling plutons with a computer program that can model multiphase flow, temperatures up to 1200??C, thermal pressurization, and temperature-dependent rock properties. A series of experiments examines the effects of host-rock permeability, size and depth of pluton emplacement, single versus multiple intrusions, the influence of a caprock, and the impact of topographically driven groundwater flow. We also reproduce and evaluate some of the pioneering numerical experiments on flow around plutons. Host-rock permeability is the principal factor influencing fluid circulation and heat transfer in hydrothermal systems. The hottest and most steam-rich systems develop where permeability is of the order of 10-15 m2. Temperatures and life spans of systems decrease with increasing permeability. Conduction-dominated systems, in which permeabilities are ???10-16m2, persist longer but exhibit relatively modest increases in near-surface temperatures relative to ambient conditions. Pluton size, emplacement depth, and initial thermal conditions have less influence on hydrothermal circulation patterns but affect the extent of boiling and duration of hydrothermal systems. Topographically driven groundwater flow can significantly alter hydrothermal circulation; however, a low-permeability caprock effectively decouples the topographically and density-driven systems and stabilizes the mixing interface between them thereby defining a likely ore-forming environment.

  7. Petrography and geochemistry of the Arroyo de la Virgen and Isla Mala plutons, southern Uruguay: Early proterozoic tectonic implications

    NASA Astrophysics Data System (ADS)

    Preciozzi, F.; Bourne, J. H.

    1992-10-01

    The Arroyo de la Virgen pluton (AVP) and the Isla Mala pluton (IMP) are relatively small zoned intrusions of Early Proterozoic age. Radiometric age determinations suggest that the IMP is a composite pluton. The composition of the AVP ranges from granodiorite to leucogranite, whereas that of the IMP ranges from hornblendite to leucogranite. Both intrusions feature hornblende (with relict clinopyroxene cores) and biotite as mafic minerals. Muscovite and garnet are present in the most evolved members of each suite. Development of secondary chlorite, epidote, and sericite is common. Quartz typically has undulose extinction. The plutons are massive except near the margins of the intrusion. Both intrusions feature a calc-alkaline chemistry, have peraluminous indices of approximately 1.0, and were emplaced at relatively high levels in the crust. Application of several tectonic discriminant diagrams suggests that the IMP formed in an active continental-margin type of tectonic environment, whereas the AVP is a subalkaline, post-orogenic pluton. The ages of the IMP leucogranite and the AVP are similar (2290 and 2225 Ma, respectively). The age of the IMP leucogranite represents the minimum reliable age of the principal metamorphic event in southern Uruguay. A number of small dikes were emplaced into both intrusions approximately 300 million years later and represent a distinct phase of intrusive activity in the region.

  8. Geochemistry of Mesozoic plutons, southern Death Valley region, California: Insights into the origin of Cordilleran interior magmatism

    USGS Publications Warehouse

    Ramo, O.T.; Calzia, J.P.; Kosunen, P.J.

    2002-01-01

    Mesozoic granitoid plutons in the southern Death Valley region of southeastern California reveal substantial compositional and isotopic diversity for Mesozoic magmatism in the southwestern US Cordillera. Jurassic plutons of the region are mainly calc-alkaline mafic granodiorites with ??Ndi of -5 to -16, 87Sr/86Sri of 0.707-0.726, and 206Pb/204Pbi of 17.5-20.0. Cretaceous granitoids of the region are mainly monzogranites with ??Ndi of -6 to -19, 87Sr/86Sri of 0.707-0.723, and 206Pb/204Pbi of 17.4-18.6. The granitoids were generated by mixing of mantle-derived mafic melts and pre-existing crust - some of the Cretaceous plutons represent melting of Paleoproterozoic crust that, in the southern Death Valley region, is exceptionally heterogeneous. A Cretaceous gabbro on the southern flank of the region has an unuasually juvenile composition (??Ndi -3.2, 87Sr/86Sri 0.7060). Geographic position of the Mesozoic plutons and comparison with Cordillera plutonism in the Mojave Desert show that the Precambrian lithosphere (craton margin) in the eastern Mojave Desert region may consists of two crustal blocks separated by a more juvenile terrane.

  9. Petrology and radiogeology of the Stripa pluton

    SciTech Connect

    Wollenberg, Harold; Flexser, Steve; Andersson, Lennart

    1980-12-01

    To better define the character of the rock encompassing the thermomechanical and hydrological experiments at the Stripa mine in central Sweden, and to help determine the size of the Stripa pluton, detailed studies were conducted of the petrology and radiogeology of the quartz monzonite and adjacent rocks. Petrologic studies emphasized optical petrography, with supplementary X-ray diffraction, X-ray fluorescence and microprobe analyses. Radiogeologic investigations were based primarily on surface and underground gamma-ray spectrometric measurements of uranium, thorium and potassium, supplemented by laboratory gamma spectrometric analyses and fission-track radiographic determinations of the locations and abundance of uranium in the rock matrix. Both the quartz monzonite and the metavolcanic leptite which it intruded are strongly fractured. Two stages of fracture filling are evident; an earlier stage encompassing quartz, sericite, feldspar, epidote, and chlorite, and a later stage dominated by carbonate minerals. The Stripa quartz monzonite is chemically and mineralogically distinct from other plutons in the region. Muscovite is the predominant mica in the quartz monzonite; biotite has been altered to chlorite, hornblende is absent, and accessory minerals are scarce. In contrast, in other plutons in the Stripa region biotite and hornblende are prominent mafic minerals and accessory minerals are abundant. The Stripa quartz monzonite is also considerably more radioactive than the leptite and other plutons in the region. Uranium and thorium abundances are both- 30 ppm, considerably higher than in "normal" granitic rocks where the thorium-to-uranium ratio generally exceeds 2. Potassium-argon dating of muscovite from the Stripa quartz monzonite indicates that this rock may be older, at 1691 million years than granitic rock of the neighboring Gusselby and Kloten massifs, whose ages, based on K-Ar dating of biotite, are respectively 1604 and 1640 m.y. Heat flow and heat

  10. Prevalence and associated risk factors of Kola nut chewing among secondary school students in Osogbo, Nigeria.

    PubMed

    Erinfolami, Adebayo; Eegunranti, Adekunle; Ogunsemi, Olawale; Oguntuase, Akin; Akinbode, Abiola; Erinfolami, Gloria

    2011-02-22

    The objectives of this study were to determine the prevalence and pattern of Kola nut use among secondary school students in Osogbo, Osun State, Nigeria. The study also aimed to determine the association of socio-demographic variables (of the students and their parents) with kola nut chewing. A questionnaire consisting of socio-demographic variables, the stimulant use section of the WHO Students Drug Use Questionnaire was administered on three hundred and eighty-five (385) randomly selected students of the two Local Government Areas of Osogbo. The prevalence rate of kola nut use was calculated and some socio demographic variables were determined. The 30-day prevalence rate of kola nut use was 11.2%. The one-year prevalence of kola nut use was 29.1 percent and the lifetime rate was 74.8 percent. Majority of users started at age 14 years or below. Kola nut use was associated with lower age group, poor school attendance, polygamous background, low education of mother, high education of father and the description of mother as being too permissive. The findings suggest the need to increase the awareness of the dangers of kolanut use among adolescents. Control program are urgently needed to prevent student wastage.

  11. MEASUREMENTS OF THE CONFINEMENT LEAKTIGHTNESS AT THE KOLA NUCLEAR POWER STATION (UNIT 2) IN RUSSIA

    SciTech Connect

    GREENE,G.A.; GUPPY,J.G.

    1998-08-01

    This is the final report on the INSP project entitled, ``Kola Confinement Leaktightness'' conducted by BNL under the authorization of Project Work Plan WBS 1.2.2.1. This project was initiated in February 1993 to assist the Russians to reduce risks associated with the continued operation of older Soviet-designed nuclear power plants, specifically the Kola VVER-440/230 Units 1 and 2, through upgrades in the confinement performance to reduce the uncontrolled leakage rate. The major technical objective of this-project was to improve the leaktightness of the Kola NPP VVER confinement boundaries, through the application of a variety of sealants to penetrations, doors and hatches, seams and surfaces, to the extent that current technology permitted. A related objective was the transfer, through training of Russian staff, of the materials application procedures to the staff of the Kola NPP. This project was part of an overall approach to minimizing uncontrolled releases from the Kola NPP VVER440/230s in the event of a serious accident, and to thereby significantly mitigate the consequences of such an accident. The US provided materials, application technology, and applications equipment for application of sealant materials, surface coatings, potting materials and gaskets, to improve the confinement leaktightness of the Kola VVER-440/23Os. The US provided for training of Russian personnel in the applications technology.

  12. Prevalence and associated risk factors of Kola nut chewing among secondary school students in Osogbo, Nigeria

    PubMed Central

    Erinfolami, Adebayo; Eegunranti, Adekunle; Ogunsemi, Olawale; Oguntuase, Akin; Akinbode, Abiola; Erinfolami, Gloria

    2011-01-01

    The objectives of this study were to determine the prevalence and pattern of Kola nut use among secondary school students in Osogbo, Osun State, Nigeria. The study also aimed to determine the association of socio-demographic variables (of the students and their parents) with kola nut chewing. A questionnaire consisting of socio-demographic variables, the stimulant use section of the WHO Students Drug Use Questionnaire was administered on three hundred and eighty-five (385) randomly selected students of the two Local Government Areas of Osogbo. The prevalence rate of kola nut use was calculated and some socio demographic variables were determined. The 30-day prevalence rate of kola nut use was 11.2%. The one-year prevalence of kola nut use was 29.1 percent and the lifetime rate was 74.8 percent. Majority of users started at age 14 years or below. Kola nut use was associated with lower age group, poor school attendance, polygamous background, low education of mother, high education of father and the description of mother as being too permissive. The findings suggest the need to increase the awareness of the dangers of kolanut use among adolescents. Control program are urgently needed to prevent student wastage. PMID:25478098

  13. Zircon-pyrochlore ores of Proterozoic Gremyakha-Vyrmes polyphase massif, Kola Peninsula: source and evolution

    NASA Astrophysics Data System (ADS)

    Sorokhtina, Natalia; Belyatsky, Boris; Antonov, Anton; Kononkova, Natalia; Lepekhina, Elena; Kogarko, Lia

    2017-04-01

    The alkaline-ultrabasic Gremyakha-Vyrmes massif occurs within the Central Kola terrane in the northern part of the Fennoscandian Shield and consists of diverse rock complexes: basic-ultrabasic rocks, foidolites, alkaline metasomatic rocks and carbonatites, alkaline granites and granosyenites. Nb-Zr ore deposit is confined to alkaline metasomatic rocks developed over foidolites. The metasomatites are represented by albitites and aegirinites occur as submeridionally orientated zones extending up to 6-8 km and several hundred meters thickness. They are mainly composed of albite and aegirine, but amphibole, annite, microcline, fluorapatite, titanite, ilmenite, pyrochlore group minerals, zircon are present [Sorokhtina et al., 2016]. Carbonatites are developed sporadically and accessory zircon but not the pyrochlore is observed only in contact zones with albitites and aegerinites. In metasomatites, zircon and pyrochlore are main rare metal minerals, which are formed at the latest stages of crystallization. Ca-dominant fluorcalcio- and hydroxycalciopyrochlores are the most abundant, whereas U-dominant pyrochlore, oxyuranobetafite, zero-valent-dominant (Ba, Sr-dominant) pyrochlore, hydro- or kenopyrochlore are rare. The pyrochlore-group minerals form heterogeneous metacrystals containing inclusions of host rock minerals, calcite, ilmenite, zircon, sulfides, and graphite. While pyrochlore is replaced by Si-rich "pyrochlore" (SiO2 is up to 18 wt.%.), cation-deficient hydrated pyrochlore, Fe-Si-Nb, U-Si-Nb, and Al-Si-Nb phases along fracture zones and margins. The early generation zircon is represented by large heterogeneous metacrystals filled with inclusions of various host rock minerals, calcite, ilmenite, thorite, thorianite and sulfides, while the late zircons are empty of inclusions. Zircons are nearly stoichiometric in composition; but intermediate zones are enriched in Pb, Y and Th, and overgrowths are enriched Hf only. According to CL and ion-microprobe analysis

  14. Model of formation of the Khibiny-Lovozero ore-bearing volcanic-plutonic complex

    NASA Astrophysics Data System (ADS)

    Arzamastsev, A. A.; Arzamastseva, L. V.; Zhirova, A. M.; Glaznev, V. N.

    2013-09-01

    The paper presents the results of a study of the large Paleozoic ore-magmatic system in the northeastern Fennoscandian Shield comprising the Khibiny and Lovozero plutons, the Kurga intrusion, volcanic rocks, and numerous alkaline dike swarms. As follows from the results of deep drilling and 3D geophysical simulation, large bodies of rocks pertaining to the ultramafic alkaline complex occur at the lower level of the ore-magmatic system. Peridotite, pyroxenite, melilitolite, melteigite, and ijolite occupy more than 50 vol % of the volcanic-plutonic complex within the upper 15 km accessible to gravity exploration. The proposed model represents the ore-magmatic system as a conjugate network of mantle magmatic sources localized at different depth levels and periodically supplying the melts belonging to the two autonomous groups: (1) ultramafic alkaline rocks with carbonatites and (2) alkali syenites-peralkaline syenites, which were formed synchronously having a common system of outlet conduits. With allowance for the available isotopic datings and new geochronological evidence, the duration of complex formation beginning from supply of the first batches of melt into calderas and up to postmagmatic events, expressed in formation of late pegmatoids, was no less than 25 Ma.

  15. Lead isotopic evidence for interaction between plume and lower crust during emplacement of peralkaline Lovozero rocks and related rare-metal deposits, East Fennoscandia, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Zartman, R. E.; Kogarko, L. N.

    2017-05-01

    The Lovozero alkaline massif—an agpaitic nepheline syenite layered intrusion—is located in the central part of the Kola Peninsula, Russia, and belongs to the Kola ultramafic alkaline and carbonatitic province (KACP) of Devonian age. Associated loparite and eudialyte deposits, which contain immense resources of REE, Nb, Ta, and Zr, constitute a world class mineral district. Previous Sr, Nd, and Hf isotope investigations demonstrated that these rocks and mineral deposits were derived from a depleted mantle source. However, because the Sr, Nd, and Hf abundances in the Kola alkaline rocks are significantly elevated, their isotopic compositions were relatively insensitive to contamination by the underlying crustal rocks through which the intruding magmas passed. Pb occurring in relatively lower abundance in the KACP rocks, by contrast, would have been a more sensitive indicator of an acquired crustal component. Here, we investigate the lead isotopic signature of representative types of Lovozero rocks in order to further characterize their sources. The measured Pb isotopic composition was corrected using the determined U and Th concentrations to the age of the crystallization of the intrusion (376 ± 28 Ma, based on a 206Pb/204Pb versus 238U/204Pb isochron and 373 ± 9 Ma, from a 208Pb/204Pb versus 232Th/204Pb isochron). Unlike the previously investigated Sr, Nd, and Hf isotopes, the lead isotopic composition plot was well outside the FOZO field. The 206Pb/204Pb values fall within the depleted MORB field, with some rocks having lower 207Pb/204Pb but higher 208Pb/204Pb values. Together with other related carbonatites having both lower and higher 206Pb/204Pb values, the combined KACP rocks form an extended linear array defining either a 2.5-Ga secondary isochron or a mixing line. The projection of this isotopic array toward the very unradiogenic composition of underlying 2.4-2.5-Ga basaltic rocks of the Matachewan superplume and associated Archean granulite facies

  16. Thermal maturation of incrementally assembled plutons

    NASA Astrophysics Data System (ADS)

    Davis, J.; Coleman, D. S.; Heizler, M. T.

    2009-12-01

    The Cretaceous zoned intrusive suites of the Sierra Nevada batholith (SNB) were each assembled over 8-11 million years through incremental amalgamation of sheeted intrusions. Emplacement as small sheet-like increments inhibits development of a voluminous zone of melt bearing rock; instead the active magma body represents only a small portion of the total volume intruded. Plutons formed incrementally will have a protracted thermal history (T-t) that can be elucidated using thermochronologic techniques yielding insights into the thermal evolution of the lithosphere at magma chamber-pluton scales. Thermal histories are derived for plutons from the dike-like John Muir Intrusive Suite (JMIS) and the laccolithic Mount Whitney Intrusive Suite (MWIS), both located in the eastern-central SNB, by correlating estimated zircon saturation and argon closure temperatures with U-Pb zircon and titanite, 40Ar/39Ar amphibole, biotite, and K-feldspar ages. Close agreement among zircon and hornblende ages indicate rapid cooling following intrusion. However, hornblende and biotite ages are separated by 6-9 million years indicating slow protracted cooling. We interpret these data to reflect the thermal maturation of an incrementally assembled magma system in which temperatures cycled between ~500-300°C for millions of years. Hornblende ages were not reset by younger intrusions, therefore maximum reheating temperatures did not exceed ~500°C for geologically significant durations. T-t cooling curves from the intrusive suites are used to calibrate finite difference numerical simulations of pluton assembly. Intrusion geometries are modeled (HEAT 3D, Wohletz, 2007) by stacking horizontal increments from the top-down and bottom-up and vertical increments are emplaced syntaxially and antitaxially and are designed to generate plutons of the approximate dimensions, depth of emplacement, and age range of the Sierran suites. Numerical simulations yield the following general observations: 1) an

  17. Petrogenesis of Post-collisional high Ba-Sr granitoids: the Solarya Pluton, NW Turkey

    NASA Astrophysics Data System (ADS)

    Unal, Alp; Kamaci, Omer; Altunkaynak, Safak

    2015-04-01

    In NW Turkey, the Late Oligocene-Early Miocene phase of post-collisional magmatism is characterized by widespread granitic pluton emplacements straddling the continental collision zone marked by the Izmir-Ankara suture zone (IASZ). This granitic magmatism produced both low Ba-Sr- and high Ba-Sr granitoids with distinct geochemical properties. One of the major plutons emplaced to the north of İzmir-Ankara suture zone, the Solarya pluton is representative of high Ba-Sr granitoids. We present here whole-rock chemical and Sr-Nd-Pb-O isotopic compositions, as well as 40Ar/39Ar ages of the Solarya pluton to evaluate the timing, nature and genesis of potassic, high Ba-Sr granites. The Solarya pluton consists of three coeval granitic members (K-Feldspar megacrystalline granodiorite, fine grained granodiorite and haplogranite) and associated mafic magmatic enclaves/dykes of gabbroic diorite to dioritic in composition. K-feldspar megacrystalline granodiorite, fine grained granodiorite and haplogranite are high K calc-alkaline in character whereas low silica mafic magmatic enclaves and dykes are mildly alkaline and display shoshonitic affinity. Both granitic members and mafic enclaves/dykes are characterized by high Ba (710-2489 ppm), Sr (305-708ppm), low Y and HREE contents and lack of significant negative Eu anomalies. They are metaluminous and display enrichment in LILE and depletion in P, Ta, Nb and Ti. Sr-Nd-Pb and O isotope compositions of mafic enclaves and dykes are similar to their host granitoids. They have initial 87Sr/86Sr values of 0.70702- 0.70805 and 143Nd/144Nd values of 0.51235-0.51250 and their ɛNd values range between -4,9 and -2,05. 206Pb/204Pb and 207Pb/204 Pb isotopic values vary from 18,75 to 18,88 and 15,68 to 15,73, respectivelly. Whole rock and quartz 18O isotopic ratios range between 8 and 10,6. All these isotopic characteristics and major-trace element compositions of Solarya pluton and associated mafic enclaves/dykes suggest a subcontinental

  18. Gotu Kola (Centella asiatica): Nutritional Properties and Plausible Health Benefits.

    PubMed

    Chandrika, Udumalagala Gamage; Prasad Kumarab, Peramune A A S

    2015-01-01

    Centella asiatica L. (Gotu Kola) is a nutritionally important plant and a valued traditional medicine in South East Asia. In this review, the chemical composition, nutritional values, and health benefits of C. asiatica have been discussed in detail to emphasize its usage as traditional food and medicine. C. asiatica is one of the most commonly used green leafy vegetables (GLVs) in some countries including Sri Lanka due to its high amounts of medicinally important triterpenoids and beneficial carotenoids. It is consumed in the form of GLVs and in the preparation of juice, drink, and other food products. It is also known to contain vitamins B and C, proteins, important minerals, and some other phytonutrients such as flavonoids, volatile oils, tannins, and polyphenol. In vitro and in vivo studies have shown important health benefits like antidiabetic, wound-healing, antimicrobial, memory-enhancing, antioxidant, and neuroprotecting activities. However, detailed scientific approaches on clinical trials regarding health benefits and nutritional values of C. asiatica are limited, hindering the perception of its benefits, mechanisms, and toxicity in order to develop new drug prototypes. In vitro studies have shown that the method of processing C. asiatica has an impact on its nutritional values and health-related beneficial compounds. The composition of its compounds is influenced by different biotic and abiotic factors which need to be studied in detail to provide information to the public in order to maximize the usage of this valuable plant.

  19. U-Pb ages and Hf isotope compositions of zircons in plutonic rocks from the central Famatinian arc, Argentina

    NASA Astrophysics Data System (ADS)

    Otamendi, Juan E.; Ducea, Mihai N.; Cristofolini, Eber A.; Tibaldi, Alina M.; Camilletti, Giuliano C.; Bergantz, George W.

    2017-07-01

    The Famatinian arc formed around the South Iapetus rim during the Ordovician, when oceanic lithosphere subducted beneath the West Gondwana margin. We present combined in situ U-Th-Pb and Lu-Hf isotope analyses for zircon to gain insights into the origin and evolution of Famatinian magmatism. Zircon crystals sampled from four intermediate and silicic plutonic rocks confirm previous observations showing that voluminous magmatism took place during a relatively short pulse between the Early and Middle Ordovician (472-465 Ma). The entire zircon population for the four plutonic rocks yields coherent εHf negative values and spreads over several ranges of initial εHf(t) units (-0.3 to -8.0). The range of εHf units in detrital zircons of Famatinian metasedimentary rocks reflects a prolonged history of the cratonic sources during the Proterozoic to the earliest Phanerozoic. Typical tonalites and granodiorites that contain zircons with evolved Hf isotopic compositions formed upon incorporating (meta)sedimentary materials into calc-alkaline metaluminous magmas. The evolved Hf isotope ratios of zircons in the subduction related plutonic rocks strongly reflect the Hf isotopic character of the metasedimentary contaminant, even though the linked differentiation and growth of the Famatinian arc crust was driven by ascending and evolving mantle magmas. Geochronology and Hf isotope systematics in plutonic zircons allow us understanding the petrogenesis of igneous series and the provenance of magma sources. However, these data could be inadequate for computing model ages and supporting models of crustal evolution.

  20. Proterozoic subduction and terrane amalgamation in the southwestern Grenville province, Canada: Evidence from ultrapotassic to shoshonitic plutonism

    NASA Astrophysics Data System (ADS)

    Corriveau, Louise

    1990-07-01

    A late Grenvillian (1089-1076 Ma) subduction regime followed by terrane amalgamation is postulated as the paleoenvironment of a 400-km-long belt of potassium-rich alkaline and shoshonitic plutons in the Central metasedimentary belt of the southwestern Grenville province, Canada. Emplacement of the plutons postdates the regional metamorphism in the country rock, but predates major shear zones that form a structural boundary for the plutonic belt. The extent, timing, and magmatic affinities of the suite delineate the Gatineau domain within the current Mont-Laurier terrane of Quebec and are compelling evidence for the allochthonous nature of the Elzevir terrane and its extension eastward to Rideau Lake in Ontario and northward into the Gatineau domain. The belt trends northeast, the emplacement ages are younger to the southeast, and the magmatic affinities are those of island-arc ultrapotassic to shoshonitic rocks. This is interpreted to reflect the existence of a southeast-dipping, northeast-trending subduction zone beneath the combined Elzevir-Gatineau terrane between 1089 and 1076 Ma. Subsequent to subduction, amalgamation of the Elzevir terrane to the other terranes formed the Central metasedimentary belt, which then accreted and collided with the allochthonous polycyclic belt. These events provide evidence that the Ottawan orogeny commenced at ca. 1090 Ma in the Central metasedimentary belt. A modern analogue of this plutonism and its tectonic setting may have been the magmatism and arc-continent collision and subduction setting of the Sunda are, Indonesia.

  1. Fluorine in Olivines from Plutonic, Extrusive, and Hypabyssal Suites

    NASA Astrophysics Data System (ADS)

    Guggino, S. N.; Hervig, R. L.; Bell, D. R.

    2007-12-01

    Fluorine contents in a wide range of naturally-occurring olivine grains were determined by secondary ion mass spectrometry (SIMS) using a Cs+ primary beam, detection of negative secondary ions and an auxiliary electron gun for charge neutralization. A range of minerals and glasses containing 3 to 1300 ppm F were used to calibrate the secondary ion signal. Matrix effects appear to be small, and because fluorine has a high electron affinity, sensitivity is high (sub-ppm). Olivines from the study by Simkin and Smith (J. Geol., 1970) were analyzed for their F contents and span a range of suites that include upper mantle xenoliths and kimberlites, plutonic intrusives, ophiolites, shallow hypabyssal picrites and teschenites, and extrusive alkaline and tholeiitic basalts. Overall, the olivines in this study show a range of F concentrations from 0.5 to 32 ppm. Olivines from high- pressure environments show the highest individual and average F values, however large variations are also observed in this suite. Mantle xenoliths from this sample collection show a maximum and average F value of 14 and 4.1 ppm, respectively, and one olivine from kimberlite contains 32 ppm F. Earlier analyses from our laboratory (Hervig and Bell, 2005 Fall AGU) show a larger range in F from mantle-derived olivines. Plutonic intrusives and ophiolites, including layered intrusives and cumulates, show a range of F contents from 0.5 to 15 ppm, with an average value of 4 ppm. Olivines from the Kiglapait layered intrusion, Labrador show F content increasing with degree of fractional crystallization until the P2O5 content of the rock begins to increase. At this point, F in olivine decreases, presumably indicating partitioning of F into apatite. In the Hawaiian suites studied, F in olivine was high (8-12 ppm) in evolved andesites and lower (1-8 ppm) in more primitive basalts. Hypabyssal suites include a peridotite dike from Skye, (F < 1 ppm), a chilled olivine dolerite from Bornaskitaig (F = 2 ppm), a

  2. Digital relief 3D model of the Khibiny massive (Kola peninsula)

    NASA Astrophysics Data System (ADS)

    Chesalova, Elena; Asavin, Alex

    2015-04-01

    On the basis of maps of 1: 50,000 and 1: 200,000 3D model Khibiny massif developed. We used software ARC / INFO v10.2 ESRI. This project will be organised to build background for gas pollution monitoring network. We planned to use the model to estimate local heterogeneities in the composition of the atmosphere at the emanation of greenhouse gases in the area, the construction of models of vertical distribution of the content of trace gases in the rock mass. In addition to the project GIS digital elevation model contains layers of geological and tectonic map that allows us to estimate the area of the output of certain petrographic rock groups characterized by different ratios of emitted hydrocarbons (CH4/ H2). The model allows to construct a classification of fault in the array. At first glance, there are two groups of faults - the ancient associated with the formation of the intrusive phases sequence, and the young - due to recent tectonic shifts. Ancient faults form a common semicircular structure of the pluton cause overall asymmetry Khibin heights with the transition to the border area between the Khibiny and Lovoozero. Modern tectonics mainly represented by radial and chord faults which are formed narrow mountain valleys and troughs. It remains an open question as to which system fault (old or young) is more productive to gas emanations? On the one hand the system characterized by a large old depth, on the other hand a young more active faults. Address these issues require further detailed observations. The essential question is to assess the possibility of maintaining a constant concentration gradient of these impurities in the atmosphere due to gas emanations of fracture zones and areas enriched occluded gases. In the simulation of these processes can be used initially set parameters: 1 the flow rate of the gas impurities 2 the value of wind flows in closed and open valley 3 Assessment of thermal diffusion coefficients determined by the temperature gradient

  3. Petrogenesis of Mesoproterozoic granitic plutons, eastern Llano Uplift, central Texas, USA

    NASA Astrophysics Data System (ADS)

    Smith, R. K.; Gray, Walt; Gibbs, Tyson; Gallegos, M. A.

    2010-08-01

    The Llano Uplift of central Texas is a gentle structural dome exposing ˜ 1370 to 1230 Ma metaigneous and metasedimentary rocks of Grenville affinity along the southern margin of Laurentia. The metamorphic rocks were subsequently intruded by ˜ 1119 to 1070 Ma late syn- to post-tectonic granites collectively known as the Town Mountain Granite (TMG). The eastern most of the TMG, the Marble Falls (MF), Kingsland (KL), and Lone Grove (LG) plutons, are metaluminous to marginally peraluminous, high-K, calc-alkaline, ferroan, biotite-calcic amphibole granites [Fe/(Fe + Mg) = 0.71-0.92 and 0.78-0.91 for biotite and calcic amphibole, respectively] displaying distinct variation trends with increasing silica content. They are chemically and texturally zoned and have mineralogical and chemical characteristics similar to A-type granites; i.e., 1) Fe-rich biotites, calcic amphiboles, accessory fluorite, and sporadic rapakivi texture, 2) high K 2O (> 4 wt.%), 3) low Al 2O 3 (< 16 wt.%) and CaO (< 3 wt.%), 4) high Fe/(Fe + Mg), 5) enrichments in Zr, Nb, REE, Ga/Al, and 6) depleted Eu. However, in contrast to typical A-type granites (having low Sr and Ba) the MF, KL,and LG plutons are enriched in Sr and Ba; i.e., up to 229 ppm and 1090 ppm, respectively. On granite discrimination diagrams [(K 2O + Na 2O)/CaO vs. Zr + Nb + Ce + Y (ppm) and Zr (ppm) vs. Ga/Al*10,000] the KL and MF plutons plot within the A-type field, whereas the LG pluton compositions are divided between A-type and fractionated granite fields (I-, S- and M-types). On tectonic discrimination diagrams (Y vs. Nb ) the MF and KL granites plot in the "within-plate" granite field, but the LG pluton plots across several fields including "within-plate" and "volcanic arc plus syn-collisional" fields. Consequently the tectonic classification on a geochemical basis for the LG pluton is unclear. Based on thermal metamorphic mineral assemblages, normative Q-Ab-Or plots, and Q-Ab-Or-H 2O experimental data (Johannes and Holtz

  4. Petrology of Aztec Wash pluton, Eldorado Mountains, southern Nevada

    SciTech Connect

    Falkner, C.M.; Miller, C.F. ); Wooden, J.L. )

    1993-04-01

    Aztec Wash pluton, a 50 km[sup 2] intrusive complex in the northern Eldorado Mountains, was emplaced ca. 16 Ma (Faulds et al., 1990) during extension within the Colorado River Corridor. The pluton displays extreme compositional variability, ranging from olivine gabbro (ca. 50 wt% SiO[sub 2]) to highly evolved aplite (76% SiO[sub 2]). Most of the intrusion is medium grained, homogeneous granite (ca. 72% SiO[sub 2]), but 1/3 is highly heterogeneous and dominated by mafic to intermediate rocks; a 6 [times] 3km, N-S mafic zone almost bisects the pluton. Well-displayed magma mingling and late mafic and felsic dikes verify the coexistence of mafic and felsic melts. Hornblende barometry indicates that the entire exposed portion of Aztec Wash pluton was emplaced at very shallow depth (pluton has undergone little tilting. Mafic dikes that preceded emplacement of the pluton are variably dipping and in some cases sub horizontal, possibly suggesting a more complex pre-pluton deformational history. The authors propose the following emplacement history for Aztec Wash pluton: felsic magma intruded shallow levels of crust; the base of the magma chamber was intruded by basalt; after the upper portion of the initial magma was largely crystallized, basalt ascended into, perhaps remobilized, and mingled with felsic magma; this ascent may have been facilitated by E-W extension of the crystallizing pluton; more discrete syn- to post-pluton, mafic to felsic dikes mark additional intrusive pulses triggered by basalt intrusion and extensional fracturing. Field relations suggest that the mingling led to mixing in both the main units and the late dikes, but geochemical data indicate that mixing, if it occurred, was not a simple 2-end member process.

  5. Genesis of peat-bog soils in the northern taiga spruce forests of the Kola Peninsula

    SciTech Connect

    Nikonov, V.V.

    1981-01-01

    The characteristics of soil formation processes in the Peat-Bog soils of waterlogged spruce phytocenoses on the Kola Peninsula are investigated. It is found that the ash composition of the peat layer is determined primarily by the composition of the buried plant residues. The effect of the chemical composition of water feeding the peat bogs is determined. (Refs. 7).

  6. Thermal Modeling of Large Composite Plutons

    NASA Astrophysics Data System (ADS)

    Bartley, J. M.; Wohletz, K.; Coleman, D. S.; Glazner, A. F.

    2004-12-01

    Field and geochronologic evidence indicate that large plutons commonly amalgamate from many small intrusive increments [e.g., Glazner et al., 2004, GSA Today; Coleman et al., 2004, Geology]. To investigate the thermal consequences of this process, we model the growth of composite intrusions using the program HEAT. HEAT uses a finite-difference scheme to track transport and storage of heat, and resulting temperature variations, in a 2-D or 3-D intrusion and its wall rocks. Heat advected by wall-rock displacement is conserved kinematically by distributing the heat of intruded rock into adjacent mesh locations following a system determined by the aspect ratio of each intrusive increment. Modeling to date focuses on laccolithic plutons formed by stacking of sills. In a typical model, an 1100°C sill of intermediate-composition magma with a solidus of 750°C, 100-m-thick and 10-km-wide, is emplaced every 10 ka (10 mm/yr vertical inflation rate) for 600 ka to form a tabular pluton 6 km thick. Model runs to date have yielded at least three intriguing results. 1) Stacking of sills from bottom to top produces higher sustained temperatures than stacking from top to bottom. Over the first half of a 600 ka emplacement time, a bottom-up intrusion completely solidifies between increments but, during the latter half, a partial-melt zone becomes a steady-state feature. Dimensions of the partial melt zone vary through a 10 ka intrusive cycle, but the thickness reaches nearly 2 km by the time the last sill is emplaced. An otherwise identical top-down intrusion solidifies completely after each intrusive increment until the last 35 ka, when a small zone of partial melt persists between increments. The large composite complexes of the Sierra Nevada such as the Tuolumne and Whitney intrusive suites appear to have grown from their tops down, but bottom-up plutons also have been widely reported. 2) The partial-melt zone in a bottom-up intrusion mainly forms below each new intrusive

  7. Cooling history of nested plutons from the Variscan Tichka plutonic complex (Morocco)

    NASA Astrophysics Data System (ADS)

    Lécuyer, Christophe; Gasquet, Dominique; Allemand, Pascal; Martineau, François; Martinez, Isabelle

    2017-03-01

    Four imbricated mafic to felsic plutons of Variscan age from Morocco have been investigated for their cooling history and geochemical interactions with surrounding continental rocks. Oxygen isotope compositions of whole rocks and minerals have been used to model the cooling rates of these kilometer-sized intrusions. By combining both the knowledge of oxygen-self diffusion data of rock-forming minerals and the determination by IR-spectroscopy of the water content of quartz, the cooling times are estimated ranging from 105 to 5 × 105 years in agreement with the shallow emplacement (4-6 km depth) of these intrusions into the continental crust. Such fast cooling rates could explain why after assimilation of the various country rocks, heterogeneities of both neodymium and strontium isotope ratios were still preserved. A progressive δ18O increase from the mafic to felsic terms of the plutonic suite, which does not excess 1 to 1.5‰, could be explained by the assimilation of metamorphosed pelitic and volcanic rocks that constitute the basement of the Tichka plutonic complex.

  8. Intrusive rocks and plutonic belts of southeastern Alaska, U.S.A.

    USGS Publications Warehouse

    Brew, David A.; Morrell, Robert P.; Roddick, J.A.

    1983-01-01

    About 30 percent of the 175,000-km2 area of southeastern Alaska is underlain by intrusive igneous rocks. Compilation of available information on the distribution, composition, and ages of these rocks indicates the presence of six major and six minor plutonic belts. From west to east, the major belts are: the Fairweather-Baranof belt of early to mid-Tertiary granodiorite; the Muir-Chichagof belt of mid-Cretaceous tonalite and granodiorite; the Admiralty-Revillagigedo belt of porphyritic granodiorite, quartz diorite, and diorite of probable Cretaceous age; the Klukwan-Duke belt of concentrically zoned or Alaskan-type ultramafic-mafic plutons of mid-Cretaceous age within the Admiralty-Revillagigedo belt; the Coast Plutonic Complex sill belt of tonalite of unknown, but perhaps mid-Cretaceous, age; and the Coast Plutonic Complex belt I of early to mid-Tertiary granodiorite and quartz monzonite. The minor belts are distributed as follows: the Glacier Bay belt of Cretaceous and(or) Tertiary granodiorite, tonalite, and quartz diorite lies within the Fair-weather-Baranof belt; layered gabbro complexes of inferred mid-Tertiary age lie within and are probably related to the Fairweather-Baranof belt; the Chilkat-Chichagof belt of Jurassic granodiorite and tonalite lies within the Muir-Chichagof belt; the Sitkoh Bay alkaline, the Kendrick Bay pyroxenite to quartz monzonite, and the Annette and Cape Fox trondhjemite plutons, all interpreted to be of Ordovician(?) age, together form the crude southern southeastern Alaska belt within the Muir-Chichagof belt; the Kuiu-Etolin mid-Tertiary belt of volcanic and plutonic rocks extends from the Muir-Chichagof belt eastward into the Admiralty-Revillagigedo belt; and the Behm Canal belt of mid- to late Tertiary granite lies within and next to Coast Plutonic Complex belt II. In addition, scattered mafic-ultramafic bodies occur within the Fairweather-Baranof, Muir-Chichagof, and Coast Plutonic Complex belts I and II. Palinspastic

  9. Relationship of voluminous ignimbrites to continental arc plutons: Petrology of Jurassic ignimbrites and contemporaneous plutons in southern California

    USGS Publications Warehouse

    Fohey-Breting, N. K.; Barth, A.P.; Wooden, J.L.; Mazdab, F.K.; Carter, C.A.; Schermer, E.R.

    2010-01-01

    Volcanism was broadly associated in both space and time with Mesozoic plutonism in the Cordillera continental margin arc, but the precise petrogenetic relationships between volcanic rocks and adjacent zoned plutons are not known. Igneous rocks in a tilted crustal section in California include four laterally extensive Jurassic ash flow tuffs from 550 to >1100 m thick underlain at deeper structural levels by Jurassic plutons. Zircon geochronology confirms previous correlations of individual tuffs, suggesting ignimbrites with eruptive volumes up to 800 km3 were deposited both during the apparent Early Jurassic plutonic lull as well as contemporaneous with solidification of regionally widespread Middle and Late Jurassic plutons. The tuffs are weakly to strongly porphyritic (5 to 55% phenocrysts) monotonous intermediate porphyritic dacite to low-silica rhyolite and show strong bulk rock chemical affinity to contemporaneous plutons. Trace element compositions of zircons from the tuffs and contemporaneous plutonic rocks record large and consistent differences in Hf/Zr and REE over similar ranges in Ti abundances, supporting bulk compositional similarities and illuminating similarities and variations in thermal histories despite the effects of hydrothermal alteration. ?? 2009 Elsevier B.V. All rights reserved.

  10. From steep feeders to tabular plutons - Emplacement controls of syntectonic granitoid plutons in the Damara Belt, Namibia

    NASA Astrophysics Data System (ADS)

    Hall, Duncan; Kisters, Alexander

    2016-01-01

    Granitoid plutons in the deeply eroded south Central Zone of the Damara Belt in Namibia commonly show tabular geometries and pronounced stratigraphic controls on their emplacement. Subhorizontal, sheet-like pluton geometries record emplacement during regional subhorizontal shortening, but the intrusion of spatially and temporally closely-related granitoid plutons at different structural levels and in distinct structural settings suggests independent controls on their levels of emplacement. We describe and evaluate the controls on the loci of the dyke-to-sill transition that initiated the emplacement of three syntectonic (560-530 Ma) plutons in the basement-cover stratigraphy of the Erongo region. Intrusive relationships highlight the significance of (1) rigidity anisotropies associated with competent sedimentary packages or pre-existing subhorizontal granite sheets and (2) rheological anisotropies associated with the presence of thick ductile marble horizons. These mechanical anisotropies may lead to the initial deflection of steep feeder conduits as well as subsequent pluton assembly by the repeated underaccretion of later magma batches. The upward displacement of regional isotherms due to the heat advection associated with granite emplacement is likely to have a profound effect on the mechanical stratification of the upper crust and, consequently, on the level at which granitoid pluton emplacement is initiated. In this way, pluton emplacement at progressively shallower crustal depths may have resulted in the unusually high apparent geothermal gradients recorded in the upper crustal levels of the Damara Belt during its later evolution.

  11. Amino acid composition of two masticatory nuts (Cola acuminata and Garcinia kola) and a snack nut (Anacardium occidentale).

    PubMed

    Adeyeye, E I; Asaolu, S S; Aluko, A O

    2007-06-01

    The amino acid compositions of Cola acuminata, Garcinia kola and Anacardium occidentale were evaluated by ion-exchange chromatography. Glutamic acid was the most concentrated acid in the samples. In all the amino acids determined, A. occidentale had the most concentrated acid on a pairwise basis. The total amino acids were 356.24 mg/g protein, 112.90 mg/g protein and 659.17 mg/g protein for C. acuminata, G. kola and A. occidentale, respectively. The percentage total essential amino acids were 38.39% (C. acuminata), 47.05% (G. kola) and 51.04% (A. occidentale). Also the percentage total acidic amino acids were 38.16% (C. acuminata), 30.61% (G. kola) and 30.35% (A. occidentale). The calculated isoelectric points were 2.0 (C. acuminata), 0.7 (G. kola) and 3.9 (A. occidentale), showing they can all be precipitated at acidic pH. While threonine was the limiting amino acid in A. occidentale, it was valine in both C. acuminata and G. kola. The percentage cystine (Cys) levels in the total sulphur amino acid were 44.27% (C. acuminata), 37.75% (G. kola) and 50.51% (A. occidentale). The aim of this work was to compare the amino acid profile of the samples. It is recommended that C. acuminata and G. kola consumption be avoided by ulcer patients because of their high levels of acidic amino acids. A. occidentale amino acid scores ranged from 42% to 127%, suggesting that it could be used to enhance the protein quality of cereals through food complementation.

  12. The chemical and isotopic differentiation of an epizonal magma body: Organ Needle pluton, New Mexico

    USGS Publications Warehouse

    Verplanck, P.L.; Farmer, G.L.; McCurry, M.; Mertzman, S.A.

    1999-01-01

    Major and trace element, and Nd and Sr isotopic compositions of whole rocks and mineral separates from the Oligocene, alkaline Organ Needle pluton (ONP), southern New Mexico, constrain models for the differentiation of the magma body parental to this compositionally zoned and layered epizonal intrusive body. The data reveal that the pluton is rimmed by lower ??(Nd) (~-5) and higher 87Sr/86Sr (~0.7085) syenitic rocks than those in its interior (??(Nd) ~ 2, 87Sr/86Sr ~0.7060) and that the bulk compositions of the marginal rocks become more felsic with decreasing structural depth. At the deepest exposed levels of the pluton, the ??(Nd)~-5 lithology is a compositionally heterogeneous inequigranular syenite. Modal, compositional and isotopic data from separates of rare earth element (REE)-bearing major and accesory mineral phases (hornblende, titanite, apatite, zircon) demonstrate that this decoupling of trace and major elements in the inequigranular syenite results from accumulation of light REE (LREE)-bearing minerals that were evidently separated from silicic magmas as the latter rose along the sides of the magma chamber. Chemical and isotopic data for microgranular mafic enclaves, as well as for restite xenoliths of Precambrian granite wall rock, indicate that the isotopic distinction between the marginal and interior facies of the ONP probably reflects assimilation of the wall rock by ??(Nd) ~-2 mafic magmas near the base of the magma system. Fractional crystallization and crystal liquid separation of the crystally contaminated magma at the base and along the margins of the chamber generated the highly silicic magmas that ultimately pooled at the chamber top.

  13. Garcinia kola aqueous suspension prevents cerebellar neurodegeneration in long-term diabetic rat - a type 1 diabetes mellitus model.

    PubMed

    Farahna, Mohammed; Seke Etet, Paul F; Osman, Sayed Y; Yurt, Kıymet K; Amir, Naheed; Vecchio, Lorella; Aydin, Isınsu; Aldebasi, Yousef H; Sheikh, Azimullah; Chijuka, John C; Kaplan, Süleyman; Adem, Abdu

    2017-01-04

    The development of compounds able to improve metabolic syndrome and mitigate complications caused by inappropriate glycemic control in type 1 diabetes mellitus is challenging. The medicinal plant with established hypoglycemic properties Garcinia kola Heckel might have the potential to mitigate diabetes mellitus metabolic syndrome and complications. We have investigated the neuroprotective properties of a suspension of G. kola seeds in long-term type 1 diabetes mellitus rat model. Wistar rats, made diabetic by single injection of streptozotocin were monitored for 8 months. Then, they were administered with distilled water or G. kola oral aqueous suspension daily for 30 days. Body weight and glycemia were determined before and after treatment. After sacrifice, cerebella were dissected out and processed for stereological quantification of Purkinje cells. Histopathological and immunohistochemical analyses of markers of neuroinflammation and neurodegeneration were performed. Purkinje cell counts were significantly increased, and histopathological signs of apoptosis and neuroinflammation decreased, in diabetic animals treated with G. kola compared to diabetic rats given distilled water. Glycemia was also markedly improved and body weight restored to non-diabetic control values, following G. kola treatment. These results suggest that G. kola treatment improved the general condition of long-term diabetic rats and protected Purkinje cells partly by improving the systemic glycemia and mitigating neuroinflammation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Paleocene plutonism and its tectonic implications, North Cascades, Washington

    SciTech Connect

    Miller, R.B. ); Bowring, S.A. ); Hoppe, W.J. )

    1989-09-01

    U-Pb zircon geochronology has identified a northwest-trending belt of Paleocene (68-59 Ma) plutons within the crystalline core of the North Cascades. Most of these plutons show amphibolite facies assemblages and solid-state foiliation. They document extensive Paleogene dynamothermal metamorphism in the core, and combined with other recent studies, demonstrate ongoing metamorphism from mid-Cretaceous to mid-Eocene time. The Paleocene plutons were emplaced during an interval that marked a magmatic lull throughout much of the northern Cordillera. The distribution of latest Cretaceous and Paleocene plutons suggests that magmatism in the North Cascades core records the same eastward retreat that occurred farther north in the Cordillera.

  15. Infrasound research at Kola Regional Seismological Centre, Russia

    NASA Astrophysics Data System (ADS)

    Asming, Vladimir; Kremenetskaya, Elena

    2013-04-01

    A small-aperture infrasound array has been installed in Kola Peninsula, Russia 17 km far from the town of Apatity in the year 2000. It comprises 3 Chaparral V microbarographs placed closely to the APA seismic array sensors and equipped with pipe wind reducing filters. The data are digitized at the array site and transmitted in real time to a processing center in Apatity. To search for infrasound events (arrivals of coherent signals) a beamforming-style detector has been developed. Now it works in near real time. We analyzed the detecting statistics for different frequency bands. Most man-made events are detected in 1-5 Hz band, microbaromes are typically detected in 0.2-1 Hz band. In lower frequencies we record mostly a wind noise. A data base of samples of infrasound signals of different natures has been collected. It contains recordings of microbaromes, industrial and military explosions, airplane shock waves, infrasound of airplanes, thunders, rocket launches and reentries, bolides etc. The most distant signals we have detected are associated with Kursk Magnetic Anomaly explosions (1700 km far from Apatity). We implemented an algorithm for association of infrasound signals and preliminary location of infrasound events by several arrays. It was tested with Apatity data together with data of Sweden - Finnish infrasound network operated by the Institute of Space Physics in Umea (Sweden). By agreement with NORSAR we have a real-time access to the data of Norwegian experimental infrasound installation situated in Karasjok (North Norway). Currently our detection and location programs work both with Apatity and Norwegian data. The results are available in Internet. Finnish militaries routinely destroy out-of-date weapon in autumns at the same compact site in North Finland. This is a great source of repeating infrasound signals of the same magnitude and origin. We recorded several hundreds of such explosions. The signals have been used for testing our location routines

  16. Plutonic rocks of Jurassic age in the Alaska-Aleutian Range batholith: chemical variation and polarity.

    USGS Publications Warehouse

    Reed, B.I.; Miesch, A.T.; Lanphere, M.A.

    1983-01-01

    Plutonic rocks of Jurassic age exposed on the Pacific side of this batholith form a compositionally continuous calc-alkaline suite that ranges from hornblende gabbro to quartz monzonite. Tonalite and quartz diorite are the dominant rock types. Trend-surface analysis of 102 samples indicates that the direction of slope of the trend is approximately normal to the Jurassic magmatic arc. K2O and SiO2 increase towards the E-SE and the other oxides towards the W-NW. If the chemical trends reflect the approximate geometry of a palaeo-subduction zone, the polarity of the Jurassic magmatic arc is to the NW, i.e. subduction was directed towards the SE. Thus the palaeo-subduction zone is on the opposite side of the arc from the position that has generally been assumed, indicating that the Jurassic plutonic rocks were not generated in response to classical Andean-type convergent plate margins. The magmatic arc may have been formed in an intra-ocean environment and subsequently has been rafted northwards and accreted to this part of the N Pacific rim during the late Mesozoic. Middle and Upper Jurassic clastics underlying Cook Inlet to the SE and derived from the magmatic arc are classified as back-arc deposits, rather than as an arc-trench gap sequence.-L.C.H.

  17. Petrogenesis of the reversely-zoned Turtle pluton, southeastern California

    SciTech Connect

    Allen, C.M.

    1989-01-01

    Few plutons with a reversed geometry of a felsic rim and mafic core have been described in the geologic literature. The Turtle pluton of S.E. California is an intrusion composed of a granitic rim and granodioritic core and common microgranitoid enclaves. Field observations, mineral textures and chemistries, major and trace element geochemistry, and isotopic variability support a petrogenetic model of in situ, concomitant, magma mixing and fractional crystallization of rhyolitic magma progressively mixed with an increasing volume of andesitic magma, all without chemical contribution from entrained basaltic enclaves. Hornblende geobarometry indicates the Turtle pluton crystallized at about 3.5 kb. A crystallization sequence of biotite before hornblende (and lack of pyroxenes) suggests the initial granitic magma contained less than 4 wt% H{sub 2}O at temperatures less than 780C. U-Pb, Pb-Pb, Rb-Sr and oxygen isotope studies indicate the terrane intruded by the Turtle pluton is 1.8 Ga, that the Turtle pluton crystallized at 130 Ma, that the Target Granite and garnet aplites are about 100 Ma, and that these intrusions were derived from different sources. Models based on isotopic data suggest the rhyolitic end member magma of the Turtle pluton was derived from mafic igneous rocks, and was not derived from sampled Proterozoic country rocks. Similarity of common Sr and Pb isotopic ratios of these rocks to other Mesozoic intrusions in the Colorado River Region suggest the Turtle pluton and Target Granite have affinities like rocks to the east, including the Whipple Mountains and plutons of western Arizona. P-T-t history of the southern Turtle Mountains implies uplift well into the upper crust by Late Cretaceous time so that the heating and deformation events of the Late Cretaceous and Tertiary observed in flanking ranges did not affect the study area.

  18. Discrimination of alkalinity in granitoid Rocks: A potential TIMS application

    NASA Technical Reports Server (NTRS)

    Ruff, Steven W.

    1995-01-01

    In mineral exploration, the ability to distinguish and map petrochemical variations of magmatic rocks can be a useful reconnaissance tool. Alkalinity is one such petrochemical parameter and is used in the characterization of granitoid rocks. In quartz normative plutonic rocks, alkalinity is related to the composition and abundance of feldspars. Together with quartz abundance, knowledge of feldspar modes allows the classification of these igneous rocks according to the Streckeisen diagram. Alternative classification schemes rely on whole rock geochemistry instead of mineral identifications. The relative ease of obtaining whole rock analyses means that geochemical classifications tend to be favored in exploration geology. But the technique of thermal infrared spectroscopy of rocks yields information on mineralogy and is one that can be applied remotely. The goal of the current work then is to establish whether data from TIMS can be used to distinguish the mineralogical variations that relate to alkalinity. An ideal opportunity to test this thesis arises from the work presented in a paper by Dewitt (1989). This paper contains the results of mapping and analysis of Proterozoic plutonic rocks in north-central Arizona. The map resulting from this work delineates plutons according to alkalinity in an effort to establish a trend or polarity in the regional magmatism. Also contained within this paper are brief descriptions of the mineralogy of half of the region's plutons. This combination of mineralogical and geochemical information was the rationale behind choosing this area as a site for TIMS over flights. A portion of the region centered on the northern Bradshaw Mountains was selected because it contains plutons of all three alkalinity classifications (alkali-calcic, calc-alkalic, and calic) present on DeWitt's map within a relatively small area. The site was flown in August of 1994 and the data received a few days before the writing of this manuscript. Most of this

  19. Latest Mesozoic-Early Cenozoic Continental Extension and Related Alkaline Magmatism in Central Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Kadioglu, Y. K.

    2009-04-01

    The Central Anatolian crystalline complex (CACC) in Turkey includes a suite of latest Mesozoic-early Cenozoic plutonic rocks intruding the metamorphic and ophiolitic basement rocks. The intrusive rocks consist of three groups of granitoid, syenitoid, and gabbroids plutons. The granitoid units occur around the periphery of the CACC as large plutonic bodies, whereas the syenitoid assemblages crop out in the inner part of the CACC as small plutons. All the felsic plutons are crosscut by the gabbroid rocks in the region. The alkaline rocks of the CACC change in composition from nordmarkite through pulaskite to lusitanite, and are made of silica-saturated and silica-undersaturated magmas. The silica under-saturated alkaline rocks have gradual contacts with the silica-saturated alkaline rocks and constitute the main component of the alkaline rocks in the CACC. Nepheline, pseudoleucite, cancrinite, nosean, melanite and arfvedsonite are the main typical mineral compositions of the silica-undersaturated alkaline rocks. The leucite- and pseudoleucite-bearing rocks have porphyritic textures intruding the other main subunits of the alkaline rocks at high topographic elevations in the region. They are mostly composed of foid syenite, monzosyenite, monzodiorite and include rare amount of monzogabbro and foidolite. Each subunit has a transitional contact with the others and is crosscut by alkali feldspar foid syenite veins. Felsic dykes intrude the alkaline rock units and fluorite-bearing hydrothermal veins, which manifest themselves as alteration zones. The alkaline rocks have an abundance of xenolithic enclaves but lack any magma mixing-mingling produced enclaves. Normalized elemental patterns of the analyzed alkaline rocks show a slight enrichment in large ion lithophile elements (LILE) and light rare earth elements relatively to high field strength elements (HFSE) and heavy rare earth elements (HREE). The less fluid mobile, LILE and LREE concentration in the alkaline rocks

  20. Geophysical modeling and structure of Ushuaia Pluton, Fuegian Andes, Argentina

    NASA Astrophysics Data System (ADS)

    Peroni, Javier Ignacio; Tassone, Alejandro Alberto; Menichetti, Marco; Cerredo, María Elena

    2009-10-01

    Within the area of Ushuaia Bay (Tierra del Fuego, southernmost South America) the deformed Lower Cretaceous sedimentary rocks of Yahgán Formation host the Ushuaia Pluton. The intrusive body is oval in map view; it is compositionally varied with rocks ranging from the ultrabasic to the mesosiliceous realm. The emplacement time is constrained within the Albian-Cenomanian span by new amphibole K/Ar data. Meso- and microstructures of Ushuaia Pluton and its host indicate a synkinematic emplacement with a dominant extensional component. A set of transcurrent and normal faults related to the sinistral strike-slip Beagle Channel Fault System affects the pluton and its host. On the basis of aeromagnetic data combined with field information, a new model is presented for the Ushuaia Pluton. Modeling results fit well with a laccolithic body with an estimated volume of around 111 km 3. The model pluton cross-section displays a central zone with an average thickness of 2000 m which progressively thins toward the margins (˜ 500 m) and a southern root which reaches 5000 m deep. The combined structural and geophysical model supports a transtensive scenario for the Ushuaia Pluton emplacement at Early-Late Cretaceous boundary.

  1. Pb isotopes in Ascension Island rocks: oceanic origin for the gabbroic to granitic plutonic xenoliths

    NASA Astrophysics Data System (ADS)

    Weis, D.

    1983-02-01

    The Pb isotopic compositions and U and Pb concentrations of the lava series (alkali basalt to comendite) and of their plutonic xenoliths (gabbro to alkaline granite) of Ascension Island are reported. The data are used to evaluate the source of the xenoliths which formed two differentiation suites: the acidic and intermediate xenoliths together with most of the lavas on the one hand, and the gabbroic xenoliths and a basaltic tuff on the other hand. The Pb isotopic compositions imply a mantle origin for the source magmas of the xenoliths and confirm the possibility of generating granitic rocks in an oceanic environment by fractional crystallization of a mantle-derived magma whose geochemical and isotopic characteristics are comparable to the source magmas of oceanic island basalts.

  2. The Neutron Tomography Studies of the Rocks from the Kola Superdeep Borehole

    NASA Astrophysics Data System (ADS)

    Kichanov, S. E.; Kozlenko, D. P.; Ivankina, T. I.; Rutkauskas, A. V.; Lukin, E. V.; Savenko, B. N.

    The volume morphology of a gneiss sample K-8802 recovered from the deep of 8802 m of the Kola Superdeep Borehole and its surface homologue sample PL-36 have been studied by means of neutron radiography and tomography methods. The volumes and size distributions of a biotite-muscovite grains as well as grains orientation distribution have been obtained from experimental data. It was found that the average volumes of the biotite-muscovite grains in surface homologue sample is noticeably larger than the average volume of grains in the deep-seated gneiss sample K-8802. This drastically differences in grains volumes can be explained by the recrystallization processes in deep of the Kola Superdeep Borehole at high temperatures and high pressures.

  3. Zircon crystal morphology and internal structures as a tool for constraining magma sources: Examples from northern Portugal Variscan biotite-rich granite plutons

    NASA Astrophysics Data System (ADS)

    Brites Martins, Helena C.; Simões, Pedro P.; Abreu, Joana

    2014-09-01

    In northern Portugal, large volumes of granitoids were emplaced during the last stage (D3) of the Variscan orogeny and display a wide range of petrological signatures. We studied the morphologies and internal structures of zircons from syn-, late- and post-D3 granitoids. The sin-D3 granitoids include the Ucanha-Vilar, Lamego, Felgueiras, Sameiro, and Refoios do Lima plutons, the late- and post-D3 granitoids are represented by the Vieira do Minho and the Vila Pouca de Aguiar plutons, respectively. Typological investigations after Pupin (1980) along with scanning electron microprobe imaging reveal that the external morphology of zircon changes consistently with a decrease in the crystallization temperature. Zircon populations from the Refoios do Lima and the Vieira do Minho granites show gradual changes in the internal morphologies and their typologic evolution trends are consistent with their mainly crustal origin. The Sameiro, Felgueiras, Lamego and Ucanha-Vilar granites have more complex internal and external morphology and typological evolution trends that cross the domain of the calc-alkaline to the aluminous granites compatible with a mixing process. Finally, the morphological types of the Vila Pouca de Aguiar granites are found both in calc-alkaline and sub-alkaline granites and their typological evolutionary trends follow the calc-alkaline/sub-alkaline trend, suggesting crustal sources with some mantle contribution.

  4. Adakitic-like magmatism in western Ossa-Morena Zone (Portugal): Geochemical and isotopic constraints of the Pavia pluton

    NASA Astrophysics Data System (ADS)

    Lima, S. M.; Neiva, A. M. R.; Ramos, J. M. F.

    2013-02-01

    Granitic rocks are a major component of the Earth's continental crust and occur in a wide variety of tectonic settings. Their chemical and isotopic characterization is crucial to the recognition of the potential sources and mechanisms involved in their generation. In this study, we present the first whole rock chemical and isotopic (Sr-Nd-O) data for the Pavia pluton (328-317 Ma), located near the western border of the Ossa-Morena Zone (Évora Massif, Portugal). Major and trace element geochemistry suggests that the different granitic phases composing this intrusive body (enclaves, granites (s.l.) and crosscutting dikes) represent independent magma pulses and the majority is similar to TTGs and adakites. The little Sr-Nd-O isotopic variation, with (87Sr/86Sr)328 = 0.70428-0.70560, ɛNd328 ranging between - 3.4 and + 0.4 and δ18O varying from + 5.6‰ to + 8.4‰ implies an isotopically similar protolith for all phases. The most viable mechanism for the generation of the Pavia pluton adakitic-like magmatism is assimilation-fractional crystallization of a mantle-derived magma. This mechanism was also invoked to explain the genesis of other plutons within the Évora Massif but they have a distinct chemistry (typical arc calc-alkaline rocks). The chemical differences between them and the Pavia pluton granitic rocks are interpreted as the result of lower degrees of crustal assimilation and higher degrees of contamination of mantle-derived magmas by the sinking slab (after subduction blocking and subsequent slab break-off).

  5. Reconstruction of early Holocene paleoclimate and environment in the SW Kola region, Russian Arctic

    NASA Astrophysics Data System (ADS)

    Grekov, Ivan; Kolka, Vasiliy; Syrykh, Liudmila; Nazarova, Larisa

    2016-04-01

    In the current period of the global climate change it becomes necessary to have a clear understanding of not only the changes taking place in the components of the natural environment, but also to understand development of all interactions between those components. Quaternary terrigenic sediments and lakes of the Kola Peninsula store information about the development of the region in the Late Glacial and Holocene: movements of the glacier, neotectonic activity, post-glacial rebound, formation and development of natural environments after deglaciation. Multi-proxy study of landscapes evolution of the Kola Peninsula in the Late Quaternary will help to establish a detailed reconstruction of climatic and environmental changes of this poor studied sector of the Arctic. Quaternary history on the Kola Peninsula is represented mainly by Late Pleistocene and Holocene sediments covering the Baltic Shield (Lavrova, 1960; Evzerov, 2015). Several palaeolimnological investigations in the Baltic Shield area have been performed earlier (Donner et al., 1977; Anundsen, 1985; Berglund, 2004). Studies of the southern coast of the Kola Peninsula have shown that marine transgression took place in the Late Pleistocene that was then replaced by a regression with variable speed. The slowdown of the uplift of the area took place between 8800 - 6800 BP (cal. years) and corresponded to the time of the Tapes transgression of the Arctic Ocean (Evzerov et al. 2010; Kolka, et al., 2013). Palaeoclimatic studies based on micro-paleontological analyzes indicate uneven development of the Kola Peninsula landscapes in the Late Glacial and Early Holocene. The northern coast of the Peninsula became free of ice first. In this area tundra-steppe vegetation was established for a short time and was later replaced by tundra (Snyder et al, 2000). Southern part of the Kola Peninsula was dependent on the conditions of deglaciation of the White Sea basin and cleared of ice much later (Evzerov et al., 2010; Kolka

  6. A double-blind, placebo-controlled study on the effects of Gotu Kola (Centella asiatica) on acoustic startle response in healthy subjects.

    PubMed

    Bradwejn, J; Zhou, Y; Koszycki, D; Shlik, J

    2000-12-01

    Investigations of the pharmacologic profile of medicinal plants have revealed that a number of plants with purported anxiolytic activity bind to cholecystokinin (CCK) receptors. This finding is intriguing in view of the proposed involvement of CCK in the pathophysiology of fear and anxiety. This double-blind, placebo-controlled study was undertaken to evaluate the anxiolytic activity of Gotu Kola (Centella asiatica) in healthy subjects. Gotu Kola has been used for centuries in Ayurvedic and traditional Chinese medicine to alleviate symptoms of depression and anxiety. Recent studies in the rat have shown that long-term pretreatment with Gotu Kola decreases locomotor activity, enhances elevated-plus maze performance, and attenuates the acoustic startle response (ASR). In this study, the authors evaluated the effects of Gotu Kola on the ASR in humans. Subjects were randomly assigned to receive either a single 12-g orally administered dose of Gotu Kola (N = 20) or placebo (N = 20). The results revealed that compared with placebo, Gotu Kola significantly attenuated the peak ASR amplitude 30 and 60 minutes after treatment. Gotu Kola had no significant effect on self-rated mood, heart rate, or blood pressure. These preliminary findings suggest that Gotu Kola has anxiolytic activity in humans as revealed by the ASR. It remains to be seen whether this herb has therapeutic efficacy in the treatment of anxiety syndromes.

  7. Plume-derived rare gases in 380 Ma carbonatites from the Kola region (Russia) and the argon isotopic composition in the deep mantle

    NASA Astrophysics Data System (ADS)

    Marty, Bernard; Tolstikhin, Igor; Kamensky, Igor L.; Nivin, Valentin; Balaganskaya, Elena; Zimmermann, Jean-Louis

    1998-12-01

    In an effort to document the source of the parental melts to carbonatites, we have measured rare gases in 380 Ma carbonatites and associated mineral assemblages from the Kola Peninsula, eastern part of the Baltic shield in Russia. These series were emplaced during widespread Devonian magmatism when several large ultrabasic-alkaline-carbonatite massifs were formed. 4He/ 3He ratios vary from 1×10 6 to 1×10 7 in the bulk He extracted by melting of samples from three localities, including the large Kovdor massif. A comparison of measured abundances of 3He and 4He with those expected from in-situ production revealed a large (up to 10 5 times) excess of 3He, implying a significant contribution from a mantle-derived 3He-bearing fluid. Crushing of these samples allowed extraction of fluids with 4He/ 3He ratios down to 38,000, lower than those of mid-ocean ridge basalts and in the range of 4He/ 3He observed in 3He-rich ocean island basalts (OIBs) related to mantle plumes. 20Ne/ 22Ne up to 12.1±0.2 are higher than the atmospheric value of 9.80, implying the occurrence of primordial (solar-type) neon in the carbonatite source. 20Ne/ 22Ne and 21Ne/ 22Ne ratios display a good correlation, with the regression line close to (slightly to the right of) the Loihi Seamount correlation. Extrapolation of the regression to solar 20Ne/ 22Ne of 13.8 gives a 21Ne/ 22Ne of 0.045 for the plume end-member, well below the mid-ocean ridge basalt (MORB) source (upper mantle) end-member of 0.07. The measured 40Ar/ 36Ar ratios up to 2790 correlate very well with the Ne isotopic ratios, and the best estimate of the 40Ar/ 36Ar ratio of the plume source is within 5000±1000. Although the 3He/ 22Ne ratio in the plume source appears to be comparable to the solar value within a factor of 2, the 22Ne/ 36Ar ratio, computed from Ne-Ar isotope correlation, is two orders of magnitude lower than the solar value. Such difference is unlikely to be due to magmatic fractionation since the observed 4He/ 40Ar

  8. Anatomy of the Cretaceous Hobenzan pluton, SW Japan: Internal structure of a small zoned pluton, and its genesis

    NASA Astrophysics Data System (ADS)

    Imaoka, Teruyoshi; Nakashima, Kazuo; Kamei, Atsushi; Hayasaka, Yasutaka; Ogita, Yasuo; Ikawa, Toshiyuki; Itaya, Tetsumaru; Takahashi, Yoshio; Kagami, Hiroo

    2014-11-01

    Field, petrographic, geochemical, and K-Ar and U-Pb age data were used to elucidate the internal structure of the Cretaceous Hobenzan pluton, SW Japan, and the processes which generated that structure. The pluton is elongated E-W with dimensions of about 6.5 × 2.0 km (13 km2), and was emplaced at ~ 95 Ma as a pluton in accretionary complexes. The pluton contains an early tonalite, but most of the body consists of later granitoids that show a continuous differentiation series from biotite-hornblende granodiorite (GD) to hornblende-biotite granite (HBG) and biotite granite (BG). The contacts between the GD and HBG are gradational. The pluton provides an exceptional cross-sectional view of a simple cooling magma body. The GD shows no vertical variations in modal and chemical compositions, whereas the HBG displays differentiation from the lowermost exposure to the top of the pluton. Initial Sr isotope ratios (SrI) in the HBG increase from the lower part to the top of the pluton. The granitoids show continuous compositional variations from 65 to 79 wt.% SiO2 (anhydrous basis), and magmatic differentiation was dominantly controlled by crystal fractionation of hornblende and plagioclase. Field, elemental and Sr-Nd isotope data are consistent with limited operation of assimilation with pelitic rocks and fractional crystallization (AFC), in which assimilation increased with higher degrees of differentiation. The Hobenzan pluton retains a history of granitoid magma evolution in a subvolcanic magma reservoir. The GD formed as a rigid sponge, and melt fraction increases inwards from the walls, forming the HBG mush by fractional crystallization, coupled with small degrees of assimilation of adjacent schists. A more evolved and enriched low-density melt segregated from the mushy cumulate of the HBG by incomplete crystal-melt separation, and moved upwards with the assistance of gas-driven filter pressing, as indicated by the presence of miarolitic cavities, thus forming the BG

  9. Survey of lunar plutonic and granulitic lithic fragments

    NASA Technical Reports Server (NTRS)

    Bickel, C. E.; Warner, J. L.

    1978-01-01

    A catalog of lunar plutonic rocks and granulitic impactites belonging to the ANT suite has been compiled. The coarser-grained, plutonic rocks in the compilation are probably pristine; they belong to two groups, Mg-rich plutonic rocks and anorthosites, with a preponderance of the latter type. The granulitic impactites, however, have bulk and mineral compositions that fall between the two groups defined by the pristine nonmare samples of Warren and Wasson (1977). Thus the granulitic impactites may have originated by metamorphism of mixed impactites in early breccia sheets. The catalog, representative of the lunar crust before the end of heavy bombardment, suggests a crust with over 78 vol. % plagioclase and about equal proportions of material with noritic and troctolitic affinity.

  10. An AMS study of the Takidani pluton (Japan)

    NASA Astrophysics Data System (ADS)

    Hartung, Eva; Caricchi, Luca; Floess, David; Wallis, Simon; Harayama, Satoru

    2016-04-01

    Large plutonic bodies are typically constructed incrementally often by under-accretion of distinct successive magma pulses. Petrography and geochemistry of the Takidani Pluton (1.54 Ma ± 0.23 Ma) in the Northern Japanese Alps show that the chemical and textural variability observed at the roof of this intrusion is best explained by the segregation of residual melt from a crystallising magma body. We carried out a magnetic susceptibility survey (bulk susceptibility and anisotropy of magnetic susceptibility) to identify the structures associated with the emplacement and extraction of residual melts from a magmatic mush. Additionally, we determined shape preferred orientations (SPO) of amphibole at several locations within the Takidani pluton. From bottom to top of the intrusion, the bulk susceptibility is about constant in the main granodioritic part, decreases roofwards within the porphyritic unit, before increasing again within the marginal granodiorite close to the contact with the overlaying Hotaka Andesite. Such variability mimics the major and trace elements compositional variability measured in the whole rock samples. Magnetic foliations are observed at the western tectonic contact of the pluton potentially indicating overprint, while most other magnetic fabrics across the pluton are characterised by triaxial ellipsoids of magnetic susceptibility or magnetic lineations. Our preliminary data and the lack of internal contacts indicate that Takidani Pluton was likely emplaced as a series of successive magma pulses finally merging to produce a large connected magma body. While amphibole foliations may likely be the results of super-solidus tectonic overprint, anisotropy of magnetic susceptibility data may be related to post-emplacement melt segregation.

  11. Geochemistry of the Topuk Pluton associated with the Kozbudaklar W-skarn deposit (Western Anatolia, Turkey): Implication for crystallization conditions

    NASA Astrophysics Data System (ADS)

    Orhan, Ayşe; Demirbilek, Mehmet; Mutlu, Halim

    2017-06-01

    The Kozbudaklar scheelite-bearing skarn deposit in the Tavşanlı Zone, western Turkey, occurs at the contact between Eocene Topuk pluton and Triassic İnönü marble of calcic character. The Topuk pluton is medium-coarse grained, granodiorite in composition and has a hypidiomorphic equigranular texture. The host rock contains mafic microgranular enclaves (MME) of monzodiorite-monzogabbro composition and is interrupted by porphyritic granodiorite and granite-aplite vein rocks. The pluton is calk-alkaline, metaluminous and composed of I-type melt character. δ18O and δD compositions of silicate minerals from granodioritic host rock are 5.9-10.6‰ and -77.0 to -71.4‰ and conformable with the range of unaltered I-type granites. Trace element contents indicate that pluton is crystallized from mantle-derived magma interacted with continental crust in a volcanic arc or subduction related setting. Major and trace element concentrations of Topuk pluton are quite consistent with geochemical patterns of Cu-skarn granitoids. Results of mineral chemistry analysis of the pluton yield that plagioclases are of oligoclase-andesine, amphiboles are of magnesio-hornblende and biotites are of ferro-magnesian composition. Amphiboles and biotites of granodioritic host rock are represented by calc-alkaline, I-type melt composition evolved in a subduction environment. Based on the results of plagioclase-Al in hornblende and amphibole chemistry data from the pluton, two different stages are proposed for the magma crystallization. The first stage was developed in a relatively deeper environment (>15 km) under high pressure (>4 kbar) and low log ƒO2 (>-17.6) conditions which reflect fractional crystallization and magma-mixing depth of basaltic magma and these conditions are not correlated with scheelite mineralization. The second crystallization stage of magma which proceeded at shallow depths (<6 km) was also developed in two separate phases with respect to P-T conditions. The first

  12. The geochemical and genetic role of organic substances in postmagmatic derivatives of alkaline plutons

    NASA Astrophysics Data System (ADS)

    Ermolaeva, V. N.; Chukanov, N. V.; Pekov, I. V.; Kogarko, L. N.

    2009-12-01

    Solid bituminous substances (SBS) are common components of the late hydrothermal mineral assemblages of peralkaline pegmatites. SBS are formed in a reductive setting as a result of progressive sorption of minor carbon-bearing molecules (CO, CO2, CH4, C2H6, C2H4, etc.), their polymerization, transformation into aromatic compounds (reformation), and selective oxidation on microporous zeolite-like Ti-, Nb-, and Zrsilicates serving as sorbents and catalysts. The oxygen-bearing aromatic compounds with hydrophile functional groups (-OH, -C=O, -COOH, -COO) act as complexing agents with respect to Th, REE, U, Zr, Ti, Nb, Ba, Sr, Ca, resulting in transfer of these bitumenophile elements under low-temperature hydrothermal conditions in the form of water-soluble macroassociates of the micelle type. Th, REE, and to a lesser extent, U, Zr, Ti, and Nb concentrate at the late stage of the hydrothermal process as microphases impregnating SBS or macroscopic segregations of Th and REE minerals. At the final stage, homogeneous SBS break down into organic (partly together with Ca, Sr, Ba, and Pb) and mineral (with Th, Ln, Y, Ti, Nb, Ca, Na, K, Si) microphases.

  13. A Pan-African alkaline pluton intruding the Saramuj Conglomerate, south-west Jordan

    NASA Astrophysics Data System (ADS)

    Jarrar, Ghaleb; Wachendorf, Horst; Zachmann, Dieter

    1993-04-01

    The geological setting, petrography and bulk mineral chemistry of a monzodiorite and a presumably consanguineous megaporphyry with large (up to 25 cm) labradorite megacrysts, both intruding the upper Proterozoic Saramuj Conglomerate in south-west Jordan (south eastern shore of the Dead Sea), were examined. The crystallization temperatures of the monzodiorite and the megaporphyry as determined from pyroxene thermometry and supported by contact metamorphic mineralogy are about 700 and 900°C, respectively. The intrusion depth of the monzodiorite is about 3 4 km. The monzodiorite was emplaced in the Saramuj Conglomerate at about 595 + 2 Ma ago according to Rb/Sr and U/Pb age determinations. The stratigraphic positions of the monzodiorite, megaporphyry and their host rock (the Saramuj Conglomerate) were compared with time-equivalent lithologies in the Arabian-Nubian Shield.

  14. Comprehensive paleoseismic geological studies in a key site in southwestern Kola Peninsula (Northeast of the Fennoscandian Shield)

    NASA Astrophysics Data System (ADS)

    Nikolaeva, S. B.; Nikonov, A. A.; Shvarev, S. V.; Rodkin, M. V.

    2016-07-01

    This paper considers the results of detailed paleoseismic and geological investigations in a key site in the wall of the Imandra Lake depression (Kola Peninsula Region, Northeast of the Fennoscandian Shield). Study of different groups of paleoseismic deformations developed in the fault zone and the application of new methods and techniques made it possible to identify a large seismotectonic zone characterized by great earthquakes at the end of the Late Glacial and in the Holocene. The investigation data are indicative of the necessity to estimate the seismic potential in the Kola Atomic plant area in a different way.

  15. Petrogenesis of Neogene plutonic rocks from south Ardestan, Iran; mantle-derived arc magmatism

    NASA Astrophysics Data System (ADS)

    Babazadeh, Shahrouz; Ghorbani, Mohammad Reza; Bröcker, Michael; D'Antonio, Massimo; Cottle, John; Gebbing, Thorsten; Carmine Mazzeo, Fabio; Ahmadi, Parham

    2017-04-01

    The south Ardestan region in the Urumieh-Dokhtar arc covers an area of about 250 km2 that is characterized by plutonic rocks with a compositional spectrum ranging from gabbro, gabbro-norite, gabbroic diorite, diorite, tonalite to granodiorite. Gabbroic rocks are mainly tholeiitic in character, whereas the diorites, tonalites and granodiorites show increasingly stronger calc-alkaline affinity. Gradual compositional variation and limited variation in radiogenic isotopic ratios indicate that these different rock types are petrogenetically related and most probably are derived from a common primitive source. U-Pb LA-ICP-MS dating of zircon from four granitoids yielded ages that range from 25 to 24 Ma. For tonalitic rocks, internal Rb-Sr isochron ages (biotite, feldspars) indicate cooling ages that lie in the range 20.4 ± 0.1 to 22.1 ± 0.5 Ma, slightly younger than the zircons' ages. Their uniform initial Sr-Nd isotopic values imply that the major source component has probably been an asthenospheric mantle domain. This is further supported by the mantle-derived geochemical affinity of the plutonic rocks. A geodynamic model is presented in which the asthenospheric upwelling and partial melting in the south Ardestan has been triggered by Late Oligocene-Miocene rollback of the Neotethyan subducting slab. These melts were subsequently slightly modified through assimilation, fractional crystallization (AFC) en-route to the surface (A less than 6%). The trace element rich and high radiogenic Sr signature of some gabbros, this is the likely perturbation and then mobilization of Sr in the rock system during alteration. 43% fractional crystallization dominated by plagioclase and orthopyroxene is found responsible for magmatic evolution from gabbro to gabbroic diorite. Whereas, 44% fractional crystallization of a plagioclase-dominated mineral assemblage that also include clinopyroxene, titanomagnetite and orthopyroxene is found responsible for the evolutionary path from the

  16. Garcinia kola seeds: is the aqueous extract a true aphrodisiac in male Wistar rats?

    PubMed

    Yakubu, M T; Quadri, A L

    2012-01-01

    The age long acclaimed aphrodisiac potentials of Garcinia kola seeds in some parts of Western Nigeria has not been substantiated with scientific evidence. In this study, we have decided to evaluate the effect of aqueous seed extract of G. kola at the doses of 25, 50 and 100 mg/kg body weight on sexual behaviour of male rats. Male rats weighing 215.00 ± 18.58 g were randomized completely into four groups (A-D) of six animals each. Animals in group A received, orally, 0.5 ml of distilled water only while those in groups B, C and D received same volume containing 25, 50 and 100 mg/kg body weight of the seed extract respectively. Frequencies of mount (MF), intromission (IF), genital toilet (GTF) and ejaculation (EF) as well as latencies of mount (ML), intromission (IL) and ejaculation (EL) were evaluated following the pairing of male rats (1:1) with non-oestrous female rats. The parameters were monitored for the first (15-30 min), second (75-90 min) and third (180195 min) observatory periods. The levels of testosterone, luteinizing (LH) and follicle stimulating hormones (FSH) were also determined. Phytochemical screening of the extract revealed the presence of saponins (2.78%), cardiac glycosides (0.26%), cardenolides and dienolides (0.24%), flavonoids (1.28%) and steroids (1.14%). The 25 and 100 mg/kg body weight increased (P<0.05) the MF whereas the ML was decreased by all the doses of the extract. MF and ML were not altered during the second observatory period whereas the 50 mg/kg body weight increased these parameters during the third observatory period. Other sexual behaviour parameters as well as serum testosterone, FSH and LH were not significantly altered throughout the observatory periods. Overall, the results revealed that G. kola seeds did not have sex enhancing potential as claimed. Therefore, the acclaimed pro sexual effect of Garcinia kola seeds is scientifically untrue. This study has refuted the claim that one of the rationales for consuming the seeds

  17. Alpine-type tectonics in the Paleoproterozoic Lapland-Kola Orogen

    NASA Astrophysics Data System (ADS)

    Mudruk, S. V.; Balagansky, V. V.; Gorbunov, I. A.; Raevsky, A. B.

    2013-07-01

    The Kola region in the northeastern Baltic Shield is characterized by diverse Paleoproterozoic collision processes. The Keivy Terrane is one of the major tectonic units in the northeastern foreland of the Paleoproterozoic Lapland-Kola Collisional Orogen, which markedly differs in a number of parameters from other tectonic units of the Kola region. The study of the Keivy Terrane allowed us to unravel one more basic difference: the large Paleoproterozoic sheath synform of the Serpovidny (Crescentic) Range localized in this terrane. Its core is occupied by volcanic and sedimentary rocks, which correlate with the fill of the Imandra-Varzuga Rift; the limbs are composed of metamorphosed mature sedimentary rocks known as Keivy paraschists of Neoarchean or Paleoproterozoic age. The lower limb of the Serpovidny Synform is strongly squeezed, whereas the upper limb consists of almost undeformed rocks. The deformed rocks underwent ductile flow under conditions of simple or general shear. In the degree of its asymmetry and main parameters, the Serpovidny Synform is similar to the plunging and recumbent anticlines in the Helvetic nappes of the Alps. It is concluded that the Paleoproterozoic core of the Serpovidny Sheath Synform, or plunging anticline, is a fragment of the almost completely eroded deep Serpovidny Nappe of the Helvetic type. During the collision related to the Lapland-Kola Orogeny (1.9-2.0 Ga), this nappe was pushed out northward from the Paleoproterozoic Imandra-Varzuga Rift, which is situated 50 km south of the Serpovidny structure, and thrust over the Keivy paraschists. The latter, together with underlying the Lebyazhka Gneiss, were folded in the process of thrusting and were involved in the structure of the Serpovidny Synform. The Keivy paraschists make up a para-autochthon or a separate nappe of the Pennine type. The Archean Lebyazhka metafelsic volcanics underlie the Keivy paraschists and overlie granitoids of the Archean basement that remained undeformed

  18. Fractionated alkaline rare-metal granites: two examples

    NASA Astrophysics Data System (ADS)

    Liverton, Timothy; Botelho, Nilson F.

    2001-04-01

    Two suites of tin-related alkaline granites are compared: the Seagull-Thirtymile granites of the Yukon, which were emplaced in a cordilleran setting and the Paranã suite of Goiás, which were emplaced in an incipient rift environment. The geochemistry of these two suites is similar and both have evolved small volumes of Li-Rb rich alkali feldspar leucogranites. Both fall partly, but not wholly, within the compositional fields defined for 'A-types' on various tectonic discrimination diagrams. Halogen contents and major element chemistry of Fe-Li micas from the Seagull-Thirtymile suite indicate that these plutons were reduced magmas that evolved magmatic/hydrothermal systems with increasing Cl content in a shallow, at least periodically 'open' system. The most important Sn-granites of the Paranã suite of Goiás were also emplaced at shallow depth and developed extensive greisen in active shear zones, which contrasts with a more passive environment for the Seagull granites. Both of these suites may be classified as low-P 2O 5 alkaline types and they display particularly Fe 2+-rich biotite micas that separate the alkaline plutons from S-type tin granites.

  19. Ferrobasalt-rhyolite immiscibility in tholeiitic volcanic and plutonic series (Invited)

    NASA Astrophysics Data System (ADS)

    Charlier, B.; Namur, O.; Kamenetsky, V. S.; Grove, T. L.

    2013-12-01

    One atmosphere experiments show that silicate liquid immiscibility develops between Fe-rich and Si-rich melts below 1000-1020°C in compositionally diverse lavas that represent classical tholeiitic trends, such as Mull, Iceland, Snake River Plain and Sept Iles. Extreme iron enrichment along the evolution trend is not necessary; immiscibility also develops during iron depletion and silica enrichment after Fe-Ti oxide saturation. Natural liquid lines of descent for major tholeiitic series also approach or intersect the experimentally-defined compositional space of immiscibility. The importance of ferrobasalt-rhyolite unmixing in both volcanic and plutonic environments is supported by worldwide occurrence of immiscible globules in the mesostasis of erupted basalts, and by unmixed melt inclusions in cumulus phases of major layered intrusions such as Sept Iles, Skaergaard and Sudbury. A clear case of liquid immiscibility is also recorded in intrusive tholeiitic gabbros from the Siberian Large Igneous Province and is evidenced by textures and compositions of millimeter-sized silicate melt pools trapped in native iron. An important implication of immiscibility in natural ferrobasaltic provinces is the development of a compositional gap characterized by the absence of intermediate compositions, a major feature observed in many tholeiitic provinces and referred to as the Daly gap. The compositions of experimental silica-rich immiscible melts coincide with those of natural rhyolites with high FeOtot and low Al2O3, which suggests a potential role for large-scale immiscibility in the petrogenesis of late-stage ferroan silicic melts. No evidence for the paired ferrobasaltic melt is observed in volcanic provinces, probably because of its uneruptable characteristics. Instead, Fe-Ti×P-rich gabbros crystallized at depth and are the cumulate products of immiscible Fe-rich melts in plutonic settings, a feature clearly evidenced in the Sept Iles intrusion. The production of

  20. The geochemistry of volcanic, plutonic and turbiditic rocks from Sumba, Indonesia

    NASA Astrophysics Data System (ADS)

    Lytwyn, J.; Rutherford, E.; Burke, K.; Xia, C.

    2001-06-01

    Rocks that reveal the geology of Sumba for times before the Later Miocene (˜16 Ma) are relatively few and are not particularly well exposed. This has led to uncertainty about the nature of the basement rocks of the island and especially about whether Sumba originated as a fragment of Australia, or of that part of southeastern Eurasia which many authors have called Sundaland. A third possibility is that Sumba is underlain by arc material generated on the ocean floor and is not a fragment of either continent. We have studied the geochemistry of volcanic, plutonic and turbiditic rocks collected from Sumba in an attempt to provide additional insight into the island's origin and history between Late Cretaceous (˜86 Ma) and Early Miocene (˜16 Ma) times. Late Cretaceous to Early Oligocene (˜31 Ma) volcanic rocks on Sumba range compositionally from basalts to andesites, and are of typical oceanic island-arc affinity, exhibiting geochemical characteristics similar to those of high-Al basalts and their derivatives. Compositions indicate evolution along both calc-alkaline and tholeiitic trends. Some samples show indications of possible modifications by slab-derived melts and/or related fluids and also of contamination by turbiditic sediments. Gabbros and diorites collected from the Paleocene Tanadaro intrusion are compositionally similar to the associated volcanic rocks and, we consider, represent the plutonic equivalents of high-Al basalt. The geochemistry of Cretaceous turbiditic sedimentary rocks on Sumba indicates close proximity to an intra-oceanic island-arc environment. These results are consistent with the geochemical, sedimentological, stratigraphic, paleontological and paleomagnetic results of other investigators which together indicate that: (1) Late Cretaceous to Early Oligocene volcanic, plutonic and volcaniclastic rocks of Sumba are island-arc- and forearc-related; (2) the arc involved appears to have been what we refer to as the Great Indonesian Volcanic

  1. SHRIMP U-Pb dating and geochemistry of the Cretaceous plutonic rocks in the Korean Peninsula: A new tectonic model of the Cretaceous Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Kim, Sung Won; Kwon, Sanghoon; Park, Seung-Ik; Lee, Changyeol; Cho, Deung-Lyong; Lee, Hong-Jin; Ko, Kyoungtae; Kim, Sook Ju

    2016-10-01

    The Cretaceous tectonomagmatism of the Korean Peninsula was examined based on geochemical and geochronological data of the Cretaceous plutonic rocks, along with distribution of volcano-sedimentary nonmarine N- to NE-trending fault bounded sedimentary basins. We conducted sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb ages and whole-rock geochemical compositions of 21 Cretaceous plutonic rocks, together with previously published data, from the central to southern Korean Peninsula. Four age groups of plutonic rocks were identified: Group I (ca. 119-106 Ma) in the northern to central area, Group II (ca. 99-87 Ma) in the central southern area, Group III (ca. 85-82 Ma) in the central to southern area, and Group IV (ca. 76-67 Ma) in the southernmost area. These results indicate a sporadic trenchward-younging trend of the Cretaceous magmatism in the Korean Peninsula. The Group I, II, and III rocks are dominated by high-K calc-alkaline I-type rocks with rift-related A-type granitoids. In contrast, the Group IV rocks are high-K calc-alkaline I-type plutonic rocks with no A-type rocks. The geochemical signatures of the entire groups indicated LREEs (light rare earth elements) enrichments and negative Nb, Ta, and Ti anomalies, indicating normal arc magmatism. A new tectonic model of the Cretaceous Korean Peninsula was proposed based on temporal and spatial distribution of the Cretaceous plutons represented by four age groups; 1) magmatic quiescence throughout the Korean Peninsula from ca. 160 to 120 Ma, 2) intrusions of the I- and A-type granitoids in the northern and central Korean Peninsula (Group I plutonic rocks from ca. 120 to 100 Ma) resulted from the partial melting of the lower continental crust due to the rollback of the Izanagi plate expressed as the conversion from flat-lying subduction to normal subduction. The Gyeongsang nonmarine sedimentary rift basin in the Korean Peninsula and adakite magmatism preserved in the present-day Japanese Islands

  2. Emplacement and fabric-forming conditions of plutons from structural and magnetic fabric analysis: A case study of the Plana pluton (Central Bulgaria)

    NASA Astrophysics Data System (ADS)

    Georgiev, Neven; Henry, Bernard; Jordanova, Neli; Jordanova, Diana; Naydenov, Kalin

    2014-08-01

    The relationship between intensity parameters, such as the corrected anisotropy degree P‧ and mean susceptibility Km for plutons with similar magnetic mineralogy, yields a criterion to determine the origin of their magnetic fabric: for a same mineralogy, the higher the P‧ values for the same mean susceptibility Km (irrespective of its absolute value) the higher tectonic effect was possible. Using this criterion, comparison of the magnetic fabric of the Upper Cretaceous mid- to shallow crustal level Plana pluton with that of other small Upper Cretaceous plutonic bodies in Sredna Gora Zone (Central and Southeast Bulgaria) highlights the structural evolution of the Plana pluton. The central part of Plana pluton and its southwest, west and east margins have preserved their emplacement fabric. Along its northern contact the pluton is affected by the last movements within the Okol Shear Zone where high-temperature S/L mylonites developed. The fabric of the pluton at its southeastern border was disturbed during the intrusion of the neighboring Gutsal pluton. The similarity in the orientation of magmatic and magnetic structures preserved in the central and southern parts of the Plana pluton and the transition from magmatic to high-temperature superimposed foliations and lineations at its north contact point to a composite superimposed shear-induced and emplacement-related magmatic magnetic fabric. Nearly vertical orientation of magnetic and magmatic foliations and lineations from the undeformed parts of the pluton shows a process of vertical magma rising and emplacement. The sub-vertical high-temperature solid-state mylonitic foliation and dip-parallel stretching lineation in the pluton along its northern contact reveals the transpression nature of the deformation in the vicinity of Okol Shear Zone with a strong pure shear component. The smooth transition between the deformed and undeformed parts of Plana pluton reveals the syn-kinematic character of the emplacement.

  3. The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

    NASA Astrophysics Data System (ADS)

    Dahlquist, J. A.; Pankhurst, R. J.; Rapela, C. W.; Casquet, C.; Fanning, C. M.; Alasino, P.; Baez, M.

    2006-03-01

    New geochronological and geochemical data are reported for the San Blas Pluton (SBP), in the northwestern Sierra de Velasco, Sierras Pampeanas, which intrudes Ordovician granitoids developed during the Famatinian orogeny. A precise Carboniferous age of 340±3 Ma is established by U-Pb dating of zircon using a sensitive high-resolution ion microprobe (SHRIMP). The SBP illustrates several petrological and geochemical characteristics of previously reported Carboniferous granitoids in the Sierras Pampeanas. Their generation is consistent with a regional reheating of the crust at approximately 342 Ma, which resulted in the formation of relatively large amounts of granitic melts that were emplaced in higher crustal levels along master fractures (older master shear zones of Lower Paleozoic age). The SBP can be chemically defined as a typical A-type granitoid related to postcollisonal or postorogenic magmatism. Its high REE content and extraordinarily high U and Th concentrations may have economic significance. Many previously published Devonian and Carboniferous K-Ar dates are reset Ordovician ages, but the existence of other Carboniferous bodies in the Sierra de Velasco cannot be discounted until detailed mapping of the whole Sierra is completed.

  4. The Plutón Diorítico Moat: Mildly alkaline monzonitic magmatism in the Fuegian Andes of Argentina

    NASA Astrophysics Data System (ADS)

    González Guillot, M.; Escayola, M.; Acevedo, R.; Pimentel, M.; Seraphim, G.; Proenza, J.; Schalamuk, I.

    2009-12-01

    The Plutón Diorítico Moat (Moat Dioritic Pluton, PDM) is the largest of several isolated Cretaceous plutons exposed in the Fuegian Andes of Argentina. It is made of a large variety of rock types ranging from ultramafic bodies (pyroxenites and hornblendites) to syenites. The petrological diversity is thought to have been originated by fractional crystallization of a mantle-derived magma combined with minor assimilation of continental crust (AFC). Its geochemical characteristics indicate a mildly-alkaline monzonitic affinity, contrasting with the typical calc-alkaline plutons of the Southern Patagonian Batholith (PB) to the south, in the Chilean archipelago. The PDM original magma is arc-related and its crystallization, as indicated by the Rb-Sr mineral isochron age of 115 ± 3 Ma, is coeval with some plutons of the PB. Therefore a similar tectonic regime is assumed for the emplacement of these plutonic bodies, both south and north of the Beagle channel. Differences in magma sources and degree of partial melting are inferred to account for the contrasting lithological and geochemical characteristics of the PB and PDM. The data suggest that the original magmas of the PDM were generated at greater depths in the mantle, by a smaller degree of partial melting, compared with the PB. The Barros Arana basalts, exposed to the north in Chile, forming a back-arc volcanic complex, display the same mildly-alkaline shoshonitic affinity, and are considered in this study as the volcanic equivalents of the PDM. All the plutons in the Argentinean Fuegian Andes display similar lithological and geochemical characteristics and are, therefore, grouped in this work under the name of Magmatismo Potásico Fueguino ( Fuegian Potassic Magmatism).

  5. Widespread tannin intake via stimulants and masticatories, especially guarana, kola nut, betel vine, and accessories.

    PubMed

    Morton, J F

    1992-01-01

    Tannins are increasingly recognized as dietary carcinogens and as antinutrients interfering with the system's full use of protein. Nevertheless, certain tannin-rich beverages, masticatories, and folk remedies, long utilized in African, Asiatic, Pacific, and Latin American countries, are now appearing in North American sundry shops and grocery stores. These include guarana (Paullinia cupana HBK.) from Brazil, kola nut (Cola nitida Schott & Endl. and C. acuminata Schott & Endl.) from West Africa, and betel nut (Areca catechu L.) from Malaya. The betel nut, or arecanut, has long been associated with oral and esophageal cancer because of its tannin content and the tannin contributed by the highly astringent cutch from Acacia catechu L. and Uncaria gambir Roxb. and the aromatic, astringent 'pan' (leaves of Piper betel L.) chewed with it. In addition to the constant recreational/social ingestion of these plant materials, they are much consumed as aphrodisiacs and medications. Guarana and kola nut enjoy great popularity in their native lands because they are also rich in caffeine, which serves as a stimulant. Research and popular education on the deleterious effects of excessive tannin intake could do much to reduce the heavy burden of early mortality and health care, especially in developing countries.

  6. Impact of acid and trace metals deposition on freshwater invertebrates in north-eastern Fennoscandia and Kola Peninsula

    SciTech Connect

    Yakovlev, V.

    1996-12-31

    Freshwater invertebrate communities in a total 400 lakes and streams in northeastern Norway, Finnish Lapland and the Kola Peninsula, subjected to the atmospheric deposition were studied. The severe influence of toxic heavy metals, dusts from smelters and mineral enrichment factories were found in the Kola Peninsula. The negative acidification effects on benthic communities were found in the Jarfjord (Norway), Enontekio, Ranua-Posio and Kittila-Kolari (Finnish Lapland) areas and in the Kola Peninsula (Russia). Taxa groups, known to be sensitive to acidification, such as gammarids, snails, mayflies, stone flies, were represented with few species and in a low abundance. Heavy metals accumulation in biota is recorded in areas surrounding nickel smelters in the Kola Peninsula. The metal concentration invertebrates in remote areas is rather wide and depend on an air deposition, characteristics of lake catchment areas, as well as water acidity. The environmental variables, such as lake hydrological type, altitude of lakes, dominant substratum type, abundance of macrophytes and mosses in sampling area, content of pollutants in water also show significant relationships with metal concentration in invertebrates. The most severe negative effects on biota were found in waters with low pH and simultaneously contaminated by heavy metals. The biological method for estimation of simultaneously water acidification and contamination is suggested.

  7. Miscellaneous investigations series: Bedrock geologic map of the Lone Mountain pluton area, Esmeralda County, Nevada

    SciTech Connect

    Maldonado, F.

    1984-12-31

    The joint attitudes were measured in the field and plotted on aerial photos at a scale of 1:24,000. The pluton is intensely jointed, primarily as a result of cooling and movement of the magma within a northwest-trending stress field. Foliation, in general, is poorly developed, and quality varies from area to area, but it is best developed close to the contacts with the metasedimentary rocks. A prominent northwest foliation direction was observed that parallels the northwest elongation of the exposed pluton. Faults in the pluton are difficult to identify because of the homogeneity of the rock. Several faults were mapped in the northern part of the area where they have a northeast trend and intersect the northwest-trending lamprophyre dikes with little apparent displacement. A major fault that bounds the northern part of the pluton is downthrown to the north and strikes northeast. This fault offsets the alluvium, the metasedimentary rocks, and the pluton and forms fault scraps as high as 10 m. Aeromagnetic data (US Geological Survey, 1979) suggest the following: (1) the local magnetic highs in the central part of the Lone Mountain pluton are probably related to topographic highs (peaks) where the flight lines are closer to the pluton; (2) a magnetic low in the northeastern part of Lone Mountain coincides with the pluton-country rock contact, which may be very steep; (3) the contours for the southwestern part of the mapped area indicate that the pluton-country rock contact is not as steep as that in the northeastern part and that the pluton probably coalesces at depth with the Weepah pluton, a pluton exposed south of the mapped area; and (4) the contours for the area of the Lone Mountain pluton express a northwest-trending gradient that parallels the northwest elongation of the Lone Mountain pluton and the northwest-trending stress field. 10 refs.

  8. Geochemistry and zircon U-Pb-Hf isotopes of the granitoids of Baolidao and Halatu plutons in Sonidzuoqi area, Inner Mongolia: Implications for petrogenesis and geodynamic setting

    NASA Astrophysics Data System (ADS)

    Hu, Chuansheng; Li, Wenbo; Xu, Cheng; Zhong, Richen; Zhu, Feng

    2015-01-01

    The Baolidao and Halatu plutons are located in the Northern Orogenic Belt (NOB) in Sonidzuoqi area of Inner Mongolia, which has an important significance for the tectonic evolution of Xing-Meng Orogenic Belt (XMOB). The two plutons have been intensively studied but the conclusions are still controversial. Combined with the previous study, this paper gives new geological data about the two correlative plutons for gaining a better understanding of their petrogenesis and the geodynamic setting. The Baolidao granitoids contain two different series, calc-alkaline series mainly formed in the Ordovician and high K calc-alkaline series mainly formed in the Carboniferous. The Halatu granites are formed in the Triassic and belong to high-K calc-alkaline series. This study got the zircon U-Pb ages of 316-322 Ma for the Baolidao granitoids and 233 ± 2 Ma for the Halatu syenogranites, respectively. In the tectonic discrimination diagrams, they mainly fall into the area of post-orogenic granites (POG). Hf isotopic analyses for the Baolidao granitoids (Sample BLD-1 and 3) shows εHf (t) = 3.0-14.0, with two-stage Hf model age (TDM2) of 436-1138 Ma. The Halatu syenogranite (Sample HLT-1) also shows a depleted εHf (t) = 3.8-8.2, with TDM2 of 741-1024 Ma, suggesting the major involvement of juvenile crustal components. The various εHf values of the Carboniferous Baolidao and Triassic Halatu granitoids indicates a hybrid magma source of juvenile material with old crustal component, and the εHf (t) values decrease from the Carboniferous to Triassic, suggesting the increasing proportion of old continental material during this period. Combined with the regional geology, the Carboniferous Baolidao granitoids are possibly not arc rocks, but originated from the post-collisional setting. The Triassic Halatu granites were formed in the subsequently extensional environment.

  9. Estimation of Pressure and Temperature of Intrusive Rocks Crystallisation: A Case Study of Naqadeh, Pasveh and Delkeh Plutons, W Iran

    NASA Astrophysics Data System (ADS)

    Mazhari, Seyed Ali; Bea, Fernando; Amini, Sadraddin; Ghalamghash, Jalil

    The Naqadeh, Pasveh and Delkeh plutons of North Sanandaj-Sirjan Zone, W Iran, are medium to high potassium calc-alkaline intrusive rocks composed of mafic and felsic rocks. Six samples were selected as representative of different units of these plutons for estimation of pressure and temperature of magmatic crystallisation. Al-in-hornblende barometry and crosstie contents of amphiboles suggest <4.5 kbar (1.6-4.5 kbar) pressure for emplacement depth of intrusives. Different thermometer methods indicate various stages of magmatic evolution from near liquidus to sub-solidus temperatures. The highest temperature resulted from orthopyroxene-clinopyroxene solvus thermometry which is more than 1100°C, reflecting initial crystallisation of pyroxene from dioritic magma. Hornblende-clinopyroxene thermometry show another hyper-solidus crystallisation phase during magmatic cooling. The temperature come from hornblende-plagioclase thermometer (695-760°C) probably refer to late stage crystallisation of the magma near solidus condition. Calculated temperature of feldspar thermometry show scatter results (281-1086°C) implies sub-solidus re-equilibration of the feldspar during magmatic and post-magmatic evolution.

  10. Magma flow recorded by magmatic and magnetic fabrics in a shallow granitic pluton: La Gloria Pluton, central Chile

    NASA Astrophysics Data System (ADS)

    Payacán, I. J.; Gutiérrez, F. J.; Gelman, S. E.; Bachmann, O.; Parada, M. A.

    2013-12-01

    To better understand the dynamics of a small, shallow, silicic magma reservoir, magmatic and magnetic (AMS) fabrics are compared in samples obtained from La Gloria Pluton (LGP), a 10 Ma granitic intrusion located in southern Andes. The magnetic fabric of LGP, mainly given by magnetite, is characterized by oblate shapes. Magnetic lineations have a NW trend with subhorizontal dip, following the main pluton elongation, while magnetic foliation planes have dips varying gradually from vertical at the walls to subhorizontal toward the center and the roof of the pluton. On the basis of numerical simulations, magnetic fabric was interpreted to represent the shear record induced by magmatic convection along solidification fronts as the reservoir reached its rheological locking point. Magmatic fabric (mineral orientation) was determined on 12 samples along the pluton. Three mutually orthogonal thin sections were produced for each sample, perpendicular to the AMS tensor axes. Size and orientation of individual crystals were obtained by image analysis. A 2-D tensor for two mineral groups (plagioclase and amphibole+biotitie) was defined in each mineral plane projecting the crystal lengths on the main crystal orientation (given by Bingham statistics). A 3-D magmatic fabric tensor was obtained. In order to compare the magmatic and magnetic fabrics, magmatic anisotropy parameters were defined similar to the AMS tensors. Magmatic fabric and anisotropy parameter values vary depending on the location inside the pluton: (1) Samples located at the borders exhibit vertical foliations and lineations with a NW trend, similar to the magnetic fabric tensors and higher anisotropy values for plagioclase than amphibole+biotite,; (2) samples located at the center of the LGP commonly present subvertical foliations/lineations, which differ from the magnetic fabric, and higher magmatic anisotropy degree values for amphibole+biotite than plagioclase. Based on numerical simulations of the fluid

  11. Fracture controls on valley persistence: the Cairngorm Granite pluton, Scotland

    NASA Astrophysics Data System (ADS)

    Hall, A. M.; Gillespie, M. R.

    2017-09-01

    Valleys are remarkably persistent features in many different tectonic settings, but the reasons for this persistence are rarely explored. Here, we examine the structural controls on valleys in the Cairngorms Mountains, Scotland, part of the passive margin of the eastern North Atlantic. We consider valleys at three scales: straths, glens and headwater valleys. The structural controls on valleys in and around the Cairngorm Granite pluton were examined on satellite and aerial photographs and by field survey. Topographic lineaments, including valleys, show no consistent orientation with joint sets or with sheets of microgranite and pegmatitic granite. In this granite landscape, jointing is not a first-order control on valley development. Instead, glens and headwater valleys align closely to quartz veins and linear alteration zones (LAZs). LAZs are zones of weakness in the granite pluton in which late-stage hydrothermal alteration and hydro-fracturing have greatly reduced rock mass strength and increased permeability. LAZs, which can be kilometres long and >700 m deep, are the dominant controls on the orientation of valleys in the Cairngorms. LAZs formed in the roof zone of the granite intrusion. Although the Cairngorm pluton was unroofed soon after emplacement, the presence of Old Red Sandstone (ORS) outliers in the terrain to the north and east indicates that the lower relief of the sub-ORS basement surface has been lowered by <500 m. Hence, the valley patterns in and around the Cairngorms have persisted through >1 km of vertical erosion and for 400 Myr. This valley persistence is a combined product of regionally low rates of basement exhumation and of the existence of LAZs in the Cairngorm pluton and sub-parallel Caledonide fractures in the surrounding terrain with depths that exceed 1 km.

  12. Fracture controls on valley persistence: the Cairngorm Granite pluton, Scotland

    NASA Astrophysics Data System (ADS)

    Hall, A. M.; Gillespie, M. R.

    2016-12-01

    Valleys are remarkably persistent features in many different tectonic settings, but the reasons for this persistence are rarely explored. Here, we examine the structural controls on valleys in the Cairngorms Mountains, Scotland, part of the passive margin of the eastern North Atlantic. We consider valleys at three scales: straths, glens and headwater valleys. The structural controls on valleys in and around the Cairngorm Granite pluton were examined on satellite and aerial photographs and by field survey. Topographic lineaments, including valleys, show no consistent orientation with joint sets or with sheets of microgranite and pegmatitic granite. In this granite landscape, jointing is not a first-order control on valley development. Instead, glens and headwater valleys align closely to quartz veins and linear alteration zones (LAZs). LAZs are zones of weakness in the granite pluton in which late-stage hydrothermal alteration and hydro-fracturing have greatly reduced rock mass strength and increased permeability. LAZs, which can be kilometres long and >700 m deep, are the dominant controls on the orientation of valleys in the Cairngorms. LAZs formed in the roof zone of the granite intrusion. Although the Cairngorm pluton was unroofed soon after emplacement, the presence of Old Red Sandstone (ORS) outliers in the terrain to the north and east indicates that the lower relief of the sub-ORS basement surface has been lowered by <500 m. Hence, the valley patterns in and around the Cairngorms have persisted through >1 km of vertical erosion and for 400 Myr. This valley persistence is a combined product of regionally low rates of basement exhumation and of the existence of LAZs in the Cairngorm pluton and sub-parallel Caledonide fractures in the surrounding terrain with depths that exceed 1 km.

  13. Magmatic tempo of Earth's youngest exposed plutons as revealed by detrital zircon U-Pb geochronology.

    PubMed

    Ito, Hisatoshi; Spencer, Christopher J; Danišík, Martin; Hoiland, Carl W

    2017-09-29

    Plutons are formed by protracted crystallization of magma bodies several kilometers deep within the crust. The temporal frequency (i.e. episodicity or 'tempo') of pluton formation is often poorly constrained as timescales of pluton formation are largely variable and may be difficult to resolve by traditional dating methods. The Hida Mountain Range of central Japan hosts the youngest exposed plutons on Earth and provides a unique opportunity to assess the temporal and spatial characteristics of pluton emplacement at high temporal resolution. Here we apply U-Pb geochronology to zircon from the Quaternary Kurobegawa Granite and Takidani Granodiorite in the Hida Mountain Range, and from modern river sediments whose fluvial catchments include these plutons in order to reconstruct their formation. The U-Pb data demonstrate that the Kurobegawa pluton experienced two magmatic pulses at ~2.3 Ma and ~0.9 Ma; whereas, to the south, the Takidani pluton experienced only one magmatic pulse at ~1.6 Ma. These data imply that each of these magmatic systems were both spatially and temporally distinct. The apparent ~0.7 Myr age gap between each of the three magmatic pulses potentially constrains the recharge duration of a single pluton within a larger arc plutonic complex.

  14. Interplay of plutonism and regional deformation in an obliquely convergent arc, southern Coast Belt, British Columbia

    NASA Astrophysics Data System (ADS)

    Brown, E. H.; Talbot, J. L.; McClelland, W. C.; Feltman, J. A.; Lapen, T. J.; Bennett, J. D.; Hettinga, M. A.; Troost, M. L.; Alvarez, K. M.; Calvert, A. T.

    2000-06-01

    The Coast Plutonic Complex is an extensive zone of continental growth that formed along the Mesozoic convergent margin of northwestern North America. The orogeny creating this belt involved terrane accretion and assembly, massive upward transfer and emplacement of sial in the form of batholiths constituting a magmatic arc, and transformation of broad tracts of sedimentary and volcanic rocks into crystalline continental crust, all operating in more or less the same space and time. The mechanisms and interplay of these orogenic processes are well displayed in the Harrison Lake area of the southern Coast Belt, British Columbia. Great structural relief across the area exhibits a present-day architecture defined by thin, thrust-stacked terrane sheets and early concordant pluton sheets folded on a macroscopic scale, all truncated by oblique dextral-reverse faults and overlain by later floored plutons. Construction of this complex began with terrane assembly on orogen-normal thrusts during a lull in plutonism in the Early Cretaceous. Low-grade metamorphism during this event indicates only modest crustal thickening. Subsequent plutons intruded into the assembled terranes appear to be composites of sheets. Early pluton sheets are now steeply dipping due to folding but were likely intruded as horizontal bodies. Large ovoid post folding plutons are mostly subhorizontal floored bodies, at least in part sheeted. These plutons are underlain by Barrovian mineralogic aureoles that indicate downward vertical displacement of 10 km or more during plutonism, suggesting pluton emplacement by vertical inflation. Magmatic fabrics in these bodies, and the discordant relation of plutons to regional structures, preclude emplacement in active fault zones. Penetrative strain aureoles flanking plutons are mostly limited to zones a few hundred meters wide, and regional tectonic structures are widely preserved. Tectonic deformation of the arc is characterized by contraction and strike-slip, not

  15. ABCGheritage project - promoting geotourism in northern Finland, northern Norway and the Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Pihlaja, Jouni; Johansson, Peter; Lauri, Laura S.

    2014-05-01

    Nature tourism has been a growing business sector in the Barents area during the recent decades. With the purpose to develop nature tourism in a sustainable way, a cooperation project ABCGheritage - Arctic Biological, Cultural and Geological Heritage has been carried out. Project has received partial funding from the EU Kolarctic ENPI program. In the geoheritage part of the project the main activities were aimed to develop pro-environmental ways of geotourism in the area. The three main participants in the geoheritage part of the project are the Geological Survey of Finland, Northern Finland Office, the Geological Institute of the Kola Science Centre of the Russian Academy of Sciences and Bioforsk Soil and Environment from northeastern Norway. The duration of the project is 2012-2014 and most of the work has already been completed even if most of the results are not published yet. Totally ten different tasks have been implemented in the geological part of the project. The largest task has been the preparation of a geological outdoor map and guide book of the Khibiny Tundra locating in the central part of the Kola Peninsula. In Finland already 11 such maps have been published, and the experiences gained during their production have been used in this project, too. Geological heritage trails to the Khibiny Tundra have also been created and they will be drawn on the map. The second concrete result is the Barents Tour for Geotourist -guide, which will be published as a guide book, web pages and an exhibition. The route comprises ca 35 best geological demonstration sites along the circle route from northern Finland to northeastern Norway, from there to Kola Peninsula and then back to Finland. Information of the route will be available for all interested travelers. In addition to the geological outdoor map of the Khibiny Tundra and "Barents Tour for Geotourists"-guide, the primary outputs of the project are the geological nature trails on the field, geological

  16. Anorthosites and alkaline rocks from the deep crust of peninsular India

    NASA Technical Reports Server (NTRS)

    Leelanandam, C.; Ratnakar, J.; Reddy, M. Narsimha

    1988-01-01

    The anorthosite and alkaline rock localities in the Precambrian Shield of Peninsular India were reviewed. There are approximately 50 localities of such rocks, generally restricted to the Eastern Ghats mobile belt. The alkaline plutons are typically confined to the margin of the Eastern Ghats. The anorthosites are all greater than 500 sq km, but many exhibit similarities to one another. It was suggested that the anorthosites are associated with cryptic sutures, and are thought to have originated as a result of ponding of basaltic magmas. An analogy was drawn between the Eastern Ghats belt and the Grenville Province of the Canadian Shield.

  17. The primary circuit materials properties results analysis performed on archive material used in NPP V-1 and Kola NPP Units 1 and 2

    SciTech Connect

    Kupca, L.; Beno, P.

    1997-04-01

    A very brief summary is provided of a primary circuit piping material properties analysis. The analysis was performed for the Bohunice V-1 reactor and the Kola-1 and -2 reactors. Assessment was performed on Bohunice V-1 archive materials and primary piping material cut from the Kola units after 100,000 hours of operation. Main research program tasks included analysis of mechanical properties, corrosion stability, and microstructural properties. Analysis results are not provided.

  18. Reconnaissance study of the Taylor Mountains pluton, southwestern Alaska

    USGS Publications Warehouse

    Hudson, Travis L.; Miller, Marti L.; Klimasauskas, Edward P.; Layer, Paul W.

    2010-01-01

    The Taylor Mountains pluton is a Late Cretaceous to early Tertiary (median age 65 + or ? 2 Ma) epizonal, composite biotite granite stock located about 235 km (145 mi) northeast of Dillingham in southwestern Alaska. This 30 km2 (12 mi2) pluton has sharp and discordant contacts with hornfels that developed in Upper Cretaceous clastic sedimentary rocks of the Kuskokwim Group. The three intrusive phases in the Taylor Mountains pluton, in order of emplacement, are (1) porphyritic granite containing large K-feldspar phenocrysts in a coarse-grained groundmass, (2) porphyritic granite containing large K-feldspar and smaller, but still coarse, plagioclase, quartz, and biotite phenocrysts in a fine-grained groundmass, and (3) fine-grained, leucocratic, equigranular granite. The porphyritic granites have different emplacement histories, but similar compositions; averages are 69.43 percent SiO2, 1.62 percent CaO, 5.23 percent FeO+MgO, 3.11 percent Na2O, and 4.50 percent K2O. The fine-grained, equigranular granite is distinctly felsic compared to porphyritic granite; it averages 75.3 percent SiO2, 0.49 percent CaO, 1.52 percent FeO+MgO, 3.31 percent Na2O, and 4.87 percent K2O. Many trace elements including Ni, Cr, Sc, V, Ba, Sr, Zr, Y, Nb, La, Ce, Th, and Nd are strongly depleted in fine-grained equigranular granite. Trace elements are not highly enriched in any of the granites. Known hydrothermal alteration is limited to one tourmaline-quartz replacement zone in porphyritic granite. Mineral deposits in the Taylor Mountains area are primarily placer gold (plus wolframite, cassiterite, and cinnabar); sources for these likely include scattered veins in hornfels peripheral to the Taylor Mountain pluton. The granite magmas that formed the Taylor Mountains pluton are thought to represent melted continental crust that possibly formed in response to high heat flow in the waning stage of Late Cretaceous subduction beneath interior Alaska.

  19. Petrogenesis and tectonic implications of the Early Carboniferous to the Late Permian Barleik plutons in the West Junggar (NW China)

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Han, Bao-Fu; Ren, Rong; Chen, Jia-Fu; Wang, Zeng-Zhen; Zheng, Bo

    2017-02-01

    The Paleozoic accretionary orogenesis and continental crustal growth in Central Asia are thought to have close relationship with the evolution of the Paleo-Asian Ocean (PAO). The well-exposed plutons in the northern Barleik Mountains of the West Junggar region, NW China, may provide essential insights into the evolution of the Junggar Ocean, a branch of the PAO, and mechanism of continental crustal growth. Our work on the Barleik plutons indicates an early suite of 324-320 Ma diorite and a late suite of 314-259 Ma quartz syenite and granitic porphyry. All the plutons are characterized by high-K calc-alkaline to shoshonitic signatures, varying depletion in Nb, Ta, Sr, P, Eu, and Ti, low initial 87Sr/86Sr ratios (0.70241-0.70585), strongly positive εNd(t) values (+ 5.7-+7.7), and young one-stage Nd model ages (390-761 Ma), suggesting that they resulted from different batches of magma that were produced by fractional crystallization of a metasomatized mantle source with minor crustal contamination. The diorite is coeval with the youngest arc magmatic rocks, indicating a subduction-related origin. By contrast, the quartz syenite and granitic porphyry are geochemically similar to A2-type granites, with high Zr, Ga, and FeOT/[FeOT + MgO], and are coeval with the widespread plutons in the West Junggar. This, together with the occurrence of Late Carboniferous fluvial deposits and the lack of < 320 Ma ophiolitic and subduction-related metamorphic lithologies, definitively indicates a post-collisional setting after the closure of the Junggar Ocean. Slab breakoff accompanied by asthenospheric upwelling and basaltic underplating is a possible geodynamic process that is responsible for the post-collisional magmatism and vertical crustal growth in the region. Thus a tectonic switch from subduction to post-collision started at the end of the Early Carboniferous ( 320 Ma), probably as a result of the final closure of the Junggar Ocean.

  20. Nd and Sr isotopic signatures of Mesozoic plutons in northeastern North America

    SciTech Connect

    Foland, K.A.; Jiang-feng, C.; Gilbert, L.A.; Hofmann, A.W.

    1988-08-01

    Nd and Sr initial isotope ratios are reported for 17 Mesozoic plutons of the Monteregian Hills and White Mountain series provinces in northeastern North America. Some variation in the isotopic ratios at most localities is caused by crustal-contamination processes. When the crustal assimilation effects are taken into account, the initial ratios for apparently uncontaminated, mantle-derived parental magmas show only restricted range in /sup 87/Sr//sup 86/Sr (0.7032 to 0.7040) and epsilon/sub Nd/ (T) (+5.4 to +2.3), which are inversely correlated. These ratios characterize alkaline to subalkaline magmas emplaced over more than 400 km/sup 2/ and about 80 m.y. The isotopic and trace-element characteristics are broadly similar to those of many modern ocean-island basalts, specifically the New England Seamounts, suggesting similar time-integrated, lithophile-element-depleted mantle sources. The results are consistent with plume-related mantle sources deeper than the subcontinental mantle.

  1. Efficiency of remediation of technogenic barrens around the Pechenganikel works in the Kola Subarctic

    NASA Astrophysics Data System (ADS)

    Koptsik, G. N.; Koptsik, S. V.; Smirnova, I. E.

    2014-05-01

    Remediation of the technogenic barrens around the Pechenganikel works on the Kola Peninsula resulted in the improvement of the soil properties, namely, in a decrease in acidity and enrichment with nutrients, which continued for several years. However, the reaction of most of the treated soils remained strongly acid, and the concentrations of available calcium, magnesium, potassium, and phosphorus were much lower than their background levels and the demands of the plants for nutrients (especially, for magnesium and potassium). The soils were depleted in available manganese and zinc. Most of the treated soils contained the same (or higher) amounts of available nickel and copper compounds in comparison with their untreated analogues. The willow plantations on the remediated plots were in a satisfactory state, but they experienced a deficit of magnesium, manganese, and zinc; they consumed elevated amounts of nickel and copper. Recommendations on the nutrient regime of the soils aimed at decreasing the mobility and biological availability of heavy metals were made.

  2. A catastrophic holocene event in the lake bottom sediments of the Kola region (northeastern Fennoscandian shield)

    NASA Astrophysics Data System (ADS)

    Nikolaeva, S. B.; Lavrova, N. B.; Denisov, D. B.

    2017-03-01

    Horizons with seismogenic sediments are revealed in the bottom sediments of the lake basins in the southwestern Kola Peninsula. In the borehole cores, they are represented by material that sharply differs from the overlying and underlying sediments: fragments of gyttia, siltstone, wood, sand, and peat that are embedded in the sapropelic matrix and look like breccia. These sediments reflect a strong catastrophic event from the Holocene that occurred 6000-5400 14C yr BP. The seismic events that happened in the middle Holocene in the northeastern Fennoscandian shield indicate a significant role of the tectonic component in the damping process of relaxation of the Earth's crust in the unloading of the recent glacier cover.

  3. Alternative technologies for remediation of technogenic barrens in the Kola Subarctic

    NASA Astrophysics Data System (ADS)

    Koptsik, G. N.; Koptsik, S. V.; Smirnova, I. E.

    2016-11-01

    The efficiency of remediation of technogenic barrens under the reduction of air pollutant emissions from the Severonikel smelter in the Kola Subarctic is determined largely by the soil state and the technology applied. The covering of the contaminated soils with artificially made material based on organomineral substrates and the following liming and fertilization promoted a sharp and long-term reduction of acidity, decrease in the biological availability of heavy metals, increase in the supply with nutrients, and improvement of the life state of willow and birch plantations. The effect of economically more profitable chemo-phytostabilization is short-term; it requires constant maintenance. Under the current production and a high level of soil contamination, repeated measures are required to optimize the soil reaction, supply with nutrients, and to correct the availability of heavy metals in the soils based on the results of continuous monitoring

  4. Mechanism and duration of plutonic processes in oceanic crust: the example of the South Rallier du Baty intrusive complex, Kerguelen Archipelago

    NASA Astrophysics Data System (ADS)

    Ponthus, Léandre; Guillaume, Damien; de Saint Blanquat, Michel; le Romancer, Marc; Pearson, Norman; Grégoire, Michel; O'Reilly, Sue Y.

    2017-04-01

    The Kerguelen plateau was initiated by a large-scale tholeiitic-transitional magmatic episode. The rocks of the Kerguelen archipelago, dominated by basalts, record an evolution from this early transitional magmatism to Kerguelen plume-related alkaline magmatism. The latter is characterised by a wide range of volcanic and plutonic rocks from basic to differentiated felsic rocks, which outcrop at different locations in the archipelago but are especially abundant in the southwest of Kerguelen archipelago. This is the location of outcrop of the South Rallier Du Baty Intrusive Center (SRDBIC) which constitutes the largest plutonic body, classically interpreted as a cauldron. The SRDBIC is an elliptical plutonic body of 13 by a minimum of 17 km with a N100-110 long axis. The rock composition range from gabbro to quartz rich-syenite and define a typical alkaline oversaturated magmatic serie. The contact is generally outward dipping but we have identified two contrasting geometries: one steeply dipping and crosscutting the basaltic lava flows, the other more shallowly dipping and concordant. At the scale of the Kerguelen archipelago, the orientation of the basaltic lava flows constituting the wall-rocks of the SRDBIC is very regular but is not strictly horizontal, showing a low dip (3-5°) toward the SE, due to recent tilting. We observe a change in this orientation when approaching the SRDBIC: all around the east and south margins of the SRDBIC, we measure a progressive tilting of the plateau basalts, reaching dips of 20-40° away from the SRDBIC. The amplitude of this tilt suggests that the thickness of the SRDIC is between 2.5 and 3.5 km, defining a total volume of 200-400 km3. The spatial coincidence between this change in basalt orientation and the intrusive centre clearly shows a causal relationship related to uplifting of the plateau basalts during the formation of the SRDBIC. Field observations and fabric studies show that the plutonic complex was formed by

  5. An ecotoxicity assessment of contaminated forest soils from the Kola Peninsula.

    PubMed

    Paton, Graeme I; Viventsova, Ekaterina; Kumpene, Jurate; Wilson, Michael J; Weitz, Hedda J; Dawson, Julian J C

    2006-02-15

    Point source copper and nickel contamination emanating from smelters of the Kola Peninsula, NW Russia, has been observed since the mid-1960s. Previous studies have concentrated on the spatial distribution of heavy metals and their effects on forest ecology and indigenous mammals and birds. Soil is perceived as the major repository for the metal pollutants but there is a need to link the soil concentration of pollutants on the Kola Peninsula with biological parameters. Many standard methods currently used in soil ecotoxicology are developed and refined with artificial amendments and rarely modified for use in historically contaminated environments. In this study, forest soils were sampled along a 34 km transect from the smelter and analysed both chemically and with a range of ecologically relevant biological tests. Soil respiration, total nematode count, microbial heterotrophic numbers and minimal inhibitory concentrations to copper and nickel were carried out on bulk soil. The soil pore water was tested with bacterial and fungal bioluminescence-based biosensors. The heterotrophic numbers and their inhibitory concentration showed strong correlation with heavy metal concentrations while decreasing biosensor luminescence was related to increasing copper concentrations present in the pore waters. Overall, there were considerable impacts on some microbial parameters but other measures including respiration and nematode populations were insensitive to pollutant levels. While chemical analysis of heavy metals proved essential in defining the extent of contamination, environmentally relevant ecotoxicological tests complemented these data by demonstrating pollutant impact. Ecotoxicological approaches that study both the bulk soil and pore water may represent the key to understanding the fate of heavy metal in soils.

  6. Geology of the Redcap Mountain area, Coast Plutonic Complex, British Columbia

    SciTech Connect

    Hill, M.L.

    1985-01-01

    The Redcap Mountain area lies within the Coast Plutonic Complex about 60 km northeast of Prince Rupert, British Columbia. Detailed geologic investigations in this area provide information on the protolith of the Central Gneiss Complex, the conditions and timing of metamorphism and deformation, and the timing of plutonism. These results have significant implications for the tectonic history of this part of the Coast Plutonic Complex.

  7. Deeply Eroded Massif Anorthosite and Nepheline Syenite of the Chimakurti-Uppalapadu Plutons, Peninsular India: Cospatial but not Comagmatic

    NASA Astrophysics Data System (ADS)

    Kumar, K.; Frost, C. D.; Frost, B. R.

    2001-12-01

    Massif anorthosites are generally thought to be ultimately of mantle origin. However, the lack of samples representing primitive liquid compositions and paucity of early cumulates limits the understanding of the processes that produced them. Some of the most deeply eroded massif anorthosite complexes are exposed within the southern Eastern Ghat Belt of Peninsular India, and provide an excellent opportunity to study the processes that operated in the deep magma chambers beneath the massifs. In this area Si-undersaturated nepheline syenites are associated with anorthosite complexes, a case that is not reported elsewhere in the world. The objectives of the present study are two fold: 1) to identify the processes that acted at the lowest level of the anorthosite complexes and 2) to determine the relationship between cospatial anorthosites and nepheline syenites. Cospatial alkaline-tholeiitic magmatism is strikingly displayed in the Chimakurti-Uppalapadu plutons within Prakasam Province. The Chimakurti pluton is concentrically zoned, and from core to margin consists of 1) olivine clinopyroxenite, 2) anorthosite, 3) olivine gabbronorite and 4) gabbronorite. It emplaced at mid-crustal depths (~6 kb; 16-18 km) and is undeformed and unmetamorphosed. Comparably deep-seated massifs are strongly metamorphosed (Adirondacks) and unmetamorphosed ones typically have shallow emplacement histories (Laramie). Unlike many massif anorthosite complexes, the Chimakurti pluton is associated with a gravity high of the order of 20 to 30 mGal; consistent with the presence of ultramafic cumulates. The Uppalapadu pluton is composed of nepheline syenite (NS). An arcuate band of hornblende syenite with pockets of quartz syenite and ferro-syenite (HQF series) is present between the two plutons. Field, petrographic, mineralogical and geochemical evidence suggests that the Clinopyroxenite-Anorthosite-Gabbro (CAG) suite of Chimakurti is formed by crystal-liquid fractionation (compounded by

  8. Paleomagnetism of Devonian dykes in the northern Kola Peninsula and its bearing on the apparent polar wander path of Baltica in the Precambrian

    NASA Astrophysics Data System (ADS)

    Veselovskiy, Roman V.; Bazhenov, Mikhail L.; Arzamastsev, Andrey A.

    2016-04-01

    Mafic dykes and large alkaline and carbonatite intrusions of Middle-Late Devonian age are widespread on the Kola Peninsula in NE Fennoscandia. These magmatic rocks are well characterized with petrographic, geochemical and geochronological data but no paleomagnetic results have been reported yet. We studied dolerite dykes from the northern part of the Peninsula and isolated three paleomagnetic components in these rocks. A low-temperature component is aligned along the present-day field, while a major constituent of natural remanent magnetization is an intermediate-temperature component (Decl. = 79.6°, Inc. = 78.5°, α95 = 5,9°, N = 17 sites) that is present in most Devonian dykes but is found in some baked metamorphic rocks and Proterozoic dykes too. Finally, a primary Devonian component could be reliably isolated from two dykes only. Rock-magnetic studies point to presumably primary low-Ti titanomagnetite and/or pure magnetite as the main remanence carriers but also reveal alteration of the primary minerals and the formation of new magnetic phases. The directions of a major component differ from the Middle Paleozoic reference data for Baltica but closely match those for the 190 ± 10 Ma interval recalculated from the apparent polar wander path of the craton. We assume that this Early Jurassic component is a low-temperature overprint of chemical origin. The main impact of the new results is not to mid-Paleozoic or Early Mesozoic times but to much older epochs. Analysis of paleomagnetic data shows that the directionally similar remanences are present in objects with the ages ranging from 500 Ma to 2 Ga over entire Fennoscandia. Hence we argue that an Early Jurassic remagnetization is of regional extent but cannot link it to a certain process and a certain tectonic event. If true, this hypothesis necessitates a major revision of the APWP for Baltica over a wide time interval.

  9. Origin and evolution of calcalkaline plutons in the Northeast Kingdom batholith, Vermont

    SciTech Connect

    Ayuso, R.A.; Arth, J.G.

    1985-01-01

    Geochemical and petrographic study of five calcalkaline Devonian plutons in the Northeast Kingdom batholith suggests that they were generated from similar sources but evolved differently. The modally homogeneous Willoughby granite (WG) and the Derby granodiorite (DG) are the most aluminous plutons and contain muscovite and biotite (+/- garnet). The West Charleston diorite (WCD) and the Nulhegan granodiorite (NG) are relatively mafic plutons containing pyroxene, hornblende, and biotite. The Echo Pond (EP) has a granodioritic core but is dioritic along its southern margin. Regular variations of major and trace elements are found in NG and in the relatively sodic DG. More erratic chemical variations are found for WG. The more mafic plutons have higher Sr and lower Rb, Nb and Ta compared to the more felsic WG and DG. Rare-earth patterns for all plutons show higher light than heavy rare-earths. However, the more mafic plutons are comparatively less enriched, have smaller Eu anomalies, and tend to have higher contents of heavy rare earths than the WG and DG. The felsic Willoughby pluton is the best candidate for an upper crustal minimum melt. A deeper origin for the more mafic plutons is likely. Significant differences in the rare earths and ferromagnesian elements indicate that the WG, DG, and EP cannot be related by a simple fractionation scheme to the more mafic plutons.

  10. Mantle plume related Paleozoic riftogenic alkaline magmatism of Mongolia: isotope and geocemical evidence.

    NASA Astrophysics Data System (ADS)

    Yarmolyuk, V.; Savatenkov, V.; Kozlovsky, A.

    2003-04-01

    Paleozoic alkaline magmatic activity in Mongolia associates with series of W-E trending rifts, ranged from south to north. The rifts system was evolved northward at three stages beginning from later Carboniferous-earlier Permian to later Permian. The isotopic-geochemical composition of the rocks from five volcano-plutonic bimodal complexes was studied. These complexes belong to the Gobi-Tien Shan Zone (GTZ) 310-290 Ma and the Gobi-Altai Zone (GAZ) 270 Ma of riftogenic alkaline magmatism. The studied volcano-plutonic complexes are formed by mafic rocks alkaline basalts and felsic rocks alkaline riolites (comendite and pantelerite) with subordinate rocks of intermedial composition (trachidacites, trachiandesites) and associated plutons of alkaline granites. Basaltic rocks of GTZ are characterized by positive eNd(T) values (+4.2 +7.0), 87Sr/86Sr(T) value ranged from 0.7036 to 0.7049, enrichment in Th, LREE, Sr, P, Zr, Hf, Ti and pronounced depletion in Nb and Ta. GTZ felsic rocks have general enrichment in most incompatible trace element (K, Rb, Th, Zr, Hf and REE) and depletion in Nb, Ta, Sr, P, Eu and Ti. The range of eNd(T) of alkaline riolites demonstrates general shift to more positive values (+5.8 +7.3) comparatively to that of basalts. Generally rocks of GAZ and GTZ volcano-plutonic complexes have similar geochemical features. However the GAZ alkaline riolites have more differentiated character (higher silica content, more strong depletion in Ti, Sr and Eu, enrichment in Rb and REE). Furthermore eNd(T) and 87Sr/86Sr(T) values of GAZ basalts demonstrate more wide scatter from +0.2 to +8.1 and from 0.7037 to 0.7054 respectively. Geochemical trends in the trace elements (REE, Y, Th, Nb, Ta) and in Sr-Nd isotope composition suggest that basaltic rocks were derived from OIB-like mantle sourse and underwent contamination during of fraction crystallization by material of subduced oceanic crust (Neoproterozoic ?). Felsic rocks were generated from OIB-like basaltic melt

  11. Antispasmodic and spasmolytic effects of methanolic extract from seeds of Garcinia kola on isolated rat small intestine.

    PubMed

    Udia, P M; Braide, V B; Owu, D U

    2009-12-01

    The antispasmodic and spasmolytic effects of methanolic extract of seeds of Garcinia kola Heckel were studied on smooth muscle preparations in vitro. The influence of the extract on rat duodenum, jejunum and ileum was investigated using acetylcholine and barium chloride as agonists. The extract exhibited dose-dependent antispasmodic effects on contractions induced by acetylcholine, and dose-dependent spasmolytic effects on spasms induced by cumulatively increased concentrations of acetylcholine and barium chloride. The graded log concentration-response curves for acetylcholine were non-parallel but shifted to the right in the presence of the extract. It is concluded that the Garcinia kola extract inhibits smooth muscle activity via other mechanisms but not involving neither cholinergic nor adrenergic receptor interaction.

  12. The Geochronology and Geochemistry of Caldera-related Plutons in the Southern Rocky Mountain Volcanic Field: Insight into the Volcanic-plutonic Connection

    NASA Astrophysics Data System (ADS)

    Zimmerer, M. J.; Mills, R. D.; Tappa, M. J.; McIntosh, W. C.; Coleman, D. S.

    2009-12-01

    Preliminary Ar-Ar and U-Pb results from the Questa (NM) and Mt. Aetna (CO) caldera systems indicate that their caldera-related plutons are not cumulates or residual material from which caldera-collapse ignimbrites differentiated. Rio Grande rift-related faulting and erosion at both locations provide exposures of intracaldera volcanic rocks and subcaldera intrusions, allowing for the comparison of cogenetic volcanic and plutonic rocks. Resurgent plutons at both locations are indistinguishable in age to the associated ignimbrite, however the majority of plutons are either younger or older than the caldera-forming event. The geochemistry of the resurgent plutons and corresponding ignimbrite is similar. These results challenge the common interpretation that melt for ignimbrite eruptions is derived from crystal-mushes, which are then preserved as plutons. The Questa caldera, northern New Mexico, formed during the 25.4 Ma eruption of the peralkaline Amalia Tuff. Peralkaline phases of two resurgent plutons, Virgin Canyon and Canada Pinabete, are geochemically similar to the Amalia Tuff, but these phases have yet to be successfully dated. The metaluminous phase of the Canada Pinabete pluton is indistinguishable in age to the Amalia Tuff, suggesting that the peralkaline phase is also contemporaneous. The remaining seven plutons associated with the Questa caldera were emplaced between 25.2 and 19.4 Ma. Postcaldera plutonism was coeval with volcanism, though these plutons have not been geochemically linked to any postcaldera volcanic rocks. The Mt. Aetna complex consists of the Mt. Princeton batholith and the nested Mt. Aetna caldera. The Mt. Princeton batholith has been inferred to be the less-evolved source of the 37.2 Ma Wall Mountain Tuff. During the eruption of the 34.0 Ma Badger Creek Tuff, the fully crystallized Mt. Princeton batholith was involved in the Mt. Aetna caldera collapse. New Ar-Ar and U-Pb ages indicate the Mt. Princeton batholith is too young to be the

  13. Zircon U-Pb ages and emplacement history of the Nodoushan plutonic complex in the central Urumieh-Dokhtar magmatic belt, Central Iran: Product of Neotethyan subduction during the Paleogene

    NASA Astrophysics Data System (ADS)

    Shahsavari Alavijeh, Badieh; Rashidnejad-Omran, Nematollah; Corfu, Fernando

    2017-08-01

    The Nodoushan plutonic complex is composed of a wide range of felsic and mafic rocks straddling several of the major orogenic zones in Iran. Diorite porphyry, diorite, granodiorite and granite intrusives belong to the central part of the Urumieh-Dokhtar magmatic belt, which is part of the Alpine-Himalayan orogenic belt. Monzogabbroic members of the complex are instead located within the bordering Sanandaj-Sirjan magmatic-metamorphic zone. These plutons were emplaced into Permian and lower Cretaceous sedimentary units and Eocene calc-alkaline volcanic and subvolcanic rocks. New U-Pb zircon ages reveal that the plutonic complex was assembled incrementally over ca. 15 m.y. during three main episodes at 40.487 ± 0.063 Ma near the Middle/Late Eocene boundary, at 30.52 ± 0.11 Ma and 30.06 ± 0.10 Ma in the Early Oligocene (Middle Rupelian) and at 24.994 ± 0.037 and 24.13 ± 0.19 Ma in the Late Oligocene (latest Chattian). The activity recorded in the Nodoushan plutonic complex represents the final stages of subduction-related magmatism prior to the eventual Miocene collision between the Arabian and Eurasian blocks.

  14. Why are plutons dry? Outgassing mechanisms of crustal magmatic bodies

    NASA Astrophysics Data System (ADS)

    parmigiani, andrea; Huber, Christian; Bachmann, Olivier; Leclaire, Sébastien

    2016-04-01

    Magma bodies crystallizing to completion within the crust (i.e., forming plutons) typically undergo significant amounts of second boiling (i.e. cooling and crystallization of dominantly anhydrous minerals lead to volatile saturation and bubble nucleation/growth). The low water content (< 1 wt % H2O) and vanishing residual porosity of most plutons, despite the high volatile concentrations of their magma sources (commonly > 6 wt % H2O for evolved compositions in subduction zones), testify that outgassing from crystalline mushy reservoirs must be an efficient and widespread process. Understanding this outgassing mechanism is key to understand how volatiles are transferred from mantle depths to the surface. From the hydrodynamics point of view, the mass balance of exsolved volatiles in these plutonic bodies is controlled by the difference between the rate of degassing (formation of bubbles by 2nd boiling) and outgassing (transport of gas out of the magma body). In this study, we use pore-scale multiphase modeling to constrain these rates as function of the crystal and volatile contents in the magma. Because second boiling is a slow process, one can consider equilibrium degassing as a valid assumption. Outgassing, on the other end, is controlled by the competition between buoyancy, capillary and viscous forces. Our numerical simulations are used to determine the most efficient setting for gas to escape its magmatic trap. The high viscosity of interstitial melts and capillary forces (due to the non-wetting nature of the gas phase with most of the mineral phases in magmatic systems) strongly limits gas transport until vertically extensive gas channels are generated. We show that channels can readily form in volatile-rich coarse-grained mush zones in the upper crust, and allow efficient outgassing at crystallinities around 50-75 vol%, when millimetric bubbles can still win capillary resistive forces.

  15. Uplift and subduction erosion in southwestern Mexico since the Oligocene: pluton geobarometry constraints

    NASA Astrophysics Data System (ADS)

    Morán-Zenteno, Dante J.; Corona-Chavez, Pedro; Tolson, Gustavo

    1996-06-01

    Details of the late Oligocene to Middle Miocene uplift and tectonic erosion episodes of the southwestern continental margin of Mexico can be inferred using Al tot geobarometry of igneous hornblendes, geochronology, and field relations. On the basis of such analyses carried out between Acapulco and Huatulco we find the following: (1) Calc-alkaline batholiths exposed along the coast from Acapulco to Huatulco, mostly in the 35-25 Ma age range, were emplaced at depths between 13 and 20 km. (2) The contact relationships between these plutons and their host rocks, and the exposure of volcanic counterparts, 70 km from the coastline, indicate a landward decrease in the amount of uplift. (3) A comparison of the time differences between intrusion and cooling ages of batholiths along the coast suggest that cooling rates were, in general, higher between Acapulco and Huatulco than those along the margin between Puerto Vallarta and Manzanillo, 700 km northwest of Acapulco. (4) The uplift of this coastal belt occurred during the late stages of magmatism and after its cessation, triggering intensive subaerial erosion of supracrustal rocks and the exposure of midcrustal rocks such as granitic batholiths and amphibolite facies metamorphic assemblages of the Xolapa Complex. These findings, in conjunction with the geometry of the present continental margin, as well as the offshore tectonic and stratigraphic features, support previous interpretations of very active late Oligocene to Middle Miocene subduction erosion after the onset of strike-slip tectonics related to the detachment and subsequent eastward displacement of the Chortis block. Subduction erosion involved both trench sediments and crystalline (continental framework) rocks. Different rates of continental framework erosion are assessed on the basis of the bathymetric fluctuations of the upper slope trench sediments and the age of the accretionary prism. Subsidence of the offshore continental basement suggests intense episodes

  16. Petrology of the shoshonitic Çambaşı pluton in NE Turkey and implications for the closure of the Neo-Tethys Ocean: Insights from geochemistry, geochronology and Sr-Nd isotopes

    NASA Astrophysics Data System (ADS)

    Özdamar, Şenel; Roden, Michael F.; Billor, Mehmet Z.

    2017-07-01

    The Eastern Pontide Orogenic Belt (EPOB) is one of the well-preserved continental magmatic arcs in the Alpine-Himalayan Belt and consists of Paleozoic to Miocene plutonic bodies. This paper presents new geological, bulk-rock major and trace element analyses, biotite Ar-Ar ages and Sr-Nd isotope data on representative samples from the Çambaşı granitic body exposed in the northwestern part of the EPOB. Although the majority of the plutons in the EPOB show calc-alkaline affinity and I-type character, the Çambaşı pluton has a shoshonitic affinity and an I-type, metaluminous signature. The pluton is composed of mainly monzonite, quartz monzonite and granite bodies including monzo-dioritic mafic microgranular enclaves (MMEs). Excluding the MMEs, these rocks have 57.7-70.2 wt.% SiO2, 13.1-17.5 wt.% Al2O3, 3.06-3.64 wt.% Na2O, 3.66-5.92 wt.% K2O, 0.33-3.3 wt.% MgO and Mg# < 30, indicating intermediate to evolved compositions. They are characterized by light rare earth element (LREE)-enrichment, relatively flat heavy rare earth element (HREE) patterns with small negative Eu anomalies and moderately fractioned REE patterns [average (La/Yb)N = 11.32]. Decreasing Fe2O3T, MgO, CaO, TiO2, Ba, Eu, and Sr with increasing SiO2 contents are consistent with fractional crystallization and can be related to fractionation of plagioclase, clinopyroxene, hornblende, apatite and Fe-Ti oxides. Initial 87Sr/86Sr ratios vary between 0.70470 and 0.70478, while those of 143Nd/144Nd lie between 0.51262 and 0.51263. Major, trace element and initial Sr-Nd homogeneity show that fractional crystallization played a key role in the evolution of the pluton. 40Ar/39Ar dating of four biotite samples from the pluton gave plateau ages of between 44.62 ± 0.1 Ma and 44.10 ± 0.0 Ma, which are interpreted as cooling ages of the plutonic rocks. We suggest that the Çambaşı pluton formed in a post-collisional extensional setting where partial melting of chemically enriched lithospheric mantle was

  17. Nutrient and phytochemical composition of two varieties of Monkey kola (Cola parchycarpa and Cola lepidota): An underutilised fruit.

    PubMed

    Ene-Obong, Henrietta N; Okudu, Helen O; Asumugha, Ukamaka V

    2016-02-15

    The nutrient and phytochemical composition of two varieties of Monkey kola: Cola parchycarpa and Cola lepidota were determined. The pulps were extracted, grated and dried using solar dryer. Dried pulps were milled into flour with attrition milling machine (0.5mm sieve size). The nutrient compositions were determined using standard AOAC methods. Gravimetric and spectrophotometric methods were used for phytochemical determinations. There were significant (p<0.05) differences in the proximate and some mineral and vitamin composition of the two varieties. Most abundant minerals were calcium (195-199mg for C. parchycarpa), potassium (204-209mg/100g for C. lepidota) and β-carotene (2755-5028μg/100g for C. parchycarpa). Calcium:phosphorus and sodium:potassium ratios were adequate (>1.0 and ⩽0.06, respectively). Monkey kola had substantial amounts of iron, zinc, and copper; the B-vitamins and vitamin C. The phytochemical contents were quiet high, the most abundant being flavonoids (415-494mg/100g). Monkey kola is a fruit that should be fully exploited for its potential health benefits.

  18. Effect of dietary Garcinia kola seed on selected serum electrolytes and trace metals in male Albino rats.

    PubMed

    Agada, P O; Braide, V B

    2009-06-01

    The effects of various doses of dietary intake of Garcinia kola seed powder [incorporated in animal feed at levels of 5% w/w, 10% w/w and 20% w/w and fed daily for six weeks] on serum levels of selected electrolytes [K+, Na+, CI-, HCO3-, Mg2+ and Ca2+] and trace metals [Cu2+, Zn2+ and Mn2+] were studied in male Albino rats [100-150 g body wt]. The pair-fed controls received basal feed diet daily for six weeks. Results showed a significant [P<0.05] dose dependent elevation of serum CI-, HCO3-, Ca2+, Mg2+, Cu2+, Zn2+ and Mn2+. These findings point to a possible relationship with already documented histopathology of various organs [such as the gonads] induced by Garcinia kola seed. It is also conjectured that the documented antibacterial, anti-inflammatory, anti-spasmodic, antidiabetic and antifertility effects of Garcinia kola seed may have underlying involvement of alterations in body levels of trace metals and electrolytes.

  19. Emplacement mode of a composite post-collisonal pluton in the Klamath Mountains (California, USA)

    NASA Astrophysics Data System (ADS)

    Machek, M.; Zavada, P.; Spicak, A.

    2011-12-01

    The Klamath Mountains represent an accreationary complex on the northwest California and southwestern Oregon. It consists of four arcuate belts representing terranes of former island archipelago environments that span in age from Paleozoic to Jurrasic and are divided by eastward dipping thrust faults (Snoke and Barnes, 2006). During and after the accretion, the entire thrust sheet was penetrated by numerous plutonic bodies. The Castle Crags pluton was selected for detailed internal fabrics to understand the emplacement mode of post-collisional plutons. Castle Crags pluton that intruded the Eastern Klamath terrane and in particular ultramafic Trinity Complex subterrane is an elliptical NW-SE elongated pluton with 12 km and 7 km in its long and short dimension, respectively. It is a well exposed composite plutonic body with about 1 km vertical crossfall. The pluton is affected by prominent NW-SE trending vertical joints and another less well developed vertical set perpendicular to the first one. The pluton is zoned and consists of three following igneous varieties: 1) marginal fine-grained granodioritic facies with abundant subsolidus shear zones, 2) coarse-grained granodiorite and 3) central, circular in plan-form and about 2 km in diameter, domain of trondhjemite. Numerous miarolitic cavities with macroscopically measurable trends mark the transition between the central trondhjemite and surrounding granodiorite (Vennum, 1980 a,b). Macroscopic foliations, jointing and sampling on the Castle Crags was carried out along the main crest of the pluton and numerous sideway crests and valleys gaining about 70 samples. The internal magmatic foliations and magnetic foliations show a concentric pattern of margin-parallel vertical foliations. The magnetic lineations reveal plunge trends parallel to the margins of the pluton and continuously increasing plunge angles from the margin to the core of the pluton. The zonality and fabric pattern of the pluton can reflect either

  20. Alkaline "Permanent" Paper.

    ERIC Educational Resources Information Center

    Pacey, Antony

    1991-01-01

    Discussion of paper manufacturing processes and their effects on library materials focuses on the promotion of alkaline "permanent" paper, with less acid, by Canadian library preservation specialists. Standards for paper acidity are explained; advantages of alkaline paper are described, including decreased manufacturing costs; and…

  1. Anodes for alkaline electrolysis

    DOEpatents

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  2. Glomerophyric plagioclase in epizonal plutons: synneusis or peritectic reaction relationship

    SciTech Connect

    Hogan, J.P.

    1985-01-01

    Glomerophyric plagioclase, a common texture in epizonal granites often attributed to synneusis, may record the peritectic liquidus relationship in the ternary feldspar system. This texture represents a crystallization process rather than a coincidental union of phenocrysts in the melt. Petrologic studies of the Northport monzogranite, Maine, yield P-T conditions of 1.5-1.0 Kb, 703/sup 0/C. Plagioclase crystallized early in the Northport pluton with dendritic, discontinuously zoned cores (An/sub 40/) and normal oscillatory zoned margins (An/sub 35/ to An/sub 10/). Magmatic resorption of the plagioclase resulted in embayment of the margins and dendritic cores. Textural evidence suggests plagioclase and alkali feldspar did not coprecipitate. Alkali feldspar crystallization was initiated concurrent with resorption of plagioclase along the peritectic portion of the liquidus boundary. A model for the formation of glomerophyric plagioclase clusters, derived from the study of the Northport pluton, suggests that a narrow halo of plagioclase like component in the surrounding melt, produced during resorption, envelops individual plagioclase phenocrysts. Overlap of these enrichment halos shifts the bulk composition of the intervening melt off the boundary line into the plagioclase field, resulting in crystallization of a thin layer of plagioclase which bonds the resorbed phenocrysts together.

  3. Guidelines to classification and nomenclature of Arabian felsic plutonic rocks

    USGS Publications Warehouse

    Ramsay, C.R.; Stoeser, D.B.; Drysdall, A.R.

    1986-01-01

    Well-defined procedures for classifying the felsic plutonic rocks of the Arabian Shield on the basis of petrographic, chemical and lithostratigraphic criteria and mineral-resource potential have been adopted and developed in the Saudi Arabian Deputy Ministry for Mineral Resources over the past decade. A number of problems with conventional classification schemes have been identified and resolved; others, notably those arising from difficulties in identifying precise mineral compositions, continue to present difficulties. The petrographic nomenclature used is essentially that recommended by the International Union of Geological Sciences. Problems that have arisen include the definition of: (1) rocks with sodic, zoned or perthitic feldspar, (2) trondhjemites, and (3) alkali granites. Chemical classification has been largely based on relative molar amounts of alumina, lime and alkalis, and the use of conventional variation diagrams, but pilot studies utilizing univariate and multivariate statistical techniques have been made. The classification used in Saudi Arabia for stratigraphic purposes is a hierarchy of formation-rank units, suites and super-suites as defined in the Saudi Arabian stratigraphic code. For genetic and petrological studies, a grouping as 'associations' of similar and genetically related lithologies is commonly used. In order to indicate mineral-resource potential, the felsic plutons are classed as common, precursor, specialized or mineralized, in order of increasing exploration significance. ?? 1986.

  4. Guidelines to classification and nomenclature of Arabian felsic plutonic rocks

    NASA Astrophysics Data System (ADS)

    Ramsay, C. R.; Stoeser, D. B.; Drysdall, A. R.

    Well-defined procedures for classifying the felsic plutonic rocks of the Arabian Shield on the basis of petrographic, chemical and lithostratigraphic criteria and mineral-resource potential have been adopted and developed in the Saudi Arabian Deputy Ministry for Mineral Resources over the past decade. A number of problems with conventional classification schemes have been identified and resolved; others, notably those arising from difficulties in identifying precise mineral compositions, continue to present difficulties. The petrographic nomenclature used is essentially that recommended by the International Union of Geological Sciences. Problems that have arisen include the definition of: (1) rocks with sodic, zoned or perthitic feldspar, (2) trondhjemites, and (3) alkali granites. Chemical classification has been largely based on relative molar amounts of alumina, lime and alkalis, and the use of conventional variation diagrams, but pilot studies utilizing univariate and multivariate statistical techniques have been made. The classification used in Saudi Arabia for stratigraphic purposes is a hierarchy of formation-rank units, suites and super-suites as defined in the Saudi Arabian stratigraphic code. For genetic and petrological studies, a grouping as 'associations' of similar and genetically related lithologies is commonly used. In order to indicate mineral-resource potential, the felsic plutons are classed as common, precursor, specialized or mineralized, in order of increasing exploration significance.

  5. Archean to Paleoproterozoic polymetamorphic history of the Salma eclogite in Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Imayama, Takeshi; Oh, Chang-Whan; Park, Chan-Soo; Yi, Keewook; Jung, Haemyeong

    2015-04-01

    One of the most important questions in the Earth Science is when and how plate tectonics operate in the Precambrian time. The tectonic and thermal evolution of the Precambrian eclogite is significant key for understanding the Precambrian geodynamic mechanisms. Eclogites in Kola Peninsula, Russia are some of the oldest eclogites of the world, but there has been much debate about the timing of eclogite-facies metamorphism: Archean (e.g. Volodichev et al. 2004; Mints et al., 2010) or Paleoproterozoic (e.g. Skublob et al., 2011, 2012). The controversy is mainly because of the lack of zircon dating coupled with the formation of garnet and omphacite. In this study, we present geochronological, petrographic, and geochemical data from the Salma eclogites in the Kola Peninsula, Russia to characterize subduction and collision processes in the Precambrian. Microstructural observations, P-T analyses, zircon inclusion analyses, and U-Pb zircon dating revealed multiple metamorphic stages that the Salma eclogite underwent. The amphibolite facies metamorphic event firstly occurred at 2.73-2.72 Ga during Archean. In the Paleoproterozoic period, the Salma eclogites underwent prograde stage of epidote-amphibolite facies metamorphism. The eclogite facies metamorphic event took place under the P-T condition of 16-18 kbar and 740-770 °C at 1.89-1.88 Ga, with a subsequent granulite facies metamorphism during decompression stage from 18 kbar to 9-12 kbar. Finally, later amphibolite facies metamorphism occurred at 8-10 kbar and 590-610 °C on cooling. The Archean metamorphic zircons that contain inclusions of Grt + Am + Bt + Pl + Qtz + Rt are unzoned grains with dark CL, and they are relatively enriched in HREE. In contrast, the 1.89-1.88 Ga sector or concentric zoned zircons with pale-grey CL include inclusions of Grt + Omp + Ca-Cpx + Am + Bt + Qtz + Rt, and they have the flat pattern of HREE due to the amounts of abundant garnet during the eclogite-facies metamorphism. Whole rock

  6. Emplacement, rapid burial, and exhumation of 90-Ma plutons in southeastern Alaska

    USGS Publications Warehouse

    Himmelberg, G.R.; Haeussler, P.J.; Brew, D.A.

    2004-01-01

    In southeastern Alaska, granodiorite-tonalite plutons of the Admiralty-Revillagigedo belt intruded the Jurassic-Cretaceous Gravina belt along the eastern side of the Alexander terrane around 90 Ma. These plutons postdate some deformation related to a major contractional event between the previously amalgamated Wrangellia and Alexander terranes and the previously accreted terranes of the North American margin. We studied the aureole mineral assemblages of these plutons near Petersburg, Alaska, determined pressure and temperature of equilibration, and examined structures that developed within and adjacent to these plutons. Parallelism of magmatic and submagmatic fabrics with fabrics in the country rock indicates synchroneity of pluton emplacement with regional deformation and suggests that magma transport to higher crustal levels was assisted by regional deformation. Replacement of andalusite by kyanite or sillimanite indicates crustal thickening soon after pluton emplacement. Regional structural analysis indicates the crustal thickening was accomplished by thrust burial. Thermobarometric analyses indicate the aureoles reached near-peak temperatures of 525 to 635 ??C at pressures of 570 to 630 MPa. Consideration of the rate of thermal decay of the aureoles suggests that burial was rapid and occurred at rates around 5 to 8 mm/year. Structural observations indicate there was contractional deformation before, during, and after emplacement of the 90-Ma plutons. Initial exhumation of the Admiralty-Revillagedo belt in the Petersburg area may have occurred along a thrust west of the pluton belt within the Gravina belt. ?? 2004 NRC Canada.

  7. Crystal structure of hydrogen-bearing vuonnemite from the Lovozero alkaline massif

    SciTech Connect

    Rastsvetaeva, R. K. Aksenov, S. M.; Verin, I. A.; Lykova, I. S.

    2011-05-15

    Hydrogen-bearing vuonnemite from the Shkatulka hyperagpaitic pegmatite (the Lovozero alkaline massif, Kola Peninsula) was studied by single-crystal X-ray diffraction. The triclinic unit-cell parameters are as follows: a = 5.4712(1) Angstrom-Sign , b = 7.1626(1) Angstrom-Sign , c = 14.3702(3) Angstrom-Sign , {alpha} = 92.623(2) Degree-Sign , {beta} = 95.135(1) Degree-Sign , {gamma} = 90.440(1) Degree-Sign , sp. gr. P1, R = 3.4%. The Na{sup +} cations and H{sub 2}O molecules are ordered in sites between the packets. The water molecules are hydrogen bonded to the PO{sub 4} tetrahedra.

  8. Geochronology, geochemistry and origins of the Paleozoic-Triassic plutons in the Langshan area, western Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Wang, Zeng-Zhen; Han, Bao-Fu; Feng, Li-Xia; Liu, Bo

    2015-01-01

    The Langshan area is the northeastern part of the Alxa block and adjacent to the Inner Mongolia-Da Hinggan Orogenic Belt (IMDOB) to the north, and geochronological and geochemical studies of the Langshan plutons would be helpful for unraveling the relationship of the magmatism in the Langshan area with that in the IMDOB. Based on zircon U-Pb ages presented in this study and in published papers, five magmatic stages are recognized in Langshan area: Late Silurian (∼418 Ma), Carboniferous (328-304 Ma), Early Permian (294-272 Ma), Late Permian (260-254 Ma) and Middle-Late Triassic (245-227 Ma). The Late Silurian two-mica granite is peraluminous and has a source from ancient continental crust, indicating a collision event. The late Early Carboniferous mafic plutons are subalkaline, show appinitic affinities, and may originate from the subduction-modified continental lithospheric mantle. The late Early Permian granodiorite is weakly peraluminous and high-K calc-alkaline and may be derived from ancient continental crust, while the late Early Permian alkaline gabbro-diorite displays EM I-like Sr-Nd isotopic signatures, indicating an enriched subcontinental lithospheric mantle source. The Late Permian granodiorite is calc-alkaline and peraluminous and may result from the partial melting of ancient lower continental crust, whereas the Late Permian leuconorite belongs to low-K tholeiitic series and has a cumulate origin from an enriched mantle source with the input of juvenile mantle materials. The Paleozoic-Triassic magmatic stages in the Langshan area are consistent with the main magmatic periods in the northern NCC, which are the Late Silurian to Middle Devonian (∼418-386 Ma) and Early Carboniferous to Late Triassic (∼342-211 Ma, with three magmatic stages of Carboniferous, Permian and Triassic). Especially, the Carboniferous to Late Triassic magmatic period in the northern NCC are closely comparable with that in the IMDOB, indicating the two domains might be

  9. Plutons and accretionary episodes of the Klamath Mountains, California and Oregon

    USGS Publications Warehouse

    Irwin, William P.; Wooden, Joseph L.

    1999-01-01

    The Klamath Mountains consist of various accreted terranes and include many plutons that range in composition from gabbro to granodiorite. Some of the plutons (preaccretionary plutons) were parts of terranes before the terranes accreted; others (accretionary plutons) intruded during or after the accretion of their host terrane(s). This report attempts to (1) graphically illustrate how the Klamath Mountains grew by the accretion of allochthonous oceanic terranes during early Paleozoic to Cretaceous times, (2) identify the plutons as either preaccretionary or accretionary, and (3) genetically relate the plutonic intrusions to specific accretionary episodes. The eight accretionary episodes portrayed in this report are similar to those shown by Irwin and Mankinen (1998) who briefly described the basis for the timing of the episodes and who illustrated the ~110 degrees of clockwise rotation of the Klamath Mountains since Early Devonian time. Each episode is named for the accreting terrane. In all episodes (Figs. 1-8), the heavy black line represents a fault that separates the accreting oceanic rocks on the left from earlier accreted terranes on the right. The preaccretionary plutons are shown within the accreting oceanic crustal rocks to the left of the heavy black line, and the accretionary plutons in most instances are shown intruding previously accreted terranes to the right. Episodes earlier than the Central Metamorphic episode (Fig. 1), and that may have been important in the formation of the early Paleozoic nucleous of the province (the Eastern Klamath terrane), are not known. The 'Present Time' distribution of the accreted terranes and plutons is shown at a large scale in Figure 9. The schematic vertical section (Fig. 10) depicts the terranes as a stack of horizontal slabs that include or are intruded by vertical plutons. Note that at their base the ~170 Ma preaccretionary plutons of the Western Hayfork subterrane are truncated by the ~164 Ma Salt Creek

  10. Antibacterial and cytotoxic cytochalasins from the endophytic fungus Phomopsis sp. harbored in Garcinia kola (Heckel) nut.

    PubMed

    Jouda, Jean-Bosco; Tamokou, Jean-de-Dieu; Mbazoa, Céline Djama; Douala-Meli, Clovis; Sarkar, Prodipta; Bag, Prasanta Kumar; Wandji, Jean

    2016-11-14

    The continuous emergence of multidrug-resistant (MDR) bacteria drastically reduced the efficacy of our antibiotic armory and consequently, increased the frequency of therapeutic failure. The search for bioactive constituents from endophytic fungi against MDR bacteria became a necessity for alternative and promising strategies, and for the development of novel therapeutic solutions. We report here the isolation and structure elucidation of antibacterial and cytotoxic compounds from Phomopsis sp., an endophytic fungus associated with Garcinia kola nuts. The fungus Phomopsis sp. was isolated from the nut of Garcinia kola. The crude extract was prepared from mycelium of Phomopsis sp. by maceration in ethyl acetate and sequentially fractionated by column chromatography. The structures of isolated compounds were elucidated on the basis of spectral studies and comparison with published data. The isolated compounds were evaluated for their antibacterial and anticancer properties by broth microdilution and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide methods respectively. The samples were also tested spectrophotometrically for their hemolytic properties against human red blood cells. The fractionation of the crude extract afforded three known cytochalasins including 18-metoxycytochalasin J (1), cytochalasins H (2) and J (3) together with alternariol (4). The cytochalasin compounds showed different degrees of antibacterial activities against the tested bacterial pathogens. Shigella flexneri was the most sensitive microorganism while Vibrio cholerae SG24 and Vibrio cholerae PC2 were the most resistant. Ampicillin did not show any antibacterial activity against Vibrio cholerae NB2, Vibrio cholerae PC2 and Shigella flexneri at concentrations up to 512 μg/mL, but interestingly, these multi-drug resistant bacterial strains were sensitive to the cytochalasin metabolites. These compounds also showed significant cytotoxic properties against human cancer cells (LC50

  11. Isolation and characterization of an antibacterial biflavonoid from an African chewing stick Garcinia kola Heckel (Clusiaceae).

    PubMed

    Xu, Hong-Xi; Mughal, Sumaya; Taiwo, Oluronke; Lee, Song F

    2013-05-20

    The use of African chewing sticks in maintaining oral health is widely practiced in African countries. It has been reported that chewing stick users have a lower rate of dental caries and a better general oral health than non-users. It is generally thought that the beneficial effect of chewing stick is attributed to the mechanical cleansing effect and antimicrobial substances present in the stick. However, the active antimicrobial substances remain uncharacterized. To provide a scientific basis for the anti-caries effect of African chewing sticks, the authors purify an active antibacterial compound from Garcinia kola Heckel, a Nigerian chewing stick and examined the antibacterial activity of this compound against the cariogenic bacterium Streptococcus mutans. Methanol extract was prepared from Garcinia kola and was further fractionated by solvent extractions. Silica gel chromatography was used to purify the antibacterial compound from the active fraction. The identity of the purified compound was determined by NMR analysis. The antibacterial activity of the purified compound was examined by standard microbiological assays. The antibacterial activity was found in the ether fraction and the active compound was isolated and determined to be a biflavonoid named GB1. GB1 was active against Streptococcus mutans and other oral bacteria with minimum inhibitory concentration (MIC) values of 32-64μg/ml. The basis for the antibacterial effect of GB1 was investigated using Streptococcus mutans as the target. At 256μg/ml, GB1 exhibited some bacteriocidal activity against Streptococcus mutans and induced the aggregation of Streptococcus mutans. GB1 has no apparent effects on protein synthesis and DNA synthesis but inhibited glucose uptake and utilization by Streptococcus mutans suggesting that GB1 exerts its antibacterial effect by inhibiting metabolism. GB1 also inhibited the formation of water-insoluble glucan by the extracellular glucosyltransferases from Streptococcus

  12. A PCR Detection Method for Rapid Identification of Melissococcus pluton in Honeybee Larvae

    PubMed Central

    Govan, V. A.; Brözel, V.; Allsopp, M. H.; Davison, S.

    1998-01-01

    Melissococcus pluton is the causative agent of European foulbrood, a disease of honeybee larvae. This bacterium is particularly difficult to isolate because of its stringent growth requirements and competition from other bacteria. PCR was used selectively to amplify specific rRNA gene sequences of M. pluton from pure culture, from crude cell lysates, and directly from infected bee larvae. The PCR primers were designed from M. pluton 16S rRNA sequence data. The PCR products were visualized by agarose gel electrophoresis and confirmed as originating from M. pluton by sequencing in both directions. Detection was highly specific, and the probes did not hybridize with DNA from other bacterial species tested. This method enabled the rapid and specific detection and identification of M. pluton from pure cultures and infected bee larvae. PMID:9572987

  13. The comparative effects of chronic consumption of kola nut (Cola nitida) and caffeine diets on locomotor behaviour and body weights in mice.

    PubMed

    Umoren, E B; Osim, E E; Udoh, P B

    2009-06-01

    The comparative effects of chronic [28 days] consumption of kola nut and its active constituent, caffeine diets on locomotor behaviour and body weights in mice were investigated. Thirty adult Swiss white mice [15-30 g body weight], were used for the study. The open field-maze was employed for the evaluation of locomotor behaviour. Mice in the control group [n=10] were fed normal rodent chow, mice in the kola nut-fed group [n=10] were fed kola diet [25 % wt/wt of rodent chow] while those in the caffeine-fed group [n=10] were fed caffeine diet [0.66% wt/wt of rodent chow] for 4 weeks. All animals were allowed free access to clean drinking water. Daily food intake, water intake and body weight change were also measured. Daily food intake in the kola nut and caffeine-fed group of mice was significantly [P<0.001 respectively] lower than the control. There was also a significant [P<0.001] decrease in daily water intake in the caffeine-fed group compared to the control whereas, the apparent decrease of water intake in the kola nut-fed group was not significantly different from the control. Body weight change was also significantly [P<0.001 and P<0.05 respectively] lower in the kola nut and caffeine-fed groups of mice when compared to the control. The frequency of rearing in the open field was significantly [P<0.01] lower in the caffeine-fed group of mice when compared to the control. The frequency of grooming was also significantly [P<0.05] lower in the caffeine-fed group of mice when compared to the control. There was also a significant [P<0.05] decrease in the frequency of light-dark transitions in the light/dark transition box for the caffeine-fed group when compared to the control. The results showed that chronic consumption of kola nut and caffeine diets caused decrease in food intake and body weight. Consumption of caffeine-diet also significantly decreased water intake and locomotor activity. The effect of kola nut-diets on water intake and locomotor activity was

  14. Alkaline battery operational methodology

    SciTech Connect

    Sholklapper, Tal; Gallaway, Joshua; Steingart, Daniel; Ingale, Nilesh; Nyce, Michael

    2016-08-16

    Methods of using specific operational charge and discharge parameters to extend the life of alkaline batteries are disclosed. The methods can be used with any commercial primary or secondary alkaline battery, as well as with newer alkaline battery designs, including batteries with flowing electrolyte. The methods include cycling batteries within a narrow operating voltage window, with minimum and maximum cut-off voltages that are set based on battery characteristics and environmental conditions. The narrow voltage window decreases available capacity but allows the batteries to be cycled for hundreds or thousands of times.

  15. Age and intrusive relations of the Lamarck granodiorite and associated mafic plutons, Sierra Nevada, California

    SciTech Connect

    Joye, J.L.; Bachl, C.A.; Miller, J.S.; Glazner, A.F. . Dept. of Geology); Frost, T.P. ); Coleman, D.S. . Dept. of Earth, Atmospheric and Planetary Sciences)

    1993-04-01

    The compositionally zoned Late Cretaceous Lamarck granodiorite, west of Bishop, hosts numerous mafic intrusions ranging from hornblende gabbro to mafic granodiorite. Frost and Mahood (1987) suggested from field relations that the Lamarck and the associated mafic plutons were co-intrusive. Contact relations between the Lamarck host and the mafic intrusions are variable (sharp to diffuse) and in places suggest commingling. In order to constrain the intrusive relationships between the Lamarck and its associated mafic plutons, the authors have analyzed feldspars from the Mt. Gilbert pluton and the Lamarck granodiorite to see if feldspar compositions in the Mt. Gilbert overlap those in the Lamarck host and determined U-Pb zircon ages for the Mt. Gilbert and Lake Sabrina plutons to see if they have the same age as the Lamarck granodiorite. Feldspars from the Lamarck granodiorite are normally zoned and range compositionally from An[sub 38--32]; those in the Mt. Gilbert diorite are also normally zoned but range compositionally from An[sub 49--41] and do not overlap the Lamarck host. Four to five zircon fractions from each pluton were handpicked and dated using U-Pb methods. The Mt. Gilbert mafic diorite has a concordant age of 92.5 Ma and the Lake Sabrina diorite has a concordant age of 91.5 Ma. Ages for the two plutons overlap within error, but multiple fractions from each suggest that the Lake Sabrina pluton is slightly younger than the Mt. Gilbert pluton. These data and field relationships indicate: (1) plagioclase phenocrysts in the Mt. Gilbert pluton were not derived from the Lamarck granodiorite despite their textural similarity; but (2) the Lamarck granodiorite and its associated mafic plutons are co-intrusive as supported by the close agreement of the ages with the crystallization age obtained by Stern and others for the Lamarck granodiorite.

  16. Geochemistry and petrogenesis of high-K "sanukitoids" from the Bulai pluton, Central Limpopo Belt, South Africa: Implications for geodynamic changes at the Archaean-Proterozoic boundary

    NASA Astrophysics Data System (ADS)

    Laurent, Oscar; Martin, Hervé; Doucelance, Régis; Moyen, Jean-François; Paquette, Jean-Louis

    2011-04-01

    The Neoarchaean Bulai pluton is a magmatic complex intrusive in the Central Zone of the Limpopo Belt (Limpopo Province, South Africa). It is made up of large volumes of porphyritic granodiorites with subordinate enclaves and dykes of monzodioritic, enderbitic and granitic compositions. New U-Pb LA-ICP-MS dating on zircon yield pluton-emplacement ages ranging between 2.58 and 2.61 Ga. The whole pluton underwent a high-grade thermal overprint at ~ 2.0 Ga, which did not affect the whole-rock compositions for most of the major and trace-elements, as suggested by a Sm-Nd isochron built up with 16 samples and yielding an age consistent with U-Pb dating. The whole-rock major- and trace-element compositions evidence that the Bulai pluton belongs to a high-K, calc-alkaline to shoshonitic suite, as well as unequivocal affinities with "high-Ti" sanukitoids. Monzodioritic enclaves and enderbites have both "juvenile" affinities and a strongly enriched signature in terms of incompatible trace elements (LREE, HFSE and LILE), pointing to an enriched mantle source. Based on trace-element compositions, we propose the metasomatic agent at their origin to be a melt deriving from terrigenous sediments. We therefore suggest a two-step petrogenetic model for the Bulai pluton: (1) a liquid produced by melting of subducted terrigenous sediments is consumed by reactions with mantle peridotite, producing a metasomatic assemblage; (2) low-degree melting of this metasomatized mantle gives rise to Bulai mafic magmas. Such a model is supported by geochemical modelling and is consistent with previous studies concluding that sanukitoids result from interactions between slab melts and the overlying mantle wedge. Before 2.5 Ga, melting of hydrous subducted metabasalts produced large volumes of TTG (Tonalite-Trondhjemite-Granodiorite) forming most of the volume of Archaean continental crust. By constrast, our geochemical study failed in demonstrating any significant role played by melting of

  17. The Permian mafic dyke swarm of the Panticosa pluton (Pyrenean Axial Zone, Spain): simultaneous emplacement with the late-Variscan extension

    NASA Astrophysics Data System (ADS)

    Gil-Imaz, Andrés; Lago-San José, Marceliano; Galé, Carlos; Pueyo-Anchuela, Óscar; Ubide, Teresa; Tierz, Pablo; Oliva-Urcia, Belén

    2012-09-01

    The Panticosa dyke swarm was emplaced into the late Carboniferous (301 ± 7 Ma) Panticosa pluton. It consists of diabase and lamprophyre dykes. According to their composition, two lithotypes are differentiated: (i) an early system of calc-alkaline affinity and N-S average trend and (ii) a late system of alkaline affinity and E-W average trend. The fracture pattern distribution with respect to both dyke systems suggests that all dykes occupied pre-existing fractures. The magnetic fabric analysis and petrological data indicate that the emplacement model differed for each dyke system. For the calc-alkaline dykes, magma flow and tectonic stress conditions influenced emplacement. The emplacement of alkaline dykes, on the other hand, was mainly controlled by tectonic stress. The combined interpretation of structural and magnetic fabric data suggests an emplacement history for all late-Variscan dykes during a constant regional N-S trending extension. This study emphasizes the role of pure extension in the late-Variscan evolution of the Pyrenean Axial Zone.

  18. Localized ductile deformation in the Rieserferner Pluton (Eastern Alps)

    NASA Astrophysics Data System (ADS)

    Ceccato, Alberto; Pennacchioni, Giorgio

    2017-04-01

    In the Rieserferner Pluton (Eastern Alps, 32±0.2 Ma, Romer et al., 2003) the post-magmatic cooling and exhumation stages were accompanied by a series of solid-state deformations including jointing, quartz veining, dyke emplacement, localized (cm-dm) ductile shearing and brittle-ductile faulting. The earliest stage of post-magmatic deformation includes the formation of pervasive steeply-dipping joints mainly arranged in two "conjugate" sets striking respectively E-W and NW-SE. These joints were extensively intruded by synkinematic aplite-pegmatite dykes and by quartz veins. Joints, veins and (locally) dikes were exploited as strike-slip ductile shear zones consistently with a WNW-ESE shortening. The mylonitized quartz veins are relatively coarse grained (mm-grain size) and show dominant dynamic recrystallization by grain boundary migration. A later set of joints is shallowly dipping E and is also commonly filled with quartz (and local epidote) veins. Ductile shearing of these vein-filled joints resulted in localized tonalite mylonites and quartz mylonites with a top-to-east kinematics. The quartz mylonites are fine grained (10-20 μm grain size) and resulted from dominant subgrain rotation recrystallization. The foliation of associated tonalite mylonites is marked by biotite+plagioclase+white mica+epidote±sphene±garnet. The "high-temperature" mylonites are crosscut by swarms of steeply-dipping fractures and faults striking N-S and showing a characteristic anastomosing-irregular pattern. These fractures are clustered in zones as large as 10 m and are associated with veins filled with calcite+white mica and with basic dykes (dated at 26 Ma: Steenken et al., 2000). Fluid-rock interactions along these fractures induced weakening and development of local low-temperature mylonites, where deformation mechanisms included pressure-solution and low-temperature plasticity of quartz. The orientation and kinematics of E-dipping mylonites and later low-temperature mylonites

  19. Melt segregation evidence from a young pluton, Takidani Granodiorite (Japan)

    NASA Astrophysics Data System (ADS)

    Hartung, Eva; Caricchi, Luca; Floess, David; Wallis, Simon; Harayama, Satoru; Chiaradia, Massimo; Kouzmanov, Kalin

    2016-04-01

    We are presenting new petrological data from one of the youngest exposed plutons in the world, the Takidani Granodiorite (Japan), which has been suggested as a source for large volume ignimbrites (> 300km3). Takidani Granodiorite (1.54 Ma ± 0.23 Ma) is located within the active Norikura Volcanic Chain in the Northen Japan Alps and has been previously linked to large andesitic (1.76 Ma ± 0.17 Ma) and rhyolitic eruptions (1.75 Ma ± 0.17 Ma). The pluton is vertically zoned and consists of granites (67 to 68 wt.% SiO2) in the lower section, granodiorites (65 to 66 wt.% SiO2) in the middle section, a chemically more evolved fine-grained porphyritic unit (67 to 71 wt.% SiO2) near the roof and a marginal granodiorite at the roof (67 to 68 wt.% SiO2). The porphyritic texture of the more evolved unit near the roof indicates rapid crystallisation, which could be the result of the late intrusion of this unit at the roof of the magmatic system. However, no sharp contact is found between the underlying granodiorite and the porphyritic unit. Instead, a gradual change in rock fabric, whole-rock chemistry and mineralogy is observed suggesting that melt was extracted from the granodiorite. Electron microprobe analyses of plagioclases show three main crystal populations (Type I, II and III) with distinct anorthite and Fe contents. Type I plagioclase (An30-40) occurs dominantly within the marginal granodiorite at the roof. Type II plagioclase (An40-45) are common in the granodiorite and porphyritic unit. Type III plagioclase (An45-50) is predominantly present in the granite. All plagioclase populations share a common sodic rim (An22) across the different units. Takidani Granodiorite rocks are compared to crystallisation experiments from similar magmatic suites. Emplacement conditions of the Takidani Granodiorite are obtained from the latter as well as barometry, thermometry and hygrometry indicating that magmas were ultimately emplaced at around 200 MPa, 850° C to 875° C and

  20. Assessment of environmental impact zones in the Kola Peninsula forest ecosystems.

    PubMed

    Lukina, N; Nikonov, V

    2001-01-01

    This paper describes the condition of forest ecosystems subjected to smelter pollution in the Kola peninsula. This assessment is based on the parameters of the biogeochemical cycle. The defoliation index was used to delimit three basic forest states: background, defoliating, sparse. Close to the smelter, due to expansion of the area not covered by vegetation, a fourth type of state, so-called "industrial deserts", has been observed. The concentrations of sulphur, copper and nickel in the precipitation in the forests generally declined with distance from the smelter. The defoliating forests are noted for the highest Ca, Mg, K concentrations in the summer precipitation. In sparse forests and industrial deserts a decrease in the Ca, Mg, K concentrations in the summer precipitation in comparison with the defoliating forests, despite the particle emissions, could be attributed to the reduction in forest biomass. The higher levels of soil and soil leachate carbon and acidity in the defoliating forests was due to higher litterfall and to the higher dissolution of fulvic acids by the acidic precipitation. This increase in organic matter levels affects soil cation exchange capacity and cation saturation. The pine trees demonstrated significant changes in the uptake of elements in all types of forests under pollution. Elevated levels of S, Ni, Cu and K and reduced levels of Mg, Mn and Zn were found in the needles of different age classes.

  1. Raman spectra of probably shock-metamorphosed zircon in structures of the Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Kaulina, Tatiana; Nerovich, Luidmila; Lialina, Luidmila; Il'chenko, Vadim; Bocharov, Vladimir; Kunakkuzin, Evgeny

    2016-04-01

    Zircon crystals were studied by means of Raman spectroscopy from certain structures of the Kola Peninsula, for which impact events are expected according to geological and geochemical data: circular structure in Javrozersky area of the Tanaelv belt and granophyres of Jarva-Varaka layered massif of the Monchegorsky ore district. Zircons from anorthosites of the Javrozersky area showed some features of impact zircons: wavy extinction, blurred "aurora-like" CL image and a presence of additional bands in the Raman spectrum, which may indicate the presence of ZrSiO4 with the scheelite-type structure (reidite) surrounded by zircon material. Zircon crystals of Yavra-Varaka granophyres showed variation of Raman spectra from the core part of crystals with typical zircon Raman pattern to complete absence of spectral bands in the marginal parts and rims. There was also a transition zone between cores and marginal parts of crystals, where the Raman spectrum is "blurred". Such pattern may be associated with the transformation of crystalline zircon to diaplectic glass under the influence of shock metamorphism, since the Jarva-Varaka massif according to geological and geochemical data is compared with the Sudbury structure, for which impact origin is assumed. The work is supported by RSF grant N 16-17-10051.

  2. Petrological imaging of an active pluton beneath Cerro Uturuncu, Bolivia

    NASA Astrophysics Data System (ADS)

    Muir, Duncan D.; Blundy, Jon D.; Hutchinson, Michael C.; Rust, Alison C.

    2014-03-01

    Uturuncu is a dormant volcano in the Altiplano of SW Bolivia. A present day ~70 km diameter interferometric synthetic aperture radar (InSAR) anomaly roughly centred on Uturuncu's edifice is believed to be a result of magma intrusion into an active crustal pluton. Past activity at the volcano, spanning 0.89 to 0.27 Ma, is exclusively effusive and almost all lavas and domes are dacitic with phenocrysts of plagioclase, orthopyroxene, biotite, ilmenite and Ti-magnetite plus or minus quartz, and microlites of plagioclase and orthopyroxene set in rhyolitic groundmass glass. Plagioclase-hosted melt inclusions (MI) are rhyolitic with major element compositions that are similar to groundmass glasses. H2O concentrations plotted versus incompatible elements for individual samples describe a trend typical of near-isobaric, volatile-saturated crystallisation. At 870 °C, the average magma temperature calculated from Fe-Ti oxides, the average H2O of 3.2 ± 0.7 wt% and CO2 typically <160 ppm equate to MI trapping pressures of 50-120 MPa, approximately 2-4.5 km below surface. Such shallow storage precludes the role of dacite magma emplacement into pre-eruptive storage regions as being the cause of the observed InSAR anomaly. Storage pressures, whole-rock (WR) chemistry and phase assemblage are remarkably consistent across the eruptive history of the volcano, although magmatic temperatures calculated from Fe-Ti oxide geothermometry, zircon saturation thermometry using MI and orthopyroxene-melt thermometry range from 760 to 925 °C at NNO ± 1 log. This large temperature range is similar to that of saturation temperatures of observed phases in experimental data on Uturuncu dacites. The variation in calculated temperatures is attributed to piecemeal construction of the active pluton by successive inputs of new magma into a growing volume of plutonic mush. Fluctuating temperatures within the mush can account for sieve-textured cores and complex zoning in plagioclase phenocrysts

  3. Characterization of HANARO neutron radiography facility in accordance with ASTM standard E545-91/E803-91 for KOLAS/ISO17025.

    PubMed

    Cheul-Muu, Sim; Ki-Yong, Nam; In-Cheol, Lim; Chang-Hee, Lee; Ha-Lim, Choi

    2004-10-01

    As neutron radiography is even more in demand for industrial applications of aircraft, turbine blade, automobile, explosive igniters, etc, it is necessary to review the standards which are the most appropriate for preparing the procedures for setting up the QA system. Recently, Korea Of Lab Accreditation Scheme (KOLAS) was originated from ISO 17025. It is widely recognized by research peer groups for conducting valid tests. The neutron radiography facility (NRF) of High Flux Advanced Neutron Application Reactor (HANARO), which started ion 1996, is the preliminary stages of KOLAS. The HANARO NRF is not only characterized using ASTM standards E545-91/E803-91 to satisfy the requirements of KOLAS, but in the design phase of the tomography system.

  4. Segregation of immiscible liquids: From droplet size to plutonic scale

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Wu, B.; Wang, T.; Hui, H.

    2016-12-01

    Silicate liquid immiscibility has been evidenced as discrete glassy droplets in volcanic rocks microscopically. Furthermore, this process has been proposed to have resulted in mafic and felsic fractions on outcrop scale in plutons. However, it is unclear how tiny discrete immiscible liquid droplets could be segregated from a continuous melt (medium) and lead to magmatic differentiation on a chamber scale. The settling of immiscible liquid droplets depends on their sinking (or floating) velocities, which could be described using the Stokes' law. The discrete liquid droplets during settling could collide and coalesce with each other, resulting in larger droplets, which is different from the collision of crystals in the magma. The coalescence can significantly increase the droplet velocities, which are proportional to the square of the droplet radii according to the Stokes' law. In a slow-cooling magma chamber, the exsolution and settling of the discrete liquid droplets may reach "equilibrium", which here we call the steady state. Numerical analyses using population dynamics equations have been carried out to study how physical properties of melts affect the segregation of immiscible liquids at the steady state. Our preliminary results indicate that the residence time (average time it takes for discrete droplets to settle) of discrete melt with viscosity higher than that of the medium could be longer than that of discrete melt with viscosity lower than that of the medium, by even more than one order of magnitude. Furthermore, the residence time is approximately proportional to the square root of the medium viscosity, inversely proportional to the square root of the density difference and inversely proportional to the exsolution rate if the discrete melt is exsolved as initially small droplets ( 10 µm in radius). This study could shed light on understanding the feasibility of formation of plutons through liquid immiscibility in dynamics.

  5. Cretaceous plutonic rocks in the Donner Lake-Cisco Grove area, northern Sierra Nevada, California

    USGS Publications Warehouse

    Kulow, Matthew J.; Hanson, Richard E.; Girty, Gary H.; Girty, Melissa S.; Harwood, David S.

    1998-01-01

    The northernmost occurrences of extensive, glaciated exposures of the Sierra Nevada batholith occur in the Donner Lake-Cisco Grove area of the northern Sierra Nevada. The plutonic rocks in this area, which are termed here the Castle Valley plutonic assemblage, crop out over an area of 225 km2 and for the most part are shown as a single undifferentiated mass on previously published geological maps. In the present work, the plutonic assemblage is divided into eight separate intrusive units or lithodemes, two of which each consist of two separate plutons. Compositions are dominantly granodiorite and tonalite, but diorite and granite form small plutons in places. Spectacular examples of comb layering and orbicular texture occur in the diorites. U-Pb zircon ages have been obtained for all but one of the main units and range from ~120 to 114 Ma, indicating that the entire assemblage was emplaced in a narrow time frame in the Early Cretaceous. This is consistent with abundant field evidence that many of the individual phases were intruded penecontemporaneously. The timing of emplacement correlates with onset of major Cretaceous plutonism in the main part of the Sierra Nevada batholith farther south. The emplacement ages also are similar to isotopic ages for gold-quartz mineralization in the Sierran foothills west of the study area, suggesting a direct genetic relationship between the voluminous Early Cretaceous plutonism and hydrothermal gold mineralization.

  6. Plutonism, oblique subduction, and continental growth: An example from the Mesozoic of California

    SciTech Connect

    Glazner, A.F. )

    1991-08-01

    Major episodes of Mesozoic plutonism in California correlate with periods of oblique subduction and trench-parallel transport of western California along intrabatholithic faults. Major episodes of plutonism occurred in the Late Jurassic, during left-oblique convergence, and in the mid-Cretaceous, during right-oblique convergence. In contrast, a conspicuous lull in plutonism (but continuation of volcanism) in the earliest Cretaceous coincides with a time when the North America-Farallon convergence vector, although large in magnitude, was oriented perpendicular to the trench. This correlation suggests that plutonism is facilitated by strike-slip faulting within the batholithic belt; one explanation, which helps to solve the plutonic room problem, is that plutons are passively emplaced at releasing bends in the strike-slip faults, and volume is conserved by thrusting at the trench. If this correlation is generally applicable, then it implies that mid-crustal plutonism is limited beneath areas in which the convergence vector is subperpendicular to the trench. Continental growth in such areas may occur dominantly by volcanism.

  7. Structure of the Castillo granite, Southwest Spain: Variscan deformation of a late Cadomian pluton

    NASA Astrophysics Data System (ADS)

    EguíLuz, L.; Apraiz, A.; ÁBalos, B.

    1999-12-01

    A geometrical reconstruction of the 500 Ma old Castillo granite pluton (SW Iberia) is completed on the basis of structural and geophysical (rock magnetism) techniques. The pluton is intrusive into latest Proterozoic-earliest Cambrian metasediments and conforms a tabular intrusion 6 km in diameter and 1.7 km thick that was emplaced at a depth of 10 km. Its magnetic fabric reveals that the strike of moderately to steeply dipping magmatic flow planes forms a high angle to the regional tectonic trends. Magnetic foliations and associated moderately to gently plunging magnetic lineations represent magmatic flow planes and directions. The internal anisotropy of the granite together with the structure shown by the country rocks attest the lateral propagation of the pluton and its latter inflation. The pluton's root zone would correspond to a likely thin, subvertical feeder structure initiated near the orientation of regional σ1 at the time of emplacement. During the Variscan orogeny the pluton was tilted and underwent localized brittle-ductile strain in relation to shear zone deformation in the footwall of a major ductile thrust. Tilting permits the observation and study of a vertical profile of the intrusion. Localized deformation caused superposition of tectonic zonations on the magmatic ones, a reactivation of the basal contact of the pluton, and dismemberment from its root. This and other granitoid plutons of similar age emplaced at a similar depth constrained the creation of crustal mechanical heterogeneity and anisotropy. This controlled the site of pluton emplacement, the nucleation of a major ductile thrust, and localization of deformation and tectonic displacements along the pluton margins during later orogenic reactivation.

  8. Use of Digital Elevation Models to understand map landforms and history of the magmatism Khibiny Massif (Kola Peninsula, Russia)

    NASA Astrophysics Data System (ADS)

    Chesalova, Elena; Asavin, Alex

    2016-04-01

    most intense free gas emission. The technical possibilities that are offered by Remote Sensing (RS) and Geographical Information Systems (GIS) facilitate the geomorphological investigation of inhospitable and inaccessible mountain areas Digital Elevation Models (DEMs) are valuable tools for approximation of the real world's continuous surface. They allow a visual analysis of the earth's surface morphology, quanti?cation of sediment volumes and the calculation of topographic derivatives such as the slope gradient, slope aspect and pro?le curvature that consume ?eld investigations and optimize time The project has been sponsored by programmm Presidium of RAS P44. Reference Ivanyuk G, Kalashnikov A, Mikhailova J, Konoplyova N, Goryainov P, Yakovenchuk V, Pakhomovsky Y. Self-Organization of the Khibiny Alkaline Massif (Kola Peninsula, Russia). In Earth Sciences, Dr. Imran Ahmad Dar(Ed.), ISBN: 978-953-307-861-8, InTech, Available from: http://www.intechopen.com/books/earth-sciences/self-organization-of-the-khibiny-alkaline -massif -kolapeninsula-russia INTECH Open Access Publisher; 2012, Head7, P.131-156.

  9. Alkaline phosphatase: an overview.

    PubMed

    Sharma, Ujjawal; Pal, Deeksha; Prasad, Rajendra

    2014-07-01

    Alkaline phosphatase (ALP; E.C.3.I.3.1.) is an ubiquitous membrane-bound glycoprotein that catalyzes the hydrolysis of phosphate monoesters at basic pH values. Alkaline phosphatase is divided into four isozymes depending upon the site of tissue expression that are Intestinal ALP, Placental ALP, Germ cell ALP and tissue nonspecific alkaline phosphatase or liver/bone/kidney (L/B/K) ALP. The intestinal and placental ALP loci are located near the end of long arm of chromosome 2 and L/B/K ALP is located near the end of the short arm of chromosome 1. Although ALPs are present in many mammalian tissues and have been studied for the last several years still little is known about them. The bone isoenzyme may be involved in mammalian bone calcification and the intestinal isoenzyme is thought to play a role in the transport of phosphate into epithelial cells of the intestine. In this review, we tried to provide an overview about the various forms, structure and functions of alkaline phosphatase with special focus on liver/bone/kidney alkaline phosphatase.

  10. Zircon U-Pb age, Lu-Hf isotope, mineral chemistry and geochemistry of Sundamalai peralkaline pluton from the Salem Block, southern India: Implications for Cryogenian adakite-like magmatism in an aborted-rift

    NASA Astrophysics Data System (ADS)

    Renjith, M. L.; Santosh, M.; Li, Tang; Satyanarayanan, M.; Korakoppa, M. M.; Tsunogae, T.; Subba Rao, D. V.; Kesav Krishna, A.; Nirmal Charan, S.

    2016-01-01

    The Sundamalai peralkaline pluton is one among the Cryogenian alkaline plutons occurring in the Dharmapuri Rift Zone (DRZ) of the Salem Block in the Southern Granulite Terrane (SGT) of India. Here we present zircon U-Pb age and Lu-Hf isotopic composition, mineral chemistry and geochemistry of the pluton to explore the petrogenesis and geodynamic implications. Systematic modal variation of orthoclase, Na-plagioclase, Ca-amphibole (ferro-edenite and hastingsite) and quartz developed quartz-monzonite and granite litho units in the Sundamalai pluton. Thermometry based on amphibole-plagioclase pair suggests that the pluton was emplaced and solidified at around 4.6 kbar pressure with crystallization of the major phases between 748 and 661 °C. Estimated saturation temperature of zircon (712-698 °C) is also well within this range. However, apatite saturation occurred at higher temperatures between 835 and 870 °C, in contrast with monazite saturation (718-613 °C) that continued up to the late stage of crystallization. Estimated oxygen fugacity values (log fO2: -14 to -17) indicate high oxidation state for the magma that stabilized titanite and magnetite. The magmatic zircons from Sundamalai pluton yielded a weighted mean 206Pb/238U age of 832.6 ± 3.2 Ma. Geochemically, the Sundamalai rocks are high-K to shoshonitic, persodic (Na2O/K2O ratio > 1), silica-saturated (SiO2:65-72 wt.%), and peralkaline in composition (aluminum saturation index, ASI < 1; Alkalinity index, AI < 0). The initial magma was mildly metaluminous which evolved to strongly peralkaline as result of fractional crystallization (plagioclase effect) controlled differentiation between quartz-monzonite and granite. Both rock types have high content of Na2O (5.1-6.3 wt.%), Ba (350-2589 ppm) and Sr (264-1036 ppm); low content of Y (8.7-17 ppm) and Yb (0.96-1.69 ppm); elevated ratios of La/Yb (11-46) and Sr/Y (46-69) and are depleted in Ti, with a positive Sr anomaly suggesting an adakite-like composition and

  11. The granite pluton of Zahedan (SE Iran): a petrological and magnetic fabric study of a syntectonic sill emplaced in a transtensional setting

    NASA Astrophysics Data System (ADS)

    Sadeghian, M.; Bouchez, J. L.; Nédélec, A.; Siqueira, R.; Valizadeh, M. V.

    2005-05-01

    The ˜32 Ma, NW-SE elongate, 75 km-long granite pluton of Zahedan is one of the most conspicuous geological features of southeast Iran. It is composed of metaluminous to weakly peraluminous rocks, corresponding to magnetite- and ilmenite-bearing I-type granitoids, ranging from diorites to granites. All rocks, including the late andesitic to dacitic dykes, belong to the high-K calk-alkaline series. Field and structural relationships, as well as evidence for mixing-mingling, can be used to unravel the magmatic history of the different rock types. Microstructural examinations and magnetic fabric measurements were performed on a collection of oriented specimens from the northern part of the pluton. Ubiquitous flat-lying foliations argue in favour of a sill-like body, except for the diorite. The biotite-bearing granitic facies, at the pluton's periphery, was the first batch of magma which initiated the sill. This sill probably behaved as a N-S-directed décollement zone, marked by conspicuous 'magmatic-cataclastic' microstructures and N-S treading lineations. The intrusion of the hornblende-bearing granodiorite, with typical magmatic structures, inflated the sill. Deformation occurred at the same time, with E-W to NW-SE stretching, marked by lineations. The main dioritic stock forming the floor of the sill is considered to be a remnant of the feeder-zone. An abundant dyke swarm marks the end of the syntectonic emplacement of the Zahedan sill. A three-dimentional model of emplacement is proposed in the context of the latest episodes in the closure of the Neo-Tethys during which the Lut Block ended its northward migration with respect to the Afghan blocks.

  12. Geochemistry and isotopic signatures of Paleogene plutonic and detrital rocks of the Northern Andes of Colombia: A record of post-collisional arc magmatism

    NASA Astrophysics Data System (ADS)

    Bustamante, Camilo; Cardona, Agustín; Archanjo, Carlos J.; Bayona, Germán; Lara, Mario; Valencia, Victor

    2017-04-01

    Between the Late Cretaceous and Paleogene, the Northern Andes experienced subduction and collision due to the convergence between the oceanic Caribbean Plate and the continental margin of Ecuador and Colombia. Subduction-related calc-alkaline plutonic rocks form stocks of limited areal expression or local batholiths that consist mostly of diorites and granodiorites. We investigated two stocks (Hatillo and Bosque) exposed in the Central Cordillera of Colombia that had U-Pb zircon crystallization ages between 60 and 53 Ma. Relatively low radiogenic Sr, Nd and Pb isotopes from selected samples account for a heterogeneous crustal source, whereas negative anomalies of Nb and Ti, high LREE/HREE and Sr/Y > 28 ratios indicate that the magmas were emplaced in a continental magmatic arc setting. ƐHf(i) values of the dated zircons were between - 4 and + 7 and suggest some contamination of the magmas during their ascent through the crust. The high Sr/Y ratios recorded both in the investigated plutons as well as in other Paleogene plutons in the Central Cordillera suggest that the magmas differentiate in high-pressure conditions (garnet stability field). This differentiation probably occurred at the base of a thickened crust through the Mesozoic subduction and accretion of oceanic arcs to the continental margin during the Lower Cretaceous and Paleocene. The existence of other Paleogene granitoids with evidence of shallower differentiation signatures may be also an inheritance of along strike variations in the Northern Andean continental crust due to Cretaceous to Paleogene oblique convergence. The Hf isotope results from Paleogene detrital zircons from volcanoclastic rocks of the eastern Colombian basins reinforce the possibility of a distal magmatic focus.

  13. Perspectives of humic substances application in remediation of highly heavy metals contaminated soils in Kola Subarctic

    NASA Astrophysics Data System (ADS)

    Tregubova, Polina; Turbaevskaya, Valeria; Zakharenko, Andrey; Kadulin, Maksim; Smirnova, Irina; Stepanov, Andrey; Koptsik, Galina

    2016-04-01

    Northwestern part of Russia, the Kola Peninsula, is one of the most heavy metals (HM) contaminated areas in the northern hemisphere. The main polluters, mining-and-metallurgical integrated works "Pechenganikel" and "Severonikel", are surrounded by heavily damaged barren lands that require remediation. The main contaminating metals are Ni and Cu. Using of exogenous humic substances could be possible effective and cost-efficient solution of HM contamination problem. Rational application of humates (Na-K salts of humic acids) can result in improvement of soil properties, localization of contamination and decreasing bioavailability through binding HM in relatively immobile organic complexes. Our research aim was to evaluate the influence of increasing doses of different origin humates on i) basic properties of contaminated soils; ii) mobility and bioavailability of HMs; iii) vegetation state and chemistry. In summer 2013 a model field experiment was provided in natural conditions of the Kola Peninsula. We investigated the Al-Fe-humus abrazem, soil type that dominates in technogenic barren lands around the "Severonikel" work. These soils are strongly acid: pHH2O was 3.7-4.1; pHKCl was 3.4-4.0. The exchangeable acidity is low (0.8-1.6 cmol(+)/kg) due to the depletion of fine particles and organic matter, being the carriers of exchange positions. The abrazems of barrens had lost organic horizon. 12 sites were created in 1 km from the work. In those sites, except 2 controls, various amendments were added: i) two different by it's origin types of humates: peat-humates and coal-humates, the last were in concentrations 0.5% and 1%; ii) lime; iii) NPK-fertilizer; iv) biomates (organic degradable cover for saving warm and erosion protection). As a test-culture a grass mixture with predominance of Festuca rubra and Festuca ovina was sowed. As a result we concluded that humates of different origin have unequal influence on soil properties and cause decreasing as well as

  14. Assessment of current exposure levels in different population groups of the Kola Peninsula.

    PubMed

    Travnikova, I G; Shutov, V N; Bruk, G Ya; Balonov, M I; Skuterud, L; Strand, P; Pogorely, Ju A; Burkova, T F

    2002-01-01

    Activity concentrations of 137Cs and 90Sr in samples of vegetation and natural food products collected in the Kola Peninsula in 1998 and 1999 indicate a very slow decrease in contamination levels during the last decade, mainly due to the physical decay of the radionuclides. The activity concentrations of 137Cs in reindeer meat decreased with a half-life of about 9 years. 137Cs in lichen, moss and fungi is significantly higher than in natural vegetation (grasses) and agricultural plants (potatoes). The activity concentrations of 137Cs in reindeer meat were two orders of magnitude higher than those in locally produced beef and pork. Consumption of reindeer meat, fish, mushrooms and berries constituted the main contribution to the internal dose from 137Cs and 90Sr for reindeer-breeders in the Lovozero area. The estimated committed doses due to 137Cs intake in this group were about 10 microSv per month in summer 1998 and 15 microSv per month in winter, 1999. There was good agreement between internal dose estimates based on intake assessment and whole body measurements. The population of Umba settlement, which is not involved in reindeer breeding, received individual committed doses due to 137Cs intake of about 0.5 microSv per month, about a factor of 20 less than the reindeer-breeders in Lovozero. In this case, the main contribution to the internal dose of the general population came from consumption the of 137Cs in mushrooms and forest berries. The contribution of 90Sr to the internal dose varied from 1% to 5% in the different population groups studied.

  15. Modelling and Evaluation of Environmental Impact due to Continuous Emissions of the Severonickel Plant (Kola Peninsula)

    NASA Astrophysics Data System (ADS)

    Mahura, A.; Gonzalez-Aparicio, I.; Nuterman, R.; Baklanov, A.

    2012-04-01

    In this study, evaluation of potential impact - through concentration, deposition and loadings patterns - on population and environment due to continuous anthropogenic emissions (on example of sulfates) of the Cu-Ni smelters of the Russian North is given. To estimate impact, the Danish Emergency Response Model for Atmosphere (DERMA) was employed to perform long-term simulations of air concentration, time integrated air concentration (TIAC), dry (DD) and wet (WD) deposition patterns resulting from continuous emissions of the Severonickel smelters located on the Kola Peninsula (Murmansk region, Russia). To perform such simulations the 3D meteorological fields (from the European Center for Medium-Range Weather Forecasts, ECMWF) for the year 2000 were used as input. For simplicity, it has been assumed that normalized releases of sulfates from smelters location occurred at a constant rate every day. For each daily release the atmospheric transport, dispersion, dry and wet deposition due to removal processes were estimated during 10 day interval. Output from these long-term simulations is an essential input for evaluation of impact, doses, risks, and short- and long-term consequences, etc. Detailed analyses of simulated concentration and deposition fields allowed evaluating the spatial and temporal variability of resulted patterns on different scales. Temporal variability of both wet and dry deposition as well as their contribution into total deposition have been estimated. On an annual scale, the concentration and deposition patterns were estimated for the most populated cities of the North-West Russia. The modeled annual fields were also integrated into GIS environment as well as layers with population density (from the Center for International Earth Science Information Network, CIESIN) and standard administrative division of the North-West Russia and bordering countries. Furthermore, the estimation of deposited amounts (loadings) of sulfates for selected regions of

  16. Iron variation within a granitic pluton as determined by near-infrared reflectance

    NASA Technical Reports Server (NTRS)

    Baird, A. K.

    1984-01-01

    One-hundred fifty-one previously chemically analyzed samples of tonalite from the Lakeview Mountains pluton, southern California batholith, were analyzed for their iron content using near-infrared spectrophotometry. Compared to the earlier analyses of the same sample set by X-ray fluorescence spectrography, the infrared data have higher analytical variance but clearly define patterns of compositional zonation in the pluton which are closely similar to those patterns obtained from X-ray data; petrogenetic interpretations for the pluton would be the same from either data set. Infrared spectral data can be obtained directly in the field with relatively simple instruments and field measurements can be made to average local heterogeneities that often mask significant plutonic variations.

  17. Volcanic-plutonic parity and the differentiation of the continental crust.

    PubMed

    Keller, C Brenhin; Schoene, Blair; Barboni, Melanie; Samperton, Kyle M; Husson, Jon M

    2015-07-16

    The continental crust is central to the biological and geological history of Earth. However, crustal heterogeneity has prevented a thorough geochemical comparison of its primary igneous building blocks-volcanic and plutonic rocks-and the processes by which they differentiate to felsic compositions. Our analysis of a comprehensive global data set of volcanic and plutonic whole-rock geochemistry shows that differentiation trends from primitive basaltic to felsic compositions for volcanic versus plutonic samples are generally indistinguishable in subduction-zone settings, but are divergent in continental rifts. Offsets in major- and trace-element differentiation patterns in rift settings suggest higher water content in plutonic magmas and reduced eruptibility of hydrous silicate magmas relative to dry rift volcanics. In both tectonic settings, our results indicate that fractional crystallization, rather than crustal melting, is predominantly responsible for the production of intermediate and felsic magmas, emphasizing the role of mafic cumulates as a residue of crustal differentiation.

  18. Iron variation within a granitic pluton as determined by near-infrared reflectance

    NASA Technical Reports Server (NTRS)

    Baird, A. K.

    1984-01-01

    One-hundred fifty-one previously chemically analyzed samples of tonalite from the Lakeview Mountains pluton, southern California batholith, were analyzed for their iron content using near-infrared spectrophotometry. Compared to the earlier analyses of the same sample set by X-ray fluorescence spectrography, the infrared data have higher analytical variance but clearly define patterns of compositional zonation in the pluton which are closely similar to those patterns obtained from X-ray data; petrogenetic interpretations for the pluton would be the same from either data set. Infrared spectral data can be obtained directly in the field with relatively simple instruments and field measurements can be made to average local heterogeneities that often mask significant plutonic variations.

  19. Geochemical and temporal relationships between plutonic and volcanic rocks from the Aleutian arc: a pilot study

    NASA Astrophysics Data System (ADS)

    Cai, Y.; Rioux, M. E.; Kelemen, P. B.; Goldstein, S. L.

    2013-12-01

    Aleutian arc volcanics are predominantly basaltic while known plutonic rocks are systematically more felsic and have compositions that overlap estimates for the bulk composition of the continental crust. The Aleutian arc is unique among active intra-oceanic arcs in its widespread exposure of Paleogene and Neogene mid-crustal plutonic rocks, as well as the lavas and sediments that these plutons intruded. Thus, understanding the genesis of Aleutian plutonic rocks is a key to understanding continental genesis and evolution via arc magmatism. We have measured major, trace element contents and Sr-Nd-Hf-Pb isotope compositions of 26 mafic to intermediate plutonic rocks, ranging in age from ~32-9 Ma, across the Aleutian arc and compared them with spatially associated Quaternary volcanic rocks. The samples cover a large range of Mg# (73 to 35). Most samples do not show substantial Eu anomalies, and they represent primary magmas rather than differentiated cumulates. Compared to associated volcanics, the plutonic rocks show similar to slightly higher SiO2 and K2O contents at a given Mg#. For many trace elements, the plutonic and volcanic rocks are similar (e.g., elemental concentrations and La/Sm, Th/Nd, Lu/Hf, Dy/Yb ratios). However, the plutonic rocks show on average higher Nd and Hf isotope ratios and lower Pb isotope ratios than volcanic rocks from the same island. The difference in isotope compositions between the plutonic rocks and their volcanic neighbors indicates differences in the mantle sources. This could reflect temporal variation of mantle composition under the Aleutians. Based on U-Pb zircon geochronology of representative samples, the data may indicate decreasing Nd (-Hf) isotope ratios of the sub-Aleutians mantle through time in some regions. However, more data is necessary from plutonic rocks to determine if this will hold up. Alternatively, the compositional differences (e.g. higher Si and K) between the plutonics and the volcanics could reflect different

  20. Petrology and Geochemistry of Neoproterozoic Arc Plutons Beneath the Atlantic Coastal Plain, SRS, SC

    SciTech Connect

    Maryak, M.

    1998-10-21

    In this report is presented first a brief review of the regional geologic setting of the Savannah River Site, descriptions of the plutonic rock units sampled here, whole rock geochemical data on the plutonic igneous rocks, and finally, a discussion of how the crystalline basement rocks of the Savannah River Site formed and how they may correlate with other terranes exposed in the Piedmont of the Carolinas, Georgia, and Virginia.

  1. Tertiary epizonal plutonic rocks of the Selway-Bitterroot Wilderness, Idaho County, Idaho

    SciTech Connect

    Motzer, W.E.

    1996-01-01

    Geologic mapping in the Selway-Bitterroot Wilderness identified approximately 731 kmS of epizonal plutonic granitic rocks within the Bitterroot lobe of the Idaho batholith. From north to south, the intrusions are the Rock Lake Creek stock and the Whistling Pig, Running Creek, Bad Luck and Painted Rocks plutons. The stock and plutons consist of medium- to coarse-grained biotite and hornblende-biotite syenorgranite to monzogranite and quartz syenite capped by fine-grained biotite leucogranite. These rocks are intruded by late-synplutonic leucogranite dikes and post plutonic porphyritic rhyolite to rhyodacite and basalt dikes. The medium-grained granitic rocks are high in SiO2, K2O, Na2O, Ga, Th, U, W and Zr, but low in Al7O3, CaO, MgO, Cr, Ni, Co and V. Most of the granites are peraluminous. Rare-earth element (REE) plots (rock sample/chondrite) show enrichment in light REE over heavy REE with strong EU depletions. K-Ar biotite radiometric age determinations for medium-grained granites in all of the plutons range from approximately 51 Ma (Whistling Pig pluton) to 43.7 Ma (Painted Rocks pluton). Petrogenetic studies suggest that the plutons were rapidly emplaced to within 3.0 km of the paleosurface. The types, textures and color of the rocks result from devolatilization of the crystallizing melt and very low-grade hydrothermal alteration. The fluorine-rich melts are the fractionated with accumulate residue; they are considered to be anorogenic (A-type) granites intruded into the center of a metamorphic core complex.

  2. [Advances of alkaline amylase production and applications].

    PubMed

    Yang, Haiquan; Liu, Long; Li, Jianghua; Du, Guocheng; Chen, Jian

    2012-04-01

    Alkaline amylase is one of alkaline enzymes with optimum pH in the alkaline range, and it could keep stability and efficiently hydrolyze starch under alkaline conditions. Alkaline amylase finds wide applications in textile, detergent, pharmaceutical, food and other fields. Alkaline amylases could be produced by alkaliphilic microorganisms. In this work, the advances of alkaline amylase production and applications were reviewed.

  3. Alkaline flooding injection strategy

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1992-03-01

    The objective of this project is to improved alkali-surfactant flooding methods, and this includes determining the proper design of injection strategy. Several different injection strategies have been used or suggested for recovering heavy oils with surfactant-enhanced alkaline flooding methods. Oil recovery was compared for four different injection strategies: (1) surfactant followed by polymer, (2) surfactant followed by alkaline polymer, (3) alkaline surfactant followed by polymer, and (4) alkali, surfactant, and polymer mixed in a single formulation. The effect of alkaline preflush was also studied under two different conditions. All of the oil recovery experiments were conducted under optimal conditions with a viscous, non-acidic oil from Hepler (KS) oil field. The coreflood experiments were conducted with Berea sandstone cores since field core was not available in sufficient quantity for coreflood tests. The Tucker sand of Hepler field is a Class I fluvial dominated deltaic reservoir, as classified by the Department of Energy, which has been selected as the site of a DOE-sponsored field pilot test.

  4. Uranium-Lead Zircon Ages and Sr, Nd, and Pb Isotope Geochemistry of Selected Plutonic Rocks from Western Idaho

    USGS Publications Warehouse

    Unruh, Daniel M.; Lund, Karen; Kuntz, Mel A.; Snee, Lawrence W.

    2008-01-01

    Across the Salmon River suture in western Idaho, where allochthonous Permian to Cretaceous oceanic rocks are juxtaposed against Proterozoic North American rocks, a wide variety of plutonic rocks are exposed. Available data indicate much variation in composition, source, and structural state of these plutons. The plutonic rocks were long described as the western border zone of the Cretaceous Idaho batholith but limited pre-existing age data indicate more complicated origins. Because the affinity and age of the plutonic rocks cannot be reliably determined from field relations, TIMS U-Pb dating in conjunction with Sr, Nd, and Pb isotopic studies of selected plutons across the suture in western Idaho were undertaken. The data indicate three general groups of plutons including (1) those that intruded the island arc terranes during the Triassic and Jurassic, those that intruded near the western edge of oceanic rocks along the suture in the Early Cretaceous, and the plutons of the Idaho batholith that intruded Proterozoic North American rocks in the Late Cretaceous. Plutons that intruded Proterozoic North American rocks commonly include xenocrystic zircons and in several cases, ages could not be determined. The least radiogenic Sr and most radiogenic Nd are found among the Blue Mountains superterrane island arc samples. Suture-zone plutons have isotopic characteristics that span the range between Idaho batholith and island arc samples but mostly follow island arc signatures. Plutons of the Idaho batholith have the most radiogenic initial Pb and Sr ratios and the least radiogenic Nd of the samples analyzed.

  5. Possible cryptic tectono-magnetic fabrics in `post-tectonic' granitoid plutons of the Canadian Shield

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.; Kehlenbeck, Manfred M.

    1996-01-01

    Two late Archean granitic plutons forcefully intruded and thermally metamorphosed Archean schists. Feldspar magacrysts aligned concentrically with the margins during inflation. Substantial tectonic deformation never affected the plutons. Nevertheless, both plutons show the same, consistently oriented, cryptic magnetic fabric revealed by anisotropy of low field susceptibility (AMS) from 134 samples. They have an NE-SW vertical magnetic foliation and a magnetic lineation trending 060/15. Eigenvalues of the orientation distribution of principal susceptibilities show that the magnetic fabrics have almost identical strengths, orientations and symmetry in both plutons. We propose a post-magmatic reactivation of the earlier regional tectonic shortening. This imparted a 'cryptic tectonic' magnetic fabric on the plutons that overprinted the magmatic AMS fabric in most outcrops. The plutons' AMS fabrics are subparallel to the much older schistosity of the country rocks. Because multidomain magnetite provides > 99% of the low field susceptibility of the rocks, it controls the AMS. However, we see no alignment of the magnetite grains. Thus, magnetic anisotropy may be due to stress alignment of intragranular domain walls and not controlled by grain shape, as usually assumed for magnetite.

  6. Origin of mineralogical zoning in an intermediate subvolcanic pluton by crystal settling and conductive cooling

    SciTech Connect

    Hildebrand, R.S.

    1985-01-01

    The Rainy Lake Intrusive Complex is one of nine sheet-like intermediate plutons that are compositionally, temporally, and spatially linked to andesitic stratovolcanoes in the western Great Bear Magmatic Zone, an early Proterozoic continental magmatic arc. The pluton, exposed in oblique cross section, has a flat roof and is 1.5 km thick by 12 km long. The observed distribution of plagioclase phenocrysts in the body closely resembles the sinusoidal olivine distribution patterns found in lava lakes and some mafic sills. The shape of the curve indicates that the volume fraction plagioclase phenocrysts in the pluton at the time of intrusion ranged for 10% near the roof to 50% near the base. Calculations indicate that the plagioclase phenocrysts were denser than the surrounding melt. The effects of different crystal concentrations on the viscosity, and hence settling velocities, were computed as a function of height in the pluton; settling velocities ranged, at the time of intrusion, from 160 meters per year near the top to less than 1 meter per year near the base. The observed sinusoidal distribution curve for plagioclase can be explained by the interplay between crystal settling and the solidification of the pluton from the top downwards and the bottom upwards. This suggests that whole body convection did not play a major role in the cooling of the pluton.

  7. Possible mechanism of horizontal overpressure generation of the Khibiny, Lovozero, and Kovdor ore clusters on the Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Rebetsky, Yu. L.; Sim, L. A.; Kozyrev, A. A.

    2017-07-01

    The paper discusses questions related to the generation of increasing crustal horizontal compressive stresses compared to the idea of the standard gravitational state at the elastic stage or even from the prevalence of horizontal compression over vertical stress equal to the lithostatic pressure. We consider a variant of superfluous horizontal compression related to internal lithospheric processes occurrin in the crust of orogens, shields, and plates. The vertical ascending movements caused by these motions at the sole of the crust or the lithosphere pertain to these and the concomitant exogenic processes giving rise to denudation and, in particular, to erosion of the surfaces of forming rises. The residual stresses of the gravitational stressed state at the upper crust of the Kola Peninsula have been estimated for the first time. These calculations are based on the volume of sediments that have been deposited in Arctic seas beginning from the Mesozoic. The data speak to the possible level of residual horizontal compressive stresses up to 90 MPa in near-surface crustal units. This estimate is consistent with the results of in situ measurements that have been carried out at the Mining Institute of the Kola Science Center, Russian Academy of Sciences (RAS), for over 40 years. It is possible to forecast the horizontal stress gradient based on depth using our concept on the genesis of horizontal overpressure, and this forecasting is important for studying the formation of endogenic deposits.

  8. Gotu Kola (Centella Asiatica) extract enhances phosphorylation of cyclic AMP response element binding protein in neuroblastoma cells expressing amyloid beta peptide.

    PubMed

    Xu, Yanan; Cao, Zhiming; Khan, Ikhlas; Luo, Yuan

    2008-04-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder that shows cognitive deficits and memory impairment. Extract from the leaves of Gotu Kola (Centella Asiatica) have been used as an alternative medicine for memory improvement in Indian Ayurvedic system of medicine for a long time. Although several studies have revealed its effect in ameliorating the cognitive impairment in rat models of AD and stimulating property on neuronal dendrites of hippocampal region, the molecular mechanism of Gotu Kola on neuroprotection still remains to be elucidated. In this study, we report that phosphorylation of cyclic AMP response element binding protein (CREB) is enhanced in both a neuroblastoma cell line expressing amyloid beta 1-42 (Abeta) and in rat embryonic cortical primary cell culture. In addition, the contribution of two major single components to the enhanced CREB phosphorylatioin was examined. Furthermore, inhibitors were applied in this study revealing that ERK/RSK signaling pathway might mediate this effect of Gotu Kola extract. Taken together, we provide a possible molecular mechanism for memory enhancing property of Gotu Kola extract for the first time.

  9. Isotopic constraints on the petrogenesis of jurassic plutons, Southeastern California

    USGS Publications Warehouse

    Mayo, D.P.; Anderson, J.L.; Wooden, J.L.

    1998-01-01

    The 165 Ma Eagle Mountain intrusion is a heterogeneous, enclave-bearing, metaluminous remnant of the Cordilleran Jurassic arc that cuts regionally metamorphosed pre-Mesozoic rocks in the southeastern Mojave Desert of California. The main phase of the intrusion consists of granodiorite to tonalite host facies, diorite mixed facies, and homogeneous monzogranite facies. The host facies contains microdiorite enclaves interpreted as intermingled masses of mafic magma. Late-phase leucogranite stocks cut the main phase. Mineral equilibria indicate emplacement at ???6.5 km depth, with solidus temperatures ranging from 760??C for diorite to 700??C for felsic granodiorite. Although uniform radiogenic-isotope compositions (Sri = 0.7085, ???Ndi = -9.4) suggest derivation from a single source, no known source has the composition required. A hybrid source is proposed, consisting of various proportions of juvenile mantle and recycled lower crust. Calculations indicate that the source of the Eagle Mountain intrusion comprised >60% juvenile mantle and <40% recycled crust. On the basis of their isotopic compositions, other mafic Jurassic plutons in the region were derived from sources containing different proportions of mantle and crustal components.

  10. Geochemical characteristics of the Bulgarmarse Granite of the Fall River Pluton in the Avalonian Superterrane of southeastern New England

    SciTech Connect

    Mancuso, C.I.; Puffer, J.H. . Dept. of Geological Sciences)

    1993-03-01

    The 600 m.y. Bulgarmarsh Granite of the Fall River Pluton crops out along the SE margin of the Pennsylvanian-age Narragansett Basin in the Dedham terrane of the New England Avalonian Superterrane. The Bulgarmarsh is a coarse-grained, quartz-rich, very leucooratic granite, in which mafic minerals, generally less than 5--8%, occur chiefly as chlorite, biotite and garnet disequilibrium intergrowths. Most of the granite is very slightly deformed, but there are many localized zones of deformation, both brittle and plastic, that vary in degree of intensity. The Bulgarmarsh intrudes Basin margin metavolcanics similar to those of Price Neck Formation that crop out within the Basin in Newport and on Gould Island. The Bulgarmarsh Granite has many of the mineralogical and geochemical characteristics of an A-type granite. Its geochemistry places it in the post-orogenic classification of Maniar and Piccoli (1989). New major and minor element geochemical data clearly discriminate between the Bulgarmarsh Granite and the adjacent calc-alkaline Metacom Granite Gneiss. Avalonian Orogeny, occupying a place in geologic history similar to that of the Newport Granite.

  11. Petrological constraints on the origin of the plutonic massif of the Ghaleh Yaghmesh area, Urumieh-Dokhtar magmatic arc, Iran

    NASA Astrophysics Data System (ADS)

    Fazeli, Bahareh; Khalili, Mahmoud; Toksoy Köksal, Fatma; Esfahani, Mahin Mansouri; Beavers, Roy

    2017-05-01

    The Oligocene Ghaleh Yaghmesh plutonic massif (GYPM) consists of diorite, quartz-diorite, tonalite and granodiorite and evolving from metaluminous nature. All the samples are predominantly medium-K calc-alkaline series, having typical characteristics of I-type granitoids. A significant geochemical criteria of the GYPM is the impoverishment of high-field-strength elements (HFSE) (e.i. Zr, Nb, Ti and Hf) and the overabundance of large-ion-lithophile elements (LILE) (e.i. K, Sr, U, Ba and Cs), with respect to the light rare elements (LREE) as compared to chondritic concentration. These geochemical criteria suggest the involvement of sedimentary components in the generation of rocks studied. Furthermore, variable Pb/Ce amounts, linear trend of all rocks studied on Ti/Zr vs. Yb/Hf diagram, as well as some characteristics petrographic features (e.i. acicular apatite, corroded margin of the plagioclases, the amphiboles and some of the pyroxenes, oscillatory zoning of plagioclases) and the presence of mafic microgranular enclave (MME) indicate that the Ghaleh Yaghmesh parental magma was likely generated by the partial melting of a mixed source dominantly composed of amphibolite and possibly meta-sedimentary source. The overall geochemical and petrographic features are consistent with the interpretation of the Urumieh-Dokhtar Magmatic Arc as an active continental margin during subduction of the Neo-Tethyan oceanic crust underneath the Central Iranian microcontinent.

  12. Efficacy of Garcinia kola 0.5% Aqueous Eye Drops in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension

    PubMed Central

    Adefule-Ositelu, Adebukunola O.; Adegbehingbe, Bernice O.; Adefule, Adebayo K.; Adegbehingbe, Olayinka O.; Samaila, Elsie; Oladigbolu, Kehinde

    2010-01-01

    Purpose: To evaluate the intraocular pressure (IOP) lowering efficacy of Garcinia kola 0.5% aqueous solution eye drops in patients with newly diagnosed primary open-angle glaucoma or ocular hypertension (POAG/OH). Materials and Methods: A randomized, double-masked, multicenter, active-controlled prospective study. Patients who met the inclusion criteria were randomly assigned in equal numbers to receive Timolol 0.5% eye drops as a control medication (A = Group 1 eyes) or Garcinia kola 0.5% eye drops as the study medication (B = Group 2 eyes). All drops were instilled at 6 am and 6 pm daily. Goldman applanation tonometry was performed at 9 am, 12 pm and 3 pm at baseline, week-6, week-12 and week-24 visits. Voluntary and actively elicited reports of adverse events were documented. The mean change in IOP over 24 weeks was the primary outcome measure. Both groups were compared for statistically significant differences at all visits. A P < 0.05 was considered statistically significant. Results: A total of 178 patients were randomly assigned to G. kola and Timolol groups. At baseline there were no differences in mean IOP between groups, based on age, sex, or diagnosis. At the end of the study period (24th week), the mean (± SD) reduction in IOP was 12.93 ± 2.3 mmHg (47.8% ± 0.8% reduction) in G. Kola group and 13.09 ± 2.8 mm Hg (48.2% ± 1.03% reduction) in the Timolol group (P > 0.05). Adverse events were mild in nature with no statistically significant differences between groups (P > 0.05). Conclusions: Garcinia kola ophthalmic solution significantly reduces IOP as compared to baseline. The IOP lowering effect of both treatments was equivalent. PMID:20543944

  13. [Impact of industrial pollution on emission of carbon dioxide by soils in the Kola Subarctic Region].

    PubMed

    Koptsik, G N; Kadulin, M S; Zakharova, A I

    2015-01-01

    Soil emission of carbon dioxide, the key component of carbon cycle and the characteristic of soil biological activity, has been studied in background and polluted ecosystems in the Kola subarctic, the large industrial region of Russia. Long-term air pollution by emissions of "Pechenganikel" smelter, the largest source of sulphur dioxide and heavy metals in Northern Europe, has caused the technogenic digression of forest ecosystems. As a result of the digression, the tree layer was destructed, the number of plant species was diminished, the activity of soil biota was weakened, the soils were polluted and exhausted, biogeochemical cycles of elements were disturbed and productivity of ecosystems shrunk. Field investigations revealed the decrease of the in.situ soil respiration in average from 190-230 mg C-CO2/m2 x per h in background pine forests to 130-160, 100, and 20 mg C-CO2/m2.per h at the stages of pine defoliation, sparse pine forest and technogenic barrens of the technogenic succession, respectively. The soil respira- tion in birch forests was more intense than in pine forests and tended to decrease from about 290 mg C-CO2/m2 x per h in background forests to 210-220 and 170-190 mg C-CO2/m2 x per h in defoliating forests and technogenic sparse forests, respectively. Due to high spatial variability of soil respiration in both pine and birch forests significant differences from the background level were found only in technogenic sparse forests and barrens. Soil respiration represents total production of carbon dioxide by plant roots and soil microorganisms. The decrease in share of root respiration in the total soil respiration with the rise of pollution from 38-57% in background forests up to zero in technogenic barrens has been revealed for the first time for this region. This indicates that plants seem to be more sensitive to pollution as compared to relatively resistant microorganisms. Soil respiration and the contribution of roots to the total respiration

  14. Constraints on the depth of generation and emplacement of a magmatic epidote-bearing quartz diorite pluton in the Coast Plutonic Complex, British Columbia

    USGS Publications Warehouse

    Chang, J.M.; Andronicos, C.L.

    2009-01-01

    Petrology and P-T estimates indicate that a magmatic epidote-bearing quartz diorite pluton from Mt. Gamsby, Coast Plutonic Complex, British Columbia, was sourced at pressures below ???1.4 GPa and cooled nearly isobarically at ???0.9 GPa. The P-T path indicates that the magma was within the stability field of magmatic epidote early and remained there upon final crystallization. The pluton formed and crystallized at depths greater than ???30 km. REE data indicate that garnet was absent in the melting region and did not fractionate during crystallization. This suggests that the crust was less than or equal to ???55 km thick at 188 Ma during the early phases of magmatism in the Coast Plutonic Complex. Late Cretaceous contractional deformation and early Tertiary extension exhumed the rocks to upper crustal levels. Textures of magmatic epidote and other magmatic phases, combined with REE data, can be important for constraining the P-T path followed by magmas. ?? 2009 Blackwell Publishing Ltd.

  15. Is there a geochemical link between volcanic and plutonic rocks in the Organ Mountains caldera?

    NASA Astrophysics Data System (ADS)

    Memeti, V.; Davidson, J.

    2013-12-01

    Results from separate volcanic and plutonic studies have led to inconsistent conclusions regarding the origins and thus links between volcanic and plutonic systems in continental arcs and the magmatic processes and time scales responsible for their compositional variations. Some have suggested that there is a geochemical and geochronological disconnect between volcanic and plutonic rocks and hence have questioned the existence of magma mush columns beneath active volcanoes. Investigating contemporary volcanic and plutonic rocks that are spatially connected is thus critical in exploring these issues. The ca. 36 Ma Organ Mountains caldera in New Mexico, USA, represents such a system exposing contemporaneous volcanic and plutonic rocks juxtaposed at the surface due to tilting during extensional tectonics along the Rio Grande Rift. Detailed geologic and structural mapping [1] and 40Ar/39Ar ages of both volcanics and plutons [2] demonstrate the spatial and temporal connection of both rock types with active magmatism over >2.5 myr. Three caldera-forming ignimbrites erupted within 600 kyr [2] from this system with a total erupted volume of 500-1,000 km3 as well as less voluminous pre- and post-caldera trachyte and andesite lavas. The ignimbrite sequence ranges from a crystal-poor, high-SiO2 rhyolite at the base to a more crystal-rich, low-SiO2 rhyolite at the top. Compositional zoning with quartz-monzonite at the base grading to syenite and alaskite at the top is also found in the Organ Needle pluton, the main intrusion, which is interpreted to be the source for the ignimbrites [1]. Other contemporaneous and slightly younger plutons have dioritic to leucogranitic compositions. We examined both volcanic and plutonic rocks with petrography and their textural variations with color cathodoluminescence, and used whole rock element and Sr, Nd and Pb isotope geochemistry to constrain magma compositions and origins. Electron microprobe analyses on feldspars have been completed to

  16. Advanced alkaline water electrolysis

    NASA Astrophysics Data System (ADS)

    Wakabayashi, N.; Torikai, E.; Kawami, Y.; Takenaka, H.

    Results are presented of experimental studies of possible separators and electrodes for use in advanced, high-temperature, high-pressure alkaline water electrolyzers. Material evaluations in alkaline water electrolyzers at temperatures from 100 to 120 C have shown a new type polytetrafluoroethylene membrane impregnated with potassium titanate to be the most promising when the separator is prepared by the hydrothermal treatment of a porous PFTE membrane impregnated with hydrated titanium oxide. Measurements of cell voltages in 30% KOH at current densities from 5 to 100 A/sq dm at temperatures up to 120 C with nickel electrodes of various structures have shown the foamed nickel electrode, with an average pore size of 1-1.5 mm, to have the best performance. When the foamed nickel is coated by fine powdered nickel, carbonyl nickel or Raney nickel to increase electrode surface areas, even lower cell voltages were found, indicating better performance.

  17. Alkaline quinone flow battery.

    PubMed

    Lin, Kaixiang; Chen, Qing; Gerhardt, Michael R; Tong, Liuchuan; Kim, Sang Bok; Eisenach, Louise; Valle, Alvaro W; Hardee, David; Gordon, Roy G; Aziz, Michael J; Marshak, Michael P

    2015-09-25

    Storage of photovoltaic and wind electricity in batteries could solve the mismatch problem between the intermittent supply of these renewable resources and variable demand. Flow batteries permit more economical long-duration discharge than solid-electrode batteries by using liquid electrolytes stored outside of the battery. We report an alkaline flow battery based on redox-active organic molecules that are composed entirely of Earth-abundant elements and are nontoxic, nonflammable, and safe for use in residential and commercial environments. The battery operates efficiently with high power density near room temperature. These results demonstrate the stability and performance of redox-active organic molecules in alkaline flow batteries, potentially enabling cost-effective stationary storage of renewable energy. Copyright © 2015, American Association for the Advancement of Science.

  18. Mineral potential of selected felsic plutons in the eastern and southeastern Arabian Shield, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    du Bray, Edward A.

    1983-01-01

    Most of the plutons studied are similar to metallogenically specialized granites described elsewhere in the world and found associated with deposits of tin, tungsten, or molybdenum and other rare metals. Only four of the plutons, the Sitarah, Tarban, and Gaharra monzogranites and the Bwana granite, contained highly anomalous amounts of tin, tungsten, or molybdenum and altered zones- and (or) numerous quartz veins and otherwise appeared to have noteworthy mineral potential. Additional work on at least these four plutons is suggested.

  19. Melt segregation and assembly of the youngest exposed magma chamber in the world: Takidani Pluton (Japan)

    NASA Astrophysics Data System (ADS)

    Hartung, E.; Caricchi, L.; Floess, D.; Wallis, S.; Harayama, S.

    2014-12-01

    Segregation of residual melt from partially crystallized magmas is a process of paramount importance for the chemical evolution of magmas and the construction of reservoirs of potentially eruptible magma. In this study we investigate the Takidani pluton, one of the youngest exposed plutons on Earth (˜1Ma). This chemically zoned magmatic body is located within the active Norikura Volcanic Chain in the Northern Japan Alps and associated with large dacitic to rhyolitic deposits (Nyukawa Pyroclastic Flow Deposit and Ebisutoge-Fukuda tephra). Our study focuses on the physical processes responsible for the extraction of residual melt from a crystallizing magma and the construction of the subvolcanic reservoirs that fed large silicic eruptions. Detailed structural mapping and sampling along four transects from the base to the top of the pluton were carried out along with a magnetic susceptibility survey. Our preliminary results indicate that the pluton was assembled by multiple intrusions. The pluton can be broadly separated into three distinct lithological units: 1) fine grained granite; 2) equigranular granodiorite that locally grades into either porphyritic granodiorite or granite towards the roof of the intrusion; and 3) mafic granodiorite. Units 1) and 2) form the core of the intrusion and together represent about 70% of the total volume of the pluton. Our results show that the equigranular granodiorite is internally inhomogeneous with felsic lenses of lower magnetic susceptibility. The magnetic susceptibility decreases gradually towards the roof of the pluton reaching its lowest value within leucrocratic porphyritic units. Higher magnetic susceptibility values at the contact with the roof correspond to a slightly more mafic porphyritic unit. Melt segregation and evolution of the Takidani Granodiorite are being further investigated using bulk rock and mineral chemistry (EMPA and LA-ICP-MS) together with anisotropy of magnetic susceptibility.

  20. Record of Hybridization Preserved in Zircon, Aztec Wash Pluton, NV

    NASA Astrophysics Data System (ADS)

    Bromley, S. A.; Miller, C. F.; Claiborne, L. L.; Wooden, J. L.; Mazdab, F. K.

    2007-12-01

    The mid-Miocene Aztec Wash pluton comprises a smaller granite zone and a larger, highly heterogeneous zone in which evidence for interaction between basaltic and granitic magmas is ubiquitous. Granitic rocks in both zones show textural and compositional evidence for crystal accumulation and melt fractionation. In the heterogeneous zone, basalts have chilled, crenulate margins against granitic rocks, and there is widespread evidence for mechanical contamination of each lithology (coarse resorbed alkali feldspar in fine-grained mafic rock; mafic enclaves in granite). "Grey rocks" of intermediate composition are exposed on dm to 100's of m-scale as enclaves, pods, and initially subhorizontal sheets. They are variable texturally, but most are dominantly fine- grained and equigranular. Textures of grey rocks are consistent with rapid solidification from melt-rich magma, and, in combination with isotopic compositions intermediate between felsic and mafic rocks of the pluton, suggest an origin by near-complete homogenization of a hybrid melt (Bleick et al. 2005; Ericksen 2005). The elemental chemistry of zircon preserves information about the evolving magmatic environment in which it was hosted (Claiborne et al., 2006). Owing to its slow dissolution rate, it has the potential to survive periods of undersaturation with only partial resorption. Thus, it may record drastic shifts in T and melt chemistry that would accompany mafic-felsic hybridization. We are investigating zircon zoning patterns by cathodoluminescence (CL) and elemental compositions by SHRIMP-RG to evaluate the record of processes that they preserve. Temperatures of zircon growth are estimated using Ti-in-zircon thermometry (Watson et al. 2006), assuming a(TiO2) of ca. 0.7 (sphene +/-ilmenite are ubiquitous). Zircons from the granite zone yield estimated T's of 700-860 C, whereas those from grey rocks range from 710- 910 C. While both granite and grey zircon populations show dramatic T variations among and

  1. Ar/Ar age data of muscovite from the Keivy Terrane (central Kola Peninsula, arctic European Russia) imply a prolonged fluid-assisted recrystallisation

    NASA Astrophysics Data System (ADS)

    de Jong, K.; Ruffet, G.; Marker, M.

    2012-04-01

    Single grain muscovite 40Ar/39Ar age data from metasediments of the Keivy Terrane point to a prolonged recrystallisation, and imply that the younger age set in metamorphic terranes with a long history cannot always be simply interpreted as due to late and slow cooling. The Keivy terrane is an element of the Palaeoproterozoic Lapland-Kola collisional belt developed along the northern margin of the Fennoscandian (Baltic) Shield. It comprises a lower series of late Archaean meta-volcanic rocks, intruded by earliest Palaeoproterozoic alkali granites that are covered by strongly deformed quartz-rich kyanite-staurolite-garnet-micaschists of the Keivy unit that have yielded magmatic zircons as young as ~2.35 Ga, which were derived from the substratum's alkaline granite. 40Ar/39Ar step-heating dating with a defocussed laser beam of muscovite grains from seven metasediments of the Keivy unit yielded saddle-shaped age spectra in most experiments. In five out of seven cases the base of the saddle corresponded to a plateau age in the range of 1667 to 1593 Ma (60-90% of the gas release; 1 sigma errors: 1.0-1.2 Ma). We do not simply interpret these 40Ar/39Ar ages in the classical way as due to cooling, because the saddle shape of the spectra enables a more complete and detailed interpretation. Saddle-shaped age spectra may result from the presence of different argon reservoirs in partially recrystallised and chemically distinct micas that degas over a different energy interval: a primary, not recrystallised or inherited domain (low and high temperature steps) and a newly formed or recrystallised one (saddle minimum in the intermediate steps). The younger subdomains formed by growth or recrystallisation could characterise the last isotopic record during an extended (re)crystallisation history. It is striking that 1612 and 1615 Ma saddle minimum ages in two samples correspond to a plateau age of 1612 Ma in another sample. Also elevated high and/or low temperature apparent ages of

  2. Pressure, temperature and oxygen fugacity conditions of calc-alkaline granitoids, Eastern Desert of Egypt, and tectonic implications

    NASA Astrophysics Data System (ADS)

    Helmy, H. M.; Ahmed, A. F.; El Mahallawi, M. M.; Ali, S. M.

    2004-02-01

    Five calc-alkaline plutons; Um Tagher, Abu Zawil, Um Gidri, Um Anab and El Ghuzah, in the northern Eastern Desert of Egypt were subjected to petrographic and mineralogical investigations. They are composed of varying proportions of quartz + plagioclase + potash feldspar + biotite + hornblende ± epidote ± calcite + titanite + magnetite + apatite and zircon. Electron microprobe analyses of coexisting hornblende and plagioclase (hornblende-plagioclase thermometry), Al content in hornblende (aluminum-in-hornblende barometry) and the assemblage titanite-magnetite-quartz were used to constrain the P, T and fO 2 during the crystallization of the parent magmas in the different plutons. The plutons crystallized under varying pressures (5.4-2.1 kbar) and wide range of temperature (785-588 °C) from highly oxidized magmas (log fO 2 -21 to -13). The pressure data discriminate three categories of granitoid emplaced at different crustal levels: (a) upper crust granitoids (e.g., El Ghuzah, and Abu Zawil) emplaced at depths <9 km; (b) intermediate crust granitoids (e.g., Um Gidri and Um Anab) emplaced at depths <13 km; and (c) lower crust granitoids (e.g., Um Tagher) emplaced at depths <21 km. The depths of emplacement seem to increase from northwest to southeast. It is likely that the magmas forming these plutons were generated at different depths; they were similar in composition but varied substantially in their water and volatile contents. High water and volatile contents allowed the magma of some plutons to reach shallower crustal levels without complete solidification. Although these complexes were crystallized at different depths, they were later uplifted to the same level by upward faulting.

  3. Granitoid pluton formation by spreading of continental crust: the Wiley Glacier complex, northwest Palmer Land, Antarctica

    NASA Astrophysics Data System (ADS)

    Vaughan, Alan P. M.; Wareham, Christopher D.; Millar, Ian L.

    1997-12-01

    The emplacement mechanism, geometry, and isotope geochemistry of plutons of the Wiley Glacier complex suggest that new continental crust grew by multiple injection of tonalitic dykes during dextral transtension in the Antarctic Peninsula magmatic arc in Early Cretaceous times. The suggested mechanism is analogous to basalt dyke injection during sea-floor spreading. During normal-dextral shear, the Burns Bluff pluton, a sheeted, moderately east-dipping, syn-magmatically sheared tonalite-granodiorite intruded syn-magmatically sheared quartz diorite of the Creswick Gap pluton and 140 ± 5 Ma hornblende gabbro. UPb dating of zircon and ArAr dating of hornblende and biotite suggest that both granite s.l. plutons were emplaced between 145 and 140 Ma, but that extensional shearing was active from the time of emplacement until ca. 127 Ma. The Burns Bluff pluton is chilled at its margin, and grades through mylonitised, porphyritic tonalite-granodiorite sheets and tonalite-granodiorite sheets with minor chilling, to a kilometre-scale body of coarse-grained, hypidiomorphic tonalite-granodiorite. Co-magmatic microdiorite forms dykes and abundant synplutonic mafic enclaves. These dykes opened as echelon veins during episodic dextral shear and were deformed to trains of enclaves during continued normal-dextral shear. Pluton-marginal porphyritic and hypidiomorphic tonalite-granodiorite forms large, fault-hosted sheets emplaced progressively under extension with minor dextral shear. Kinematic indicators from pluton-marginal granite s.l. dykes suggest that early in pluton accretion, intrusive sheets cooled rapidly, with simple shear prior to full crystallisation changing to ductile simple shear during cooling. Kinematic indicators towards the pluton core suggest that as the pluton grew, and cooled more slowly, emplacement switched from sheeting to in situ inflation with simple shear distributed across a broad zone prior to full crystallisation of magma. Cross

  4. Strontium and oxygen isotopic variations in Mesozoic and Tertiary plutons of central Idaho

    USGS Publications Warehouse

    Fleck, R.J.; Criss, R.E.

    1985-01-01

    Regional variations in initial 87Sr/86Sr ratios (ri) of Mesozoic plutons in central Idaho locate the edge of Precambrian continental crust at the boundary between the late Paleozoic-Mesozoic accreted terranes and Precambrian sialic crust in western Idaho. The ri values increase abruptly but continuously from less than 0.704 in the accreted terranes to greater than 0.708 across a narrow, 5 to 15 km zone, characterized by elongate, lens-shaped, highly deformed plutons and schistose metasedimentary and metavolcanic units. The chemical and petrologic character of the plutons changes concomitantly from ocean-arc-type, diorite-tonalite-trondhjemite units to a weakly peraluminous, calcic to calcalkalic tonalite-granodiorite-granite suite (the Idaho batholith). Plutons in both suites yield Late Cretaceous ages, but Permian through Early Cretaceous bodies are confined to the accreted terranes and early Tertiary intrusions are restricted to areas underlain by Precambrian crust. The two major terranes were juxtaposed between 75 and 130 m.y. ago, probably between 80 and 95 m.y. Oxygen and strontium isotopic ratios and Rb and Sr concentrations of the plutonic rocks document a significant upper-crustal contribution to the magmas that intrude Precambrian crust. Magmas intruding the arc terranes were derived from the upper mantle/subducted oceanic lithosphere and may have been modified by anatexis of earlier island-arc volcanic and sedimentary units. Plutons near the edge of Precambrian sialic crust represent simple mixtures of the Precambrian wall-rocks with melts derived from the upper mantle or subducted oceanic lithosphere with ri of 0.7035. Rb/Sr varies linearly with ri, producing "pseudoisochrons" with apparent "ages" close to the age of the wall rocks. Measured ??18O values of the wall rocks are less than those required for the assimilated end-member by Sr-O covariation in the plutons, however, indicating that wall-rock ??18O was reduced significantly by exchange with

  5. Timing of K-alkaline magmatism in the Balkan segment of southeast European Variscan edifice: ID-TIMS and LA-ICP-MS study

    NASA Astrophysics Data System (ADS)

    Dyulgerov, Momchil; Ovtcharova-Schaltegger, Maria; Ulianov, Alexey; Schaltegger, Urs

    2017-08-01

    The Variscan orogen in southeast Europe is exposed in isolated remnants, affected by a subsequent Alpine tectono-magmatic overprint. Unlike the central European Variscides, in SE Europe the juxtaposition and correlation of the events and products are impeded by the scarcity of Variscan domains with preserved magmatic, metamorphic, sedimentological and structural characteristics. To reveal the particular evolution of the Variscan orogen in Balkan Mts, we present the results of ID-TIMS and LA-ICP-MS dating of three potassic-alkaline intrusions: Svidnya, Buhovo-Seslavtsi and Shipka. The age determinations from the plutons do not permit to establish their unequivocal ages, but they bracket the time interval of emplacements. Based on geochronological, tectonic and stratigraphic evidence the emplacement interval for plutons could be: 317-310 Ma for Svidnya, 330-310 Ma for Buhovo-Seslavtsi and 320-303 Ma for Shipka. These results show that the generation of potassic-alkaline magmas was post-Visean and is contemporaneous with the adjacent numerous calc-alkaline granitoid plutons. Thus, the Variscan orogen in the Balkan Mts is not characterized by a time-dependent geochemical evolution of magma generation. Hence, the observed differences in the rocks' compositions can be interpreted solely by distinction between the magma sources. The available data for both potassic-alkaline and calc-alkaline rocks indicate that the major episodes of crustal stacking and shearing in the Balkan part of the Variscan edifice are pre-Visean ( 330 Ma). The present study reveals that the potassic-alkaline rocks from the Balkan Mts are younger than the central European potassic granitoids (durbachites). It suggests that melting of enriched mantle source took place at different times throughout the Variscan orogen. In spite of the alkaline character of the magmas, the studied zircons show a complex nature, with inherited cores and magmatic overgrowths. The observed heterogeneities in the zircons

  6. Soil catenas on denudation plains in the forest-tundra and northern taiga zones of the Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Urusevskaya, I. S.

    2017-07-01

    Morphogenetic features of soils of two catenas developed on sandy to loamy sandy moraine deposits in the forest-tundra and northern taiga zones on denudation plains of the Kola Peninsula are discussed. It is shown that these catenas are similar with respect to the major directions of soil formation, regularities of soil distribution by the elements of mesotopography, and the factors of the soil cover differentiation. The differences between the catenas are of quantitative character and are related to the intensities of manifestation of the particular processes and features. Both catenas are characterized by the pronounced differentiation of soils with respect to their moistening with hydromorphic peat bog soils in the subordinate positions and Al-Fe-humus podzols in the automorphic positions.

  7. [Occupational morbidity among miners engaged into contemporary method of extracting copper-nickel ores in Kola Transpolar regions].

    PubMed

    Siurin, S A; Shilov, V V

    2014-01-01

    The risks for developing occupational pathology and its specific features were studied in 358 Kola Transpolar copper-nickel miners who were diagnosed with 722 cases of occupational diseases (OD) in the years 1990-2013. The highest risk for developing OD, which are dominated by the diseases of the musculoskeletal system, has been found in tunnellers (OR = 12,8) and operators of drilling rigs (OR = 10,4). A significant increase in the risk of OD has been established in miners with length of service at 11-15 years and over 25 years. The conclusion is made about the need to improve the technical, medical and organizational measures targetted at preventing health problems in this group of workers.

  8. Changes in the molecular hydrogen concentration in an underground mine (Lovozero rare-metal deposit, Kola Peninsula)

    NASA Astrophysics Data System (ADS)

    Nivin, V. A.; Pukha, V. V.; Lovchikov, A. V.; Rakhimov, R. G.

    2016-12-01

    Long-term monitoring yielded significant variations in the hydrogen volume concentration in an underground mine at the developed Lovozero rare-metal deposit of the nepheline-syenite massif in the Kola Peninsula. The deposit is characterized by emission of natural combustible gases. Basic structural elements of the time series obtained include relatively stable and long ranges of low background concentrations, low- and medium-amplitude rises of various duration, and short-term, commonly high-amplitude peaks. The range structure is characterized by a general decreasing trend, a low intensity random noise component, and seasonal and off-seasonal periodic and other cyclical components. Periodic circadian and semidiurnal harmonics are the most pronounced.

  9. Magma ascent and emplacement in a continental rift setting: lessons from alkaline complexes in active and ancient rift zones

    NASA Astrophysics Data System (ADS)

    Hutchison, William; Lloyd, Ryan; Birhanu, Yelebe; Biggs, Juliet; Mather, Tamsin; Pyle, David; Lewi, Elias; Yirgu, Gezahgen; Finch, Adrian

    2017-04-01

    A key feature of continental rift evolution is the development of large chemically-evolved alkaline magmatic systems in the shallow crust. At active alkaline systems, for example in the East African Rift, the volcanic complexes pose significant hazards to local populations but can also sustain major geothermal resources. In ancient rifts, for example the Gardar province in Southern Greenland, these alkaline magma bodies can host some of the world's largest rare element deposits in resources such as rare earths, niobium and tantalum. Despite their significance, there are major uncertainties about how such magmas are emplaced, the mechanisms that trigger eruptions and the magmatic and hydrothermal processes that generate geothermal and mineral resources. Here we compare observations from active caldera volcanoes in the Ethiopian Rift with compositionally equivalent ancient (1300-1100 Ma) plutonic systems in the Gardar Rift province (Greenland). In the Ethiopian Rift Valley we use InSAR and GPS data to evaluate the temporal and spatial evolution of ground deformation at Aluto and Corbetti calderas. We show that unrest at Aluto is characterized by short (3-6 month) accelerating uplift pulses likely caused by magmatic fluid intrusion at 5 km. At Corbetti, uplift is steady ( 6.6 cm/yr) and sustained over many years with analytical source models suggesting deformation is linked to sill intrusion at depths of 7 km. To evaluate the validity of these contrasting deformation mechanisms (i.e. magmatic fluid intrusion and sill emplacement) we carried out extensive field, structural and geochemical analysis in the roof zones of two alkaline plutons (Ilímaussaq and Motzfeldt) in Greenland. Our results show that the volatile contents (F, Cl, OH and S) of these magmas were exceptionally high and that there is evidence for ponding of magmatic fluids in the roof zone of the magma reservoir. We also identified extensive sill networks at the contact between the magma reservoir and the

  10. Effectiveness of Gotu Kola Extract 750 mg and 1000 mg Compared with Folic Acid 3 mg in Improving Vascular Cognitive Impairment after Stroke

    PubMed Central

    Wibowo, Samekto

    2016-01-01

    This study aimed to determine the effectiveness of gotu kola (Centella asiatica) in improving cognitive function in patients with vascular cognitive impairment (VCI). This study uses a quasi-experimental design. Subjects in this study were patients with poststroke cognitive impairment who were treated at two hospitals in Yogyakarta, Indonesia. The number of subjects was 48: 17 subjects were treated with 1000 mg/day of gotu kola extract, 17 subjects treated with 750 mg/day of gotu kola extract, and 14 subjects treated with 3 mg/day of folic acid for 6 weeks. A Montreal Cognitive Assessment-Indonesian version (MoCA-Ina) was conducted at the beginning of treatment and after 6 weeks of therapy. It was found that all trials effectively improved poststroke VCI based on MoCA-Ina scores over the course of the study. There is no significant difference in ΔMoCA-Ina (score at the 6th week of treatment − score at the beginning) mean score among the three groups, indicating that gotu kola is as effective as folic acid in improving poststroke VCI. Gotu kola was shown to be more effective than folic acid in improving memory domain. This study suggested that gotu kola extract is effective in improving cognitive function after stroke. PMID:27340413

  11. Effectiveness of Gotu Kola Extract 750 mg and 1000 mg Compared with Folic Acid 3 mg in Improving Vascular Cognitive Impairment after Stroke.

    PubMed

    Farhana, Kun Marisa; Malueka, Rusdy Ghazali; Wibowo, Samekto; Gofir, Abdul

    2016-01-01

    This study aimed to determine the effectiveness of gotu kola (Centella asiatica) in improving cognitive function in patients with vascular cognitive impairment (VCI). This study uses a quasi-experimental design. Subjects in this study were patients with poststroke cognitive impairment who were treated at two hospitals in Yogyakarta, Indonesia. The number of subjects was 48: 17 subjects were treated with 1000 mg/day of gotu kola extract, 17 subjects treated with 750 mg/day of gotu kola extract, and 14 subjects treated with 3 mg/day of folic acid for 6 weeks. A Montreal Cognitive Assessment-Indonesian version (MoCA-Ina) was conducted at the beginning of treatment and after 6 weeks of therapy. It was found that all trials effectively improved poststroke VCI based on MoCA-Ina scores over the course of the study. There is no significant difference in ΔMoCA-Ina (score at the 6th week of treatment - score at the beginning) mean score among the three groups, indicating that gotu kola is as effective as folic acid in improving poststroke VCI. Gotu kola was shown to be more effective than folic acid in improving memory domain. This study suggested that gotu kola extract is effective in improving cognitive function after stroke.

  12. Geochemistry of biotite granites from the Lamas de Olo Pluton, northern Portugal

    NASA Astrophysics Data System (ADS)

    Fernandes, Susana; Gomes, Maria; Teixeira, Rui; Corfu, Fernando

    2013-04-01

    In the Central Iberian Zone (CIZ) extensive crustal recycling occurred during the post-thickening extension stage of the Variscan orogeny (~330-290 Ma). After the ductile deformation phase D3 (~320-300 Ma), characterized by the intrusion of large volumes of highly peraluminous granitic magmas, rapid and drastic tectonic changes at about 300 Ma gave rise to the brittle phase of deformation D4 that controlled the emplacement of Fe-K subalkaline granites (296-290 Ma; Dias et al. 1998). The Lamas de Olo Pluton (LOP) is controlled by NE-SW and NW-SE fracture systems, probably related to the Régua-Verin fault zone (Pereira, 1989). The LOP is a medium to coarse-grained, porphyritic biotite granite, accompanied by medium- to fine grained, porphyritic biotite granite (Alto dos Cabeços- AC) and a more leucocratic, fine-grained, slightly porphyritic biotite-muscovite granite (Barragens- BA). The contacts between LO and AC are generally diffuse, whereas those to BA are sharp. In fact, the BA granite can occur in dykes and sills cutting LO and AC. Microgranular enclaves and xenoliths are very rare. The LOP intrudes the Douro Group, presumably of Precambrian to Cambrian age, and two-mica granites from the Vila Real composite massif. The LOP granites consist of quartz, microcline, plagioclase, biotite, zircon, titanite, tourmaline apatite, fluorite, ilmenite, magnetite, and rutile, with muscovite in BA granite and rare allanite in the LO and AC granites. The plagioclase composition is of oligoclase (An12) - andesine (An35) for LO granite, albite (An9) - andesine (An30) for CA granite and albite (An5) - oligoclase (An20) for BA granite. There are decreases in: a) anorthite content from phenocryst to matrix plagioclase; b) Ba content from phenocryst to matrix microcline in all granites. The Fe2+ biotite has a composition similar to that of biotite from calc-alkaline to sub-alkaline rock series. The LO and AC granites are meta- to peraluminous with ASI variable between 1.05 and 1

  13. Platinum-Group Element Mineralization in the Fedorovatundra layered intrusion, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Groshev, Nikolay; Subbotin, Victor; Korchagin, Alexey

    2016-04-01

    The 2526 to 2485 Ma Fedorovatundra layered mafic intrusion in the central part of the Kola Peninsula, Russia, is the western massif of the Fedorova-Pana Complex (2526-2446 Ma), which is situated along the northern contact of the Early Proterozoic Imandra-Varzuga rift and Archean granite gneiss. The Fedorovatundra intrusion of approximately 4 km thick has two major parts: (1) located at the bottom of the intrusion Taxitic series (10 to 900 m) and composing the main volume of the massif Layered series (4000 m). The Taxitic series is distinctive, due to its predominant vary-textured often quartz-saturated norites and gabbronorites (with fewer amounts of leucogabbro, melanorite and Ol-gabbronorite) and abundant pyroxenite, less harzburgite xenoliths. Medium to coarse-grained mottled or massive leucocratic gabbronorite and leucogabbro prevails in the Layered series with mesocratic gabbronorite, pyroxenite and troctolite as subordinate rocks. Depending on its localization, geochemical features, mineral composition and economic value platinum-group element (PGE) mineralization of the Fedorovatundra intrusion is divided into 'marginal' (basal, contact) and 'reef' types. 'Marginal' type of mineralization is presented by irregular disseminated interstitial sulfides (1-2 vol. %) of pentlandite-pyrrhotite-chalcopyrite association (Cu/Ni = 1.8) in the Taxitic series. Less sulfides occur as uniformly disseminated aggregates, thin massive lenses and nests. PGE and base metals are concentrated in several ore horizons of 3.5 km long complicated structure. Thickness of ore horizons varies generally within 10-150 m, but it can rise up to 280 m in bulges. In the most common ore-bearing rock (taxitic gabbronorite) average Pt + Pd content is 1.6 ppm (Pd/Pt 4.5). The pyroxenite xenoliths occurring within the Taxitic series are practically barren of sulfide and can dilute higher PGE and base metal grades in the gabbronorite matrix. 'Marginal' mineralization of the Fedorovotundrovsky

  14. Geochemistry, geochronology and zircon Hf isotopic study of peralkaline-alkaline intrusions along the northern margin of the North China Craton and its tectonic implication for the southeastern Central Asian Orogenic Belt

    NASA Astrophysics Data System (ADS)

    Zhao, Pan; Jahn, Bor-ming; Xu, Bei; Liao, Wen; Wang, Yanyang

    2016-09-01

    A giant Permian alkaline magmatic belt has recently been identified in southern Inner Mongolia, along the northern margin of the North China Craton (NCC). This belt is mainly composed of syenite, quartz syenite, alkaline granite and mafic microgranular enclaves (MME)-bearing granodiorite. In order to study the petrogenesis and tectonic implications of these rocks, we undertook zircon U-Pb dating and geochemical analysis of two Permian alkaline plutons. The first Guangxingyuan Pluton occurs in the Hexigten area and is composed of MME-bearing tonalite, K-feldspar granite and syenite. The second Durenwuliji Pluton, located in the Xianghuangqi area, comprises syenite, quartz syenite and K-feldspar granite. Zircon U-Pb dating on tonalite, K-feldspar granite, syenite and quartz syenite from the two plutons yielded a tight range of ages from 259 to 267 Ma. The peralkaline-alkaline rocks show high abundance of total alkalis (K2O + Na2O = 7.9-12.9%) and K2O contents (3.9-8.0%), enrichment in large ion lithophile elements (LILE) and light rare earth element (LREE), and depletion of high field strength elements (HFSE). The associated tonalite and MMEs display I-type granitic geochemical affinity, with less total abundance of trace elements than the peralkaline-alkaline rocks. Zircon Hf isotopic analysis of the Guangxingyuan pluton yielded a large range of εHf(t) values from - 15.5 to + 6.7 and model ages (TDMC) from 781 to 2012 Ma. By contrast, the Hf isotopic data of the Durenwuliji pluton shows a small range of εHf(t) from + 6.2 to + 8.9 and TDMC from 667 to 816 Ma. The geochemical and Hf isotopic characteristics indicate that the parental magma was derived from a mixing of metasomatic mantle-derived mafic magma with different amount of crust-derived felsic magma, and followed by fractional crystallization. Considering previous tectonic studies in Inner Mongolia, a Permian post-orogenic extension was proposed to account for these peralkaline-alkaline intrusions following

  15. Thermochronology of the Cornubian batholith in southwest England: Implications for pluton emplacement and protracted hydrothermal mineralization

    USGS Publications Warehouse

    Chesley, J.T.; Halliday, A.N.; Snee, L.W.; Mezger, K.; Shepherd, T.J.; Scrivener, R.C.

    1993-01-01

    The metalliferous ore deposits of southwest England are associated with biotite-muscovite granites that intruded upper Paleozoic sediments and volcanic rocks at the end of the Hercynian Orogeny. The hydrothermal mineralization can be subdivided into four stages: 1. (1) exoskarns 2. (2) high-temperature tin and tungsten oxide-bearing sheeted greisen bordered veins and Sn-bearing tourmaline veins and breccias 3. (3) polymetallic quartz-tourmaline-chlorite-sulfide-fluorite-bearing fissure veins, which represent the main episode of economic mineralization 4. (4) late-stage, low-temperature polymetallic fluorite veins. U-Pb dating of monazite and xenotime and 40Ar 39Ar dating of muscovite were used to determine emplacement ages and cooling times for individual plutons within the Cornubian batholith, as well as separate intrusive phases within the plutons. In addition, 40Ar 39Ar ages from hornblende and secondary muscovite and Sm-Nd isochron ages from fluorite were employed to determine the relationship between pluton emplacement and different stages of mineralization. The U-Pb ages indicate that granite magmatism was protracted from ~300 Ma down to ~275 Ma with no evidence of a major hiatus. There is no systematic relation between the age of a pluton and its location within the batholith. The U-Pb ages for separate granite phases within a single pluton are resolvable and indicate that magma emplacement within individual plutons occurred over periods of as much as 4.5 myrs. Felsic porphyry dike emplacement was coeval with plutonism, but continued to ~270 Ma. The geochronologic data suggest that the Cornubian batholith originated from repeated melting events over 30 myrs and was formed by a series of small coalescing granitic bodies. Cooling rates of the main plutons are unrelated to emplacement age, but decrease from the southwest to the northeast from ~210??C myr-1 to ~60??C myr-1 with a mean of 100??C myr-1. These slow cooling rates appear to reflect the addition of

  16. Reconnaissance geochemical exploration of plutons of syenite and shonkinite, southern Asir, Kingdom of Saudi Arabia

    SciTech Connect

    Overstreet, W.C.; Assegaff, A.B.; Hussain, M.A.; Naqvi, M.I.; Selner, G.I.; Matzko, J.J.

    1985-01-01

    Reconnaissance geochemical exploration for rare metals in plutons of syenite and shonkinite disclosed generally less than 20 ppM Nb in rocks, wadi sediments, and concentrates. The sparsity of Nb is accompanied by low values for La, Sn, W, Y, and Zr and relatively high but insignificant values for Be and Mo. Base and precious metals are either below their respective limits of determination in the various sample media or are present at background levels commensurate with average crustal abundances in felsic rocks. Pegmatite dikes associated with the syenite plutons are rare and lack vermiculite. The present investigation disclosed no possible ore deposits in the plutons covered by the field work. Known kyanite-topaz-natroalunite rocks in the vicinity of the surveyed areas should be examined for possible deposits of Cu, Mo, or Au associated with high-alumina hydrothermal deposits. 27 refs., 7 figs., 21 tabs.

  17. Tectonic significance of early Oligocene plutonism on Adak Island, central Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Citron, G. P.; Kay, R. W.; Mahlburg Kay, S.; Snee, L. W.; Sutter, J. F.

    1980-08-01

    Six biotite and two hornblende separates from the Hidden Bay pluton, Adak Island, yielded K-Ar dates that cluster about an average of 33.13 ± 0.41 m.y. B.P. This average is interpreted as the time of intrusion of the pluton and provides the first documentation of an early Oligocene magmatic event in the central Aleutian island arc. Biotite and hornblende from the nearby Kagalaska pluton on Adak Island yielded nearly concordant K-Ar dates that have an average of 13.15 ± 0.55 m.y. B.P., in good agreement with published dates of about 13 to 14 m.y. B.P. *Present address: Amoco Production Company, P.O. Box 3092, Houston, Texas 77001

  18. Use of olivine and plagioclase saturation surfaces for the petrogenetic modeling of recrystallized basic plutonic systems

    NASA Technical Reports Server (NTRS)

    Hanson, G. N.

    1983-01-01

    During petrogenetic studies of basic plutonic rocks, there are at least three major questions to be considered: (1) what were the relative proportions of cumulate crystals and intercumulus melt in a given sample? (2) what is the composition and variation in composition of the melts within the pluton? and (3) what is the original composition of the liquids, their source and evolution prior to the time of emplacement? Use of both saturation surfaces can place strong limits on the compositions of potential cumulate phases and intercumulus melts. Consideration of appropriate trace elements can indicate whether a sample is an orthocumulate, adcumulate or mesocumulate. Thus, when trace element and petrographic data are considered together with the saturation surfaces, it should be possible to begin to answer the three major questions given above, even for strongly recrystallized basic plutons.

  19. Origin of the Monchegorsk Pluton and associated ores: Evidence from the Nd isotope composition of rocks and trace-element composition of olivine

    NASA Astrophysics Data System (ADS)

    Bogina, Maria; Sharkov, Evgenii; Chistyakov, Alexey; Zlobin, Valerii

    2017-04-01

    The 2.5 Ga Monchegorsk mafic—ultramafic layered pluton is located at the Kola Craton, eastern Fennoscandian Shield. It is ascribed to the Early Paleoproterozoic LIP, which was formed in relation with plume activity and is made up of the rocks of SHMS (siliceous high-magnesian series). The massif hosts PGE-Cu-Ni ores (massive ores of the Nittis and Nyud mounts, Sopcha Ore Layer represented by 2-3 m thick horizon of thin-layered peridotites among a pyroxenite zone) and chromitite ores (Sopcheozero deposit) associated with a dunite lens. The origin of these ores is frequently thought to be related to the intense contamination by host rocks. To determine whether crustal contamination was a significant process in the formation of this massif and associated ores, Sm-Nd isotope composition was analyzed throughout the vertical section of the pluton in the following rocks: peridotite from the lower part of the layered dunite-peridotite zone, dunites from the ore-bearing Sopcha Layer, orthopyroxenites (beneath and above ores), peridotite and dunite from dunite lens (beneath and above chromitites), and chromitite from the chromitite horizon of the Sopcheozero chromitite deposit), critical horizon Nyud, and contact gabbroids from the lower zone. It was revealed that the eNd in the studied rocks vary from -2.5 to -0.2, which is much lower than that of DM at that time and suggests the input of crustal rocks or recycled material. The values of eNd show upward increase (up to -2.5 in the orthopyroxenite zone) and negative correlation with Nd content, which points to insignificant assimilation of host rocks during long-term cooling and crystallization (AFC model). A sufficiently homogeneous Nd isotope composition of rocks from the peridotite zone between -0.2 and -0.8 suggests that these characteristics were acquired by a melt at the earlier stages of its evolution, prior to the emplacement in the crystallization chamber. The rocks of the Sopcha Ore Layer have eNd within the same

  20. Structure and emplacement of granite plutons in the Paleoproterozoic crust of Eastern Burkina Faso: rheological implications

    NASA Astrophysics Data System (ADS)

    Vegas, Nestor; Naba, Seta; Bouchez, Jean Luc; Jessell, Mark

    2008-11-01

    The Fada N'Gourma area in Burkina Faso is underlain by Paleoproterozoic rocks that make the northeastern West-African Craton. This region is composed of NE-trending volcano-sedimentary belts and foliated tonalites, affected by several shear zones. A generation of younger, ˜2100 Ma-old, non-foliated biotite-bearing granites intrudes the former rock units. We have investigated the younger granite pluton of Kouare that was previously considered as forming a single body with the pluton of Satenga to the west, a pluton which likely belongs to the ˜20 Ma more recent Tenkodogo-Yamba batholith. Magnetic fabric measurements have been combined with microstructural observations and the analysis of field and aeromagnetic data. The granite encloses angular enclaves of the host tonalites. Magmatic microstructures are preserved inside the pluton and solid-state, high-temperature deformation features are ubiquitous at its periphery. The presence of steeply plunging lineations in the pluton of Kouare and its adjacent host-rocks suggests that large volumes of granitic magmas became crystallized while they were ascending through the crust that was softened and steepened close to the contact. Around Kouare, the foliation in the host tonalites conforms with a map-scale, Z-shaped fold in between NNE-trending shear zones, implying a bulk clockwise rotation of the material contained in-between the shear zones, including the emplacing pluton. Regionally, the Fada N'Gourma area is concluded to result from NW-shortening associated with transcurrent shearing and vertical transfer of granitic magmas. This study concludes that the ˜2200 Myears old juvenile crust of Burkina Faso was brittle before the intrusion of the biotite-granites, became softened close to them and that gravity-driven and regional scale wrench tectonics were active together.

  1. Late Cretaceous ductile deformation, metamorphism and plutonism in the Piute Mountains, eastern Mojave Desert

    SciTech Connect

    Fletcher, J.M.; Karlstrom, K.E. )

    1990-01-10

    Late Cretaceous deformation in the Piute Mountains involved ductile thrusting on a network of anastomosing northeast and southwest directed shear zones. The shear zones often separate Proterozoic lithologies with strong competency contrasts, suggesting that Proterozoic crustal anisotropies were important in controlling the geometry of the shear zone network. Shear zones now divide the crust into wedge- and lozenge-shaped blocks. The Piute Mountains can be separated into two kinematic domains, each characterized by a dominant sense of shear. Thrusting in the southwest directed kinematic domain ended at 85 {plus minus} 7 Ma, the age of the late synkinematic East Piute pluton. Thrusting in the northeast directed kinematic domain could have lasted until 74 {plus minus} 3 Ma, the age of the Lazy Daisy pluton. Postthrusting northwest-southeast shortening produced a second generation of upright open folds with a northeast striking subvertical crenulation cleavage. F{sub 2} strain increases toward the south and is concentrated around the margins of the Lazy Daisy pluton. This deformation was synchronous with pluton emplacement. Lake Cretaceous peak metamorphism outlasted all ductile deformation. Peak metamorphic grade increases from upper greenschist facies in the north to upper amphibolite facies as the Lazy Daisy pluton is approached. Temperature and pressure of approximately 450 C and 2.5-4.0 kbar were achieved during ductile thrusting. Temperatures of 500-540 C existed at the onset of upright open folding, and peak temperatures as high as 620 C near the Lazy Daisy pluton occurred after F{sub 2} upright folding. All penetrative deformation ended before 72-71 Ma, by which time the area had cooled to below 300 C.

  2. Alkaline fuel cells applications

    NASA Astrophysics Data System (ADS)

    Kordesch, Karl; Hacker, Viktor; Gsellmann, Josef; Cifrain, Martin; Faleschini, Gottfried; Enzinger, Peter; Fankhauser, Robert; Ortner, Markus; Muhr, Michael; Aronson, Robert R.

    On the world-wide automobile market technical developments are increasingly determined by the dramatic restriction on emissions as well as the regimentation of fuel consumption by legislation. Therefore there is an increasing chance of a completely new technology breakthrough if it offers new opportunities, meeting the requirements of resource preservation and emission restrictions. Fuel cell technology offers the possibility to excel in today's motive power techniques in terms of environmental compatibility, consumer's profit, costs of maintenance and efficiency. The key question is economy. This will be decided by the costs of fuel cell systems if they are to be used as power generators for future electric vehicles. The alkaline hydrogen-air fuel cell system with circulating KOH electrolyte and low-cost catalysed carbon electrodes could be a promising alternative. Based on the experiences of Kordesch [K. Kordesch, Brennstoffbatterien, Springer, Wien, 1984, ISBN 3-387-81819-7; K. Kordesch, City car with H 2-air fuel cell and lead-battery, SAE Paper No. 719015, 6th IECEC, 1971], who operated a city car hybrid vehicle on public roads for 3 years in the early 1970s, improved air electrodes plus new variations of the bipolar stack assembly developed in Graz are investigated. Primary fuel choice will be a major issue until such time as cost-effective, on-board hydrogen storage is developed. Ammonia is an interesting option. The whole system, ammonia dissociator plus alkaline fuel cell (AFC), is characterised by a simple design and high efficiency.

  3. Comparing magnetic and magmatic fabrics to constrain the magma flow record in La Gloria pluton, central Chile

    NASA Astrophysics Data System (ADS)

    Payacán, Italo; Gutiérrez, Francisco; Gelman, Sarah E.; Bachmann, Olivier; Parada, Miguel Ángel

    2014-12-01

    This contribution illustrates a case study of a pluton (La Gloria pluton; LGP) where magnetic and magmatic fabrics are locally decoupled. We compare the magmatic fabric with the available magnetic fabric data to explore their abilities and elucidate the magma flow record of LGP. Results indicate that magnetic (controlled by multi-domain magnetite) and magmatic fabrics are generally consistent throughout LGP. Foliations define an axisymmetric pattern that gradually changes from vertical near lateral margins to less steep in the pluton interior, whereas lineations are subhorizontal following the elongation direction of the pluton. However, samples at the pluton center show marked differences between both fabrics: magnetic fabrics indicate subhorizontal magnetic lineations and foliations, and magmatic fabrics indicate subvertical lineations and foliations. Both magnetic and magmatic fabrics are interpreted to record strain caused by magma flow during thermal convection and lateral magma propagation at the transition between low and high crystallinity stages. We suggest that fabrics acquisition and consistency were determined by shear conditions (pure/simple shear rates ratio) and the orientation of the magma flow direction with respect to a rigid boundary (critical crystalline region) of the pluton. Magmatic fabric differs at the center of the pluton because pure shear is dominant and ascendant flows are orthogonal to the horizontal rigid boundary. LGP represents a whole-scale partly molten magma reservoir, where both thermal convection and lateral propagation of the magma are recorded simultaneously. This study highlights the importance of characterizing both fabrics to properly interpret magma flow recorded in plutons.

  4. Late Cretaceous and early Tertiary plutonism and deformation in the Skagit Gneiss Complex, north Cascade Range, Washington and British Columbia

    USGS Publications Warehouse

    Haugerud, R.A.; Van Der Heyden, P.; Tabor, R.W.; Stacey, J.S.; Zartman, R.E.

    1991-01-01

    The Skagit Gneiss Complex forms a more-or-less continuous terrane within the North Cascade Range. The complex comprises abundant plutons intruded at mid-crustal depths into a variety of metamorphosed supracrustal rocks of both oceanic and volcanic-arc origin. U-Pb zircon ages from gneissis plutons within and near the Skagit Gneiss Complex indicate magmatic crystallziations between 75 and 60 Ma. Deformation, recrystallization, and migmatization in part postdate intrusion of the 75-60 Ma plutons. This latest Cretaceous and earliest Tertiary plutonism and migmatization may reflect thermal relaxation following early Late Cretaceous orogeny. The complex was ductilely extended northwest-southeast shortly after intrusion of granite dikes at ~45 Ma, but before emplacement of the earliest (~34 Ma) plutons of the Cascade arc. -from Authors

  5. Petrology, geochemistry and thermobarometry of the northern area of the Flamenco pluton, Coastal Range batholith, northern Chile. A thermal approach to the emplacement processes in the Jurassic andean batholiths

    NASA Astrophysics Data System (ADS)

    Rodríguez, Natalia; Díaz-Alvarado, Juan; Rodríguez, Carmen; Riveros, Karl; Fuentes, Paulina

    2016-04-01

    The Flamenco pluton is part of a N-S alignment of Late Triassic to Early Jurassic intrusive belt comprising the westernmost part of the Coastal Range batholith in northern Chile. The Jurassic-Cretaceous voluminous magmatism related to subduction in the western active continental margin of Gondwana is emplaced in the predominantly metasedimentary Paleozoic host-rocks of the Las Tórtolas formation, which in the northern area of the Flamenco pluton present an intense deformation, including the Chañaral mélange. Geochemically, the Flamenco pluton shows a wide compositional variability (SiO2 between 48wt % and 67wt %). Gabbros, Qtz-diorites and tonalites, mesocratic and leucocratic granodiorites are classified as calc-alkaline, calcic, magnesian and metaluminous magmatism. Flamenco granitoids define cotectic linear evolution trends, typical of magmatic fractionation processes. Geochemical trends are consistent with magmas evolved from undersaturated and low-pressure melts, even though the absence of transitional contacts between intrusive units precludes in-situ fractionation. Although some granodioritic samples show crossed geochemical trends that point to the compositional field of metasediments, and large euhedral prismatic pinnite-biotite crystals, typical Crd pseudomorph, are observed in contact magmatic facies, geochemical assimilation processes are short range, and the occurrence of host-rocks xenoliths is limited to a few meters from the pluton contact. A thermal approach to the emplacement process has been constrained through the thermobarometric results and a 2D thermo-numerical model of the contact aureole. Some Qtz-diorites and granodiorites located in the north area of the pluton exhibit granulitic textures as Hbl-Pl-Qtz triple junctions, poikiloblastic Kfs and Qtz recrystallization. The Hbl-Pl pairs have been used for the thermobarometric study of this metamorphic process, resulting granoblastic equilibrium temperatures between 770 and 790 °C, whereas

  6. Construction of the Devonian bimodal Gouldsboro pluton via multiple intrusion, coastal Maine, USA

    NASA Astrophysics Data System (ADS)

    Koteas, C.

    2006-12-01

    The Gouldsboro pluton (377 ± 19 ma) (Metzger et al., 1982) of the eastern coastal Maine magmatic province preserves abundant evidence of mechanical interaction between mafic and felsic magmas, as well as the stoping and doming of country rock. Coastal Maine is a unique location where subequal volumes of felsic and mafic material have interacted and are preserved in both plutonic and volcanic complexes. The effects of generation and mobilization of large volumes of magma in the shallow crust are well-preserved. The Gouldsboro pluton provides an excellent perspective from the highest to lowest sections (southwest to northeast) of a hybrid magmatic system. The Gouldsboro magmatic complex is hosted by undated greenstone to the north that is overlain by the 477 ± 18 ma (Metzger, 1977) meta-volcanic/meta-sedimentary Bar Harbor formation. Blocks of both units are discernable as 10 cm to 2 m-diameter blocks within the pluton. The Gouldsboro granite is dominantly a fine to medium grained feldspar- rich leucocratic hornblende granite, although biotite is sometimes present. Miarolitic cavities are common in the highest exposure of the system, especially in the south where the finest grained, most leucocratic granite occurs. Other units include, from lowest to highest in the system, hybrid diorite-gabbro, hybrid granite-granodiorite, granite hosting 30 cm to 3 m-diameter globular basaltic pillows, and a previously unrecognized pyroclastic unit, very similar to the lowermost member of the Cranberry Isle series, a volcanic breccia (Seaman et al., 1999). The pyroclastic unit is intruded by medium grained granite hosting angular fragments of volcanic, mafic plutonic, and country rock. While the contact between gabbro near the base of the pluton and granite in the middle of the pluton is commonly gradational, there are complex intrusive breccias in some areas where fine to coarse, angular diorite to gabbro xenoliths are hosted by granodiorite and granite. Enclave-rich zones

  7. Granodiorite Pluton Formation at the Mid-Cenozoic Never Summer Igneous Complex, North-Central Colorado

    NASA Astrophysics Data System (ADS)

    Jacob, K. H.; Farmer, G.

    2012-12-01

    Field observations, major- and trace-element geochemistry, and Sr and Nd isotopic data were used to assess the petrogenesis of epizonal intrusive rocks and related volcanic rocks from the ~28 Ma Never Summer igneous complex in north-central Colorado. Intrusive igneous rocks at this igneous center consist of an older granodiorite pluton (the Mt Richthofen stock, MRS) that is intruded by the granitic Mt. Cumulus stock. The latter has a uniform bulk composition equivalent to that of high silica rhyolite (~77 wt % SiO2, ɛNd(T) ~ -6). Whole rock studies of the MRS reveal that it is compositionally zoned (55-67 wt % SiO2,ɛNd(T) -0.5 to -5.7, 87Sr/86Sr(T) 0.7049 to 0.7119), with the lowest wt % SiO2 and highest ɛNd(T) occurring along the western margin of the pluton. Field observations, combined with the observed compositional variations, suggest that the pluton was originally a shallowly intruded (< 2 km), ~1 km thick sill that was vertically zoned from a mafic base to more felsic roof. The entire pluton has been tilted ~25 degrees to the west after emplacement. Given the lack of obvious wall-rock assimilation at the level of pluton emplacement, the isotopic variations in the pluton most likely reflect differences in the isotopic compositions of melts from which the pluton was assembled. Obvious field evidence exists for underplating of the developing pluton by mafic, high ɛNd (T) (>-2) melts and illustrates that mafic magmas were present in the uppermost crust and likely participated in pluton formation. The higher wt % SiO2 and lower ɛNd(T) portions of the MRS, however, could not have been derived directly from the mafic magmas in any closed system process. One option is that the MRS ultimately represents the product of mixing of >70 wt % SiO2 melts (+ crystals), analogous to the melts from which the Mt. Cumulus stock crystallized, and underplating mafic magma. This model implies that two primary magmas types, high silica rhyolite and basalt/basaltic andesite

  8. An unusually rich scuttle fly fauna (Diptera, Phoridae) from north of the Arctic Circle in the Kola Peninsula, N. W. Russia.

    PubMed

    Disney, R H L

    2013-01-01

    64 species of Phoridae, in 6 genera, are reported from the Kola Peninsula, north of the Arctic Circle. The new species Megaselia elenae and Megaselia kozlovi are described. 33 species of Megaselia, only known from females, are given code numbers. Keys to the species of all the females of Megaselia and Phora are provided; and also a key to the males European Megaselia species with a notopleural cleft.

  9. Map showing the distribution and characteristics of plutonic rocks in the Tonopah 1 degree by 2 degrees Quadrangle, central Nevada

    USGS Publications Warehouse

    John, D.A.

    1987-01-01

    The accompanying table includes the name (if any) of the pluton and its location, the age of the pluton (either a radiometric age or an age inferred from field relations), modal composition, texture, mineralogy, hydrothermal alteration and mineralization related to the pluton, the source of mapping shown on this map, and published references on the pluton. Radiometric ages are either published K-Ar and fission track ages or new whole-rock Rb-Sr ages determined by A. C. Robinson on samples collected either for this study or as part of regional Sr-isotope studies by R.W. Kistler and A.C. Robinson. K-Ar ages published prior to 1977 are corrected using the new I.U.C.S. constants (Steiger and Jager, 1977). Muscovite alteration ages are reported for several plutons and represent minimum ages for emplacement of these plutons. Compositional classification follows the T. J. G.S. system (“Streckeisen, 1976) and is based either on modal analyses of slabs or estimates from hand specimens. All modes, unless otherwise noted, were measured in this study. The number of modes determined is shown in parentheses, and the range in volume percent of major minerals is given. Where no modal data are available, the color index (percentage of mafic minerals) and major mafic minerals are given for most plutons. Data tabulated on hydrothermal alteration and mineralization related to plutons are based on observations made during field studies for this project. Clear genetic relation between granitic plutonism and several mineral deposits previously attributed to granitic plutonism were not substantiated, and these inconsistencies are noted in the table.

  10. Silica in alkaline brines

    USGS Publications Warehouse

    Jones, B.F.; Rettig, S.L.; Eugster, H.P.

    1967-01-01

    Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

  11. Bifunctional alkaline oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  12. Early Variscan I-type pluton in the pre-Alpine basement of the Western Alps: The ca. 360 Ma Cogne diorite (NW-Italy)

    NASA Astrophysics Data System (ADS)

    Guillot, François; Bertrand, Jean-Michel; Bussy, François; Lanari, Pierre; Cosma, Ludovic; Pin, Christian

    2012-11-01

    Located at the internal border of the Grand-Saint-Bernard Zone, the diorite and its aureole lie on top of intensively studied Alpine eclogitic units but this pluton, poorly studied yet, has kept locally almost undeformed. The pluton intruded, at ~ 360 Ma, country-rocks mostly composed of dark shales with Na2O > K2O and minor mafic intercalations of tholeiitic basalt affinity. This association is characteristic of the Vanoise (France) basement series, where available age determinations suggest an Early Paleozoic age. Parts of the pluton, and of its hornfels aureole that is evidenced here for the first time, in the Punta Bioula section of Valsavaranche valley (NW-Italy), have been well-preserved from the Alpine deformation. Syn-emplacement hardening, dehydration-induced, probably prevented strain-enhanced Alpine recrystallization. Magmatic rock-types range continuously from subordinate mafic types at SiO2 ~ 48%, of hornblendite with cumulative or appinite affinities, to the main body of quartz diorite to quartz monzonite (SiO2 up to 62%). P-T estimates for the pluton emplacement, based on the abundance of garnet in the hornfelses, using also zircon and apatite saturation thermometry and Al-in-hornblende barometry, suggest T ~ 800-950 °C and minimum P in the 0.2-0.5 GPa range, with records of higher pressure conditions (up to 1-2 GPa?) in hornblendite phlogopite-cored amphibole. The high-K, Na > K, calc-alkaline geochemistry is in line with a destructive plate-margin setting. Based on major element data and radiogenic isotope signature (ɛNd360 Ma from - 1.2 to + 0.9, 87Sr/86Sr360 Ma from 0.7054 to 0.7063), the parental magmas are interpreted in terms of deep-seated metabasaltic partial melts with limited contamination from shallower sources, the low radiogenic Nd-content excluding a major contribution from Vanoise tholeiites. There is no other preserved evidence for Variscan magmatism of similar age and composition in the Western Alps, but probable analogs are known

  13. The results of marine electromagnetic sounding with a high-power remote source in the Kola Bay in the Barents Sea

    NASA Astrophysics Data System (ADS)

    Grigoriev, V. F.; Korotaev, S. M.; Kruglyakov, M. S.; Orekhova, D. A.; Popova, I. V.; Tereshchenko, E. D.; Tereshchenko, P. E.; Schors, Yu. G.

    2013-05-01

    The first Russian six-component seafloor electromagnetic (EM) receivers were tested in an experiment carried out in Kola Bay in the Barents Sea. The signals transmitted by a remote high-power ELF source at several frequencies in the decahertz range were recorded by six receivers deployed on the seafloor along the profile crossing the Kola Bay. Although not all the stations successfully recorded all the six components due to technical failures, the quality of the data overall is quite suitable for interpretation. The interpretation was carried out by the three-dimensional (3D) modeling of an electromagnetic field with neural network inversion. The a priori geoelectrical model of Kola Bay, which was reconstructed by generalizing the previous geological and geophysical data, including the data of the ground magnetotelluric sounding and magnetovariational profiling, provided the EM fields that are far from those measured in the experiment. However, by a step-by-step modification of the initial model, we achieved quite a satisfactory fit. The resulting model provides the basis for introducing the corrections into the previous notions concerning the regional geological and geophysical structure of the region and particularly the features associated with fault tectonics.

  14. INSTALLATION OF A POST-ACCIDENT CONFINEMENT HIGH-LEVEL RADIATION MONITORING SYSTEM IN THE KOLA NUCLEAR POWER STATION (UNIT 2) IN RUSSIA

    SciTech Connect

    GREENE,G.A.; GUPPY,J.G.

    1998-09-01

    This is the final report on the INSP project entitled, ``Post-Accident Confinement High-Level Radiation Monitoring System'' conducted by BNL under the authorization of Project Work Plan WBS 1.2.2.6 (Attachment 1). This project was initiated in February 1993 to assist the Russians in reducing risks associated with the continued operation of older Soviet-designed nuclear power plants, specifically the Kola VVER-440/230 Unit 2, through improved accident detection capability, specifically by the installation of a dual train high-level radiation detection system in the confinement of Unit 2 of the Kola NPP. The major technical objective of this project was to provide, install and make operational the necessary hardware inside the confinement of the Kola NPP Unit 2 to provide early and reliable warning of the release of radionuclides from the reactor into the confinement air space as an indication of the occurrence of a severe accident at the plant. In addition, it was intended to provide hands-on experience and training to the Russian plant workers in the installation, operation, calibration and maintenance of the equipment in order that they may use the equipment without continued US assistance as an effective measure to improve reactor safety at the plant.

  15. Morphological and biochemical investigation into the possible neuroprotective effects of kolaviron (Garcinia kola bioflavonoid) on the brains of rats exposed to vanadium.

    PubMed

    Igado, Olumayowa O; Olopade, James O; Adesida, Adebukola; Aina, Oluwasanmi O; Farombi, Ebenezer O

    2012-10-01

    In this study, the morphological and biochemical susceptibility of the rat brain to vanadium, in the form of sodium metavanadate, and the comparative ameliorative effect of Garcinia kola and kolaviron (G. kola extract), was examined. Brain regions examined were the cerebrum, cerebellum, hippocampus and the olfactory bulb. We showed that vanadium administration caused cellular vacuolation, congestion, and Purkinje cell degeneration and a marked reduction in myelin tracts. Biochemical tests revealed increased lipid peroxidation induced by vanadium, which was ameliorated with the administration of G. kola and kolaviron. Vanadium administration caused an increase in thiobarbituric acid-reactive substances (TBARS) in the cerebrum and hippocampus, whereas the administration of kolaviron resulted in a reduction of the TBARS level by 65.7 and 80%, respectively, in the regions aforementioned. Also, the administration of kolaviron resulted in an increased activity of superoxide dismutase (61.24%) in all brain regions assessed, when compared with the group administered vanadium alone. Results obtained from this study led to the conclusion that kolaviron reduces vanadium-induced oxidative stress in the brain.

  16. Iron mineralization and associated skarn development around southern contact of the Eğrigöz pluton (northern Menderes Massif-Turkey)

    NASA Astrophysics Data System (ADS)

    Uǧurcan, Okşan Gökçen; Oyman, Tolga

    2016-11-01

    The Eğrigöz pluton is located in the northern portion of the Menderes Massif, which is the largest known metamorphic core complex that is also characterized by large-scale extension. Kalkan and Karaağıl skarn deposits are located on the southern border of the Eğrigöz Pluton, whereas Katrandağ mineralization developed along the roof pendant. Skarnization in these three areas is associated with the peraluminous, I-type, calc-alkaline, high-K calc-alkaline Eğrigöz Pluton. Geochemical characteristics of the pluton indicate that it was generated in a continental arc setting. Kalkan, Karaağıl, and Katrandağ skarns are hosted in marble bands in two-mica gneiss of the Kalkan Formation, a locally dolomitic and clay-bearing limestone of the Arıkaya Formation and locally dolomitised limestone of the Balıkbaşı Formation, respectively. Skarn development occurred sequentially in two stages, prograde and retrograde. In Kalkan skarn, prograde stage is characterized by clinopyroxene (Di56-73 Hd26-43 Joh1-2), garnet (Adr45-69 Grs30-52 Alm0-1.4 Sps0.7-2.3), amphibole, and magnetite, whereas retrograde stage is dominated by epidote, amphibole, chlorite, quartz, and calcite. In Karaağıl, both calcic and magnesian skarn association occurred as a result of local variations in dolomite content in Arıkaya Formation. The prograde assemblage of magnesian skarn is composed chiefly of spinel, amphibole and olivine. These mineral assemblages were, partially or fully, altered to serpentine, talc, and chlorite during retrograde alteration. Mesh textures of the serpentine indicates that the serpentine was altered from olivine. Olivine was completely destroyed during retrograde alteration without relict grains remaining. Calcic skarn paragenesis include garnet (Grs36-80Adr20-62Alm0-2.2Sps0.2-2.6), clinopyroxene (Di81-92 Hd7-19 Jo0-1), and plagioclase, that belongs to the earlier stage, and amphibole of the retrograde stage. High grossular end member of the garnet probably

  17. Subduction-related Late Carboniferous to Early Permian Magmatism in the Eastern Pontides, the Camlik and Casurluk plutons: Insights from geochemistry, whole-rock Sr-Nd and in situ zircon Lu-Hf isotopes, and U-Pb geochronology

    NASA Astrophysics Data System (ADS)

    Karsli, Orhan; Dokuz, Abdurrahman; Kandemir, Raif

    2016-12-01

    Late Carboniferous to early Permian granitoid rocks represent a volumetrically minor component of the Eastern Pontide lithosphere, but they preserve useful information about the region's tectonomagmatic history. The Casurluk and Camlik plutons primarily consist of gabbro, gabbroic diorite, diorite, monzogabbro, monzodiorite and monzonite, which intrude early to middle Carboniferous granitic basement rocks in the region. In this study, we use in situ zircon U-Pb ages and Lu-Hf isotopic values, whole-rock Sr-Nd isotopic values, and mineral chemistry and geochemistry of these plutons to determine petrogenesis and crustal evolution; we also discuss geodynamic implications. LA-ICP-MS zircon U-Pb dating of magmatic zircons from the rocks suggests that the plutons were emplaced during the late Carboniferous to early Permian (302 Ma). The metaluminous and I-type intrusive rocks belong to the high-K calc-alkaline series. In addition, they are relatively enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs); they are depleted in heavy rare earth elements (HREEs) and high field strength elements (HFSEs), such as Nb and Ti. All of the samples have homogeneous initial ISr values (0.70675 to 0.70792) and low εNd (t) values (- 5.1 to - 3.3). Zircons from the rocks of both plutons have uniform negative to slightly positive εHf (t) values (- 3.5 to 1.4) and old Hf two-stage model ages (1323 to 1548 Ma), implying that they have the same source, as well as suggesting the involvement of old enriched lithospheric mantle materials during their magma genesis. These results, combined with the εHf (t) values and two-stage model ages, demonstrate that the primary magmas were derived from partial melting of old lithospheric mantle material metasomatized by subduction-related fluids. Considering other regional geological data from the Sakarya Zone where these plutons formed, we conclude that late Carboniferous to early Permian magmatism in the area

  18. ‘Diffuse faulting’ in the Machu Picchu granitoid pluton, Eastern Cordillera, Peru

    NASA Astrophysics Data System (ADS)

    Mazzoli, Stefano; Vitale, Stefano; Delmonaco, Giuseppe; Guerriero, Vincenzo; Margottini, Claudio; Spizzichino, Daniele

    2009-11-01

    A series of batholiths, forming part of the 'roots' of a Permo-Liassic rift system, are exposed in the high Eastern Cordillera of central Peru as a result of tectonic inversion. Shortening of the Machu Picchu granitoid pluton was accommodated by widespread shear reactivation of primary joints, by a process termed here 'diffuse faulting'. Fault-like reactivation of precursor joint surfaces, marked by chlorite, epidote and quartz shear fibres, is locally evidenced by few centimetres offsets within apparently undeformed granite. Analysis of fault slip data indicates that shear reactivation of different joint sets was kinematically consistent with ENE oriented shortening. Less frequent mylonitic shear zones appear to have evolved from the common brittle precursors. Apart from rare phyllonitic shear zones, fluid-rock interaction along the brittle precursors was generally limited, and pluton deformation appears to be mainly controlled by the geometry and distribution of primary joints. Three main sets of reactivated joints can be recognized, characterized by oblique-slip kinematics with variable reverse and strike-slip components of motion. Theoretical modelling based on quantitative fracture analysis (scan-line data) and different displacement-length relationships applied to the main reactivated joint sets yield first-order estimates of pluton finite strain. The results suggest that bulk finite strain is oblate and essentially coaxial, and is characterized by horizontal shortening not exceeding 10%. Relatively small finite strains, integrated over the size of the pluton, still result in a few kilometres of crustal shortening.

  19. Field Guide to Plutonic and Metamorphic Rocks. Earth Science Curriculum Project Pamphlet Series PS-5.

    ERIC Educational Resources Information Center

    Romey, William D.

    Suggested are methods for the collection of field evidence about processes that form plutonic and metamorphic rock. Description and discussion of these types of rocks are provided. The planning and execution of a successful field trip is discussed. Advanced field projects are also discussed. Included are five appendices, references, and a…

  20. Chaotic Flow Patterns from a Deep Plutonic Environment: a Case Study on Natural Magma Mixing

    NASA Astrophysics Data System (ADS)

    De Campos, Cristina P.

    2015-07-01

    This work focuses on the mixing between basalt and granite in a deep plutonic environment. The description of mixing patterns and measurements of fractal dimensions, and the evaluation of geochemical data from a Cambro-Ordovician granitic pluton are summarized and discussed. Different morphologic domains within the pluton reveal concentric fragmented and/or folded layers of granite in a gabbro/granite mixed matrix. This stands in contrast to two predominantly regular gabbroic regions. These regular regions are separated by tightly stretched filament areas, in which mixing is enhanced. Sharp and gradational contacts between granitic and gabbroic domains depict the interplay among frozen flows (mingling) and convection-enhanced diffusion processes (mixing). Measurements of fractal dimensions at different scales and analysis of normalized concentration variance for major elements point towards magma mixing: the compositional variability and flow patterns of the studied pluton have been greatly controlled by a natural chaotic mixing process between a granitic and a basaltic end-member. During the mixing process, coeval fractional crystallization no doubt contributed to increasing the complexity of the system. However, since flow, and therefore mixing, stops with temperature decrease, flow patterns must have retained the predominant morphology and composition of the moment at which both contrasting magmas came together and froze. Flow patterns have been preserved. With further temperature decrease, fractional crystallization took over and hybrid rocks were generated from the fractionation of magmas previously mixed in different proportions.

  1. Isotopic disequilibrium among commingled hybrid magmas: Evidence for a two-stage magma mixing-commingling process in the Mt. Perkins Pluton, Arizona

    SciTech Connect

    Metcalf, R.V.; Smith, E.I.; Reed, R.C.

    1995-09-01

    The syn-extensional Miocene Mt. Perkins pluton, northwestern Arizona, cooled rapidly due to its small size (6 km{sup 2}) and shallow emplacement (7.5 km) and allows examination of commingled rocks that experienced little isotopic exchange. Within the pluton, quartz dioritic to granodioritic host rocks (58-68 wt% SiO{sub 2}) enclose dioritic enclaves (50-55 wt% SiO{sub 2}) and a portion contains enclave-free granodiorite (70-74 wt% SiO{sub 2}). Fine-grained, crenulate enclave margins and a lack of advanced mixing structures (e.g., schlieren, flow fabrics, etc.) indicate an incipient stage of commingling. Isotopic variation between enclaves and enclosing host rocks is large (6.8 to 10.6 {epsilon}{sub Nd} units; 0.0036 to 0.0046 {sup 87}Sr/{sup 86}Sr units), suggesting isotopic disequilibrium. Comparison of an enclave core and rim suggests that isotopic exchange with the host magma was limited to the enclave rim. Enclaves and hosts collectively form a calc-alkaline suite exhibiting a large range of {epsilon}{sub Nd} (+1.2 to -12.5) and initial {sup 87}Sr/{sup 86}Sr (0.705 to 0.71267) with a correlation among {epsilon}{sub Nd}, initial {sup 87}Sr/{sup 86}Sr, and major and trace element compositions. Modeling suggests that the suite formed by magma hybridization involving magma mixing accompanied by fractional crystallization. The magma mixing must have predated commingling at the present exposure level and indicates a larger mixing chamber at depth. Isotopic and trace element data suggests mixing end-members were asthenospheric mantle-derived mafic and crustal-derived felsic magmas. Fractional crystallization facilitated mixing by reducing the rheological contrasts between the mafic and felsic mixing end-members. 58 refs., 11 figs., 3 tabs.

  2. Formation of the Yandangshan volcanic-plutonic complex (SE China) by melt extraction and crystal accumulation

    NASA Astrophysics Data System (ADS)

    Yan, Li-Li; He, Zhen-Yu; Jahn, Bor-ming; Zhao, Zhi-Dan

    2016-12-01

    The association of volcanic and shallow plutonic rocks in caldera may provide important clues to the geochemical evolution of silicic magma systems. The Yandangshan caldera is a typical example of late Mesozoic volcanic-plutonic complex in SE China. It is composed of a series of rhyolitic extrusives and subvolcanic intrusions of porphyritic quartz syenites. In this work, we conducted petrological and geochemical studies, as well as zircon dating, on the coexisting volcanic and plutonic rocks from the Yandangshan caldera. The results of SHRIMP and LA-ICP-MS zircon U-Pb dating revealed that the crystallization of the rhyolitic extrusives and subvolcanic intrusions was contemporaneous within analytical errors and in a short period (104-98 Ma). Geochemically, the volcanic rocks are characterized by high Rb/Sr and Rb/Ba ratios and depletion in Ba, Sr, P, Eu and Ti, while the shallow plutons show high K, Ba, Al, Fe and low Rb/Sr and Rb/Ba ratios with insignificant negative Eu anomalies. The volcanic and plutonic rocks have a similar range of zircon Hf isotopic compositions (εHf(t) = - 10.0 to + 1.5) and TDM2 model ages of 2.10-1.23 Ga. They also have comparable whole-rock Sr and Nd isotopic compositions ((87Sr/86Sr)i = 0.7084-0.7090; εNd(t) = - 7.8 to - 6.5) and zircon oxygen isotopic compositions (δ18O mainly = 4.5 to 6.0‰). We argue that the volcanic-plutonic complex of the Yandangshan caldera was formed by reworking of Paleoproterozoic lower crusts in the eastern Cathaysia block, and that the complex could be linked by fractional crystallization and crystal accumulation in a shallow magma chamber. The volcanic rocks represent the highly fractionated end-member, whereas the subvolcanic intrusions of porphyritic quartz syenites could be the residual crystal mushes. This case study could have a general implication for the genetic relationship between volcanic and shallow plutonic rocks in calderas.

  3. Insights Into the Formation of Rhyolite From the Searchlight Pluton: Evidence from Oriented Quartz Clusters

    NASA Astrophysics Data System (ADS)

    Froemming, N.; Deering, C. D.; Beane, R. J.; Bachmann, O.

    2012-12-01

    The Miocene Searchlight pluton (SLP) in the Colorado River extensional corridor of southern Nevada, is well-exposed and tilted near-vertical for exceptional cross-sectional study of magma reservoir dynamics and crystal fractionation of a mid- to upper-crustal pluton (3 to 13 km depth). The upper quartz monzonite section is dominated by minerals in apparent random orientation with a medium- to fine-grained texture due to direct contact with the cold host rock. The middle granitic section is dominated by coarse-grained quartz and feldspar, and interpreted to be a zone of extracted liquid from an intermediate magma. The lower monzonite section is composed of coarse-grained plagioclase and potassium feldspar. We used the crystallographic orientations of quartz clusters, as determined by Electron Backscatter Diffraction (EBSD), to test for crystal accumulation in the SLP. Clusters of quartz crystals with matched dipyramidal faces (parallel or Esterel twin orientation) may indicate a period of crystal accumulation. By analyzing representative samples from each section of the pluton, we found that the lower section (intermediate cumulate) and upper section (crystallization front) do not have quartz clusters with matched dipyramidal faces. Although plagioclase grains are aligned in the lower section, the late crystallization of quartz appears to have prevented aligned or preferred growth orientations. In contrast, the middle section has a high percentage of quartz clusters with matched dipyramidal faces - similar to that found in granite porphyry of the Vinalhaven pluton, Maine. The aligned grains may have formed by fractional crystallization, compaction and synneusis of the early forming quartz in this granitic section. We interpret the middle section of the Searchlight pluton as being similar to shallow, upper crustal plutons (3-8 km depth) such as Vinalhaven pluton. The deep vertical exposure of the SLP, shows that the middle section was formed from periodic episodes of

  4. The Petrogenesis of the Late Cretaceous Mamba Pluton from the Eastern Gangdese: Constraints from Mineralogy

    NASA Astrophysics Data System (ADS)

    Li, X.

    2011-12-01

    Occurred as stock,the late Cretaceous Mamba pluton, located at the southeast part of the Gangdese terrane, was one of the granitoid intrusions in the Mesozoic-Cenozoic Gangdese gaint magmatic belt, which is composed of Southern Gangdese, Gangdese back-arc fault uplift belt, Middle Gangdes, The Shiquanhe-Laguo Tso-Yongzhu-Nam Tso-Jiali Ophiolitic Méange Zone, and northern Gangdese from south to north, bounded by Indus-Yarlung Zangbo suture zone to the south, and Bangong Tso-Nujiang suture zone to the north(Zhu et al., 2008a), and the Mamba Pluton intruded pre-Ordovician Sumdo Group and early formed intrusions(T3, J1, J3), was unconformably overlied by Eocene Pana Formation. The modal mineralogy of selected samples from Mamba Pluton are calculated via Matlab: quartz(25%), plagioclase(40%), K-feldspar(18%), biotite(9%) and hornblende(5%), with subordinate primary epidote(<1%), and the accessory mineral phases include magnetite(1%), apatite(<1%),sphene(<1%), etc, corresponding to mega-porphyritic hornblende-biotite granodiorite. Hornblende and Biotite are the most common ferromagnesian phases in Mamba Pluton, which are chemically and structurally sensitive to prevailing physico-chemical conditions of host magmas(Czamanske and Wones, 1973; Czamanske et al., 1977; Jiang and An, 1984; Kumar and Pathak, 2010; Speer, 1987a, b; Wones and Eugster, 1965; Zhou, 1986). Specifically, Hornblende occurs as euhedral(rhombic) to subhedral crystal, composing c.a. 5% of the specimens, and depending on the samples, partially replaced by epidote, and some show simple twinnings. Biotite is euhedral to subhedral, and some of them occurs intergranular, moreover, Goethite occurs as weathering products in some biotite. Besides, the texture relationship indicates that its predated hornblende, i.e. hornblende encompasses biotite. Essentially, the K-feldspar is microcline in terms of classification. The X-ray powder diffraction analyses of K-feldspar megacrysts from Mamba Pluton provide degrees

  5. 30 Myr of Cenozoic magmatism along the Tethyan margin during Arabia-Eurasia accretionary orogenesis (Meghri-Ordubad pluton, southernmost Lesser Caucasus)

    NASA Astrophysics Data System (ADS)

    Rezeau, Hervé; Moritz, Robert; Leuthold, Julien; Hovakimyan, Samvel; Tayan, Rodrik; Chiaradia, Massimo

    2017-09-01

    Three magmatic series of substantially different ages and compositions were successively emplaced to form the composite Meghri-Ordubab pluton (MOP) in the southernmost Lesser Caucasus. The protracted incremental assembly during 30 Myr, from Middle Eocene to Early Miocene, renders this location particularly suitable to characterize the petrogenetic evolution of Cenozoic magmatism during the final stage of the Neotethyan subduction. Based on whole-rock geochemistry, two main transitions tightly constrained in time are recognized. The first transition from Middle Eocene medium-K calc-alkaline to Late Eocene-Middle Oligocene shoshonitic magmatism corresponds to a marked increase in LREE and MREE and more juvenile 87Sr/86Sr and 143Nd/144Nd ratios. The second transition to Late Oligocene-Early Miocene high-K calc-alkaline ;adakite-like; magmatism is coeval with a marked increase in Mg#, and Ni and Cr contents together with a depletion in MREE and HREE. Although the three differentiation series are derived from lower to mid-crustal hydrous magma fractionation, temporal variations of the magmatic source conditions are required to explain the contrasting chemistry of the parental magmas over time. Medium-K calc-alkaline parental magmas were generated by high degree of partial melting ( 15%) of a garnet lherzolite. The shoshonitic and adakitic magmatic series represent magmas produced by low degree (1-5%) of partial melting of a garnet lherzolite, but a higher amount of residual garnet is required to reproduce the "adakite-like" signature. The timing of the two main geochemical transitions in the MOP is correlated with a progressive evolution from a compressional to an extensional stress regime linked to (1) the final stage of the Neotethyan subduction followed by the Arabia-Eurasia continental collision during the Eocene-Oligocene, and (2) the transition toward post-collisional magmatism, combined with a switch toward transcurrent tectonics during the Late Oligocene

  6. Pluton pinning of an active Miocene detachment fault system, eastern Mojave Desert, California

    NASA Astrophysics Data System (ADS)

    Davis, Gregory A.; Fowler, T. Kenneth; Bishop, Kim M.; Brudos, Thomas C.; Julio Friedmann, S.; Burbank, Douglas W.; Parke, Mary A.; Burchfiel, B. C.

    1993-07-01

    The Miocene Kingston Range-Halloran Hills detachment fault system of the eastern Mojave Desert, California, delineates part of the eastern breakaway zone for a profoundly extended area between the Sierra Nevada and the Spring Mountains structural blocks. The shallow-dipping, west-rooting detachment fault cuts discordantly across Paleozoic and Precambrian units in the Mesozoic foreland fold-and-thrust belt, exhibits west- to southwest-trending corrugations with structural relief of up to 1.5 km, and underlies the terrestrial Shadow Valley basin. Middle Miocene fault displacement and syntectonic sedimentation in the northern basin were terminated at ˜12.4 Ma by intrusion of the large (˜130 km2), shallow-level (≥4 km depth) Kingston Peak pluton across the detachment fault soon after faulting began. Basin sedimentation and fault displacement southeast of the pluton were not, however, disrupted by its emplacement and continued to evolve. Northern "pluton-pinned" and southern "pluton-free" domains were separated by the Blacksmith Hills fault, a northeast-striking, right-slip lateral ramp that accommodated more than 3 km of postpluton differential extension between pinned and nonpinned domains. In more western regions, late phases of detachment-fault-related extension beneath formerly pinned areas (including western and central parts of the pluton itself) are believed to have led to the development of two generations of east-striking left-slip faults. Collectively, these dextral and sinistral transfer faults illustrate the complex patterns of differential extension and accommodation that can characterize detachment-fault systems as adjacent areal domains of extension are generated and die.

  7. Structural interplay between plutons during the construction of a batholith (Cerro Aspero batholith, Sierras de Córdoba, Argentina)

    NASA Astrophysics Data System (ADS)

    Pinotti, Lucio; Tubía, José M.; D'Eramo, Fernando; Vegas, Néstor; Sato, Ana M.; Coniglio, Jorge; Aranguren, Aitor

    2006-05-01

    Magnetic fabric patterns and microstructures of granitic rocks provide evidence of structural modifications as a result of the coalescence of two plutons, Alpa Corral and Talita, during the construction of a large granitic batholith, Cerro Aspero, in the Sierras Pampeanas of Córdoba (Argentina). The Alpa Corral granite is a small and nearly circular pluton, while the larger Talita pluton displays a marked N-S elongation. The NW quadrangle of the Alpa Corral pluton underwent a deformation resulting in foliation trajectories that outline a crescent moon pattern whose inner arc is concordant with the Alpa Corral/Talita contact. The highest values for the magnetic susceptibility and its anisotropy are concentrated in the coalescence zone between both plutons. The magmatic and sub-magmatic nature of the microstructures demonstrates that such a deformation was caused by the southward overriding of the largest Talita pluton while the Alpa Corral pluton was not yet fully crystallized. Rb-Sr geochronology indicates that this process took place 369±9 Ma ago, long after the Famatinian (Ordovician to Early Devonian) deformation of the country rocks, which confirms a synmagmatic, rather than a regional, deformational event.

  8. U-Pb dating and emplacement history of granitoid plutons in the northern Sanandaj-Sirjan Zone, Iran

    NASA Astrophysics Data System (ADS)

    Mahmoudi, Shahryar; Corfu, Fernando; Masoudi, Fariborz; Mehrabi, Behzad; Mohajjel, Mohammad

    2011-05-01

    The Sanandaj-Sirjan Zone (SSZ), which runs parallel to the Zagros fold and thrust belt of Iran, underwent a multistage evolution starting with Neotethys initiation, its subsequent subduction below the Iranian continental crust, and eventual closure during convergence of Arabia towards central Iran. Plutonic complexes are well developed in the northern part of the SSZ and we have dated a number of them by ID-TIMS U-Pb on zircon. The new data record the following events: a Mid Jurassic period that formed the Boroujerd Plutonic Complex (169 Ma), the Astaneh Pluton (168 Ma) and the Alvand Pluton (165 Ma); Late Jurassic emplacement of the Gorveh Pluton (157-149 Ma); Mid Cretaceous (109 Ma) formation of a I-type phase in the Hasan Salary Pluton near Saqqez, followed by Early Paleocene (60 Ma) intrusion of A-type granite in the same pluton; and the youngest intrusive event recorded so far in the SSZ with the intrusion of granite in the Gosheh-Tavandasht Complex near Boroujerd at 34.9 Ma. These different events reflect specific stages of subduction-related magmatism prior to the eventual Miocene collision between the two continental blocks.

  9. Oxygen isotope trajectories of crystallizing melts: Insights from modeling and the plutonic record

    NASA Astrophysics Data System (ADS)

    Bucholz, Claire E.; Jagoutz, Oliver; VanTongeren, Jill A.; Setera, Jacob; Wang, Zhengrong

    2017-06-01

    Elevated oxygen isotope values in igneous rocks are often used to fingerprint supracrustal alteration or assimilation of material that once resided near the surface of the earth. The δ18O value of a melt, however, can also increase through closed-system fractional crystallization. In order to quantify the change in melt δ18O due to crystallization, we develop a detailed closed-system fractional crystallization mass balance model and apply it to six experimentally- and naturally-determined liquid lines of descent (LLDs), which cover nearly complete crystallization intervals (melt fractions of 1 to <0.1). The studied LLDs vary from anhydrous tholeiitic basalts to hydrous high-K and calc-alkaline basalts and are characterized by distinct melt temperature-SiO2 trajectories, as well as, crystallizing phase relationships. Our model results demonstrate that melt fraction-temperature-SiO2 relationships of crystallizing melts, which are strongly a function of magmatic water content, will control the specific δ18O path of a crystallizing melt. Hydrous melts, typical of subduction zones, undergo larger increases in δ18O during early stages of crystallization due to their lower magmatic temperatures, greater initial increases in SiO2 content, and high temperature stability of low δ18O phases, such as oxides, amphibole, and anorthitic plagioclase (versus albite). Conversely, relatively dry, tholeiitic melts only experience significant increases in δ18O at degrees of crystallization greater than 80%. Total calculated increases in melt δ18O of 1.0-1.5‰ can be attributed to crystallization from ∼50 to 70 wt.% SiO2 for modeled closed-system crystallizing melt compositions. As an example application, we compare our closed system model results to oxygen isotope mineral data from two natural plutonic sequences, a relatively dry, tholeiitic sequence from the Upper and Upper Main Zones (UUMZ) of the Bushveld Complex (South Africa) and a high-K, hydrous sequence from the arc

  10. Long-term aerosol and trace gas measurements in Eastern Lapland, Finland: the impact of Kola air pollution to new particle formation and potential CCN

    NASA Astrophysics Data System (ADS)

    Kyrö, Ella-Maria; Väänänen, Riikka; Kerminen, Veli-Matti; Virkkula, Aki; Asmi, Ari; Nieminen, Tuomo; Dal Maso, Miikka; Petäjä, Tuukka; Keronen, Petri; Aalto, Pasi; Riipinen, Ilona; Lehtipalo, Katrianne; Hari, Pertti; Kulmala, Markku

    2014-05-01

    Sulphur and primary emissions have been decreasing largely all over Europe, resulting in improved air quality and decreased direct radiation forcing by aerosols. The smelter industry in Kola Peninsula is one of largest sources of anthropogenic SO2 within the Arctic domain and since late 1990s the sulphur emissions have been decreasing rapidly (Paatero et al., 2008; Prank et al., 2010). New particle formation (NPF) is tightly linked with the oxidizing product of SO2, namely sulphuric acid (H2SO4), since it is known to be the key component in atmospheric nucleation (Sipilä et al., 2010). Thus, decreasing sulphur pollution may lead to less NPF. However, low values of condensation sink (CS), which is determined by the amount of pre-existing particles, favours NPF. We used 14 years (1998-2011) of aerosol number size distribution and trace gas data from SMEAR I station in Eastern Lapland, Finland, to investigate these relationships between SO2, NPF and CS. The station is a clean background station with occasional sulphur pollution episodes when the air masses arrive over Kola Peninsula. We found that while SO2 decreased by 11.3 % / year, the number of clear NPF event days was also decreasing by 9.9 % / year. At the same time, CS was decreasing also (-8.0 % / year) leading to formation of more particles per single NPF event (J3 increased by 29.7 % / year in 2006-2011) but the low vapour concentrations of H2SO4 (proxy decreased by 6.2 % / year) did not allow them to grow into climatically relevant sizes. Over the time, concentrations of potential CCN (cloud condensing nuclei) were also decreasing with more moderate pace, -4.0 % / year. The events started on average earlier after sunrise when the SO2 concentration during the start of the event was higher and NPF occurred more frequently in air masses which were travelling over Kola. Despite the total decrease in sulphur pollution originating from Kola there is currently no evidence of cleaning of the emissions, rather the

  11. Alkaline battery, separator therefore

    NASA Technical Reports Server (NTRS)

    Schmidt, George F. (Inventor)

    1980-01-01

    An improved battery separator for alkaline battery cells has low resistance to electrolyte ion transfer and high resistance to electrode ion transfer. The separator is formed by applying an improved coating to an electrolyte absorber. The absorber, preferably, is a flexible, fibrous, and porous substrate that is resistant to strong alkali and oxidation. The coating composition includes an admixture of a polymeric binder, a hydrolyzable polymeric ester and inert fillers. The coating composition is substantially free of reactive fillers and plasticizers commonly employed as porosity promoting agents in separator coatings. When the separator is immersed in electrolyte, the polymeric ester of the film coating reacts with the electrolyte forming a salt and an alcohol. The alcohol goes into solution with the electrolyte while the salt imbibes electrolyte into the coating composition. When the salt is formed, it expands the polymeric chains of the binder to provide a film coating substantially permeable to electrolyte ion transfer but relatively impermeable to electrode ion transfer during use.

  12. Evaluation of Alkaline Cleaner Materials

    NASA Technical Reports Server (NTRS)

    Partz, Earl

    1998-01-01

    Alkaline cleaners used to process aluminum substrates have contained chromium as the corrosion inhibitor. Chromium is a hazardous substance whose use and control are described by environmental laws. Replacement materials that have the characteristics of chromated alkaline cleaners need to be found that address both the cleaning requirements and environmental impacts. This report will review environmentally friendly candidates evaluated as non-chromium alkaline cleaner replacements and methods used to compare those candidates one versus another. The report will also list characteristics used to select candidates based on their declared contents. It will also describe and evaluate methods used to discriminate among the large number of prospective candidates.

  13. Numerical modeling of forceful pluton emplacement and associated deformation at different crustal levels - instantaneous, continuous or episodic intrusion?

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Nabelek, P. I.

    2015-12-01

    The Papoose Flat pluton in the White-Inyo Range, California, is one of the best examples of forceful magma emplacement at mid-crustal levels that is revealed by a highly strained aureole. A thermo-rheological 2-D model of the pluton and its aureole is proposed. We explored how the frequency of magma input, from instantaneous to continuous to the bottom of the laccolith, affects the ductile width of the aureole and the crystallinity of the pluton, which has implications for eruption of magma. We modeled these aspects at mid- and upper-crustal levels. The pluton was assumed to be 5 km thick in the middle and 13 km wide. Except for instantaneous growth, pluton was assumed to grow over 5 m.y. The aureole was assumed to have power-law rheology of quartz with dependence on H2O fugacity, which was calculated using the CORK equation (Holland & Powell, 1991) Our result shows that the bottom of the Papoose Flat pluton was emplaced at the brittle-ductile transition zone of the crust. The crustal rheology profile assisted the softening of rocks around the pluton. The simulated temperature and strength profiles confirm that ductile deformation was related to thermal weakening (Saint-Blanquat et al., 2001). Results of incremental growth calculations show that the pluton remains hot and only partially crystalline for millions of years when it grows by frequent input of small batches of liquid. At the mid-crustal level, the ductile region around the pluton is much wider and exists longer than at the shallow crustal level. Brittle rheology is dominant during the late stage growth at the shallow depth. When the pluton grows instantly or by only few episodes of large batches of input, the mobile part of the pluton is thin and the ductile aureole is narrower. High-frequency incremental growth by smaller magma batches produces a large volume of mobile magma that has the potential to induce internal magmatic layering that may be reflected in aligned acquired magnetic susceptibility (AMS

  14. Structural evolution of the La Paya pluton (Sierra de Cachi, NW Argentina): insights from the study of its magnetic fabric

    NASA Astrophysics Data System (ADS)

    Aranguren, Aitor; Hongn, Fernando; María Tubía, José; Vegas, Néstor

    2017-04-01

    The La Paya granite is a pluton elongated in a northerly direction that spreads over 10 km2 in the Sierra de Cachi (Eastern Cordillera of Salta, Andean belt, NW Argentina). This pluton intrudes into high-temperature and low-pressure migmatites and schists. The metamorphic evolution of the country rocks and the emplacement of the La Paya pluton took place in an extensional tectonic setting during Ordovician times (Hongn et al., 2014). Subsequently, a compressional tectonic event led to the formation of large E-verging folds with a penetrative axial planar foliation. Due to the folding event, the current metamorphic zonation is inverted and the metamorphic degree rises towards the west. The granite is concordant with the metamorphic zonation and with the country rocks foliation. Schists with biotite and andalucite (low to medium metamorphic grade) crop out in the eastern border of the pluton and schists with cordierite (high grade) in the western border. The pluton is characterized by the coexistence of magmatic and solid-state structures. The deformation is localized in shear bands concentrated in the pluton roof. Wide sectors of the pluton core preserve medium- to coarse-grained equigranular textures of magmatic origin on which we have collected samples from 28 sites in order to perform an AMS study. Susceptibility values are very low, with k ranging between 19 and 67 x 10-6 SI. The obtained anisotropy values are in agreement with the magmatic character of the analysed samples (Pj between 1,03-1,07). The magnetic foliations are concordant with the contacts of the pluton. They show northwards trends and dips to the west that are steeper close to the eastern pluton border. Magnetic lineations are concentrated in two main maxima that define a great circle parallel to the pluton elongation. The parallelism between the magnetic fabrics from areas with magmatic structures and the structures observed in domains with solid-state deformation points to a syn

  15. Modern pollen and stomate deposition in lake surface sediments from across the treeline on the Kola Peninsula, Russia.

    PubMed

    Gervais, B R.; MacDonald, G M.

    2001-04-01

    We sampled and analyzed surface sediments from 31 lakes along a latitudinal transect crossing the coniferous treeline on the Kola Peninsula, Russia. The major vegetation zones along the transect were tundra, birch-forest tundra, pine-forest tundra, and forest. The results indicate that the major vegetation types in our study area have distinct pollen spectra. Sum-of-squares cluster analysis and principal components analysis (PCA) groupings of pollen sites correspond to the major vegetation zones. PCA ordination of taxa indicates that the first axis separates taxa typical of the forest zone (Pinus, Picea) from taxa typical of tundra and forest-tundra zones (Polypodiaceae, Ericaceae, and Betula). The current position of the coniferous treeline, defined in our region by Pinus sylvestris, occurs roughly where Pinus pollen values reach 35% or greater. Arboreal pollen (AP)/non-arboreal pollen (NAP) ratios were calculated for each site and plotted against geographic distance along the transect. AP/NAP ratios of 7 or greater are found within pine-forest tundra and forest vegetation zones. Pinus stomates (dispersed stomatal guard cells) are absent from sites north of the coniferous treeline and all but two samples from the forested sites contain stomates. Stomate concentrations among the samples are highly variable and range from 10 to 458 per ml and positively correlate with the changing Pinus pollen values.

  16. Emission of CO2 by soils in the impact zone of the Severonikel smelter in the Kola subarctic region

    NASA Astrophysics Data System (ADS)

    Kadulin, M. S.; Koptsik, G. N.

    2013-11-01

    The intensity of the in situ soil respiration in the background northern taiga spruce forests of the Kola subarctic region reaches 120-290 mg C-CO2/m2 per h. In the impact zone of the Severonikel smelter, it decreases to 90-140, 30, and 15-30 mg C-CO2/m2 per h at the stages of spruce defoliation, spruce-birch woodland, and technogenic barrens of the technogenic succession, respectively. For the first time, the impact of the industrial pollution on root respiration has been assessed, and the dependences of the CO2 emission, the contribution of mineral soil horizons to this process, the microbial biomass, and root respiration on the concentrations of available nickel and copper compounds have been determined. The efficiency of two remediation technologies applied to technogenic barrens near the smelter has been evaluated on the basis of four parameters of the soil biological activity. The results indicate that remediation with the creation of a new filled soil layer is more efficient than chemical and phytoremediation methods.

  17. Emissions from the copper-nickel industry on the Kola Peninsula and at Noril'sk, Russia

    USGS Publications Warehouse

    Boyd, Ron; Barnes, S.-J.; De Caritat, P.; Chekushin, V.A.; Melezhik, V.A.; Reimann, C.; Zientek, M.L.

    2009-01-01

    Published estimates for base metal emissions from the copper-nickel industry on the Kola Peninsula are re-examined in the light of (a) chemical data on the composition of the ores; (b) official emission figures for 1994; and (c) modelled emissions based on dry and wet deposition estimates derived from data for snow and rain samples collected in 1994. The modelled emissions, official emission figures and chemical data are mutually compatible for Ni, Cu and Co and show that previously published figures underestimated the emissions of the major elements, Ni and Cu (though within the same order of magnitude) and overestimated the emissions of As, Pb, Sb and Zn by up to several orders of magnitude, in some cases exceeding the calculated total input to the plants. Published estimates have neglected information on the nature and chemistry of the ores processed in metallurgical industries in the Noril'sk area of Siberia and the Urals. Revised emission estimates for 1994, using knowledge of the chemistry of the ores, are proposed: taken with published information on total emissions up to 2000 these data give an indication of emission levels in more recent years. ?? 2008 Elsevier Ltd. All rights reserved.

  18. Autumn migration and wintering areas of Peregrine Falcons Falco peregrinus nesting on the Kola Peninsula, northern Russia

    USGS Publications Warehouse

    Ganusevich, S.A.; Maechtle, T.L.; Seegar, W.S.; Yates, M.A.; McGrady, M.J.; Fuller, M.; Schueck, L.; Dayton, J.; Henny, C.J.

    2004-01-01

    Four female Peregrine Falcons Falco peregrinus breeding on the Kola Peninsula, Russia, were fitted with satellite-received transmitters in 1994. Their breeding home ranges averaged 1175 (sd = ??714) km2, and overlapped considerably. All left their breeding grounds in September and migrated generally south-west along the Baltic Sea. The mean travel rate for three falcons was 190 km/day. Two Falcons wintered on the coasts of France and in southern Spain, which were, respectively, 2909 and 4262 km from their breeding sites. Data on migration routes suggested that Falcons took a near-direct route to the wintering areas. No prolonged stopovers were apparent. The 90% minimum convex polygon winter range of a bird that migrated to Spain encompassed 213 km2 (n = 54). The area of the 50% minimum convex polygon was 21.5 km2 (n = 29). Data from this study agree with others from North America that show that Falcons breeding in a single area do not necessarily follow the same migratory path southward and do not necessarily use the same wintering grounds.

  19. Apatite trace element and halogen compositions as petrogenetic-metallogenic indicators: Examples from four granite plutons in the Sanjiang region, SW China

    NASA Astrophysics Data System (ADS)

    Pan, Li-Chuan; Hu, Rui-Zhong; Wang, Xin-Song; Bi, Xian-Wu; Zhu, Jing-Jing; Li, Chusi

    2016-06-01

    The abundances of trace elements including Sr, Ga and rare earth elements (REE) and halogens in apatite crystals from four intermediate-felsic plutons in the Zhongdian terrane in the Sanjiang region have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometry to evaluate the potential of apatite as a petrogenic-metallogenic indicator. The selected plutons include one that is not mineralized (the Triassic Xiuwacu pluton, or the TXWC pluton), one that hosts a porphyry-type Cu deposit (the Pulang pluton, or the PL pluton), one that hosts a porphyry-type Mo deposit (the Tongchanggou pluton, or the TCG pluton), and one that hosts a vein-type Mo deposit (the Cretaceous Xiuwacu pluton, or the CXWC pluton). Except for the CXWC pluton, the other three plutons have adakite-like trace element signatures in whole rocks. The results from this study show that REE, Sr and halogens in apatite can be used to track magma compositions, oxidation states and crystallization history. Apatite crystals from the adakite-like plutons are characterized by much higher Sr/Y and δEu than the non-adakite-type pluton. This means that apatite, which is not susceptible to alteration, is a useful tool for identifying the adakite-like plutons that no longer preserve the initial Sr/Y ratios in whole rocks due to weathering and hydrothermal alteration. Based on apatite Ga contents and δEu values, it is inferred that the parental magmas for the two adakite-like plutons containing porphyry-type Cu and Mo mineralization are more oxidized than that for the non-adakite-type pluton containing vein-type Mo mineralization. Apatite crystals from the vein-type Mo deposit have much lower Cl/F ratios than those from the porphyry-type Cu and Mo deposits. Apatite crystals from the adakite-like pluton without Cu or Mo mineralization is characterized by much lower Cl/F ratios than those from the adakite-like plutons that host the porphyry-type Cu and Mo deposits. The

  20. Oxygen regime of Siberian alkaline-ultramafic magmas

    NASA Astrophysics Data System (ADS)

    Ryabchikov, Igor; Kogarko, Liya

    2017-04-01

    Regimes of S2 and O2 are decisive factors controlling behavior of chalcophile and siderophile elements in magmatic processes. These parameters play important role during magmagenesis and in the course of crystallization and fluid mass transfer in magma chamber. Alkaline-ultramafic magmatism in Maymecha-Kotuy Province (Polar Siberia) is represented by giant intrusive complexes as well as by volcanics and dyke rocks, which include a well-known variety - meimechites. The latter are considered primary magmas of alkaline-ultramafic plutons in the region like for instance Guli intrusive complex. Sulfur content in primitive magmas estimated from the analyses of melt inclusions in olivine megacrysts from meimechites is close to 0.1 %. fO2 values calculated using olivine+clinopyroxene+spinel and spinel+melt oxygen barometers (1, 2) are 2-3 log units above QFM buffer. The relatively high oxygen potential at the early magmatic stage of alkaline-ultramafic Guli pluton provide predominance of sulfates among other forms of sulfur in the melt. This leads to the almost complete absence of sulfides in highly magnesian rocks. The oxidizing conditions exert important effect on behavior of many ore metals. At the stage of magma generation absence of sulfides in mantle materialresults in the presence of siderophile elements in metallic form and saturation of primary magmas in respect of metallic phases at an early stage of injection of the melt into the magma chamber. Later, under favorable circumstances during magma crystallization nuggets of precious metals may be formed. During further evolution of magmatic system fO2 and activity of oxidized sulfur decrease due to intensive crystallization of magnetite during the formation of koswites, then oxygen fugacity becomes even lower as a result serpentinization at a postmagmatic stage. These serpentization processes are caused by the displacement of reactions in the aqueous phase due to cooling towards the formation of methane and other

  1. Amphibole Thermometry and a Comparison of Results from Plutonic and Volcanic Systems

    NASA Astrophysics Data System (ADS)

    Sherman, T. M.; Putirka, K. D.; De Los Reyes, A. M. A.; Ratschbacher, B. C.

    2015-12-01

    Recent work (Ridolfi and Renzulli 2014) shows that amphiboles can be used to infer magmatic temperatures, even without knowledge of co-existing liquids. Here, we apply this approach, using new calibrations, to investigate felsic-mafic magma interactions, in a volcanic (Lassen Volcanic Center, a Cascade volcano) and plutonic (the Jurassic Guadalupe Igneous Complex) system. Preliminary data suggest that volcanic processes, as might be expected, preserve higher temperatures than plutonic materials (on average, volcanic amphiboles recorded 907±57.3°C while plutonic amphiboles recorded 764±59.7°C). We also find that the average T of a given mineral grain decreases with increased mineral size such that those crystallized below 800°C sometimes reach sizes beyond ~1mm, while those near 900°C appear truncated to ~0.3mm. It is not clear if T is the only control on amphibole crystal growth; however, our results would imply that larger grains not only require more time to grow but require continued undercooling. Significant cooling or heating is also recorded in many volcanically- and plutonically-grown grains, which may reflect transitioning between magmas of different T and composition. Core-to-rim cooling trends (with a common T of drop of 80oC) likely represent mafic-to-felsic magma transitions, whereas core-to-rim heating of similar magnitudes indicate a felsic-mafic transition. Some grains, though, exhibit a constant T (in the range 700-900°C) from core to rim, which perhaps indicates some shielding from magma mixing processes. Amphiboles might thus provide a reliable record of the intensity of magma mingling and mixing experienced by any particular enclave. Interestingly, volcanically-derived amphiboles appear to mostly record cooling towards the rims, while their plutonic counterparts tend to experience heating. It would thus appear that at Lassen, amphiboles are unaffected by later mafic magma recharge, but at the GIC, the plutonic amphiboles are more likely to

  2. The Port Mouton Shear Zone: intersection of a regional fault with a crystallizing granitoid pluton

    NASA Astrophysics Data System (ADS)

    Clarke, D. Barrie; McCuish, Krista L.; Vernon, Ron H.; Maksaev, Victor; Miller, Brent V.

    2002-04-01

    The peraluminous tonalite-monzogranite Port Mouton Pluton is a petrological, geochemical, structural, and geochronological anomaly among the many Late Devonian granitoid intrusions of the Meguma Lithotectonic Zone of southern Nova Scotia. The most remarkable structural feature of this pluton is a 4-km-wide zone of strongly foliated (040/subvertical) monzogranites culminating in a narrow (10-30 m), straight, zone of compositionally banded rocks that extends for at least 3 km along strike. The banded monzogranites consist of alternating melanocratic and leucocratic compositions that are complementary to the overall composition of that part of the pluton, suggesting an origin by mineral-melt and mineral-mineral sorting. Biotite and feldspar are strongly foliated in the plane of the compositional bands. These compositional variations and foliations originated by a process of segregation flow during shearing of the main magma with a crystallinity of 55-75%. Subsequent minor brittle fracturing of feldspars, twinning of microcline, development of blocky sub-grains in quartz, and kinking of micas demonstrate overprinting by a high-temperature deformation straddling the monzogranite solidus. Small folds and late sigmoidal dykes indicate dextral movement on the shear zone. This Port Mouton Shear Zone (PMSZ) is approximately co-linear with the only outcrops of Late Devonian mafic intrusions in the area, two of which are syn-plutonic with well-developed mingling textures in the marginal tonalite of the Port Mouton Pluton. Also closely co-linear with the mafic intrusions are a granitoid dyke that extends well beyond the outer contact of the Port Mouton Pluton, a swarm of large aligned angular xenolithic slabs, a zone of thin wispy schlieren banding, a large Be-bearing pegmatite, and a breccia pipe with abundant garnetiferous metapelitic xenoliths. In various ways, the shear zone may control all of these features. The Port Mouton Shear Zone is parallel to many other NE

  3. Volcanic-Plutonic Connection in the Tilzapotla Caldera Ignimbrites in Southern Mexico

    NASA Astrophysics Data System (ADS)

    Martiny, B. M.; Moran Zenteno, D. J.; Roberge, J.; Zuñiga-Lagunes, L.; Flores-Huerta, D.; Solari, L.; Lopez-Martinez, M.

    2011-12-01

    Age and compositional similarities in broad exposures of volcanic and plutonic rocks in the central sector of the late Eocene-early Oligocene silicic volcanic province in southern Mexico provide an excellent opportunity for studying the genetic connection between the volcanic and plutonic realms. The Taxco-Tilzapotla sector is of particular interest given the presence of a NW-SE oriented elliptical dome structure (50 x 35 km) that encloses the Tilzapotla caldera, three medium-grained plutons one of which contains mafic magmatic enclaves, hypabyssal intrusive bodies, rhyolitic domes, and voluminous ignimbrites. North-south trending Laramide folds in Cretaceous marine sedimentary rocks were disrupted when late Eocene magmas intruded into the upper crust, forming the dome and producing opposite plunges in pre-dome fold axes north and south of the elliptical structure. We have obtained LA-ICPMS zircon U-Pb and Ar-Ar mineral ages as well as electron microscope analyses of different magmatic facies in order to: better understand the chronology of magmatic evolution in the area; examine the possible genetic relationship between the plutonic rocks and the principal ignimbritic units, in particular the crystal-rich units; and determine possible compositional differences that might suggest the injection of different batches of magma. U-Pb crystallization ages of 37-36 Ma were determined on zircons from different facies of the Coxcatlan granodiorite. Slightly younger zircon U-Pb crystallization ages were obtained for ignimbrites from the Tilzapotla caldera (36-35 Ma) and for the more mafic Chiautle pluton (34.6 Ma) that is exposed near the southern boundary of the dome structure. Earlier work by our group established caldera collapse and extrusion of the Tilzapotla ignimbrite at 34.3 Ma. Ar-Ar dating gives cooling ages of 33 Ma in sanidine for an intracaldera ignimbrite and some late stage silicic and intermediate magmas yielded mainly between 33-32 Ma. The new and previous

  4. Genesis and evolution of water in a two-mica pluton: A hydrogen isotope study

    USGS Publications Warehouse

    Brigham, R.H.; O'Neil, J.R.

    1985-01-01

    Measurements were made of the hydrogen isotope composition of 74 samples of muscovite, biotite, vein quartz and whole rocks from the Papoose Flat pluton, eastern California, U.S.A., and adjacent metamorphic and sedimentary rocks in order to elucidate the genesis and evolution of water and hydrous minerals in a two-mica granodiorite. Electron microprobe analyses were made of all micas so that the Suzuoki-Epstein equation could be used in evaluating the data. Based on experimental, theoretical and textural evidence of mica paragenesis, a model of hydrogen isotope fractionation between an aqueous vapor and a magma during crystallization has been constructed. This model accounts for the observed hydrogen isotope relations and implies that primary hydrogen isotope compositions have been preserved in a large portion of the pluton. The ?? D-values of biotites vary widely over the range -103 to -66% with most values lying between -90 and -70??? Muscovites, on the other hand, are isotopically more uniform and have ?? D-values of -61 to -41??? with most values lying between -50 and -46??? These data are consistent with the interpretation that biotite formed over a long period of crystallization whereas muscovite formed in a narrow interval, presumably during the final stages of crystallization when alumina and water contents were at their highest. Only 8 of the 21 muscovite-biotite pairs analyzed are in hydrogen isotope equilibrium as calculated from the Suzuoki-Epstein equation. Biotites in the western half of the pluton have relatively low ?? D-values of around -85???, whereas those in the eastern half have higher values of up to -66??? This pattern is a consequence of a loss of permeability associated with the syn-intrusive deformation of the western margin of the pluton. This loss of permeability enhanced the preservation of primary hydrogen isotope relations there by diverting water evolved from the magma out through the eastern half of the pluton where some deuteric

  5. Crystal structure of modular sodium-rich and low-iron eudialyte from Lovozero alkaline massif

    NASA Astrophysics Data System (ADS)

    Rozenberg, K. A.; Rastsvetaeva, R. K.; Aksenov, S. M.

    2016-09-01

    The structure of the sodium-rich representative of the eudialyte group found by A.P. Khomyakov at the Lovozero massif (Kola Peninsula) is studied by X-ray diffraction. The trigonal cell parameters are: a = 14.2032(1) and c = 60.612(1) Å, V = 10589.13 Å3, space group R3m. The structure is refined to the final R = 5.0% in the anisotropic approximation of atomic displacement parameters using 3742|F| > 3σ( F). The idealized formula ( Z = 3) is Na37Ca10Mn2FeZr6Si50(Ti, Nb)2O144(OH)5Cl3 · H2O. Like other 24-layer minerals of the eudialyte group, this mineral has a modular structure. Its structure contains two modules, namely, "alluaivite" (with an admixture of "eudialyte") and "kentbrooksite," called according to the main structural fragments of alluaivite, eudialyte, and kentbrooksite. The mineral found at the Lovozero alkaline massif shows some chemical and symmetry-structural distinctions from the close-in-composition labyrinthite modular mineral from the Khibiny massif. The difference between the minerals stems from different geochemical conditions of mineral formation in the two regions.

  6. Crystallization processes in the Rocky Hill granodiorite Pluton, California: An interpretation based on compositional zoning of plagioclase

    NASA Astrophysics Data System (ADS)

    Loomis, Timothy P.; Welber, Paul W.

    1982-12-01

    The Rocky Hill Pluton was chosen for study of plagioclase zoning because it has an apparently simple geometry and one-stage emplacement history, documented by Putman and Alfors (1969). The pluton is divided texturally into a hypidiomorphic granular rim fades and porphyritic core facies, both comprising zoned plagioclase phenocrysts averaging 2 4 mm in diameter. Major features of compositional zoning profiles of plagioclase were found to be consistent within a sample, showing resorbed core regions followed by a sharp drop of ca. 10% An to a plateau region, and ending with normal zoning. The width of the plateau region is narrow in samples near the pluton rim but increases systematically toward the pluton core, and the outer part of the plateau develops reverse zoning in the core facies. A review of the effects of pressure, water content of the melt, and temperature on equilibrium and disequilibrium crystallization processes concludes that only variations of temperature and water content during disequilibrium crystallization of plagioclase phenocrysts can produce the observed zoning patterns. Experimental data suggest that the trend toward finer grain size toward the interior of the pluton may be due to increasing water content rather than due to increasing cooling rate. The compositional zoning of plagioclase and textural variations in the pluton can be explained by a model in which the pluton crystallized by migration of a partly crystalline “mush zone” inward from the edge of the plutonic chamber while convection within the residual magma: (1) redistributed water excluded from the mush zone and (2) slowed the cooling rate of the mush zone. The reverse zoning of plagioclase growing in the convecting magma changed to normal zoning after capture in the mush zone because the cooling rate increased and water was removed. Comparison of the results from our study of Rocky Hill with published descriptions of plutons and experimental and theoretical studies of

  7. The alkaline and alkaline-carbonatite magmatism from Southern Brazil

    NASA Astrophysics Data System (ADS)

    Ruberti, E.; Gomes, C. D. B.; Comin-Chiaramonti, P.

    2015-12-01

    Early to Late Cretaceous lasting to Paleocene alkaline magmatism from southern Brazil is found associated with major extensional structural features in and around the Paraná Basin and grouped into various provinces on the basis of several data. Magmatism is variable in size, mode of occurrence and composition. The alkaline rocks are dominantly potassic, a few occurrences showing sodic affinity. The more abundant silicate rocks are evolved undersaturated to saturated in silica syenites, displaying large variation in igneous forms. Less evolved types are restricted to subvolcanic environments and outcrops of effusive suites occur rarely. Cumulatic mafic and ultramafic rock types are very common, particularly in the alkali-carbonatitic complexes. Carbonatite bodies are represented by Ca-carbonatites and Mg-carbonatites and more scarcely by Fe-carbonatites. Available radiometric ages for the alkaline rocks fit on three main chronological groups: around 130 Ma, subcoveal with the Early Cretaceous flood tholeiites of the Paraná Basin, 100-110 Ma and 80-90 Ma (Late Cretaceous). The alkaline magmatism also extends into Paleocene times, as indicated by ages from some volcanic lavas. Geochemically, alkaline potassic and sodic rock types are distinguished by their negative and positive Nb-Ta anomalies, respectively. Negative spikes in Nb-Ta are also a feature common to the associated tholeiitic rocks. Sr-Nd-Pb systematics confirm the contribution of both HIMU and EMI mantle components in the formation of the alkaline rocks. Notably, Early and Late Cretaceous carbonatites have the same isotopic Sr-Nd initial ratios of the associated alkaline rocks. C-O isotopic Sr-Nd isotopic ratios indicate typical mantle signature for some carbonatites and the influence of post-magmatic processes in others. Immiscibility of liquids of phonolitic composition, derived from mafic alkaline parental magmas, has been responsible for the origin of the carbonatites. Close association of alkaline

  8. Hiding the Evidence: Growth of plutons by incremental emplacement of sheets in crystal mush

    NASA Astrophysics Data System (ADS)

    Miller, C. F.; Furbish, D. J.; Claiborne, L. L.; Walker, B. A.; Bleick, H. A.; Steinwinder, T. R.; Koteas, G. C.

    2006-12-01

    Growing evidence supports the notion that plutons are constructed incrementally, commonly over long periods of time, yet field evidence for the multiple injections that seem to be required is commonly sparse or absent (e.g. Glazner et al. 2004). Timescales of up to several million years, among other arguments, indicate that the dominant volume does not remain largely molten, yet if growing plutons are constructed from rapidly solidifying increments it is unlikely that intrusive contacts would escape notice. A model wherein magma increments are emplaced into crystal mush rather than either solid or crystal-poor material provides a plausible explanation for this apparent conundrum. A partially solidified intrusion undoubtedly comprises zones with contrasting melt fraction and therefore strength. The emplacement of dikes that intrude such a strength-zoned intrusion will be guided by the contrasts in the same way that dikes intruding solid media: magma spreads rather than continuing to propagate upward where it encounters a zone of higher rigidity (e.g. experiments by Kavanagh et al. 2006). We propose that ascending magma is in essence trapped by low-strength zones in plutonic mushes that are relatively melt-rich. In many cases, such zones may be subhorizontal and thus sill-like in geometry, but shapes and orientations could be highly variable, depending on the prior history of the composite intrusion. Contacts will commonly be obscure from the start because the contrast between intruding material (crystal-poorer magma) and host (crystal-richer mush) is subtle, and it may be obscured even further by subsequent destabilization of the mush. Field evidence and zircon zoning stratigraphy in plutons of the Colorado River region of southern Nevada support the hypothesis that emplacement of magma replenishments into a mush host is important in pluton construction. Except for highly fractionated dikes and sills, the dominant granite unit of the Spirit Mountain batholith

  9. Timing and nature of tertiary plutonism and extension in the Grouse Creek Mountains, Utah

    USGS Publications Warehouse

    Egger, A.E.; Dumitru, T.A.; Miller, E.L.; Savage, C.F.I.; Wooden, J.L.

    2003-01-01

    The Grouse Creek-Albion-Raft River metamorphic core complex in northwestern Utah and southern Idaho is characterized by several Tertiary plutons with a range of ages and crosscutting relations that help constrain the timing of extensional deformation. In the Grouse Creek Mountains, at least three distinct, superimposed, extension-related Tertiary deformational events are bracketed by intrusive rocks, followed by a fourth event: motion on range-bounding faults. The Emigrant Pass plutonic complex was emplaced at depths of less than 10 km into Permianage rocks. SHRIMP U-Pb zircon analysis indicates a three-stage intrusion of the complex at 41.3 ?? 0.3 Ma, 36.1 ?? 0.2 Ma, and 34.3 ?? 0.3 Ma. The two youngest phases represent distinctly younger intrusive event(s) than the oldest phase, separated by more than 5 m.y. The oldest phase cuts several metamorphosed and deformed younger-on-older faults, providing a pre-41 Ma age bracket for oldest extension-related deformation in the region. The youngest phase(s) are interpreted to have been intruded during delelopment of a map-scale. N-S-trending recumbent fold, the Bovine Mountain fold, formed during vertical shortening of roof rocks during intrusion. This second event folded older normal faults that are likely pre-41 Ma. Zircons from the youngest part of the pluton show inheritance from Archean basement (???2.5 Ga) and from its Proterozoic sedimentary cover (???1.65 Ga). The Red Butte pluton, emplaced at 15-20 km depth, intruded highly metamorphosed Archean orthogneiss at 25.3 ?? 0.5 Ma; cores of some zircons yield latest Archean ages of 2.55 Ga. The pluton is interpreted to have been intruded during a third deformational and metamorphic event that resulted in vertical flattening fabrics formed during NW to EW stretching, ultimately leading to thinning of cover and top-to-the west motion on the Ingham Pass fault. The Ingham Pass fault represents an important structure in the Grouse Creek Mountains, as it juxtaposes two parts

  10. An underground characterization program for a nuclear fuel waste disposal vault in plutonic rock

    SciTech Connect

    Thompson, P.M.; Everitt, R.A.

    1993-12-31

    The Canadian Nuclear Fuel Waste Management Program (CNFWMP) is developing a concept for disposing of nuclear fuel waste that involves placing and sealing it in a disposal vault excavated 500 to 1,000 m deep in the stable plutonic rock of the Canadian Shield. In this concept, engineered and natural barriers serve to isolate the waste from the biosphere. Since 1983, underground characterization and testing in support of the CNFWMP has been ongoing at the Underground Research Laboratory (URL) in southeastern Manitoba. This paper draws on experience gained at the URL to recommend an approach to underground characterization that would provide the necessary information to make design decisions for a disposal vault in plutonic rock.

  11. Isotopic studies of the late Archean plutonic rocks of the Wind River Range, Wyoming.

    USGS Publications Warehouse

    Stuckless, J.S.; Hedge, C.E.; Worl, R.G.; Simmons, K.R.; Nkomo, I.T.; Wenner, D.B.

    1985-01-01

    Two late Archaean intrusive events were documented in the Wind River Range by isotopic studies of the Rb-Sr and U-Th-Pb systems in whole-rock samples and the U-Pb systematics for zircon. An age of approx 2630(20) m.y. for the Louis Lake batholith and apparent ages of 2504(40) to 2575(50) m.y. for the Bear Ears pluton were obtained. Post-magmatic hydrothermal events approximately Tertiary in age, lowered delta 18O values and disturbed parent-daughter relationships in most of the isotopic systems investigated. The two intrusive units apparently were derived from different protoliths. Initial isotopic ratios and petrochemistry for the Louis Lake batholith are consistent with an early Archaean trondhjemitic to tonalitic source. The protolith for the Bear Ears pluton must have been subjected to high-grade metamorphism that caused loss of Rb and U prior to magma generation. -L.C.H.

  12. Petrology and U-Pb geochronology of buried Avalonian plutonic rocks on southeastern Cape Cod

    USGS Publications Warehouse

    Leo, G.W.; Mortensen, J.K.; Barreiro, B.; Phillips, J.D.

    1993-01-01

    Plutonic rocks have been intersected by two separate drill holes on souteastern Cape Cod. Hole CC2 is located about 7 km south of the Nauset anomaly, an east-northeast-trending magnetic lineament that was considered to separate the distinct plutonic zones of Avalon terrane. This drill hole intersected weakly foliated, fairly homogeneous biotite granite. Zircons from this granite give a U-Pb age of 584+9/-8 Ma. Hole CC1 is located about 12 km north of the Nauset anomaly. The drill core intersected foliated, sheared, biotite granodiorite and biotite-hornblende-clinopyroxene-quartz gabbro, metamorphosed to greenschist facies. The deformed and altered state of these rocks, as well as their geochemistry, suggest that their origin and possibly their ages are distinct from the granite in hole CC2. No datable zircons were obtained from rocks in CC1. -from Authors

  13. Pennsylvanian pluton stitching of Wrangellia and the Alexander terrane, Wrangell Mountains, Alaska

    SciTech Connect

    Gardner, M.C.; Bergman, S.C.; Cushing, G.W. ); Plafker, G. ); Campbell, R.B.; Dodds, C.J. ); McClelland, W.C. ); Mueller, P.A. ); MacKevett, E.M. Jr.

    1988-11-01

    A quartz monzonite-syenite-alkali granite plutonic complex in eastern Alaska crosscuts the contact of the Alexander terrane and Wrangellia and intrudes the basement rocks of both terranes. Zircon U-Pb data indicate an intrusion age of 309 {plus minus} 5 Ma (Middle Pennsylvanian) for the pluton, and {sup 40}K-{sup 40}Ar age for hornblende separates indicate cooling to about 450 C during Middle Pennsylvanian-Early Permian time. The new field relations and age data demonstrate the Wrangellia and the Alexander terrane were contiguous during the Middle Pennsylvanian. This conclusion provides an important new constraint on paleogeographic reconstructions of the northwest Cordillera, and necessitates reassessment of stratigraphic and paleomagnetic data that were cited as evidence that the terranes evolved separately until the late Mesozoic.

  14. Paleomagnetic results from seven middle Paleozoic plutons in the Appalachian Piedmont of North and South Carolina

    USGS Publications Warehouse

    Hagstrum, J.T.

    1983-01-01

    Seven isotopically dated plutons of similar middle Paleozoic age (approx. 400 Ma) were sampled for paleomagnetic study. The results from 12 sites (152 samples) within these plutons show two types of remanence behavior that appear fairly consistent with rock composition. The more leucocratic rocks (9 sites) tend to yield single-component magnetizations, of generally lower coercivities and blocking temperatures relative to the other units, that are considered to represent a recent viscous overprint, The mesocratic to melanocratic rocks show both single- and multicomponent magnetizations, the latter giving characteristic directions isolated through remagnetization-plane analysis. Three sites are considered reliable and yield paleomagnetic poles, of inferred Early Devonian age, that may reflect a 30? southward displacement from stable North America. One large site (25 samples) gives a remagnetized pole position of inferred Carboniferous age consistent with poles from North America, perhaps indicating that the Piedmont may have become part of the North American plate by this time.

  15. River Valley pluton, Ontario - A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

    NASA Technical Reports Server (NTRS)

    Ashwal, Lewis D.; Wooden, Joseph L.

    1989-01-01

    This paper presents Nd, Sr, and Pb isotopic data indicating a late-Archean/early-Proterozoic age for the River Valley anorthositic pluton of the southwestern Grenville Province of Sudbury, Ontario. Pb-Pb isotopic data on 10 whole-rock samples ranging in composition from anorthosite to gabbro yield an age of 2560 + or - 155 Ma. The River Valley pluton is thus the oldest anorthositic intrusive yet recognized within the Grenville Province. The Sm-Nd isotopic system records an age of 2377 + or - 68 Ma. High Pb-208/Pb-204 of deformed samples relative to igneous-textured rocks implies Th introduction and/or U loss during metamorphism in the River Valley area. Rb-Sr data from igneous-textured and deformed samples and from mineral separates give an age of 2185 + or - 105 Ma, indicating substantial disturbance of the Rb-Sr isotopic system.

  16. Geochemical study of Palong Pluton at Negeri Sembilan-Pahang border

    NASA Astrophysics Data System (ADS)

    Selamat Din, Khairil Izam Bin; Umor, Mohd Rozi

    2013-11-01

    The geochemical studies are carried out for igneous rocks from Palong Pluton at the border area of Negeri Sembilan and Pahang. The study area is about 250 km2, covering the area of Kemayan, Pasoh and Serting. The purposes of the geochemical study are to classify and determine the chemical characteristic of the granitic rocks, to correlate and interpret the crystallization history of igneous rocks, to determine the rock genesis and to determine the origin of magma. The Palong Pluton is divided into three groups, namely the Kemayan Granite, Serting Granite and Lui Granite. The geochemical data are presented by TAS and Harker Diagrams. The geochemical results show that Kemayan Granite, Serting Granite and Lui Granite are naturally originated from a single magma source. The magma evolution started from Kemayan Granite to Lui Granite and Serting Granite by differentiation proceses.

  17. Felsic plutonic rocks of the Midyan region, Kingdom of Saudi Arabia—I. Distribution, classification and resource potential

    NASA Astrophysics Data System (ADS)

    Ramsay, Colin R.; Drysdall, Alan R.; Clark, Malcolm D.

    About 80 large felsic plutons were emplaced in the Midyan region of the northwestern Arabian Shield between 725 and 570 Ma ago. Polymetallic mineralization, including Mo, Nb, REE, Sn, Ta, U, W and Zr, is associated with particular varieties. Five intrusive suites of regional extent and five other plutons have been identified. The oldest extensive unit is the Muwaylih suite, consisting of trondhjemite, tonalite, diorite and gabbro, with generally trondhjemitic compositional affinities and no known mineral potential. The most voluminous is the Ifal suite, a heterogeneous assemblage of biotite—hornblende monzogranite, granodiorite and quartz monzodiorite in large, oval to irregular plutons characterized by numerous intraplutonic dikes, but with no known mineral potential. The Ifal suite is intruded by plutons of the Atiyah monzogranite, with a variable number of dikes. The Muwaylih, Ifal and Atiyah suites are chemically metaluminous, but the Midyan suite consists of alkali granite to alkali-feldspar granite which is metaluminous to peralkaline. Large, irregular plutons of the Haql suite are composed of perthite leucogranite which is metaluminous to marginally peraluminous or peralkaline. Plutonic rock units of local significance include the Lawz complex, consisting of commonly granophyric syenogranite to monzogranite, the Mowasse quartz syenite and the Sawda (nepheline syenite) complex. Polymetallic Nb sbnd Zr deposits, such as those at Jabal Tawlah and Ghurayyah, are the most important known mineral resources and are related to alkali granite of the Midyan suite. Plumasitic specialized plutons, such as the Ratamah granite, have weak Sn sbnd W sbnd Ta sbnd Nb mineralization, and are related to the Haql suite. Apical and contact zones of plutons of these suites are favorable exploration target areas.

  18. Petrologic evidence for a plutonic igneous origin of anorthositic norite clasts in 67955 and 77017

    NASA Technical Reports Server (NTRS)

    Ashwal, L. D.

    1975-01-01

    Clasts of anorthositic norite in 67955 and 77017, and several other samples, are suggested to represent material which crystallized from a silicate magma in a plutonic environment. Although no statement can be made regarding the ultimate origin of the parent melt, its composition was relatively felsic, starting within the primary field of crystallization of either plagioclase or spinel. The sequence of crystallization was: plagioclase (and/or spinel) olivine - low-Ca pyroxene - high-Ca pyroxene.

  19. Structure, age and mode of emplacement of the Hercynian Bordères-Louron pluton (Central Pyrenees, France)

    NASA Astrophysics Data System (ADS)

    Gleizes, Gérard; Crevon, Gérard; Asrat, Asfawossen; Barbey, Pierre

    2006-11-01

    The Hercynian Bordères-Louron pluton (20 km2) in the Central Pyrenees intrudes Devonian and Carboniferous metasediments. It shows a concentric zoning and consists of a significant proportion of (quartz) gabbros in its periphery, and of granodiorites, biotite monzogranites and biotite-muscovite monzogranites in its core. AMS study shows that the pluton corresponds to an elongated dome with a N100°E-trending axis. The anisotropy intensity Ppara% is high in the south and in the core of the pluton, whereas it is low in the north. The shape parameter T indicates that the fabric is strongly planar in a large central band oriented NW-SE, whereas it is strongly linear in the western and eastern tips of the pluton. These characteristics suggest that the Bordères-Louron pluton emplaced in two episodes: (1) intrusion of mafic magmas along a N100°E sill parallel to the regional foliation of the host metasediments; and (2) injection of three successive silicic batches (granodiorite, biotite monzogranite, two-micas monzogranite) which pushed aside the early mafic injections. In situ U-Pb dating of zircon grains indicates that the emplacement age of the biotite monzogranite is 309 ± 4 Ma, synchronous with the D 2 dextral transpressive event and close to the ages of the eastern Pyrenean plutons, may be slightly older.

  20. Geochemical evaluation of felsic plutonic rocks in the eastern and southeastern Arabian Shield, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Du Bray, E.A.; Elliott, James E.; Stoeser, D.B.

    1983-01-01

    In a geochemical evaluation of the eastern and southeastern Arabian Shield, which included collection of 696 rock samples and 694 pan concentrate samples, a province of tin-anomalous granitoid plutons was defined. Pan concentrates collected in and around these plutons were enriched in tin and tungsten relative to the concentrate population. Rock samples of these leucocratic, muscovite-bearing, peraluminous granites contained anomalously high concentrations of lithium, fluorine, beryllium, lead, rubidium, niobium, yttrium, tin, bismuth, silver, and tungsten. Ten tin-anomalous plutons were located in the study area. The plutons are typically small, less than 10 km2 in areal extent, and circular to elliptical in plan view. The resource potential of these latest Proterozoic plutons has not been established; economically exploitable concentrations of tin, tungsten, molybdenum, or zinc may be present, and followup studies are warranted. Further, two of the plutons are characterized by higher than normal total-count radioactivity and have potential for uranium, thorium, or rare-earth element deposits.

  1. Erupted frothy xenoliths may explain lack of country-rock fragments in plutons

    PubMed Central

    Burchardt, Steffi; Troll, Valentin R.; Schmeling, Harro; Koyi, Hemin; Blythe, Lara

    2016-01-01

    Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as “xenolith graveyards”, or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of stoping. Here, we present new evidence that may explain the absence of abundant country-rock fragments in plutons. We report on vesiculated crustal xenoliths in volcanic rocks that experienced devolatilisation during heating and partial melting when entrained in magma. We hypothesise that the consequential inflation and density decrease of the xenoliths allowed them to rise and become erupted instead of being preserved in the plutonic record. Our thermomechanical simulations of this process demonstrate that early-stage xenolith sinking can be followed by the rise of a heated, partially-molten xenolith towards the top of the reservoir. There, remnants may disintegrate and mix with resident magma or erupt. Shallow-crustal plutons emplaced into hydrous country rocks may therefore not necessarily contain evidence of the true amount of magmatic stoping during their emplacement. Further studies are needed to quantify the importance of frothy xenolith in removing stoped material. PMID:27804996

  2. Multiple mafic and felsic magma interaction as exhibited in the Dartmouth Pluton, Avalon zone, southeastern Massachusetts

    SciTech Connect

    Hamidzada, N.A.; Hermes, O.D.; Murray, D.P. . Dept. of Geology)

    1993-03-01

    Dioritic to quartz monzonitic rocks of the Dartmouth Pluton exhibit excellently preserved, diverse features produced by mingling and mixing of mafic and felsic magma during multiple events. The related mafic and hybridized intermediate composition rocks occur both as discrete outcrop-sized masses or as enclaves within quartz monzonite or early-stage mixed rocks. Enclaves are rounded, lack chilled margins, and in some cases exhibit cuspate margins; they range in size from 1m--<1cm. Outcrops dominated by dioritic rock consist of well developed mafic pillows with inter-pillow infillings of hybridized rock that had been subjected to magma mixing during or prior to the final mingling process. Dioritic rocks are fine-grained with sparse plagioclase phenocrysts; they contain small, darker-colored enclaves indicative of preceding magma interaction. Major and trace element variation diagrams for this suite of rocks exhibit general linear trends consistent with mixing processes. Overall, field, petrographic, and geochemical relationships in the Dartmouth Pluton demonstrate: (1) widespread mingling of mafic and felsic magma, (2) variable degrees of mafic and felsic magma mixing, and (3) multiple and repeated episodes of mafic and felsic magma interaction. Significantly, some spatially associated dioritic and granitic rocks, including a 595 Ma alkali feldspar granite formerly considered to be part of the Dartmount Pluton, are geochemically related. Field mapping demonstrates that rocks of the mixed suite are intrusive into these rocks, thus establishing a maximum age, but raising the questions that the suite may be considerably younger.

  3. The mineralogy of the Snake Creek-Williams Canyon pluton, southern Snake Range, Nevada

    USGS Publications Warehouse

    Lee, Donald Edward; Christiansen, Eric H.

    1983-01-01

    The Snake Creek-Williams Canyon pluton of the southern Snake Range crops out over an area of about 30 km 2, about 60 km southeast of Ely, Nev. This Jurassic intrusion displays large and systematic chemical and mineralogical zonation over a horizontal distance of 5 km. Major-element variations compare closely with Dalyls average andesite-dacite-rhyolite over an SiO 2 range of 63 to 76 percent. For various reasons it was originally thought that assimilation played a dominant role in development of the Snake Creek-Williams Canyon pluton. However, based on modeling of more recently obtained trace element and isotopic data, we have concluded that the zonation is the result of in-situ fractional crystallization, with little assimilation at the level of crystallization. This report summarizes data available for each of the mineral species present in the zoned intrusion. Special attention has been paid to trends that might relate to the variation in the chemical petrology of the pluton.

  4. Erupted frothy xenoliths may explain lack of country-rock fragments in plutons.

    PubMed

    Burchardt, Steffi; Troll, Valentin R; Schmeling, Harro; Koyi, Hemin; Blythe, Lara

    2016-11-02

    Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as "xenolith graveyards", or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of stoping. Here, we present new evidence that may explain the absence of abundant country-rock fragments in plutons. We report on vesiculated crustal xenoliths in volcanic rocks that experienced devolatilisation during heating and partial melting when entrained in magma. We hypothesise that the consequential inflation and density decrease of the xenoliths allowed them to rise and become erupted instead of being preserved in the plutonic record. Our thermomechanical simulations of this process demonstrate that early-stage xenolith sinking can be followed by the rise of a heated, partially-molten xenolith towards the top of the reservoir. There, remnants may disintegrate and mix with resident magma or erupt. Shallow-crustal plutons emplaced into hydrous country rocks may therefore not necessarily contain evidence of the true amount of magmatic stoping during their emplacement. Further studies are needed to quantify the importance of frothy xenolith in removing stoped material.

  5. Erupted frothy xenoliths may explain lack of country-rock fragments in plutons

    NASA Astrophysics Data System (ADS)

    Burchardt, Steffi; Troll, Valentin R.; Schmeling, Harro; Koyi, Hemin; Blythe, Lara

    2016-11-01

    Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as “xenolith graveyards”, or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of stoping. Here, we present new evidence that may explain the absence of abundant country-rock fragments in plutons. We report on vesiculated crustal xenoliths in volcanic rocks that experienced devolatilisation during heating and partial melting when entrained in magma. We hypothesise that the consequential inflation and density decrease of the xenoliths allowed them to rise and become erupted instead of being preserved in the plutonic record. Our thermomechanical simulations of this process demonstrate that early-stage xenolith sinking can be followed by the rise of a heated, partially-molten xenolith towards the top of the reservoir. There, remnants may disintegrate and mix with resident magma or erupt. Shallow-crustal plutons emplaced into hydrous country rocks may therefore not necessarily contain evidence of the true amount of magmatic stoping during their emplacement. Further studies are needed to quantify the importance of frothy xenolith in removing stoped material.

  6. The role of pegmatites and acid fluids for REE/HFSE mobilization in the Strange Lake peralkaline granitic pluton, Canada

    NASA Astrophysics Data System (ADS)

    Gysi, A. P.; Williams-Jones, A.

    2012-12-01

    The Strange Lake pluton in Canada is a mid-Proterozoic peralkaline granitic intrusion that is host to a world-class rare earth element (REE), yttrium (Y) and high-field strength element (HFSE) deposit containing more than 50 Mt ore at >1.5 wt.% REE and >3 wt.% Zr. The highest REE/HFSE concentrations are found in pegmatite-rich zones characterized by intense alteration. Previous studies of Strange Lake and other peralkaline and alkaline intrusions, such as Khan Bogd (Mongolia) and Tamazeght (Morocco) plutons have shown that hydrothermal alteration may play an important role in the mobility of the REE/HFSE. However, the fluid chemistry and conditions of alteration (i.e., P, T, pH, fO2, ligand activity) in these systems still need to be constrained to evaluate the importance and scale of such hydrothermal mobilization. We present new data from the B-zone, a pegmatite-rich zone located in NW Strange Lake. The pegmatites are generally zoned and form two main types. The border-type pegmatites consist of quartz, K-feldspar and hematized aegirine, whereas volatile-rich pegmatites consist of hydrothermal quartz and fluorite. Transitions between both types were also observed, with the K-feldspar being partly altered and replaced by Al-Si-rich phyllosilicates. The heavy (H)REE and Zr were primarily concentrated in zirconosilicates such as elpidite, now pseudomorphed by zircon or gittinsite, whereas light (L)REE and Y were concentrated in REE-F-(CO2)-minerals such as fluocerite and bastnäsite. Textural and mineralogical observations indicate that these minerals are primary and were partly to completely leached upon fluid-rock interaction in the pegmatites. Secondary phases include Ca-F-Y-rich minerals, mainly hydrothermal fluorite, that fill vugs and replaced primary REEHFSE minerals. The presence of hydrothermal fluorite veins, micro-veins, vugs and micro-breccia in the most altered parts of the B-zone are interpreted to reflect interaction of the rocks with a F-rich fluid

  7. Detection of a Gentamicin-Resistant Burn Wound Strain of Pseudomonas Aeruginosa but Sensitive to Honey and Garcinia Kola (Heckel) Seed Extract

    PubMed Central

    Adeleke, O.E.; Coker, M.E.; Oke, O.B.

    2010-01-01

    Summary Studies on Staphylococcus aureus and Staphylococcus intermedius from dog and cat, and also on Staphylococcus aureus from wound and pyoderma infections, have shown a correlation between the site of microbial infection and antimicrobial susceptibility. Both the methanolic extract concentrate of Garcinia kola (Heckel) seeds and natural honey have been associated with activity on bacterial isolates from respiratory tract infections. In this study, selected bacteria belonging to genera from burn wound infection sites were treated with natural honey and methanolic extract concentrate of Garcinia kola in antimicrobial susceptibility tests separately and in combined form, and also with gentamicin and methanol as controls. The two natural products were found to be active on the bacterial isolates, excluding Klebsiella pneumoniae strains, all of which showed resistance to honey. Combination forms of the two natural products were active only on the strains of Pseudomonas aeruginosa. At 4 and 8 µg/ml, gentamicin was ineffective on the three strains of Klebsiella pneumoniae while 8 µg/ml was moderately active on only two strains of Pseudomonas aeruginosa. One strain of Pseudomonas aeruginosa, UCH002, was resistant to gentamicin beyond 1,000 µ/ml. Gentamicin at 4 µ/ml was inhibitory to one strain of Escherichia coli and two strains of Staphylococcus aureus. Though the antimicrobial activity of the two natural products tested had been previously reported against microbial agents of respiratory tract infection, it was also recorded in this study. The lack of activity of each of the three honey types used in this study against the Klebsiella pneumoniae strains tested underscores the need to exclude this organism from burn wound infections before embarking on treatment with honey. The sensitivity of one high-level gentamicin-resistant strain of Pseudomonas aeruginosa to honey and Garcinia kola seed extract was noteworthy considering the therapeutic failures of gentamicin

  8. From Migmatites to Plutons: Power Law Relationships in the Evolution of Magmatic Bodies

    NASA Astrophysics Data System (ADS)

    Soesoo, Alvar; Bons, Paul D.

    2015-07-01

    Magma is generated by partial melting from micrometre-scale droplets at the source and may accumulate to form >100 km-scale plutons. Magma accumulation thus spans well over ten orders of magnitude in scale. Here we provide measurements of migmatitic leucosomes and granitic veins in drill cores from the Estonian Proterozoic basement and outcrops at Masku in SW Finland and Montemor-o-Novo, central Portugal. Despite the differences in size and number of measured leucosomes and magmatic veins, differences in host rock types and metamorphic grades, the cumulative width distribution of the studied magmatic leucosomes/veins follows a power law with exponents usually between 0.7 and 1.8. Published maps of the SE Australian Lachlan Fold Belt were used to investigate the distribution of granitoid pluton sizes. The granites occupy ca. 22 % of the 2.6 × 105 km2 area. The cumulative pluton area distributions show good power law distributions with exponents between 0.6 and 0.8 depending on pluton area group. Using the self-affine nature of pluton shapes, it is possible to estimate the total volume of magma that was expelled from the source in the 2.6 × 105 km2 map area, giving an estimated 0.8 km3 of magma per km2. It has been suggested in the literature that magma batches in the source merge to form ever-bigger batches in a self-organized way. This leads to a power law for the cumulative distribution of magma volumes, with an exponent m V between 1 for inefficient melt extraction, and 2/3 for maximum accumulation efficiency as most of the volume resides in the largest batches that can escape from the source. If m V ≥ 1, the mass of the magma is dominated by small batches; in case m = 2/3, about 50 % of all magma in the system is placed in a single largest batch. Our observations support the model that the crust develops a self-organized critical state during magma generation. In this state, magma batches accumulate in a non-continuous, step-wise manner to form ever

  9. Cooling and exhumation of the Rieserferner Pluton (Eastern Alps, Italy/Austria)

    NASA Astrophysics Data System (ADS)

    Steenken, André; Siegesmund, Siegfried; Heinrichs, Till; Fügenschuh, Bernhard

    2002-03-01

    The Defereggen-Antholz-Vals (DAV) Line marks the southern border of alpine greenschist facies metamorphism within the Austroalpine basement to the south of the western Tauern window. During the Oligocene sinistral-strike slip, coeval with vertical displacement, was accompanied by the syntectonic emplacement of the Rieserferner Pluton along the north side of the fault. To the north of the DAV Line Rb/Sr as well as K/Ar-biotite cooling ages continuously increase from 16 Ma at the Rensen Pluton in the west to 30 Ma at the eastern end of the Rieserferner Pluton. Similar trends are apparent from zircon and apatite fission-track data, which increase eastward from 19 to 29 Ma, and 13 to 16 Ma, respectively. Low cooling rates allow a direct transformation into exhumation rates assuming an average geothermal gradient of 28 °C km-1. The resulting exhumation rates of less than 1 mm year-1 do not affect the depth of isotherms in a geologically significant manner. Hence, variable cooling rates within the basement north of the DAV Line are a result of differential exhumation of individual blocks. High exhumation rates bracketed between the intrusion age of the Rieserferner Pluton at 31+/-3 Ma and the apatite partial annealing zone (PAZ) range between 0.4 and 0.6 mm year-1, whereas final exposure takes place at reduced exhumation rates of 0.2 mm year-1. East-side-down tilting of the block north of the DAV Line, as indicated by variations in exhumation rates, strongly affects the western part of the area studied between the Rensen and the Central Rieserferner Pluton whereas, further east, block rotation becomes less important. A total difference in exhumation of about 2.2 km corresponding to 5° tilting between the Western and Eastern Rieserferner, as indicated by K/Ar-biotite and zircon fission-track data, occurred before going through the PAZ for apatite fission-tracks. Furthermore, the significance of the cooling ages, especially for biotite, is tested by calculating a finite

  10. Organochlorine pesticides, chlorinated dioxins and furans, and PCBs in peregrine falcon Falco peregrinus eggs from the Kola peninsula, Russia

    USGS Publications Warehouse

    Henny, C.J.; Ganusevich, S.A.; Ward, F.P.; Schwartz, T.R.; Meyburg, B-U.; Chancellor, R.D.

    1994-01-01

    Nesting of a bog-associated population of mlgfatory Peregrine Falcons, Falco peregrinus, along the Ponoy River depression, Kola Peninsula, Russia, has been studied since 1977. In 1987 91 production rates averaged 1.94 young per active nest and the number of breeding pairs increased from 4 to 10. In 1991, most eyrie sites were visited during the egg stage and a 'sample' egg was collected for contaminant analysis. Eight Peregrine Falcon eggs contained relatively low concentrations of p,p' -DOE (DOE) (geometric mean 3.5 g/g) and of other organochlorine pesticides. These DOE concentrations are similar to those reported in Peregrine Falcon eggs from an Alaskan population that had also showed a recent population increase. Eggshell thinning (11.4%) was similar to that found in Alaska. Concentrations of polychlorinated biphenyls (PCBs) were higher than DOE concentrations, comparable to the contamination profile shown by Peregrine Falcon populations in Fennoscandia, and were higher than those found in Alaskan birds. Before this study, no Peregrine Falcon eggs from Russia had 'been analyzed for PCB congeners, polychlorinated dibenzo- p-dioxins (PCDDs), or pol ychlorinated dibenzofurans (PCD Fs). Conversions of analytical concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), other PCDDs, PCDFs and PCB congeners based on relative aryl hydrocarbon hydroxylase induction potencies allowed the estimation of total 2,3,7,8- TCDD equivalents (TEQs). The TEQs are in the range that is associated with embryonic mortality in other species. Even though the Peregrine Falcon population now seems to be released from decades of a DOT problem, exposure to other contaminant continues. There is an obvious need to assess further the sources and longer-term trends of the PCBs. We also report residue concentrations from one White-tailed Eagle, Haliaeetus albicilla, egg.

  11. Long-term consequences for Northern Norway of a hypothetical release from the Kola nuclear power plant.

    PubMed

    Howard, B J; Wright, S M; Salbu, B; Skuterud, K L; Hove, K; Loe, R

    2004-07-05

    The spatial and temporal variation in radiocaesium and (90)Sr doses to two population groups of the two Northernmost counties of Norway, Troms and Finnmark, following a hypothetical accident at the Kola nuclear power plant (KNPP) have been estimated using a model implemented within a geographical information system. The hypothetical accident assumes a severe loss of coolant accident at the KNPP coincident with meteorological conditions causing significant radionuclide deposition in the two counties. External doses are estimated from ground deposition and the behaviour of the different population groups, and internal doses from predicted food product activity concentrations and dietary consumption data. Doses are predicted for reindeer keepers and other Norwegian inhabitants, taking account of existing (137)Cs and (90)Sr deposition but not including the remedial effect of any countermeasures that might be used. The predicted doses, arising mainly from radiocaesium, confirm the Arctic Monitoring and Assessment Programme assessment that residents of the Arctic are particularly vulnerable to radiocaesium contamination, which could persist for many years. External doses are predicted to be negligible compared to ingestion doses. Ingestion doses for reindeer keepers are predicted to exceed 1 mSv y(-1) for several decades primarily due to their high consumption of reindeer meat. Other Norwegians would also be potentially exposed to doses exceeding 1 mSv y(-1) for several years, especially if they consume many local products. Whilst reindeer production is the most important exposure pathway, freshwater fish, lamb meat, dairy products, mushrooms and berries are also significant contributors to predicted ingestion doses. Radionuclide fluxes, defined as the total output of radioactivity in food from an area for a unit time, are dominated by reindeer meat. The results show the need for an effective emergency response, with appropriate countermeasures, should an accident of the

  12. Structural characterization and composition of Y-rich hainite from Sakharjok nepheline syenite pegmatite (Kola Peninsula, Russia)

    NASA Astrophysics Data System (ADS)

    Lyalina, L.; Zolotarev, A.; Selivanova, E.; Savchenko, Ye.; Zozulya, D.; Krivovichev, S.; Mikhailova, Yu.

    2015-08-01

    Y-rich hainite occurs in nepheline syenite pegmatite of the Sakharjok massif (Kola Peninsula, Russia). It forms euhedral prismatic crystals up to 2 mm in length as well as rims around an unidentified mineral phase (silicate of Ca, Y, Zr and Ti). The mineral is triclinic, space group P-1, a 9.6054(10), b 5.6928(6), c 7.3344(7) Å, α 89.903(2), β 101.082(2), γ 100.830(2)°, V 386.32(7) Å3, Z = 1. The calculated density is 3.39 g/cm3. Chemical composition of Sakharjok hainite is different from the previously published data by much higher Y and Nb contents up to 0.72 and 0.20 atoms per formula unit, respectively, by the two- to five-fold depletion in the LREEs and by the strong enrichment of the HREEs. From the single-crystal X-ray diffraction data, there is a significant amount of Y in the M1 site associated with the absence of Zr in it. Nb and Zr are concentrated in the M5 site substituting Ti. Combination of single-crystal X-ray diffraction data and electron microprobe data give the empirical formula (Ca1.04Y0.63REE0.24Mn0.02)∑1.93(Na0.92Ca0.77)∑1.69Ca2.00(Na0.65Ca0.10)∑0.75(Ti0.60Zr0.21Nb0.15Fe0.03)∑0.99((Si4.00Al0.02)∑4.02O14) (F2.61O1.39)∑4.00.

  13. Urinary Schistosomiasis among Children in Murbai and Surbai Communities of Ardo-Kola Local Government Area, Taraba State, Nigeria

    PubMed Central

    Agere, H.; Wama, B. E.; Bingbeng, J. B.; Amuta, E. U.

    2016-01-01

    Background. This cross-sectional study was conducted to determine the prevalence, intensity of infection, and risk factors associated with urinary schistosomiasis among children in Murbai and Surbai communities of Ardo-Kola Local Government Area (LGA), Taraba State, Nigeria. Methods. Urine samples were analysed by the standard filtration technique using 10 ml syringe, Swinnex polypropylene filter holder (13 mm diameter), and polycarbonate membrane filters (12 μm porosity). Sociodemographic data and water contact activities were collated from children using structured questionnaires. Results. A point prevalence of 58.54% was reported out of the urine samples examined. Males were significantly more infected than their female counterparts (71.15% versus 43.66%, χ2 = 89.12, p = 0.000). The age-related prevalence showed 6–10 and 11–15 years significantly infected with 78.70% and 73.02%, respectively (χ2 = 89.12, p = 0.000). Light intensity of infection, 62.51%, was significantly higher than heavy intensity, 37.48%, among the infected children (χ2 = 365.8, p = 0.000). Water contact activities such as fishing (OR = 4.01, CI = 3.04–5.61, p = 0.000), rice farming (OR = 4.01, CI = 2.96–5.36, p = 0.000), and dry season farming (OR = 4.78, CI = 3.68–6.22, p = 0.000) were the risk factors exposing children to infection in the area. Conclusion. There is an urgent need to undertake a large scale deworming control programme using praziquantel in the area. PMID:28096819

  14. Early Paleozoic subduction processes of the Paleo-Asian Ocean: Insights from geochronology and geochemistry of Paleozoic plutons in the Alxa Terrane

    NASA Astrophysics Data System (ADS)

    Liu, Qian; Zhao, Guochun; Sun, Min; Han, Yigui; Eizenhöfer, Paul R.; Hou, Wenzhu; Zhang, Xiaoran; Zhu, Yanlin; Wang, Bo; Liu, Dongxing; Xu, Bing

    2016-10-01

    The Alxa Terrane is situated in a key area between the North China and Tarim cratons. Paleozoic magmatic records in this terrane place important constraints on the subduction processes of the southern Paleo-Asian Ocean. New data of zircon U-Pb ages and whole-rock elemental and isotopic data reveal two groups of intermediate to felsic plutons in the Alxa Terrane. One group consists of diorites and granitoids that were emplaced at ca. 460-440 Ma and characterized by lower Al2O3/TiO2 ratios and higher TiO2 contents, implying high temperature-low pressure crystallization conditions and a shallow source region. The second group is dominated by granitoids aged at ca. 420-407 Ma and displays high Sr and Ba, low Y and high rare earth elements, with very high Sr/Y ratios and mostly positive Eu anomalies. These characteristics imply low temperature-high pressure crystallization conditions and source regions at deep crustal levels where garnet is stable in the residual phase. Both of the two groups are mostly calc-alkaline to high-K calc-alkaline, depleted in Nb, Ta and Ti and enriched in Ba, K and Sr, indicative of an arc affinity most likely related to the southward subduction of the Paleo-Asian Ocean. Zircon εHf(t) and whole-rock εNd(t) values of these magmatic rocks decrease from 458 Ma to 440 Ma and increase from 417 Ma to 407 Ma, whereas whole-rock initial 87Sr/86Sr ratios display an opposite trend. Such an isotopic change suggests a tectonic switch from an advancing to a retreating subduction regime at 407 Ma. Synthesized data from this and previous studies suggest that the 460-400 Ma magmatic arc in the Alxa Terrane represented the western extension of the Paleozoic arc belt on the northern margin of the North China Craton.

  15. Cryogenian alkaline magmatism in the Southern Granulite Terrane, India: Petrology, geochemistry, zircon U-Pb ages and Lu-Hf isotopes

    NASA Astrophysics Data System (ADS)

    Santosh, M.; Yang, Qiong-Yan; Ram Mohan, M.; Tsunogae, T.; Shaji, E.; Satyanarayanan, M.

    2014-11-01

    The Southern Granulite Terrane (SGT) in India preserves the records of the formation and recycling of continental crust from Mesoarchean through Paleoproterozoic to Neoproterozoic and Cambrian, involving multiple subduction-accretion-collision associated with major orogenic cycles. A chain of unmetamorphosed and undeformed alkaline magmatic intrusions occurs along the northern margin of the SGT aligned along paleo-suture zones. Here we investigate two representative plutons from this suite, the Angadimogar syenite (AM) and the Peralimala alkali granite (PM) through field, petrological, geochemical, zircon U-Pb and Lu-Hf studies. Magma mixing and mingling textures and mineral assemblages typical of alkaline rocks are displayed by these plutons. The whole-rock major and trace element data characterize their alkaline nature. In trace element discrimination diagrams, the AM rocks straddle between the VAG (volcanic-arc granites) and WPG (within plate granites) fields with most of the samples confined to the VAG field, whereas the PM rocks are essentially confined to the WPG field. The diversity in some of the geochemical features between the two plutons is interpreted to be the reflection of source heterogeneities. Most zircon grains from the AM and PM plutons display oscillatory zoning typical of magmatic crystallization although some grains, particularly those from the PM pluton, show core-rim structures with dark patchy zoned cores surrounded by irregular thin rims resulting from fluid alteration. The weighted mean 206Pb/238U ages of the magmatic zircons from three samples of the AM syenite are in the range of 781.8 ± 3.8 Ma to 798 ± 3.6 Ma and those from two samples of the PM alkali granite yield ages of 797.5 ± 3.7 Ma and 799 ± 6.2 Ma. A mafic magmatic enclave from the AM pluton shows weighted mean 206Pb/238U age of 795 ± 3.3 Ma. The AM and PM plutons also carry rare xeneocrystic zircons which define upper intercept concordia ages of 3293 ± 13 Ma and 2530

  16. Development of modal layering in granites: a case study from the Carna Pluton, Connemara, Ireland

    NASA Astrophysics Data System (ADS)

    McKenzie, Kirsty; McCarthy, William; Hunt, Emma

    2016-04-01

    Modal layering in igneous rocks uniquely record dynamic processes operating in magma chambers and also host a large proportion of Earth's strategic mineral deposits. This research investigates the origin of biotite modal layering and primary pseudo-sedimentary structures in felsic magmas, by using a combination of Crystal Size Distribution (CSD) analysis and Electron Probe Microanalysis (EPMA) to determine the mechanisms responsible for the development of these structures in the Carna Pluton, Connemara, Ireland. The Carna Pluton is a composite granodiorite intrusion and is one of five plutons comprising the Galway Granite Complex (425 - 380 Ma). Prominent 30 cm thick modal layers are defined by sharp basal contacts to a biotite-rich (20%) granite, which grades upward over 10 cm into biotite-poor, alkali-feldspar megacrystic granite. The layering strikes parallel to, and dips 30-60° N toward the external pluton contact. Pseudo-sedimentary structures (cross-bedding, flame structures, slumping and crystal graded bedding) are observed within these layers. Petrographic observations indicate the layers contain euhedral biotite and fresh undeformed quartz and feldspar. Throughout the pluton, alkali-feldspar phenocrysts define a foliation that is sub-parallel to the strike of biotite modal layers. Together these observations indicate that the intrusion's concentric foliation, biotite layers and associated structures formed in the magmatic state and due to a complex interaction between magma flow and crystallisation processes. Biotite CSDs (>250 crystals per sample) were determined for nine samples across three biotite-rich layers in a single unit. Preliminary CSD results suggest biotite within basal contacts accumulated via fractional crystallisation within an upward-growing crystal pile, likely reflecting the yield strength of the magma as a limiting factor to gravitational settling of biotite. This is supported by the abrupt decrease in mean biotite crystal size across

  17. Thermochronology and Cooling Histories of Intrusive Suites: Implications for Incremental Pluton Assembly

    NASA Astrophysics Data System (ADS)

    Davis, J.; Coleman, D.; Heizler, M.

    2007-12-01

    Debate persists about the timescales and mechanisms of pluton emplacement and batholith formation. An understanding of whether plutons accumulate as large masses of magma or as an incremental series of pulses, in which the active magma body is small relative to the final pluton, is important for understanding the relationship between volcanoes and plutons. If volcanic eruptions < 1000 km3 are the most common size and large ignimbrites are rare, it follows that most plutons should record accumulations of small volumes of melt that were emplaced over long time intervals (millions to tens of millions of years) and therefore preserve predictable, protracted thermal histories. Modeling predicts observable differences in thermal histories of plutons and their aureoles that can be tested through thermochronology. Application of multiple chronometers (zircon and titanite U-Pb TIMS; hornblende, biotite, and K-feldspar 40Ar/39Ar; zircon and titanite (U-Th)/He) combined with K-feldspar multiple diffusion domain (MDD) modeling were used to determine the thermal history and to calibrate thermal models of two eastern California, Sierra Nevada batholith intrusive suites; the dike-like John Muir Intrusive Suite (JMIS) and the laccolithic Mt. Whitney Intrusive Suite (MWIS), and their wall rocks. Preliminary results of (U-Th)/He zircon data from the JMIS and its wall rock (the Tinemaha granodiorite) show a tight cluster of dates ranging from 75.6 to 70.4 Ma. The JMIS is thought to be mesozonal (8 to 11 km) and these data are interpreted as resulting from exhumation and additional 40Ar/39Ar data are required to determine if the thermal history reflects incremental intrusions. In contrast to the JMIS, preliminary (U-Th)/He zircon data from the MWIS and its wall rock (the Bullfrog pluton) show a wide range in dates ranging from 91.4 to 74.6 Ma that are interpreted to reflect reheating events. Amphibole 40Ar/39Ar inverse isochron dates, K- feldspar age spectra, and (U-Th)/He zircon data

  18. Intrusive rocks of the Holden and Lucerne quadrangles, Washington; the relation of depth zones, composition, textures, and emplacement of plutons

    USGS Publications Warehouse

    Cater, Fred W.

    1982-01-01

    The core of the northern Cascade Range in Washington consists of Precambrian and upper Paleozoic metamorphic rocks cut by numerous plutons, ranging in age from early Triassic to Miocene. The older plutons have been eroded to catazonal depths, whereas subvolcanic rocks are exposed in the youngest plutons. The Holden and Lucerne quadrangles span a -sizeable and representative part of this core. The oldest of the formations mapped in these quadrangles is the Swakane Biotite Gneiss, which was shown on the quadrangle maps as Cretaceous and older in age. The Swakane has yielded a middle Paleozoic metamorphic age, and also contains evidence of zircon inherited from some parent material more than 1,650 m.y. old. In this report, the Swakane is assigned an early Paleozoic or older age. It consists mostly of biotite gneiss, but interlayered with it are scattered layers and lenses of hornblende schist and gneiss, clinozoisite-epidote gneiss, and quartzite. Thickness of the Swakane is many thousands of meters, and the base is not exposed. The biotite gneiss is probably derived from a pile of siliceous volcanic rocks containing scattered sedimentary beds and basalt flows. Overlying the Swakane is a thick sequence of eugeosynclinal upper Paleozoic rocks metamorphosed to amphibolite grade. The sequence includes quartzite and thin layers of marble, hornblende schist and gneiss, graphitic schist, and smaller amounts of schist and gneiss of widely varying compositions. The layers have been tightly and complexly folded, and, in places, probably had been thrust over the overlying Swakane prior to metamorphism. Youngest of the supracrustal rocks in the area are shale, arkosic sandstone, and conglomerate of the Paleocene Swauk Formation. These rocks are preserved in the Chiwaukum graben, a major structural element of the region. Of uncertain age, but possibly as old as any of the intrusive rocks in the area, are small masses of ultramafic rocks, now almost completely altered to

  19. Geochemistry and petrogenesis of late Ediacaran (605-580 Ma) post-collisional alkaline rocks from the Katherina ring complex, south Sinai, Egypt

    NASA Astrophysics Data System (ADS)

    Azer, M. K.; Obeid, M. A.; Ren, M.

    2014-10-01

    The Katherina ring complex (KRC) in the central part of south Sinai, Egypt, is a typical ring complex of late Neoproterozoic age (605-580 Ma). It was developed during the final tectono-magmatic stage of the north Arabian-Nubian Shield (ANS) during evolution of the Pan-African crust. The KRC includes Katherina volcanics, subvolcanic bodies, ring dykes and Katherina granitic pluton. The Katherina volcanics represent the earliest stage of the KRC, which was subsequently followed by emplacement of the subvolcanic bodies and ring dykes. The Katherina granitic pluton depicts as the latest evolution stage of the KRC that intruded all the early formed rock units in the concerned area. The Katherina volcanics are essentially composed of rhyolites, ignimbrite, volcanic breccia and tuffs. Mineralogically, the peralkaline rhyolites contain sodic amphiboles and aegirine. The rhyolite whole rock chemistry has acmite-normative character. The subvolcanic bodies of the KRC are represented by peralkaline microgranite and porphyritic quartz syenite. The ring dykes are semicircular in shape and consist mainly of quartz syenite, quartz trachyte and trachybasalt rock types. The Katherina subvolcanic rocks, volcanic rocks as well as the ring dykes are alkaline or/and peralkaline in nature. The alkaline granitic pluton forms the inner core of the KRC, including the high mountainous areas of G. Abbas Pasha, G. Bab, G. Katherina and G. Musa. These mountains are made up of alkaline syenogranite and alkali feldspar granite. The mantle signature recorded in the KRC indicates a juvenile ANS crust partial melting process for the generation of this system. The evolution of the KRC rocks is mainly dominated by crystal fractionation and crustal contamination. Mineral geothermometry points to the high temperature character of the KRC, up to 700-1100 °C.

  20. Multiple intrusive events in the formation of granite plutons: Evidence from the Lee Vining Diorite, eastern California

    SciTech Connect

    McCarthy, T.C.; Furman, T. . Dept. of Environmental Sciences); Reid, J.B. Jr. . School of Natural Sciences)

    1993-03-01

    The Cretaceous Lee Vining Diorite (eastern Sierra Nevada) preserves important field, petrographic and geochemical evidence for complex intrusive events in a mesozonal magma body. The pluton comprises primarily light grey unfoliated quartz diorite, with color index varying between 10--50. A 1,400 m transect across the pluton yielded samples of (1) mafic diorite from a 300 m thick sill, (2) disaggregated basaltic dikes, (3) rounded mafic inclusions and (4) rounded hornblende-cumulate inclusions in addition to (5) quartz diorite of variable texture and color index. Internal intrusive contacts are observed in several places; the upper contact of the sill is indistinct locally, suggesting a low thermal contrast with host quartz diorite at the time of intrusion. Textural analysis of plagioclase crystals form throughout the pluton indicates a history of pervasive magma mixing. In each thin section, 20--90% of the plagioclase crystals are pitted or corroded, and up to 50% of these crystals are also completely zoned. Disequilibrium plagioclase crystals are not preferentially associated with mafic inclusion, but are distributed randomly within the pluton. Major and trace element analyses of over 40 samples taken along the transect show variations that cannot be explained through simple magma mixing or through progressive crystallization of a single magma body. The pluton is not zoned geochemically, but rather comprises small regions (< 200 m across) of uniform composition that are juxtaposed randomly. Chemical variations across the pluton likely result from both missing of small magma batches and fractional crystallization of mixed magmas. This interpretation is consistent with field and textural requirements for multiple intrusive episodes in the formation of the diorite pluton.

  1. The Middle Fork Plutonic Complex: A plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range

    SciTech Connect

    Solie, D.N.

    1988-01-01

    The 57 m.y. Middle Fork Plutonic Complex (MFPC) intrudes Paleozoic metasedimentary rocks south of the Farewell Fault zone in the north-central Alaska Range. Though spatially related to the late Cretaceous - Early Tertiary subduction-related Alaska Range batholith, MFPC is more characteristic of an extensional or anorogenic setting. A swarm of basalt, hawaiite and rhyolite dikes east of the complex intruded, and was intruded by, the plutonic rocks. Approximately 30% of the exposed rock in the 125 km[sup 2] complex is hedenbergite - fayalite syenite, [approx equal]20% is peralkalin arfvedsonite-biotite alkali-feldspar granite (AF granite), and [le]20% is pyroxene-olivine-biotite gabbro. The rest is a mixed unit including clinopyroxene-biotite-amphibole diorite, and hornblende-biotite granite (HB granite). K-Ar and Rb-Sr radiometric dating of rock types shows that they are coeval. Their close spatial and temporal relationships led to complex magmatic interactions. Calculated initial [sup 87]Sr/[sup 86]Sr for gabbro and diorite group is around 0.705 to 0.706. HB granites are heterogeneous, but fall mostly around 0.707 to 0.708. Hypersolvus syenites and AF granites form an isochron with initial [sup 87]Sr/[sup 86]Sr of 0.70965. These groupings suggest that at least three different magmas formed the MFPC; scatter of isotopic data reflects mutual contamination and assimilation. Consanguinous hypersolvus syenite and AF granite mineralogy appears to be controlled by fluorine in the magma chamber. Eruptive stratigraphy, as predicted by intrusive history of MFPC, compares favorably with volcanic stratigraphies of peralkaline volcanic systems worldwide, and MFPC may be modelled as the root zone of a peralkaline volcanic system.

  2. Fabric and microstructural analysis of the Loch Borralan pluton, Northwest Highlands, Scotland

    NASA Astrophysics Data System (ADS)

    Calhoun, Justin

    The Loch Borralan pluton was emplaced within the Assynt Region of the Moine Thrust zone during the Scandian event (ca. 435-425 Ma) of the Caledonian Orogeny (478-425 Ma). It consists of two major magma suites, the syenitic early suite (431.1 +/- 1.2 Ma), and the quartz syenitic later suite (429.2 +/- 0.5 Ma). The region is characterized by a series of in-sequence thrust faults that strike NE-SW and dip approximately 20° to the SE, including (from lower to upper): the Sole Thrust, the Borralan Thrust (hypothesized, but not exposed), the Ben More Thrust, and the Moine Thrust. A series of imbricate thrusts between the Sole and Borralan Thrusts juxtapose repeated Cambrian and Ordovician strata. The Loch Borralan pluton intruded between the Sole and Ben More thrust faults, and may be bounded below by a hypothesized Borralan Thrust fault. Based on the overlap in pluton crystallization age and orogenic activity, the combination of macroscopic field lineation and foliation measurements, anisotropy of magnetic susceptibility (AMS) lineation and foliations measurements, mineral shape preferred orientation (SPO) analysis, and petrographic deformation microstructure analysis will be used to determine if the pluton expresses deformation features and fabrics corresponding to thrust fault tectonics. The dominant magnetic mineralogy as determined by thermomagnetic data and hysteresis plots was determined to be magnetite and titanomagnetite. Some paramagnetic components were seen in the early suite, and can be attributed to biotite. Both minerals contributed to the AMS signal that was used to interpret pluton fabrics. The pluton contains S>L (foliation stronger than lineation) fabrics throughout, defined by alignment of alkali feldspar grains. The foliation strike of both the early and late suites are subparallel to the thrust faults, providing evidence that the fabrics are related to deformation. The early suite is only well exposed in the southeast at the top of the Borralan

  3. Alkaline Phosphatase in Normal Infants

    PubMed Central

    Stephen, Joan M. L.; Stephenson, Pearl

    1971-01-01

    Alkaline phosphatase was measured in plasma from children receiving vitamin D supplements in day nurseries in the London area, and from children exposed to sunlight in the West Indies. The distribution of values showed that there was no precise upper limit which could be used in the diagnosis of subclinical vitamin D deficiency. PMID:5576029

  4. Mantle metasomatism and alkaline magmatism

    SciTech Connect

    Morris, E.M.; Pasteris, J.D.

    1987-01-01

    The 24 papers in this volume were presented at the Symposium on Alkalic Rocks and Kimberlites, held at the Geological Society of America South-Central Section meeting, April 15-16, 1985, in Fayetteville, Arkansas. This two-day symposium included a total of 55 papers dealing with mantle metasomatism and the origin of alkaline magmas, kimberlites and related rocks, alkalic rocks in oceanic settings, and alkalic rocks in continental settings. Papers presented at this symposium heightened the awareness that alkaline magmatism may occur in virtually all tectonic and petrologic settings. Two papers deal specifically with data from California sites. These research papers on aspects of alkaline rock petrology contribute to a better insight into the complex diversity of alkalic systems, the mantle processes which precede and accompany alkaline magmatism, and kimberlitic and oceanic systems. Abstracts of all papers presented at the symposium and not published in full in the volume are included in an appendix to show the broad scope of data presented at the meeting.

  5. Zinc electrode in alkaline electrolyte

    SciTech Connect

    McBreen, J.

    1995-12-31

    The zinc electrode in alkaline electrolyte is unusual in that supersaturated zincate solutions can form during discharge and spongy or mossy zinc deposits can form on charge at low overvoltages. The effect of additives on regular pasted ZnO electrodes and calcium zincate electrodes is discussed. The paper also reports on in situ x-ray absorption (XAS) results on mossy zinc deposits.

  6. Magma Reservoirs from the Perspective of Supervolcanoes and Granitic Plutons: "Big Red Blobs" and "Balloons and Soda Straws" are Real

    NASA Astrophysics Data System (ADS)

    Christiansen, E. H.

    2016-12-01

    Simple models describing silicic magma reservoirs and their connections with volcanic rocks have been denigrated as "big red blobs" and "balloons-and-soda straws." Although these models are certainly generalized to convey complex relations, there are multiple reasons to accept the existence of large magma chambers and direct connections between volcanoes and plutonic rocks. These include:-Geophysical evidence (seismic, magnetotelluric, and geodetic) for the existence of large bodies of magma in the crust today. Magma is a mixture of liquids, solids, and fluids. It does not have to be melt rich, nor does it need to be mobile and eruptible; it just has to have melt present. -Eruptions of large volumes (>1,000 km3) of dacitic to rhyolitic magma and large collapse calderas (30-50 km across). -The thermal lifetimes of large bodies are extended by high recharge rates. Individual bodies of magma may exist for tens to hundreds of thousands of years.-Geochronological evidence that pluton lifetimes are similar to those of volcanic fields.-Evidence for incremental emplacement of a pluton is not evidence against the former existence of a large magma reservoir, but the natural consequence of ongoing replenishment and crystallization after eruptions cease. Thus, what might have been a large liquid-dominated system at the time of eruption of a large ignimbrite, is subsequently intruded by new batches of magma as it crystallizes and closes down. This destroys the evidence for a large red blob and creates a composite pluton. -Direct and indirect evidence connect plutons to large eruptions. This is shown by field relations, geochronology, as well as chemical, mineralogical, and isotopic similarities of volcanic and plutonic rocks. -Volcanic and plutonic differentiation patterns are very similar, but differ in some ways because cumulates are preserved in the plutonic record and because intrusions continue to differentiate (liquids separate from solids) until the last bit of liquid is

  7. Origin of reverse compositional and textural zoning in granite plutons by localized thermal overturn of stratified magma chambers

    NASA Astrophysics Data System (ADS)

    Trubač, Jakub; Janoušek, Vojtěch; Žák, Jiří; Somr, Michael; Kabele, Petr; Švancara, Jan; Gerdes, Axel; Žáčková, Eliška

    2017-04-01

    This study integrates gravimetry and thermal modelling with petrology, U-Th-Pb monazite and zircon geochronology and whole-rock geochemistry of the early Carboniferous Říčany Pluton, Bohemian Massif, in order to discuss the origin of compositional and textural zoning in granitic plutons and complex histories of horizontally stratified, multiply replenished magma chambers. The pluton consists of two coeval, nested biotite (-muscovite) granite facies: outer one, strongly porphyritic (SPm) and inner one, weakly porphyritic (WPc). Their contact is concealed but is likely gradational over several hundreds of meters. The two facies have nearly identical modal composition, are subaluminous to slightly peraluminous and geochemically evolved. Mafic microgranular enclaves, commonly associated with K-feldspar phenocryst patches, are abundant in the pluton center and indicate a repeated basic magma injection and its multistage interactions with the granitic magma and nearly solidified cumulates. Furthermore, the gravimetric data show that the nested pluton is only a small outcrop of a large anvil-like body reaching the depth of at least 14 km, where the pluton root is expected. Trace-element compositions reveal that the pluton is doubly reversely zoned. On the pluton scale, the outer SRG is geochemically more evolved than the inner WPc. On the scale of individual units, outward whole-rock geochemical variations within each facies (SPm, WPc) are compatible with fractional crystallization dominated by feldspars. The proposed genetic model invokes vertical overturn of a deeper, horizontally stratified anvil-shaped magma chamber. The overturn was driven by reactivation of resident felsic magma from the K-feldspar-rich crystal mush. The energy for the melt remobilization, extraction and subsequent ascent is thought to be provided by a long-lived thermal anomaly above the pluton feeding zone, enhanced by the multiple injections of hot basic magmas. In general, it is concluded

  8. Plutonism in the central part of the Sierra Nevada Batholith, California

    USGS Publications Warehouse

    Bateman, Paul C.

    1992-01-01

    The Sierra Nevada batholith comprises the plutonic rocks of Mesozoic age that underlie most of the Sierra Nevada, a magnificent mountain range that originated in the Cenozoic by the westward tilting of a huge block of the Earth's crust. Scattered intrusions west of the batholith in the western metamorphic belt of the Sierra Nevada and east of the Sierra Nevada in the Benton Range and the White and Inyo Mountains are satellitic to but not strictly parts of the Sierra Nevada batholith. Nevertheless, all the plutonic rocks are related in origin. The batholith lies along the west edge of the Paleozoic North American craton, and Paleozoic and early Mesozoic oceanic crust underlies its western margin. It was emplaced in strongly deformed but weakly metamorphosed strata ranging in age from Proterozoic to Cretaceous. Sedimentary rocks of Proterozoic and Paleozoic age crop out east of the batholith in the White and Inyo Mountains, and metamorphosed sedimentary and volcanic rocks of Paleozoic and Mesozoic age crop out west of the batholith in the western metamorphic belt. A few large and many small, generally elongate remnants of metamorphic rocks lie within the batholith. Sparse fossils from metasedimentary rocks and isotopic ages for metavolcanic rocks indicate that the metamorphic rocks in the remnants range in age from Early Cambrian to Early Cretaceous. Within the map area (the Mariposa 1 0 by 2 0 quadrangle), the bedding, cleavage, and axial surfaces of folds generally trend about N. 35 0 W., parallel to the long axis of the Sierra Nevada. The country rocks comprise strongly deformed but generally coherent sequences; however, some units in the western metamorphic belt may partly consist of melanges. Most sequences are in contact with other sequences, at least for short distances, but some sequences within the batholith are bounded on one or more sides by plutonic rocks. Proterozoic and Paleozoic sedimentary strata east of the Sierra Nevada and Paleozoic strata in

  9. Asymmetric textural and structural patterns of a granitic body emplaced at shallow levels: The La Chinchilla pluton, northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Macchioli Grande, M.; Alasino, P. H.; Rocher, S.; Larrovere, M. A.; Dahlquist, J. A.

    2015-12-01

    New mapping and a detailed structural study of the La Chinchilla stock, Sierra de Velasco, NW Argentina, suggest an asymmetrical shape of the pluton and provide strong evidence for its shallow emplacement depth. The pluton is a Lower Carboniferous monzogranite composed of K-feldspar, quartz, plagioclase and biotite. It exhibits an internal asymmetric textural zoning, defined by porphyritic granite in the southeastern region to equigranular granite in the northwestern region. The presence of subhorizontal dikes in the northwestern area, where the contacts dip shallowly, and subvertical dikes intruding the host rock nearby steep-dipping intrusive contacts in the southeastern region are compatible with an overall asymmetrical shape and internal structure of this pluton. Considering published crystallization ages, a dominant strain field occurring at around 12 Ma is inferred based on magmatic fabrics in the pluton and its host rock (the Huaco pluton), with a principal shortening direction oriented SW-NE, consistent with the general NW-SE strike of the body. Field evidence supports brittle fracturing and block displacement as the dominant emplacement mechanism, suggesting that magmatic stoping dominated during the late stage of the evolution of the magma chamber.

  10. River Valley pluton, Ontario: A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

    SciTech Connect

    Ashwal, L.D. ); Wooden, J.L. )

    1989-03-01

    The River Valley pluton is a ca. 100 km{sup 2} body of anorthositic and gabbroic rocks located about 50 km northeast of Sudbury, Ontario. The pluton is situated entirely within the Grenville Province, but its western margin is a series of imbricate thrust faults associated with the Grenville Front Tectonic Zone. It is dominated by coarse leuconorite and leucogabbro, with lesser anorthosite, gabbro, and rare ultramafics. Igneous textured rocks are abundant and consist of plagioclase (An{sub 60-70}) charged with Fe-Ti oxide inclusions, low Ca pyroxene (orthopyroxene and/or inverted pigeonite) and augite. The most unfractionated rocks are minor olivine gabbros with Fo{sub 70-80}. A variety of deformed and recrystallized equivalents of the igneous-textured rocks is also present, and these are composed largely of calcic plagioclase and hornblende. An Sm-Nd isochron from 3 igneous-textured leucogabbros and an augite mineral separate gives 2,377 {plus minus} 68 Ma, implying slight disturbance of the Sm-Nd whole-rock-mineral system during later metamorphism. The Rb-Sr system has been substantially disturbed, giving an age of 2,185 {plus minus} 105 Ma, which is similar to internal Pb-Pb isochron ages of 2,165 {plus minus} 130 Ma and 2,100 {plus minus} 35 Ma for two igneous-textured rocks. Initial isotopic ratios for the River Valley pluton correspond to single-stage model parameters of {mu} = 8.06, {epsilon}{sub Nd} = O to {minus}3, and I{sub Sr} = 0.7015 to 0.7021. Collectively, these suggest either an enriched mantle source or crustal contamination of a mantle-derived magma. The crustal component involved must have been older and more radiogenic than the majority of rocks exposed at the surface in the nearby Superior Province.

  11. Volcanic Perspective on Plutonism based on Patterns in Evolution in Long-Lived Continental Volcanic Systems

    NASA Astrophysics Data System (ADS)

    Grunder, A. L.; Harris, R. N.; Walker, B. A.; Giles, D.; Klemetti, E. W.

    2008-12-01

    Volcanic rocks represent a biased view of magmatism, but provide critical quenched samples and temporal constraints of magmatic evolution obscured in the plutonic record. We here draw on the records from the Aucanquilcha Volcanic Cluster (AVC; 10 to 0 Ma) in northern Chile and from the mid-Tertiary volcanic field in east-central Nevada (ECNVF; ~40-32 Ma) to consider how evolutionary patterns of intermediate composition volcanic systems bear on the magmatic reworking of the continental crust by plutons and batholiths. Despite disparate tectonic setting (subduction vs extension) and volumes (70 km crust for the ~300 km 3 AVC versus and ~40 km crust for the ~3000 km 3 ECNVF) both volcanic systems share a history of early compositionally diverse volcanism, followed by a stage of more centralized and voluminous dacitic volcanism, which in turn is followed by waning of volcanism. The compositional change and the rapid increase in magma output rate after about half the lifetime of the system is a characteristic pattern of long- lived continental volcanic systems based on a compilation of volume-composition data. The middle, voluminous stage corresponds to the hottest upper crustal conditions, deduced from Al-in-amphibole geothermobarometry and Ti-in-zircon thermometry of the AVC. The middle stage rocks also have textures indicating hybridization of mixed magmas. Simple thermal models of heat input via intraplating readily allow for generation of partially molten crust above the sill, but they do not emulate the rapid increase of magma after some incubation time. We propose that there is a feedback in which a critical thickness of partially molten crust, consisting in part of magmatic precursors, can be readily convectively stirred and mixed with magma of the underplating sill, rapidly creating a large, hybrid and relatively hot body of magma. Stirring facilitates separation of a liquid-enriched extract. The volume of liquid extracted may be small relative to residual

  12. Mineralogy, geochemistry, and evolution of the Mivehrood skarn and the associated pluton, northwest Iran

    NASA Astrophysics Data System (ADS)

    Alirezaei, Saeed; Einali, Morteza; Jones, Peter; Hassanpour, Shohreh; Arjmandzadeh, Reza

    2016-04-01

    An Upper Miocene (9.12 ± 0.19 Ma; biotite 40Ar/39Ar) shallow pluton and numerous dykes and sills of felsic-intermediate compositions intruded the Upper Cretaceous, flysch-type sediments in the Mivehrood area, northwest Iran. The intrusions caused extensive thermal metamorphism and metasomatism, leading to the formation of hornfels and skarn. A massive skarn, 1-10 m thick, immediate to the intrusive contact, is bordered by a banded skarn, 100-400 m thick, that grades outward into hornfels and original sediments. The Mivehrood pluton is characterized by steep REE pattern, high Al2O3 (14.64-16.4 wt%) and Sr (380-786 ppm), and low MgO (1.3-3.4 wt%), Y (4.8-10.7 ppm), and Yb (0.35-0.95 ppm), characteristics typical of high-silica adakites. Skarn formation started with thermal metamorphism, followed by anhydrous prograde and hydrous retrograde stages. Prograde and retrograde mineral assemblages are developed in both skarns, represented by garnet-clinopyroxene-wollastonite and epidote-actinolite-scapolite-chlorite, respectively. Granditic F-bearing garnet dominates clinopyroxene in both skarns. The banded skarn contains minor scapolite of marialite composition. The calc-silicate mineral assemblages and the mineral chemistry allow the Mivehrood skarn to be classified as a calcic, oxidized skarn. Mass balance assessments suggest that Fe, Si, and S were significantly enriched, and Na, LILEs, and LREEs were strongly depleted, in the massive skarn. In the banded skarn, Na, K, Si, and S were enriched. Significant dehydration and carbon degassing occurred in both skarns. Stockworks, veins, and replacement bodies of pyrite ± chalcopyrite locally occur in the pluton and the dykes and in the skarns. The δ34SCDT values for the sulfides fall in a narrow range around 0.0 ‰, suggesting a magmatic source for sulfur and possibly the hydrothermal water and solutes involved in the skarn formation.

  13. Timing of Proterozoic deformation, plutonism, and metamorphism in the Los Pinos Mountains, Central New Mexico

    SciTech Connect

    Shastri, L.L. . Dept. of Geology); Bowring, S.A. )

    1992-01-01

    Geochronologic, structural, and metamorphic studies within the Los Pinos Mountains (LPM), central NM provide new insights into the Proterozoic geologic history of this area. The LPM consist of a NE-trending, NW-dipping sequence of complexly deformed amphibolites and felsic schists. These have been intruded by a pervasively deformed granitic pluton. Two predominant deformational fabrics exist in the LPM. S1 is an early northwest-trending foliation, commonly parallel to compositional layering, which is folded about S2. S2 is axial planar foliation to tight to isoclinal folds and is the regional NE-trending fabric. Other fabrics and complex fold interference patterns may be related to localized strain partitioning around granitic bodies. A network of granitic dikes associated with the pluton crosscuts S2 but contains a weak foliation parallel to S2, suggesting synkinematic intrusion of the dikes. Regional metamorphism in the LPM took place at upper greenschist to lower amphibolite facies. Electron microprobe traverses of garnets show compositional variation indicative of growth zoning. No abrupt changes in composition representative of multiple metamorphic events are observed. Garnet-biotite geothermometry yields average rim temperatures of 454 [+-] 50 C. U-Pb geochronology of zircons from amphibolite, granite, and a granite dike indicates essentially the same age for all three units (1.66 Ga). The amphibolite contains abundant zircons which have complex morphologies typical of metamorphic growth; however, an igneous origin cannot yet be precluded. Spheres from the same amphibolite yield a near concordant age of 1.62 Ga. Thus, deformation, plutonism, and possibly the peak of metamorphism, were coeval at ca. 1.66 Ga, with metamorphism cooling through the blocking temperature of sphene at 1.62 Ga. The LPM are similar to other mountain ranges in south-central New Mexico where 1.66 Ga ages have been reported.

  14. Ti in zircon from the Boggy Plain zoned pluton: implications for zircon petrology and Hadean tectonics

    NASA Astrophysics Data System (ADS)

    Ickert, R. B.; Williams, I. S.; Wyborn, D.

    2011-08-01

    The understanding of zircon crystallization, and of the Ti-in-zircon thermometer, has been enhanced by Ti concentration measurements of zircon from a small, concentrically zoned pluton in south-eastern Australia, the Boggy Plain zoned pluton (BPZP). Zircon crystals from rocks ranging in composition from gabbro to aplite were analysed for U-Th-Pb dating and Ti concentrations by an ion microprobe. Geochronological data yield a 206Pb/238U age of 417.2 ± 2.0 Ma (95% confidence) and demonstrate the presence of older inherited or xenocrystic zircon. Titanium measurements ( n = 158) yield a mean Ti concentration of 11.7 ± 6.1 ppm (2SD) which corresponds to a mean crystallization temperature of 790°C for an α-TiO2 = 0.74 (estimated using mineral equilibria), or 760°C for an α-TiO2 = 1.0. Apparent zircon crystallization temperatures are similar in all intrusive phases, although the gabbro yields slightly higher values, indicating that crystallization occurred at the same temperature in all rock types. This finding is consistent with previous work on the BPZP, which indicates that liquid-crystal sorting (crystal fractionation) was the dominant control on chemical differentiation, and that late, differentiated liquids were similar in composition for all rock types. A simple forward model approximately predicts the range of crystallization temperatures, but not the shape of the distributions, due to sampling biases and complexities in the cooling and crystallization history of the pluton. The distribution of Ti concentrations has a mode at a higher Ti (higher temperature) than the sample set of Hadean detrital zircon. This is consistent with the hypothesis that the skew to low-T in the Hadean dataset is due to the presence of zircon that crystallized from wet anatectic melts.

  15. Miocene zircon crystals in dacite from Ilopango Caldera, El Salvador: Evidence for recycling of plutonic rocks

    NASA Astrophysics Data System (ADS)

    Garrison, J. M.; Korm, S.; Schmitt, A. K.; Economos, R. C.

    2011-12-01

    Ilopango Caldera is located in El Salvador and is part of the Central American Volcanic Arc (CAVA) that extends from southern Mexico to Panama. The volcanic arc is situated on crust that ranges in age from 150-28 Ma and is covered with Miocene-Recent volcanic ash and pyroclastic flow deposits. Several large eruptions are associated with Ilopango Caldera, the most recent are from the Tierra Blanca Joven (TBJ) eruption, which produced massive pyroclastic flows 1600 years BP. Older eruptions from Ilopango Caldera are referred to as the Tierra Blanca (TB) deposits, and the TB2 ignimbrite has been dated at 12,000 years. The objective of this research is to use the ages of zircon crystals from the TBJ and TB2 eruptions to establish and compare storage times for these magma reservoirs. We used a CAMECA ims 1270 at UCLA's NSF National Ion Microprobe Facility in order to obtain U-Pb and U-Th ages for individual zircon crystals from each eruption. Depth profiling and U-Pb analyses were performed on both of the zircon crystals using established analysis techniques. The data show that zircon from both eruptions have 15 Ma old cores with thin rims (few μm) that are consistent with the young eruption ages. In both cases, however the transition from core to rim composition is abrupt and does not record continuous crystallization of the zircon crystals. We conclude that the presence of the old cores is consistent with assimilation of middle Miocene plutonic rock by juvenile magma during Quaternary activity of Ilopango Caldera. The most likely source of 15 Ma old zircon are the plutons associated with middle Miocene explosive volcanism in Central America. Ash deposits recovered from the sea floor (via ODP studies) record extensive explosive volcanism from 13-15 Ma that can be traced to ignimbrite deposits of the Chalatenango Formation in south-central Guatemala and El Salvador. We conclude that 1) the zircon crystals record only brief pre-eruptive crystallization histories for the

  16. Ductile strain rate recorded in the Symvolon syn-extensional plutonic body (Rhodope core complex, Greece)

    NASA Astrophysics Data System (ADS)

    Cirrincione, Rosolino; Fazio, Eugenio; Ortolano, Gaetano; Fiannacca, Patrizia; Kern, Hartmut; Mengel, Kurt; Pezzino, Antonino; Punturo, Rosalda

    2016-04-01

    The present contribution deals with quantitative microstructural analysis, which was performed on granodiorites of the syn-tectonic Symvolon pluton (Punturo et al., 2014) at the south-western boundary of the Rhodope Core Complex (Greece). Our purpose is the quantification of ductile strain rate achieved across the pluton, by considering its cooling gradient from the centre to the periphery, using the combination of a paleopiezometer (Shimizu, 2008) and a quartz flow law (Hirth et al., 2001). Obtained results, associated with a detailed cooling history (Dinter et al., 1995), allowed us to reconstruct the joined cooling and strain gradient evolution of the pluton from its emplacement during early Miocene (ca. 700°C at 22 Ma) to its following cooling stage (ca. 500-300°C at 15 Ma). Shearing temperature values were constrained by means of a thermodynamic approach based on the recognition of syn-shear assemblages at incremental strain; to this aim, statistical handling of mineral chemistry X-Ray maps was carried out on microdomains detected at the tails of porphyroclasts. Results indicate that the strain/cooling gradients evolve "arm in arm" across the pluton, as also testified by the progressive development of mylonitic fabric over the magmatic microstructures approaching the host rock. References • Dinter, D. A., Macfarlane, A., Hames, W., Isachsen, C., Bowring, S., and Royden, L. (1995). U-Pb and 40Ar/39Ar geochronology of the Symvolon granodiorite: Implications for the thermal and structural evolution of the Rhodope metamorphic core complex, northeastern Greece. Tectonics, 14 (4), 886-908. • Shimizu, I. (2008). Theories and applicability of grain size piezometers: The role of dynamic recrystallization mechanisms. Journal of Structural Geology, 30 (7), 899-917. • Hirth, G., Teyssier, C., and Dunlap, J. W. (2001). An evaluation of quartzite flow laws based on comparisons between experimentally and naturally deformed rocks. International Journal of Earth

  17. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, D.B.; Lao, G.

    1998-01-06

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium. 3 figs.

  18. Nucleotide sequences encoding a thermostable alkaline protease

    DOEpatents

    Wilson, David B.; Lao, Guifang

    1998-01-01

    Nucleotide sequences, derived from a thermophilic actinomycete microorganism, which encode a thermostable alkaline protease are disclosed. Also disclosed are variants of the nucleotide sequences which encode a polypeptide having thermostable alkaline proteolytic activity. Recombinant thermostable alkaline protease or recombinant polypeptide may be obtained by culturing in a medium a host cell genetically engineered to contain and express a nucleotide sequence according to the present invention, and recovering the recombinant thermostable alkaline protease or recombinant polypeptide from the culture medium.

  19. Soil organic carbon sequestration as affected by afforestation: the Darab Kola forest (north of Iran) case study.

    PubMed

    Kooch, Yahya; Hosseini, Seyed Mohsen; Zaccone, Claudio; Jalilvand, Hamid; Hojjati, Seyed Mohammad

    2012-09-01

    Following the ratification of the Kyoto Protocol, afforestation of formerly arable lands and/or degraded areas has been acknowledged as a land-use change contributing to the mitigation of increasing atmospheric CO(2) concentration in the atmosphere. In the present work, we study the soil organic carbon sequestration (SOCS) in 21 year old stands of maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C.A. Mey.), and red pine (Pinus brutia Ten.) in the Darab Kola region, north of Iran. Soil samples were collected at four different depths (0-10, 10-20, 20-30, and 30-40 cm), and characterized with respect to bulk density, water content, electrical conductivity, pH, texture, lime content, total organic C, total N, and earthworm density and biomass. Data showed that afforested stands significantly affected soil characteristics, also raising SOCS phenomena, with values of 163.3, 120.6, and 102.1 Mg C ha(-1) for red pine, oak and maple stands, respectively, vs. 83.0 Mg C ha(-1) for the control region. Even if the dynamics of organic matter (OM) in soil is very complex and affected by several pedo-climatic factors, a stepwise regression method indicates that SOCS values in the studied area could be predicted using the following parameters, i.e., sand, clay, lime, and total N contents, and C/N ratio. In particular, although the chemical and physical stabilization capacity of organic C by soil is believed to be mainly governed by clay content, regression analysis showed a positive correlation between SOCS and sand (R = 0.86(**)), whereas a negative correlation with clay (R = -0.77(**)) was observed, thus suggesting that most of this organic C occurs as particulate OM instead of mineral-associated OM. Although the proposed models do not take into account possible changes due to natural and anthropogenic processes, they represent a simple way that could be used to evaluate and/or monitor the potential of each forest plantation in immobilizing organic C in soil (thus

  20. Source variation for Mesozoic granitoid plutons in the White-Inyo Range, California, and implications for changes in the lithospheric structure

    NASA Astrophysics Data System (ADS)

    Gammel, E.; Nabelek, P. I.; Phillips, E. H. W.; Scott, S. R.; Sims, K. W. W.

    2015-12-01

    The White-Inyo Range (WIR) of eastern California lies to the east of Owen's Valley and the Sierra Nevada batholith (SNB). Over twenty recognized Mesozoic, granitic to gabbroic plutons intruded into Precambrian and Cambrian sedimentary units that were previously metamorphosed to the greenschist facies. These plutons represent intrusive equivalents of volcanics erupted during two magmatic events at ca. 180-167 Ma and 102-86 Ma (Coleman et al, 2003). The motivation of this study is to understand changes in magma sources over this time period. We propose there is a time-transgressive change in source material in the WIR. Preliminary trace element data suggest that Jurassic plutons were sourced from deep crustal material, whereas later Cretaceous plutons may have had a shallower origin. This is supported by high Sr/Y ratios in the Jurassic plutons (up to 300) and relatively lower ratios in Cretaceous plutons (down to 14). Chiaradia (2015) suggests elevated Sr/Y ratios are directly linked to increasing crustal thickness, therefore the WIR plutons may record the period of crustal thinning in this region or maturation of the crust that allowed shallower melting in the Cretaceous. The highest values also suggest possible adakitic source material. REE patterns suggest that the youngest plutons (e.g. Sage Hen Flat) are more similar to samples collected from the eastern Sierra Nevada batholith than older plutons with higher La/Yb ratios. Relatively flat patterns REE patterns of Tertiary basalts and a late diabase dike in the WIR are also similar to SNB samples. Another goal of this study is to determine the degree of mixing as a function of time during the emplacement of plutons in the range. Field and petrographic analyses suggest that older plutons represent more mafic materials and younger plutons are more granitic with mafic enclaves. We propose either (1) older plutons represent initial lower lithosphere melting, and with time, there is an increase of incorporation of

  1. Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, a new mineral from nepheline syenite pegmatite in the Sakharjok massif, Kola Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Lyalina, L. M.; Zolotarev, A. A.; Selivanova, E. A.; Savchenko, Ye. E.; Krivovichev, S. V.; Mikhailova, Yu. A.; Kadyrova, G. I.; Zozulya, D. R.

    2016-12-01

    Batievaite-(Y), Y2Ca2Ti[Si2O7]2(OH)2(H2O)4, is a new mineral found in nepheline syenite pegmatite in the Sakharjok alkaline massif, Western Keivy, Kola Peninsula, Russia. The pegmatite mainly consists of nepheline, albite, alkali pyroxenes, amphiboles, biotite and zeolites. Batievaite-(Y) is a late-pegmatitic or hydrothermal mineral associated with meliphanite, fluorite, calcite, zircon, britholite-group minerals, leucophanite, gadolinite-subgroup minerals, titanite, smectites, pyrochlore-group minerals, zirkelite, cerianite-(Ce), rutile, behoite, ilmenite, apatite-group minerals, mimetite, molybdenite, and nickeline. Batievaite-(Y) is pale-cream coloured with white streak and dull, greasy or pearly luster. Its Mohs hardness is 5-5.5. No cleavage or parting was observed. The measured density is 3.45(5) g/cm3. Batievaite-(Y) is optically biaxial positive, α 1.745(5), β 1.747(5), γ 1.752(5) (λ 589 nm), 2 V meas. = 60(5)°, 2 V calc. = 65°. Batievaite-(Y) is triclinic, space group P-1, a 9.4024(8), b 5.5623(5), c 7.3784(6) Å, α 89.919(2), β 101.408(2), γ 96.621(2)°, V 375.65(6) Å3 and Z = 1. The eight strongest lines of the X-ray powder diffraction pattern [ d(Å)(I)( hkl)] are: 2.991(100)(11-2), 7.238(36)(00-1), 3.061(30)(300), 4.350(23)(0-1-1), 9.145(17)(100), 4.042(16)(11-1), 2.819(16)(3-10), 3.745(13)(2-10). The chemical composition determined by electron probe microanalysis (EPMA) is (wt.%): Nb2O5 2.25, TiO2 8.01, ZrO2 2.72, SiO2 29.96, Al2O3 0.56, Fe2O3 0.43, Y2O3 11.45, La2O3 0.22, Ce2O3 0.33, Nd2O3 0.02, Gd2O3 0.07, Dy2O3 0.47, Er2O3 1.07, Tm2O3 0.25, Yb2O3 2.81, Lu2O3 0.45, CaO 24.98, MnO 1.31, MgO 0.01, Na2O 1.13, K2O 0.02, F 2.88, Cl 0.19, H2O 6.75 (determined on the basis of crystal structure data), O = (F,Cl) -1.25, total 97.09 wt.%. The empirical formula based on the EPMA and single-crystal structure analyses is (Y0.81Ca0.65Mn0.15Zr0.12Yb0.11Er0.04Fe3+ 0.04Ce0.02Dy0.02Lu0.02La0.01Tm0.01)Σ2.00((H2O)0.75Ca0.70□0.55)Σ2.00Ca2.00(□0.61Na0

  2. Alkaline hydrothermal conversion of cellulose to bio-oil: influence of alkalinity on reaction pathway change.

    PubMed

    Yin, Sudong; Mehrotra, Anil K; Tan, Zhongchao

    2011-06-01

    The effects of alkalinity on alkaline hydrothermal conversion (alkaline-HTC) of cellulose to bio-oil were investigated in this study. The results showed that the initial alkalinity greatly influenced the reaction pathways. Under initial strong alkaline conditions with final pH greater than 7, alkaline-HTC only followed the alkaline pathway. However, under initial weak alkaline conditions with final pH of less than 7, acidic as well as alkaline pathways were involved. The main mechanism behind this change of reaction pathways under weak alkaline conditions was that carboxylic acids were first formed from cellulose via the alkaline pathway and then neutralized/acidified the alkaline solutions. Once the pH of the alkaline solutions decreased to less than 7, the acidic instead of the alkaline reaction pathway occurred. This change of the reaction pathways with initial alkalinity partly explained the inconsistent results in the literature of alkaline-HTC bio-oil compositions and yields. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Development of alkaline fuel cells.

    SciTech Connect

    Hibbs, Michael R.; Jenkins, Janelle E.; Alam, Todd Michael; Janarthanan, Rajeswari; Horan, James L.; Caire, Benjamin R.; Ziegler, Zachary C.; Herring, Andrew M.; Yang, Yuan; Zuo, Xiaobing; Robson, Michael H.; Artyushkova, Kateryna; Patterson, Wendy; Atanassov, Plamen Borissov

    2013-09-01

    This project focuses on the development and demonstration of anion exchange membrane (AEM) fuel cells for portable power applications. Novel polymeric anion exchange membranes and ionomers with high chemical stabilities were prepared characterized by researchers at Sandia National Laboratories. Durable, non-precious metal catalysts were prepared by Dr. Plamen Atanassovs research group at the University of New Mexico by utilizing an aerosol-based process to prepare templated nano-structures. Dr. Andy Herrings group at the Colorado School of Mines combined all of these materials to fabricate and test membrane electrode assemblies for single cell testing in a methanol-fueled alkaline system. The highest power density achieved in this study was 54 mW/cm2 which was 90% of the project target and the highest reported power density for a direct methanol alkaline fuel cell.

  4. The secondary alkaline zinc electrode

    NASA Astrophysics Data System (ADS)

    McLarnon, Frank R.; Cairns, Elton J.

    1991-02-01

    The worldwide studies conducted between 1975 and 1990 with the aim of improving cell lifetimes of secondary alkaline zinc electrodes are overviewed. Attention is given the design features and characteristics of various secondary alkaline zinc cells, including four types of zinc/nickel oxide cell designs (vented static-electrolyte, sealed static-electrolyte, vibrating-electrode, and flowing-electrolyte); two types of zinc/air cells (mechanically rechargeable consolidated-electrode and mechanically rechargeable particulate-electrode); zinc/silver oxide battery; zinc/manganese dioxide cell; and zinc/ferric cyanide battery. Particular consideration is given to recent research in the fields of cell thermodynamics, zinc electrodeposition, zinc electrodissolution, zinc corrosion, electrolyte properties, mathematical and phenomenological models, osmotic pumping, nonuniform current distribution, and cell cycle-life perforamnce.

  5. K-alkaline rocks and lamproites of Tomtor massif

    NASA Astrophysics Data System (ADS)

    Vladykin, Nikolai

    2015-04-01

    Tomtor massif of the largest volcano-plutonic deep alkaline-carbonatite massifs world central type. Area of massif occupy 240 km2 and carbonatites stock is 40 km2. The super large deposit of Nb, TR, Y, Sc, Sr ,REE (Frolov et al. 2001)is found within the massif. The numerical publication are devoted to the ore mineralization there. But the geological struc-ture of the massif and the chemistry of its constituting rocks are not well understood. We obtained new ages based on U-Pb zircon and mica Ar-Ar method (Kotov, Vladykin et al. 2014 Vladykin et al. 2015). The massif was created in 2 stages: 700 and 400 Ma. We (Vla-dykin et al 1998) found rocks of lamproite series and proposed a new scheme of magmatism and the ore.genesis (Vladykin 2007, 2009). Biotite - pyroxenite, peridotite originated in first stage and then intruded iolites, nepheline and alkali syenite. Syenites occupy 70% of -massif and contain 12-13% K2O and 2-4% Na2O showing the K-alkaline-ultramafic nature of Tomtor volcano-plutonic massif (Vladykin 2009). The first stage was accomplished by nelsonitov calcite, dolomite and ankerite carbonatites. Second stage (400Ma) volcanics picrite - lamproite veins and eruptive breccias meli-lite, melanephelinites, tinguaites appered. These rocks are cut by carbonatites of second stage. It was finished by intensive explosive eruption of a silicate (lamproite) tuffs lavobrec-cia kimberlite formed Ebelyakhdiamondiferous placer, melilite rocks in diatremes (feeders), as well as carbonate-phosphate (kamaforite) explosive tuffs with siderite ores. This carbona-tite complex is preserved within the subsidence caldera. Tuff eruption in conjunction with gas and hydrothermal activity determined its rare metal mineralization. These rocks contain to: Nb- 21%, TR-15%, Y-1.5%, Sc-1%, Zr- 0,5% Zn-, Sr-6%, Ti-8%, Ba-4%, V - 8000 ppm, Be- 300 ppm, Ga- 80 ppm, Cr- 1200ppm, Ni- 230 ppm, Mo- 145 ppm, Pb- 4300 ppm, Th- 1500 ppm, U-193 ppm. Picrite - olivine (rare leucite) lamproite and

  6. Mingled mafic and felsic magmas in the Jurassic Eagle Mountain pluton, southeastern California

    SciTech Connect

    Mayo, D.P. . Dept. of Geological Sciences); Wooden, J.L. )

    1993-04-01

    The metalluminous, compositionally expanded Eagle Mountain pluton ([approx] 165 Ma) was epizonally emplaced within Proterozoic metaigneous and Proterozoic-Paleozoic metasedimentary rocks in the Eagle Mountains of southeastern California. The evolution of the pluton involved mingling and partial mixing between mafic and felsic magmas. Heterogeneous rocks consisting of discrete biotite-clinopyroxene microdioritic enclaves (49--54% SiO[sub 2]) enclosed in hornblende-biotite granodiorite (57--61% SiO[sub 2]) grade into complexly mingled microdiorite and granodiorite as the proportion of microdiorite increases. The dioritic enclaves are notably potassic (2.1 [+-] .2 wt. %), containing abundant biotite (up to 23%) and interstitial patches of K-feldspar. These features are attributed to selective potassium enrichment of dioritic magma by diffusion during mingling with host granodioritic magma. A similar phenomenon was observed in experiments by Johnston and Wyllie, and attributed to relatively rapid diffusion of potassium from felsic to mafic magma. Calculated Sr[sub i] for the enclaves, intermediate dioritoids, and three of four analyzed host rocks cluster at 0.7085 [+-] 0.0002. Several homogeneous monzogranites not associated with enclaves have slightly higher Sr[sub i] (up to 0.7094) and define two separate mixing/AFC arrays on a plot of Sr[sub i] vs. 1/Sr, both anchored at the cluster of less radiogenic rocks. Alternatively, relatively rapid self-diffusion of Sr may have contributed to isotopic homogeneity during mingling of magmas from isotopically distinct sources.

  7. Emplacement and geochemical evolution of eocene plutonic rocks in the Colville batholith

    SciTech Connect

    Holder, R.W.

    1986-01-01

    Eocene plutonic rocks in the Colville batholith are divided on the basis of field evidence and chemical composition into, in order of decreasing age, (1) several calc-alkalic biotite-hornblende monzodiorite to granodiorite intrusions referred to as the Devils Elbow suite, and (2) compositionally variable calc-alkalic to alkali-calcic intrusions referred to as the Herron Creek suite. These Eocene suites are distinct from older, more voluminous, leucocratic granite and granodiorite intrusions, designated the Keller Butte suite, which are calcic and characteristically lack hornblende. Results of qualitative and computer modeling of major element variation and quantitative models of trace element variation in the chemically coherent Bridge Creek intrusions, a member of the Herron Creek suite, are compatible with fractionation of plagioclase feldspar + hornblende + biotite + magnetite + apatite from a parent magma of andesitic composition to account for the observed variation. Strongly curved variation trends preclude mixing as the primary mechanism for the observed variation. It is suggested that parallel variation trends in the other Eocene intrusions are also the result of crystal fractionation. Lateral chemical variations including a decrease in silica saturation suggest the chemical characteristics of these rocks reflect those of parental magmas derived from the mantle, with an unknown amount of crustal contribution. Rotated and angular xenoliths, discordant contacts, and temporal and spatial proximity to graben structures indicate that the Eocene plutons were passively implaced into the upper crust along graben-bounding faults during graben formation, the earlier stages of which appear to have been contemporaneous with regional mylonitic deformation.

  8. A possible concealed pluton in Beaverhead and Madison Counties, Montana, and Clark County, Idaho

    USGS Publications Warehouse

    Witkind, Irving Jerome

    1974-01-01

    A northeast-trending magnetic anomaly in parts of Beaverhead and Madison Counties, Mont., and Clark County, Idaho, may reflect the trend, shape, and size of a concealed pluton. The type of rock that forms the pluton(?) is unknown. A small volcanic pipe, possibly a diatreme, is at the southeast end of the high. The pipe, about 92 m (300 ft) in diameter, consists of a rubbly basalt-like matrix through which are scattered xenoliths of Precambrian crystalline rocks and of various Paleozoic and Mesozoic strata. It is uncertain whether the juxtaposition of the pipe and the magnetic high is meaningful or is merely fortuitous. Although no mineralized rock was found in the area underlain by the anomaly, placer gold has been found nearby. Some 113 km (70 mi) to the west, in Custer and Lemhi Counties, Idaho, a similar northeast-trending magnetic high marks the site of the Gilmore mining district. The similarities in trend, shape, and magnitude between the two anomalies suggest that the high in Beaverhead and Madison Counties should be investigated for undetected mineral deposits, possibly by a geochemical survey.

  9. Geochemistry of uranium and thorium and natural radioactivity levels of the western Anatolian plutons, Turkey

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Argyrios; Altunkaynak, Şafak; Koroneos, Antonios; Ünal, Alp; Kamaci, Ömer

    2017-01-01

    Seventy samples from major plutons (mainly granitic) of Western Anatolia (Turkey) have been analyzed by γ-ray spectrometry to determine the specific activities of 238U, 226Ra, 232Th and 40K (Bq/kg). Τhe natural radioactivity ranged up to 264 Bq/kg for 238U, 229.62 Bq/kg for 226Ra, up to 207.32 Bq/kg for 232Th and up to 2541.95 Bq/kg for 40K. Any possible relationship between the specific activities of 226Ra, 238U, 232Th and 40K and some characteristics of the studied samples (age, rock-type, colour, grain size, occurrence, chemical and mineralogical composition) was investigated. Age, major and trace element geochemistry, color, pluton location and mineralogical composition are likely to affect the concentrations of the measured radionuclides. The range of the Th/U ratio was large (0.003-11.374). The latter, along with 226Ra/238U radioactive secular disequilibrium, is also discussed and explained by magmatic processes during differentiation.

  10. Ancient plutonic processes on Mars inferred from the detection of possible anorthositic terrains

    NASA Astrophysics Data System (ADS)

    Carter, J.; Poulet, F.

    2013-12-01

    The mineralogical diversity preserved on ancient terrains of Mars provides insights into the planet's early geological state and subsequent evolution. The martian crust is predominantly composed of mafic rocks with low silica contents, with the exception of a few localized volcanic sequences that indicate some compositional evolution towards compositions richer in silicate minerals. Anorthosite, which is dominated by the silicate mineral plagioclase, is rare in the Solar System. It is thought to require an evolved magmatic source in which lighter elements have been concentrated. Anorthosite has been observed previously only on Earth within localized continental plutons of intrusive igneous origin, and more widely on the Moon where the anorthositic highland crust is thought to derive from crystallization of a primordial magma ocean. Using near-infrared spectral data obtained by the Mars Reconnaissance Orbiter, we report the detection of iron-bearing plagioclase-rich rocks at eight sites in the southern highlands of Mars with a spectral signature consistent with ferroan anorthosites. The paucity of detections suggests a localized plutonic origin similar to terrestrial anorthosites, although a lunar-like global anorthosite crust on early Mars cannot be entirely excluded. Our detections of anorthositic compositions at several locations on the martian surface suggest that magmatic processes that produce highly evolved melts were active on ancient Mars.

  11. Reworked old crust-derived shoshonitic magma: The Guarany pluton, Northeastern Brazil

    NASA Astrophysics Data System (ADS)

    Ferreira, Valderez P.; Sial, Alcides N.; Pimentel, Marcio M.; Armstrong, Richard; Guimarães, Ignez P.; da Silva Filho, Adejardo F.; de Lima, Mariucha Maria C.; da Silva, Thyego R.

    2015-09-01

    The 572 Ma Guarany stock consists of magmatic epidote-bearing hornblende monzodiorite to biotite granite that intruded Paleoproterozoic orthogneisses about 10 km inland from the coast in northeastern Brazil. Co-magmatic diorite enclaves and dikes are abundant throughout the pluton. The monzodiorite-granite pluton and diorite enclaves are shoshonitic and display continuous trends in variation diagrams. They display chemical and isotopic characteristics of crustal melts, such as enrichment in incompatible elements, high back-calculated initial 87Sr/86Sr ratios (avg. 0.71253), negative εNd (0.57Ga) values (avg. - 14.58), as well as high and variable (+ 9.1 to + 11.1‰VSMOW) δ18O (zircon) values. Correlations between O-isotope and whole-rock silica contents, as well as initial 87Sr/86Sr ratios with 1/Sr concentrations, suggest hybridization of a lower continental crustal melt with more felsic crustal rocks, concomitant with fractional crystallization. Amphibole chemistry and whole rock Zr, TiO2 and P2O5 contents suggest magma solidification at a pressure 7 kbar and near liquidus temperature 900 °C. The parental magma was likely formed by partial melting of old (tDM = 2.0 Ga) amphibolitic lower continental crustal rocks, in a post-collisional setting, probably triggered by underplating of mantle-derived mafic magma during the period of relaxation after collision.

  12. Magma accumulation rates and thermal histories of plutons of the Sierra Nevada batholith, CA

    NASA Astrophysics Data System (ADS)

    Davis, Jesse W.; Coleman, Drew S.; Gracely, John T.; Gaschnig, Richard; Stearns, Michael

    2012-03-01

    Zircon U-Pb geochronology results indicate that the John Muir Intrusive Suite of the central Sierra Nevada batholith, California, was assembled over a period of at least 12 Ma between 96 and 84 Ma. Bulk mineral thermochronology (U-Pb zircon and titanite, 40Ar/39Ar hornblende and biotite) of rocks from multiple plutons comprising the Muir suite indicates rapid cooling through titanite and hornblende closure following intrusion and subsequent slow cooling through biotite closure. Assembly of intrusive suites in the Sierra Nevada and elsewhere over millions of years favors growth by incremental intrusion. Estimated long-term pluton assembly rates for the John Muir Intrusive Suite are on the order of 0.001 km3 a-1 which is inconsistent with the rapid magma fluxes that are necessary to form large-volume magma chambers capable of producing caldera-forming eruptions. If large shallow crustal magma chambers do not typically develop during assembly of large zoned intrusive suites, it is doubtful that the intrusive suites represent cumulates left behind following caldera-forming eruptions.

  13. Syn-extensional plutonism and peak metamorphism in the albion-raft river-grouse creek metamorphic core complex

    USGS Publications Warehouse

    Strickland, A.; Miller, E.L.; Wooden, J.L.; Kozdon, R.; Valley, J.W.

    2011-01-01

    The Cassia plutonic complex (CPC) is a group of variably deformed, Oligocene granitic plutons exposed in the lower plate of the Albion-Raft River- Grouse Creek (ARG) metamorphic core complex of Idaho and Utah. The plutons range from granodiorite to garnet-bearing, leucogranite, and during intrusion, sillimanite- grade peak metamorphism and ductile attenuation occurred in the country rocks and normal-sense, amphibolite-grade deformation took place along the Middle Mountain shear zone. U-Pb zircon geochronology from three variably deformed plutons exposed in the lower plate of the ARG metamorphic core complex revealed that each zircon is comprised of inherited cores (dominantly late Archean) and Oligocene igneous overgrowths. Within each pluton, a spread of concordant ages from the Oligocene zircon overgrowths is interpreted as zircon recycling within a long-lived magmatic system. The plutons of the CPC have very low negative whole rock ??Nd values of -26 to -35, and initial Sr values of 0.714 to 0.718, consistent with an ancient, crustal source. Oxygen isotope ratios of the Oligocene zircon overgrowths from the CPC have an average ??18O value of 5.40 ?? 0.63 permil (2SD, n = 65) with a slight trend towards higher ??18O values through time. The ??18O values of the inherited cores of the zircons are more variable at 5.93 ?? 1.51 permil (2SD, n = 29). Therefore, we interpret the plutons of the CPC as derived, at least in part, from melting Archean crust based on the isotope geochemistry. In situ partial melting of the exposed Archean basement that was intruded by the Oligocene plutons of the CPC is excluded as the source for the CPC based on field relationships, age and geochemistry. Correlations between Ti and Hf concentrations in zircons from the CPC suggest that the magmatic system may have become hotter (higher Ti concentration in zircon) and less evolved (lower Hf in zircon concentration) through time. Therefore, the CPC represents prolonged or episodic magmatism

  14. Reconnaissance geochemical exploration of the plutons of quartz monzonite and granite in the Jabal Lababa and Ar Rayth areas, southern Asir, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Overstreet, W.C.; Assegaff, A.B.; Jambi, Mohammed; Hussain, M.A.; Selner, G.I.; Matzko, J.J.

    1985-01-01

    Three nonmagnetic high-density concentrates containing 1,000 to 15,000 ppm lead were found on the granitic pluton near Ar Rayth. The source of the lead is not galena, and high values for lead appear to be characteristic of the pluton but do not indicate an ore deposit.

  15. River Valley pluton, Ontario: A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

    USGS Publications Warehouse

    Ashwal, L.D.; Wooden, J.L.

    1989-01-01

    The River Valley pluton is a ca. 100 km2 body of anorthositic and gabbroic rocks located about 50 km northeast of Sudbury, Ontario. The pluton is situated entirely within the Grenville Province, but its western margin is a series of imbricate thrust faults associated with the Grenville Front Tectonic Zone. It is dominated by coarse leuconorite and leucogabbro, with lesser anorthosite, gabbro, and rare ultramafics. Igneous textured rocks are abundant and consist of plagioclase (An60-70) charged with Fe-Ti oxide inclusions, low Ca pyroxene (orthopyroxene and/or inverted pigeonite) and augite. The most unfractionated rocks are minor olivine gabbros with Fo70-80. A variety of deformed and recrystallized equivalents of the igneous-textured rocks is also present, and these are composed largely of calcic plagioclase and hornblende. Ten samples, including both igneous and deformed lithologies give a Pb-Pb whole-rock isochron of 2560??155Ma, which is our best estimate of the time of primary crystallization. The River Valley pluton is thus the oldest anorthositic intrusive yet reported from the Grenville Province, but is more calcic and augitic than typical massifs, and lacks their characteristic Fe-Ti oxide ore deposits. The River Valley body may be more akin to similar gabbro-anorthosite bodies situated at the boundary between the Archean Superior Province and Huronian supracrustal belt of the Southern Province west of the Grenville Front. An Sm-Nd isochron from 3 igneous-textured leucogabbros and an augite mineral separate gives 2377 ?? 68 Ma, implying slight disturbance of the Sm-Nd whole-rock-mineral system during later metamorphism. The Rb-Sr system has been substantially disturbed, giving an age of 2185 ?? 105 Ma, which is similar to internal Pb-Pb isochron ages of 2165 ?? 130 Ma and 2100 ?? 35 Ma for two igneous-textured rocks. It is uncertain whether these ages correspond to a discrete event at this time or represent a partial resetting of the Rb-Sr and Pb

  16. Petrogenesis and tectonic implications of the high-K Alamas calc-alkaline granitoids at the northwestern margin of the Tibetan Plateau: Geochemical and Sr-Nd-Hf-O isotope constraints

    NASA Astrophysics Data System (ADS)

    Zhang, Qichao; Liu, Yan; Huang, He; Wu, Zhenhan; Zhou, Qing

    2016-09-01

    The Alamas granitoid pluton in the eastern part of the Western Kunlun Orogen, the northwestern margin of the Tibetan Plateau, is composed of quartz diorite. Zircon separates from the pluton has SIMS U-Pb age of ∼446 Ma. Rocks from the pluton have a narrow range of SiO2 (56.84-62.57 wt%), MgO (1.76-2.94 wt%), and total alkalis (Na2O + K2O = 5.14-9.59 wt%), and are metaluminous and high-K calc-alkaline to shoshonitic in composition. They are enriched in light rare earth elements (LREEs), with (La/Yb)N = 14-25, and show weakly negative Eu anomalies. These rocks are relatively enriched in Sr (472-676 ppm) and Ba (435-2388 ppm), and depleted in Nb, Ta, Th, and Ti. Their εNd(t) values range from -6.4 to -8.4, and (87Sr/86Sr)i = 0.7184-0.7200. Zircons from the pluton show εHf(t) values of -1.4 to -8.8, and δ18O = 6.4-9.0‰. Geochemical data indicate that the granitoids were likely derived from the reworking of an ancient, deep crustal source, influenced by a minor mantle-derived component. Magmatic differentiation was dominated by the fractional crystallization of hornblende, biotite, and accessory minerals such as apatite, allanite, and Fe-Ti oxides. In summary, the Late Ordovician Alamas pluton is an I-type granitoid that was emplaced in a post-collisional environment, suggesting that this tectonic stage had already initiated prior to ∼445 Ma.

  17. Using Oxygen Isotopes of Zircon to Evaluate Magmatic Evolution and Crustal Contamination in the Halifax Pluton, Nova Scotia

    NASA Astrophysics Data System (ADS)

    Murray, K. E.; Lackey, J.; Valley, J. W.; Nowak, R.

    2007-12-01

    Oxygen isotope analysis of zircon (Zrc) is well suited for parsing out the magmatic history in granitoids. The Halifax pluton is the largest pluton (1060 km2) in the peraluminous South Mountain batholith. The Halifax pluton is mapped as a concentrically zoned body, with outer units comprising granodiorite, monzogranite and a mafic porphyry; these units are locally rich in metasedimentary xenoliths and magmatic enclaves. The exterior units surround a more felsic core of leucogranite [1]. Previous oxygen isotope studies of the pluton report high whole rock δ18O values that range from 10.7-11.7‰ [2], and indicate a significant supracrustal component in the source of the pluton. We report the first δ18O(Zrc) values from the Peggy's Cove monzogranite and an associated mafic porphyry. Samples were collected across 30 km of discontinuous exposures of the monzogranite. Values of δ18O(Zrc) vary from 7.71-8.26‰ (average = 8.15±±0.32‰(2 S.D.); n = 10). Small but systematic E-W regional variation in δ18O(Zrc) values suggests heterogeneous magmatic contamination within the monzogranite. Meter-scale magmatic enclaves, observed in close association with pods of diverse xenoliths and smaller enclaves at the western Cranberry Head locality, are slightly enriched in δ18O relative to the host monzogranite. These data combined support a model of magma mingling and heterogeneous mixing at the rim of the pluton, with contamination by high-δ18O rocks. Additional high-δ18O(Zrc) data from granodiorites on the northern margin of the Halifax pluton concur with these observations [3]. Typically, closed magmatic systems show increasing δ18O with SiO2 because more felsic magmas have a greater percentage of high-δ18O minerals such as quartz and feldspar. Thus, the Halifax pluton appears to exhibit an enrichment trend opposite of what would be expected of a closed evolving system. Emplacement mechanisms for the Halifax pluton proposed by previous workers suggest that the outer

  18. Death Valley turtlebacks: Mesozoic contractional structures overprinted by Cenozoic extension and metamorphism beneath syn-extensional plutons

    NASA Astrophysics Data System (ADS)

    Pavlis, T. L.; Miller, M.; Serpa, L.

    2008-07-01

    The term turtleback was first coined to describe the curvilinear fault surfaces that produced a distinctive geomorphic form in the Black Mountains east of Death Valley, and although it was decades before their full significance was appreciated, they remain one of the most distinctive features of the extensional structure of the Death Valley region. Historically the interpretation of the features has varied markedly, and misconceptions about their character continue to abound, including descriptions in popular field guides for the area. It the 1990's, however, the full history of the systems began to be apparent from several key data: 1) the dating of the plutonic assemblage associated with the turtlebacks demonstrated that late Miocene, syn-extensional plutonism was fundamental to their formation; 2) the plutonic assemblage forms an intrusive sheet structurally above the turtlebacks, indicating a tie between much of the high grade metamorphism and Cenozoic plutonism; 3) a modern analog for the syn-extensional plutonism in the Black Mountains was recognized beneath Death Valley with the imaging of a mid-crustal magma body; 4) the Neogene structural history was worked out in the turtlebacks showing that folding of early-formed shear zones formed the turtleback anticlinoria but overprinting by brittle faults produced the final form as they cut obliquely across the older structure; and 5) the pre-extensional structural history was clarified, demonstrating that Mesozoic basement-involved thrust systems are present within the turtlebacks, but have been overprinted by the extensional system. An unresolved issue is the significance of Eocene U-Pb dates for pegmatites within the region, but presumably these relate somehow to the pre-extensional history. Miller and Pavlis (2005; E. Sci. Rev.) reviewed many features of the turtlebacks, and our working model for the region is that the turtlebacks originated as mid-crustal ductile-thrust systems within the Cordilleran fold

  19. Open vs. closed-system behaviors in granitoid rocks during granulite-facies metamorphism: a case study from the Bulai Pluton (Central Limpopo Belt, South Africa)

    NASA Astrophysics Data System (ADS)

    Laurent, Oscar; Moyen, Jean-François; Martin, Hervé; Doucelance, Régis; Paquette, Jean-Louis

    2010-05-01

    The late-Archaean, high-K calc-alkaline Bulai pluton emplaced within the Central Zone of the Limpopo Belt, a polymetamorphic terrane characterized by at least three granulite-facies events. The youngest, Paleoproterozoic (~2.0 Ga), D3/M3 structural-metamorphic overprint reached pressure-temperature conditions as high as 9-10 kbar and 830°C. As it post-dates the emplacement of the Bulai magmas (~ 2.6 Ga), we investigated the textural and geochemical record of this event in the plutonic rocks of the batholith, focusing on chemical and isotopic re-equilibration. The regional D3/M3 episode is associated with complex strain patterns, including large shear zones, folding and possibly horizontal nappe tectonics. However, in the core of the pluton, there is very little structural field evidence for subsolidus deformation. In addition, no granulite-facies paragenesis developed in the Bulai rocks during the D3/M3 overprint, except in discrete undeformed granulitic veins that are probably related to this event. On the other hand, all rock types display granoblastic polygonal textures, suggesting that the thermal peak induced annealing, almost complete in some cases. Mineral compositions also show evidence for re-equilibration during the Paleoproterozoic metamorphism. Indeed, plagioclase is systematically unzoned, and its chemical composition is notably constant (An29-33) regardless the whole-rock composition over large ranges of SiO2 (47-75 wt.%), CaO (1.5-8 wt.%) and Na2O (2.5-4 wt.%). Similarly, hornblende and biotite compositions are homogeneous within the whole Bulai suite, and present high Ti contents suggesting equilibration at high temperatures. Furthermore, hornblende-plagioclase thermometry indicates temperatures up to 800-900°C, consistent with the thermal peak of the D3/M3 metamorphic episode. 147Sm/147Nd data on whole-rock and separated minerals provided further evidence for grain-scale equilibration, as internal isochrons of 4 individual samples yield ages

  20. Construction of an Upper Crustal Reservoir by Lateral Magma Propagation: New insights from Geochronological Data of La Gloria Pluton, Central Chile

    NASA Astrophysics Data System (ADS)

    Gutiérrez, F. J.; Guillong, M.; Payacán, I. J.; Aravena, A.; Bachmann, O.; Parada, M. A.

    2014-12-01

    La Gloria Pluton (LGP) is a 10 Ma shallow elongated NNW reservoir of 17 km length and 4-6 km width as part of a NS trend of Miocene plutons in Central Chile. New LA-ICPMS U-Pb ages in zircons of La Gloria Pluton indicate that crystallization occurs mostly within an interval between 11.2 to 10 Ma, with southeastward decreasing ages. Zircon crystallization ages are consistently older at the boundaries of the pluton than at the center for a given cross-section. At regional scale the ages of LGP follows a plutonic trend of southward decreasing age: Estero Yerba Loca (10 Ma) and San Francisco Batholith (SFB), in the north; and Cerro Mesón Alto (12.5 Ma) and San Gabriel (SG; 13 Ma), in the south. Both regional and local (within-LGP) age trends suggest: 1) a progressive northward migration of the main deep magmatic source during the Miocene; and 2) a southeastward lateral propagation of the magma during the reservoir construction. The lateral propagation of the magma is also supported by subhorizontal mineral and magnetic lineations with a preferred NNW orientation within LGP. The within-pluton age distribution and internal configuration suggest incremental construction with horizontal propagation of magma within channels. Because the lateral migration of the magma play an important role on the thermal structure of the cooling pluton we perform numerical simulations that account for reheating caused by refilling along the axial core of the pluton . We speculate that pre-existing shallow crustal structures (faults and folds) would allow lateral magma canalization, particularly between the lower highly deformed volcanic Abanico Fm. and the less deformed overlaying volcanic Farellones Fm. The pluton distribution and internal organization in and around LGP suggest incremental construction with vertical and horizontal migration of magma within channels and reservoirs, yielding plutonic complexes with protracted ages and elongated geometries.

  1. Effect of gavage treatment with pulverised Garcinia kola seeds on erythrocyte membrane integrity and selected haematological indices in male albino Wistar rats.

    PubMed

    Ahumibe, A A; Braide, V B

    2009-06-01

    This study examines the effect of the whole seed of Garcinia kola [GKS] on various blood parameters, in adult male albino rats. Five groups, of 6 animals per group, were treated by gavage with suspensions of graded concentrations of GKS daily for 5 weeks. The animals were then sacrificed and blood was obtained for estimation of the data herein presented. Packed red cell volume [PCV], hemoglobin concentration [Hb], and red blood cell count [RBC] showed significantly [P<0.05], increased response to treatment with GKS; while the platelet and white blood cell [WBC] counts showed no corresponding increase with increasing GKS dosage. The mean red blood cell volume [MCV] and mean cell hemoglobin [MCH] levels decreased with increasing GKS dosage. Prothrombin time [PT] and activated partial thromboplastin time [APPT] were both prolonged with increased GKS dosage; while the serum lipids (cholesterol and triglycerides) decreased significantly [P<0.05] with increased GKS dosage.

  2. Evaluation of the dust and methanol extracts of Garcinia kolae for the control of Callosobruchus maculatus (F.) and Sitophilus zeamais (Mots).

    PubMed

    Ogunleye, R F; Adefemi, S O

    2007-12-01

    Insecticidal effects of different doses of the dust and methanol extracts of Garcinia kolae on Callosobruchus maculatus and Sitophilus zeamais were tested. The dust had no significant effect on the two insects; none of them died even at 3 d after treatment. The methanol extracts, however, had rapid lethal effects on both C. maculatus and S. zeamais. The mortality of C. maculatus by the lowest concentration of methanol extracts ranged from 95%~100% whereas in S. zeamais, the mortality ranged from 87.5% to approximately 100% and 70% to approximately 100% in concentrations of 1 g extract+3 ml methanol and 1 g extract+5 ml methanol, respectively, from 24 to 48 h. The least concentration of 1 g extract+15 ml methanol had no significant lethal effect on Sitophilus zeamais.

  3. Was the Devonian geomagnetic field dipolar or multipolar? Palaeointensity studies of Devonian igneous rocks from the Minusa Basin (Siberia) and the Kola Peninsula dykes, Russia

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Biggin, A. J.; Veselovskiy, R. V.; Shatsillo, A. V.; Hawkins, L. M. A.; Shcherbakov, V. P.; Zhidkov, G. V.

    2017-05-01

    Defining variations in the behaviour of the geomagnetic field through geological time is critical to understanding the dynamics of Earth's core and its response to mantle convection and planetary evolution. Furthermore, the question of whether the axial dipole dominance of the recent palaeomagnetic field persists through the whole of Earth's history is fundamental to determining the reliability of palaeogeographic reconstructions and the efficacy of the magnetosphere in shielding Earth from solar wind radiation. Previous palaeomagnetic directional studies have suggested that the palaeofield had a complex configuration in the Devonian period (419-359 Ma). Here we present new high-quality palaeointensity determinations from rocks aged between 408 and 375 Ma from the Minusa Basin (southern Siberia), and the Kola Peninsula that enable the first reliable investigation of the strength of the field during this enigmatic period. Palaeointensity experiments were performed using the thermal Thellier, microwave Thellier and Wilson methods on 165 specimens from 25 sites. Six out of eight successful sites from the Minusa Basin and all four successful sites from the Kola Peninsula produced extremely low palaeointensities (<10 μT). These findings challenge the uniformitarian view of the palaeomagnetic field: field intensities of nearly an order of magnitude lower than Neogene values (except during relatively rare geomagnetic excursions and reversals) together with the widespread appearance of strange directions found in the Devonian suggest that the Earth's field during this time may have had a dominantly multipolar geometry. A persistent, low intensity multipolar magnetic field and associated diminished magnetosphere would increase the impact of solar particles on the Earth's magnetosphere, ionosphere and atmosphere with potential major implications for Earth's climate and biosphere.

  4. Was the Devonian geomagnetic field dipolar or multipolar? Palaeointensity studies of Devonian igneous rocks from the Minusa Basin (Siberia) and the Kola Peninsula dykes, Russia

    NASA Astrophysics Data System (ADS)

    Shcherbakova, V. V.; Biggin, A. J.; Veselovskiy, R. V.; Shatsillo, A. V.; Hawkins, L.; Shcherbakov, V. P.; Zhidkov, G. V.

    2017-02-01

    Defining variations in the behaviour of the geomagnetic field through geological time is critical to understanding the dynamics of Earth's core and its response to mantle convection and planetary evolution. Furthermore, the question of whether the axial dipole dominance of the recent palaeomagnetic field persists through the whole of Earth's history is fundamental to determining the reliability of palaeogeographic reconstructions and the efficacy of the magnetosphere in shielding Earth from solar wind radiation. Previous palaeomagnetic directional studies have suggested that the palaeofield had a complex configuration in the Devonian period (419-359 Ma). Here we present new palaeointensity determinations from rocks aged between 408 and 375 Ma from the Minusa Basin (southern Siberia), and the Kola Peninsula to investigate the strength of the field during this enigmatic period. Palaeointensity experiments were performed using the thermal Thellier, microwave Thellier, and Wilson methods on 165 specimens from 25 sites. Six out of eight successful sites from the Minusa Basin and all four successful sites from the Kola Peninsula produced extremely low palaeointensities (< 10 μT). These findings challenge the uniformitarian view of the palaeomagnetic field: field intensities of nearly an order of magnitude lower than Neogene values (except during relatively rare geomagnetic excursions and reversals) together with the widespread appearance of strange directions found in the Devonian suggest that the Earth's field during this time may have had a dominantly multipolar geometry. A persistent, low intensity multipolar magnetic field and associated diminished magnetosphere would increase the impact of solar particles on the Earth's magnetosphere, ionosphere and atmosphere with potential major implications for Earth's climate and biosphere.

  5. Diclofenac salts. III. Alkaline and earth alkaline salts.

    PubMed

    Fini, Adamo; Fazio, Giuseppe; Rosetti, Francesca; Angeles Holgado, M; Iruín, Ana; Alvarez-Fuentes, Josefa

    2005-11-01

    Diclofenac salts containing the alkaline and two earth alkaline cations have been prepared and characterized by scanning electron microscopy (SEM) and EDAX spectroscopy; and by thermal and thermogravimetric analysis (TGA): all of them crystallize as hydrate when precipitated from water. The salts dehydrate at room temperature and more easily on heating, but recovery the hydration, when placed in a humid environment. X-ray diffraction spectra suggest that on dehydration new peaks appear on diffractograms and the lattice of the salts partially looses crystallinity. This phenomenon is readily visible in the case of the calcium and magnesium salts, whose thermograms display a crystallization exotherm, before melting or decomposing at temperatures near or above 200 degrees C; these last salts appear to form solvates, when prepared from methanol. The thermogram of each salt shows a complex endotherm of dehydration about 100 degrees C; the calcium salt displays two endotherms, well separated at about 120 and 160 degrees C, which disappear after prolonged heating. Decomposition exotherms, before or soon after the melting, appear below 300 degrees C. The ammonium salt is thermally unstable and, when heated to start dehydration, dissociates and leaves acidic diclofenac.

  6. Mesozoic east North American alkaline magmatism: Part 1. Evolution of Monteregian lamprophyres, Québec, Canada

    NASA Astrophysics Data System (ADS)

    Bédard, Jean H.

    1994-01-01

    The Cretaceous Monteregian alkaline igneous province is composed of shallowly emplaced plutonic complexes, and cogenetic dykes and sills. The mafic dykes are principally camptonites, monchiquites and alnöites, and sample the magmas that fed the plutons. The three principal dyke suites have different incompatible trace element ratios ( Y/Ce, Zr/Nb), and are not interrelated by closed-system fractional crystallization. Zonation of pyroxene grains imply a polybaric crystallization history, indicating that magmas ascended as mafic crystal-charged mushes. Intrasuite chemical variations among monchiquites are broadly consistent with segregation of the suspended phenocrysts from interstitial "syenitic" melts. Partial resorption of suspended amphibole megacrysts, assimilation of syenitic material (5-8%) and exsolution of carbonatitic melt are required to explain the variations of Ba, Rb, K 2O, Th, La, and TiO 2. Chemical variations among mafic camptonites are acceptably modelled by fractionation of pyroxene and olivine only, implying that their amphibole-rich character is the result of postfractionation crystallization under volatile-rich conditions. High- Zr/Nb camptonites and Rb-rich (AC) monchiquites could not unequivocably be linked to the main lineages and may represent distinct sources or have been affected by crustal contaminants.

  7. The features of element concentration in natural waters of the Kola North in conditions of environmental contamination

    NASA Astrophysics Data System (ADS)

    Bazova, Mariya; Moiseenko, Tatyana

    2016-04-01

    The intensive use of fossil fuels and industrial development in last century led to the formation of acid rain and water acidification. The problem of water acidification greatly was denoted in the middle of last century in North America and in Europe as a result of air emissions of acid gases, primarily sulfur dioxide. The process of water acidification due to the interaction of two factors: 1) the high deposition of acidifying substances, taking into account the duration of exposure; 2) the sensitivity of the natural catchment area of geological, landscape, geographic and climatic characteristics (Moiseenko, 2005). The effects of acid rains on metal migration and cycling were discussed in a number of previous studies (Jeffries, 1997; Moiseenko, 1999; Manio, 2001; Moiseenko, Gashkina, 2007). The distribution of elements in water lakes has been mixed and due to the change of geochemical cycles of elements occurring in the catchment area and in water. On the Kola Peninsula as a result of long-term operation of the copper-nickel smelter was the anthropogenic acidification and water pollution metals. Increased contents of elements due to the combined effect of three factors: 1) landscape-geochemical characteristics of watersheds; 2) dispersion with flue emissions; 3) leaching elements and bonding of metals with organic matter, especially in forested watersheds and wetlands. This region is subject to long-term effects of mining and smelting industries, and therefore difficult to find of water bodies, which can serve as a background lakes. It is proved that manmade acid rain lead to leach into the water of a large group of elements entering the water as a result of man-made streams, as well as the elements that consist of the rocks forming the watersheds. In order to identify the relationships between the components of the elemental composition of the water in the lake was made a factor analysis using a computer program «STATISTICA 10". Factor analysis revealed the

  8. Fractionation of Zr and Hf during the differentiation of peralkaline magmatic system (Lovozero rare metal deposit, Kola Peninsula)

    NASA Astrophysics Data System (ADS)

    Kogarko, Liya

    2016-04-01

    Zirconium and hafnium are valuable strategic metals. We assessed principal features of the distribution of these elements in peralkaline rocks, ores and rock-forming and accessory minerals of Lovozero complex. The accumulation of these elements during the evolution of alkaline magma of Lovozero deposit up to extremely high concentrations in eudialyte ores (5-8% ZrO2 and 1200-1800 ppm Hf) has been established. These ores represent valuable complex raw material not only for Zr and Hf, but for REE as well. We evaluated partition coefficients of these elements in alkaline pyroxenes (aegirines) from porphyry-like agpaitic lujavrites of Lovozero massif which are 0.40 for zirconium and 0.58 for hafnium. We assessed variations of Zr/Hf ratio for all the rocks of Lovozero alkaline massif. The growth of this ratio in the course of the evolution of alkaline magma has been observed from 38 in the earliest magmatic phase, to 44 in the second phase and to 51-53 in the latest manifestation of alkaline magmatsm. On the basis of the obtained data and equations of equilibrium and fractional crystallization the model of the fractionation of zirconium and hafnium during the evolution of Lovozero intrusion has been constructed. We have demonstrated that the source of strongly enriched magmatic systems similar to Lovozero rare metal deposit is short-lived enriched reservoir - metasomatized and carbonatized mantle substrate. We investigated the fractionation of zirconium and hafnium in carbonatized mantle xenoliths from East Antarctica. The elevated Zr/Hf ratios (up to 125) in metasomatized xenoliths by comparison with the chondritic value have been found. The main reactions of carbonate metasomatism lead to the replacement of primary orthopyroxene by clinopyroxene 2Mg2Si2O6 + CaMg(CO3)2 = 2Mg2SiO4 + CaMgSi2O6 + 2CO2 3CaMg(CO3)2 + CaMgSi2O6 = 4CaCO3 + 2Mg2SiO4 + 2CO2 The substantial expansion of the clinopyroxene crystallization field results in increase of Zr/Hf ratio in equilibrium

  9. Alkaline fuel cell performance investigation

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more that two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  10. Developments in Alkaline Tin Electrorefining

    NASA Astrophysics Data System (ADS)

    Saba, A. E.; Afifi, S. E.; El Sherief, A. E.

    1988-08-01

    Although alkaline stannate baths for electrorefining of tin have been used for some time, there is still room for improvement The effects of alkali concentration, current density and temperature on the cathodic current efficiency have been studied, and a bath temperature of 75°C is recommended. To avoid unstable conditions in the bath, a special treatment to the anode and application of an auxiliary cathode are necessary. Many of the metallic impurities present in the crude tin anode go into the slimes in the form of hydroxides, but lead impurities can only be tolerated if concentrations are less than one percent.

  11. Alkaline fuel cell performance investigation

    NASA Technical Reports Server (NTRS)

    Martin, R. E.; Manzo, M. A.

    1988-01-01

    An exploratory experimental fuel cell test program was conducted to investigate the performance characteristics of alkaline laboratory research electrodes. The objective of this work was to establish the effect of temperature, pressure, and concentration upon performance and evaluate candidate cathode configurations having the potential for improved performance. The performance characterization tests provided data to empirically establish the effect of temperature, pressure, and concentration upon performance for cell temperatures up to 300 F and reactant pressures up to 200 psia. Evaluation of five gold alloy cathode catalysts revealed that three doped gold alloys had more than two times the surface areas of reference cathodes and therefore offered the best potential for improved performance.

  12. Compositional and kinetic controls on liquid immiscibility in ferrobasalt-rhyolite volcanic and plutonic series

    NASA Astrophysics Data System (ADS)

    Charlier, Bernard; Namur, Olivier; Grove, Timothy L.

    2013-07-01

    We present major element compositions of basalts and their differentiation products for some major tholeiitic series. The dry, low-pressure liquid lines of descent are shown to approach or intersect the experimentally-defined compositional space of silicate liquid immiscibility. Ferrobasalt-rhyolite unmixing along tholeiitic trends in both volcanic and plutonic environments is supported by worldwide occurrence of immiscible globules in the mesostasis of erupted basalts, unmixed melt inclusions in cumulus phases of major layered intrusions such as Skaergaard and Sept Iles, and oxide-rich ferrogabbros closely associated with plagiogranites in the lower oceanic crust. Liquid immiscibility is promoted by low-pressure, anhydrous fractional crystallization that drives the low Al2O3, high FeO liquids into the two-liquid field. Kinetic controls can be important in the development of two-liquid separation. The undercooling that occurs at the slow cooling rates of plutonic environments promotes early development of liquid immiscibility at higher temperature. In contrast rapid cooling in erupted lavas leads to large undercoolings and liquid immiscibility develops at significantly lower temperatures. Unmixing leads to the development of a compositional gap characterized by the absence of intermediate compositions, a feature of many tholeiitic provinces. The compositions of experimental unmixed silica-rich melts coincide with those of natural rhyolites and plagiogranites with high FeOtot and low Al2O3, suggesting the potential role of large-scale separation of immiscible Si-rich liquid in the petrogenesis of late-stage residual melts. No trace of the paired ferrobasaltic melt is found in volcanic environments because of its uneruptable characteristics. Instead, Fe-Ti ± P-rich gabbros are the cumulate products of immiscible Fe-rich melts in plutonic settings. The immiscibility process may be difficult to identify because both melts crystallize the same phases with the same

  13. Oxygen Isotope Perspectives on Magma Sources and Pluton Assembly in Convergent Margin Batholiths

    NASA Astrophysics Data System (ADS)

    Lackey, J.

    2008-12-01

    Oxygen isotope (δ18O) analysis of zircon in the Sierra Nevada batholith (SNB) yields fresh insight on the origin of this and other convergent margin batholiths. Zircon precisely and accurately maps (δ18O) variation by circumventing the effects of differentiation and sub-solidus alteration[1]. New temporal and spatial δ18O patterns are recognized, and the findings have bearing in current debates on the tempo and mode of pluton and intrusive suite assembly [2-4]. At large scales, regional belts of high and low δ18O reveal markedly contrasting budgets of crust and mantle in magma sources at different points during formation of the batholith. Contrary to original thinking, recycling of supracrustal rocks is greater in the western than eastern SNB. Gradients of δ18O show variable input of crust and mantle within these regional belts; however, sharp shifts in δ18O between some belts suggest pre-batholith lithospheric breaks. Generally, δ18O breaks do not coincide with the 0.706 Sri line suggesting isotopic decoupling, either in sources or during crustal contamination. Where present, crustal contamination is limited to veneers on plutons, and is largely restricted to the western SNB. Careful investigation of individual intrusive suites, reveals details of source longevity. In the Tuolumne suite, limited variability of δ18O suggests remarkably source homogeneity despite evidence for protracted emplacement[2,4]. In contrast, the John Muir suite shows distinct trends in its older and younger plutons, with a δ18O transition recorded in the Lake Edison granodiorite. Thus, some suites may draw from stable sources over several million years, with differentiation in the upper crust creating zoning and textural diversity; others record source switching or depletion of sources. Over time, shifts in δ18O in the SNB are punctuated by major pulses of magmatism suggesting reorganization of sources, likely in response to intra-arc deformation[5]. Overall, results show that a

  14. Felsic plutonism in the Al Amar—Idsas area, Kingdom of Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Le Bel, L.; Laval, M.

    A tonalite—trondhjemite suite, calc-alkalic plutons and alkali-feldspar granites dated 670 and 580 Ma, intrude thick volcano-sedimentary rocks of the Al Amar group E of the Al Amar fault and the Abt schist W of the fault. The tonalite—trondhjemite suite (group I) is characterized by low Rb (50 ppm) and Sr (100-400 ppm) and by weakly fractionated rare-earth patterns (La/Yb Nca 2-3) with a weak negative Eu anomaly. Calc-alkalic plutons (group II) are richer in Rb (50-150 ppm), contain variable Sr (50-1000 ppm), and have strongly fractionated rare-earth patterns (La/Yb Nca 6-22) with no Eu anomaly. Alkali-feldspar granite (group III) is characterized by high Rb (150-200 ppm) and shows fractionated rare-earth patterns (La/Yb Nca 6-18) with a well-developed Eu anomaly. Group III includes 'specialized granites' with high Rb (300-400 ppm) and Sn (28-66 ppm), and rare-earth patterns showing a distinctive 'sea gull' profile with a very strong Eu anomaly (Eu*/Eu = 20). Oxygen isotope geochemistry suggests that group I rocks (¯x δ18O ca 7.0) were mantle-derived, and that group II and III rocks intruding the Al Amar group ( δ18O ca 7.9 and 8.8 respectively) were derived by remelting of group I, whereas those intruding Abt schist ( δ18O ca 8.7 and 10.8 respectively) were partially derived by anatexis of the Afif block. Magmatogenesis reflects an island-arc development. Rocks of group I represent the initial subduction phase. Syn- to late-tectonic plutons of group II intruded the arc east of the Al Amar fault and the accretionary prism (Abt schist) to the west, which was in collision with the older Afif block. Post-tectonic group III rocks were emplaced in an already cratonized area.

  15. Natural radioactivity and radiation index of the major plutonic bodies in Greece.

    PubMed

    Papadopoulos, A; Christofides, G; Koroneos, A; Papadopoulou, L; Papastefanou, C; Stoulos, S

    2013-10-01

    The natural radioactivity of the major plutonic bodies in Greece, as well as the assessment of any potential health hazard due to their usage as decorative building materials is studied. One hundred and twenty one samples from every major plutonic body in Greece, including various rock-types from gabbro to granite, have been measured for their natural radioactivity using γ-spectrometry methodology. According to the experimental results, the natural radioactivity levels were ranged up to 315 Bq kg(-1) for (226)Ra, up to 376 Bq kg(-1) for (232)Th and up to 1632 Bq kg(-1) for (40)K, with arithmetic mean values and standard deviations of 74 (±51), 85 (±54) and 881 (±331) Bq kg(-1) respectively, which are below the international representative mean values for granite stones. The excess on the effective dose received annually indoors due to granite tiles usage is estimated considering a standard room model where granite tiles with 1.5 cm in thickness cover only the floor of the room. The increment on the external γ-radiation effective dose rate shows a Gaussian distribution well dispersed below 0.3 mSv y(-1), presenting a mean value of 0.14 (±0.06) mSv y(-1). In case of the internal α-radiation a log-normal distribution is appeared scattering below 0.5 mSv y(-1) with a mean value 0.19 (±0.13) mSv y(-1), for a well-ventilated living environment. In case of a poor-ventilated room the increment on internal effective dose rate is estimated with a mean value 0.27 (±0.19) mSv y(-1) scattering below 0.8 mSv y(-1). The majority of the samples increase the external as well as the internal dose less than 30% of the maximum permitted limit of the effective dose rate. Therefore, at least from radiological point of view, the plutonic rocks of Greece could be safely used as decorative building materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Minerals and melt inclusions as keys to understanding magma reservoir processes during formation of volcanic and plutonic mafic-ultramafic complexes in the Maimecha Kotui Province (Polar Siberia)

    NASA Astrophysics Data System (ADS)

    Simonov, Vladimir; Vasiliev, Yurii; Kotlyarov, Alexey; Stupakov, Sergey

    2016-04-01

    Magmatic complexes in the Maimecha Kotui Province (Polar Siberia) attract attention of researchers because they contain ultramafic volcanic rocks - meimechites, being products of crystallization of the ultrabasic deep mantle melts (Sobolev et al., 1991, 2009, 2011; Ryabchikov et al., 2002; Vasiliev, Gora, 2014). Effusive meimechites together with intrusive dunites of the Guli massif form ancient (253-246 Ma) volcanic and plutonic association, in which also pyroxenites and alkaline rocks are situated. Conditions of formation of this association were established with the help of minerals and melt inclusions study. The cumulative structure of the Guli massif dunites consists of rather large (2-4 mm) olivine crystals and dividing them zones (0.5-0.7 mm), filled with fine grains of clinopyroxenes and ore minerals (magnetite, ilmenite and chromite). The extended forms of well faceted pyroxene crystals testify to their fast growth from melt between cumulative olivines. Thus, crystallization of clinopyroxenes and ore minerals leads to formation between olivines ore pyroxenites, which are presented in the Guli massif by independent bodies. Analysis of olivine, Cr-spinel and clinopyroxene compositions testify to similarity of conditions of the Guli massif dunites crystallization on the one hand with formation of platinum-bearing Uralian-Alaskan-type mafic-ultramafic complexes and with another - show participation of meimechite magma. Major element composition of melt inclusions in Cr-spinel has shown that dunites of the Guli massif were crystallized with participation of subalkaline picrite magmatic systems, that are relative to melts, responsible of formation of platinum-bearing mafic-ultramafic complexes and meimechites. Peculiarities of trace and rare-earth elements distribution in melt inclusions in Cr-spinel of dunites are actually similar to inclusions in olivine of meimechites. Overall, data on composition of inclusions directly testify to formation of considered

  17. Transpressional granite-emplacement model: Structural and magnetic study of the Pan-African Bandja granitic pluton (West Cameroon)

    NASA Astrophysics Data System (ADS)

    Sandjo, A. F. Yakeu; Njanko, T.; Njonfang, E.; Errami, E.; Rochette, P.; Fozing, E.

    2016-02-01

    The Pan-African NE-SW elongated Bandja granitic pluton, located at the western part of the Pan-African belt in Cameroon, is a K-feldspar megacryst granite. It is emplaced in banded gneiss and its NW border underwent mylonitization. The magmatic foliation shows NE-SW and NNE-SSW strike directions with moderate to strong dip respectively in its northern and central parts. This mostly, ferromagnetic granite displays magnetic fabrics carried by magnetite and characterized by (i) magnetic foliation with best poles at 295/34, 283/33 and 35/59 respectively in its northern, central and southern parts and (ii) a subhorizontal magnetic lineation with best line at 37/8, 191/9 and 267/22 respectively in the northern, central and southern parts. Magnetic lineation shows an `S' shape trend that allows to (1) consider the complete emplacement and deformation of the pluton during the Pan-African D 2 and D 3 events which occurred in the Pan-African belt in Cameroon and (2) reorganize Pan-African ages from Nguiessi Tchakam et al. (1997) compared with those of the other granitic plutons in the belt as: 686 ±17 Ma (Rb/Sr) for D 1 age of metamorphism recorded in gneiss; and the period between 604-557 Ma for D 2-D 3 emplacement and deformation age of the granitic pluton in a dextral ENE-WSW shear movement.

  18. Transformation of juvenile Izu-Bonin-Mariana oceanic arc into mature continental crust: An example from the Neogene Izu collision zone granitoid plutons, Central Japan

    NASA Astrophysics Data System (ADS)

    Saito, Satoshi; Tani, Kenichiro

    2017-04-01

    Granitic rocks (sensulato) are major constituents of upper continental crust. Recent reviews reveal that the average composition of Phanerozoic upper continental crust is granodioritic. Although oceanic arcs are regarded as a site producing continental crust material in an oceanic setting, intermediate to felsic igneous rocks occurring in modern oceanic arcs are dominantly tonalitic to trondhjemitic in composition and have lower incompatible element contents than the average upper continental crust. Therefore, juvenile oceanic arcs require additional processes in order to get transformed into mature continental crust enriched in incompatible elements. Neogene granitoid plutons are widely exposed in the Izu Collision Zone in central Japan, where the northern end of the Izu-Bonin-Mariana (IBM) arc (juvenile oceanic arc) has been colliding with the Honshu arc (mature island arc) since Middle Miocene. The plutons in this area are composed of various types of granitoids ranging from tonalite to trondhjemite, granodiorite, monzogranite and granite. Three main granitoid plutons are distributed in this area: Tanzawa plutonic complex, Kofu granitic complex, and Kaikomagatake granitoid pluton. Tanzawa plutonic complex is dominantly composed of tonalite and trondhjemite and characterized by low concentration of incompatible elements and shows geochemical similarity with modern juvenile oceanic arcs. In contrast, Kofu granitic complex and Kaikomagatake granitoid pluton consists mainly of granodiorite, monzogranite and granite and their incompatible element abundances are comparable to the average upper continental crust. Previous petrogenetic studies on these plutons suggested that (1) the Tanzawa plutonic complex formed by lower crustal anatexis of juvenile basaltic rocks occurring in the IBM arc, (2) the Kofu granitic complex formed by anatexis of 'hybrid lower crust' comprising of both basaltic rocks of the IBM arc and metasedimentary rocks of the Honshu arc, and (3) the

  19. Constraints on the Depth of Generation and Emplacement of Magma in the Coast Plutonic Complex, British Columbia, From Magmatic Epidote Textures

    NASA Astrophysics Data System (ADS)

    Hamblock, J. M.; Andronicos, C. L.

    2007-12-01

    We have examined magmatic epidote-bearing plutons in the Coast Plutonic Complex to understand the depth at which they were generated and emplaced. Mt. Gamsby, located east of the Coast shear zone between Kitimat and Bella Coola, British Columbia, contains a magmatic epidote-bearing tonalite-quartz diorite pluton. This pluton had a crystallization sequence of pyroxene, amphibole, epidote, plagioclase, and biotite. The lack of garnet is consistent with trace element data, which indicate that garnet was not present in the source region and, therefore, that the magma was sourced at pressures less than ca. 1.4 GPa. Epidote inclusions in plagioclase constrain the pressure during early crystallization of the epidote to greater than 1 GPa. P-T estimates from the pluton and surrounding country rock suggest that the magma migrated to shallower levels and was emplaced at depths of ca. 0.8-1.0 GPa. Magmatic epidote also occurs in the Ecstall, Butedale, and Captain Cove plutons west of the Coast shear zone south of Prince Rupert. In the Captain Cove pluton, textures show that plagioclase crystallized before epidote, and pluton crystallization pressures are estimated to be 0.65-0.75 GPa. These data are consistent with experimental work that indicates that the crystallization of plagioclase before epidote occurs at a lower pressure than epidote before plagioclase. The magmatic epidote in the Ecstall and Butedale plutons commonly occurs as large vermicular grains intergrown with quartzofeldspathic minerals. We interpret this texture to indicate late crystallization of epidote, consistent with prior studies. Pressure estimates for the Ecstall pluton are between ca. 0.5 and 0.8 GPa and vary along strike. The pressure of emplacement of the Butedale pluton is not well constrained, but Al-in-hornblende pressures of 0.6 and 0.8 GPa have been obtained from a portion of the pluton. The pressures in the Butedale and Ecstall plutons are lower than pressures at Mt. Gamsby, which shows early

  20. Alkaline Water and Longevity: A Murine Study.

    PubMed

    Magro, Massimiliano; Corain, Livio; Ferro, Silvia; Baratella, Davide; Bonaiuto, Emanuela; Terzo, Milo; Corraducci, Vittorino; Salmaso, Luigi; Vianello, Fabio

    2016-01-01

    The biological effect of alkaline water consumption is object of controversy. The present paper presents a 3-year survival study on a population of 150 mice, and the data were analyzed with accelerated failure time (AFT) model. Starting from the second year of life, nonparametric survival plots suggest that mice watered with alkaline water showed a better survival than control mice. Interestingly, statistical analysis revealed that alkaline water provides higher longevity in terms of "deceleration aging factor" as it increases the survival functions when compared with control group; namely, animals belonging to the population treated with alkaline water resulted in a longer lifespan. Histological examination of mice kidneys, intestine, heart, liver, and brain revealed that no significant differences emerged among the three groups indicating that no specific pathology resulted correlated with the consumption of alkaline water. These results provide an informative and quantitative summary of survival data as a function of watering with alkaline water of long-lived mouse models.

  1. Alkaline detergent recycling via ultrafiltration

    SciTech Connect

    Steffani, C.; Meltzer, M.

    1995-06-01

    The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone depleting substances and placing restrictions on the use and disposal of many hazardous solvents. Lawrence Livermore National Laboratory is examining ultrafiltration as a cleaning approach that reclaims the cleaning solutions and minimizes wastes. The ultrafiltration membrane is made from sheets of polymerized organic film. The sheets are rolled onto a supporting frame and installed in a tube. Spent cleaning solution is pumped into a filter chamber and filtered through the membrane that captures oils and dirt and allows water and detergent to pass. The membrane is monitored and when pressure builds from oil and dirt, an automatic system cleans the surface to maintain solution flow and filtration quality. The results show that the ultrafiltration does not disturb the detergent concentration or alkalinity but removed almost all the oils and dirt leaving the solution in condition to be reused.

  2. Grace DAKASEP alkaline battery separator

    NASA Technical Reports Server (NTRS)

    Giovannoni, R. T.; Lundquist, J. T.; Choi, W. M.

    1987-01-01

    The Grace DAKASEP separator was originally developed as a wicking layer for nickel-zinc alkaline batteries. The DAKASEP is a filled non-woven separator which is flexible and heat sealable. Through modification of formulation and processing variables, products with a variety of properties can be produced. Variations of DAKASEP were tested in Ni-H2, Ni-Zn, Ni-Cd, and primary alkaline batteries with good results. The properties of DAKASEP which are optimized for Hg-Zn primary batteries are shown in tabular form. This separator has high tensile strength, 12 micron average pore size, relatively low porosity at 46-48 percent, and consequently moderately high resistivity. Versions were produced with greater than 70 percent porosity and resistivities in 33 wt percent KOH as low as 3 ohm cm. Performance data for Hg-Zn E-1 size cells containing DAKASEP with the properties shown in tabular form, are more reproducible than data obtained with a competitive polypropylene non-woven separator. In addition, utilization of active material is in general considerably improved.

  3. Exploring the plutonic crust at a fast-spreading ridge:new drilling at Hess Deep

    SciTech Connect

    Gillis, Kathryn M.; Snow, Jonathan E.; Klaus, Adam; Guerin, Gilles; Abe, Natsue; Akizawa, Norikatsu; Ceuleneer, Georges; Cheadle, Michael J.; Adriao, Alden de Brito; Faak, Kathrin; Falloon, Trevor J.; Friedman, Sarah A.; Godard, Marguerite M.; Harigane, Yumiko; Horst, Andrew J.; Hoshide, Takashi; Ildefonse, Benoit; Jean, Marlon M.; John, Barbara E.; Koepke, Juergen H.; Machi, Sumiaki; Maeda, Jinichiro; Marks, Naomi E.; McCaig, Andrew M.; Meyer, Romain; Morris, Antony; Nozaka, Toshio; Python, Marie; Saha, Abhishek; Wintsch, Robert P.

    2013-02-28

    Integrated Ocean Drilling Program (IODP) Hess Deep Expedition 345 was designed to sample lower crustal primitive gabbroic rocks that formed at the fast-spreading East Pacific Rise (EPR) in order to test models of magmatic accretion and the intensity of hydrothermal cooling at depth. The Hess Deep Rift was selected to exploit tectonic exposures of young EPR plutonic crust, building upon results from ODP Leg 147 as well as more recent submersible, remotely operated vehicle, and near-bottom surveys. The primary goal was to acquire the observations required to test end-member crustal accretion models that were in large part based on relationships from ophiolites, in combination with mid-ocean ridge geophysical studies. This goal was achieved with the recovery of primitive layered olivine gabbros and troctolites with many unexpected mineralogical and textural relationships, such as the abundance of orthopyroxene and the preservation of delicate skeletal olivine textures.

  4. Magmatic construction and duration of solidification of Searchlight pluton, Eldorado Mountains, Nevada (USA)

    NASA Astrophysics Data System (ADS)

    Miller, J. S.; Cates, N. L.; Miller, C. F.; Wooden, J. L.; Means, M. A.; Ericksen, S.

    2003-12-01

    The process of chamber construction and the residence time of magma in mid- to upper crustal magma bodies have been illuminated by recent advances in high-resolution geochronology. Most work has so far concentrated on young volcanic systems; few geochrononlogic data have addressed magma chamber longevity and history from studying plutons. Plutons offer an important complementary record of magma processing and solidification, and can therefore reveal much about the internal workings of magma chambers. The Miocene Searchlight pluton (Nevada, USA) is a spectacular example of a very thick magma chamber (10-12 km). Crystal accumulation (mafic quartz monzonite cumulate), coupled with roof-down solidification (upper quartz monzonite) resulted in segregation of evolved felsic melt in the chamber interior (middle granite). Initially horizontal and gradational internal contacts and coplanar magmatic fabrics between all major units, geochemical mass balance, and very limited isotopic variation among major units, suggest that the entire pluton was molten at one time. However, the time inteval over which the chamber solidified was not well known. New TIMS and in situ ion microprobe U/Pb dating of zircon, combined with our earlier and ongoing field and isotopic studies, now appear to document a protracted magma chamber history. TIMS and ion microprobe dating (Stanford/USGS SHRIMP-RG) was done on two samples, and a third sample was dated by ion microprobe only. A multi-grain, multi-fraction discordia lower intercept age of 16.7+/-0.5 Ma (MSWD=22) was obtained by TIMS from the lower mafic quartz monzonite cumulate. Ion probe dating of zircons from the same sample yielded a 206Pb/238U age of 16.9+/-0.2 Ma (MSWD=1.3; N=24) in agreement with the TIMS lower intercept age. A discordia lower intercept age of 15.7+/-0.4 Ma (MSWD=3.7, one concordant point at 15.8 Ma) was obtained from the middle granite unit. Ion probe dating of zircons from the same sample yielded a 206Pb/238U age of 16

  5. Numerical simulations of late-stage magma flow in La Gloria pluton, central Chile

    NASA Astrophysics Data System (ADS)

    Gutierrez, F. J.; Payacan, I.; Bachmann, O.; Parada, M.

    2012-12-01

    To better understand the internal dynamics of small, shallow, silicic magma reservoirs, we performed 2-D time-dependent fluid dynamical numerical simulations of a cooling magma encased in the upper crust. This model takes into account the main magmatic phases (crystals, melt, and exsolved H2O), whose stability fields were calibrated by the MELTS thermodynamic software. The results of those simulations were compared to the composition, mineralogy, and AMS data obtained for La Gloria Pluton (LGP), a 10 Ma old intrusion with c. 2.5 km of vertical exposure located in the southern Andes. LGP represents a particularly simple case of a shallow silicic magma reservoir of about 250 km3. LGP was assembled in a few pulses and cooled over a short time interval where subsolidus reequilibration was not pervasive, allowing identification of early and late magmatic conditions. LGP is vertically zoned from granodiorite/quartz monzodiorite to quartz monzonite towards the roof. Hornblende, bitotite, and minor magnetite are ubiquitous mafic phases. AMS samples were collected at 46 sites to determine the magnetic anisotropy susceptibility tensor. The magnetic fabric has an oblate shape. Lineations are weak and have a N-NW trend with a nearly horizontal dip. Foliations are more pronounced, having NW trends and dips that vary gradually from vertical at the walls to horizontal at the center and near the roof of the chamber. After 2 to 6 k.y. of simulated evolution, the resulting convection pattern in the crystallizing reservoir is consistent with the magnetic fabric, largely produced in the shear zone between the convecting liquid-dominated core and the growing solidification fronts adjacent to the walls. The bulk of the reservoir remains fairly homogeneous through time due to convection stirring. Magnetic lineations represent axisymmetric convection parallel to the main pluton elongation direction, whereas magnetic foliations represent shear localization near the magma locking point

  6. The probable continuum between emplacement of plutons and mare volcanism in lunar crustal evolution

    NASA Technical Reports Server (NTRS)

    Pieters, Carle M.

    1991-01-01

    A scenario for the formation of the Moon is advanced and is argued to be consistent with both known data and the leading hypothesis regarding the formation of the Moon. It is concluded that, although the volume of mare basalts is estimated to be only 0.1 percent of the lunar total, this value should not be taken to represent the amount of partial melt produced within the lunar interior, nor should the mare basalts be viewed as representing the only products of internal heating. The actual amount of magnetic activity is certain to be substantially larger, but cannot be estimated without a global assessment of lunar highland heterogeneity and the character, scale, and abundance of lunar plutons.

  7. The probable continuum between emplacement of plutons and mare volcanism in lunar crustal evolution

    NASA Astrophysics Data System (ADS)

    Pieters, Carle M.

    1991-06-01

    A scenario for the formation of the Moon is advanced and is argued to be consistent with both known data and the leading hypothesis regarding the formation of the Moon. It is concluded that, although the volume of mare basalts is estimated to be only 0.1 percent of the lunar total, this value should not be taken to represent the amount of partial melt produced within the lunar interior, nor should the mare basalts be viewed as representing the only products of internal heating. The actual amount of magnetic activity is certain to be substantially larger, but cannot be estimated without a global assessment of lunar highland heterogeneity and the character, scale, and abundance of lunar plutons.

  8. The plutonic-volcanic connection: are we even on the right track? (Invited)

    NASA Astrophysics Data System (ADS)

    Lundstrom, C.; Chakraborty, P.; Zambardi, T.

    2013-12-01

    The connection between silicic volcanic and plutonic rocks is full of contradictions. Foremost, granitic plutons reflect long slow incremental emplacement yet vast amounts of aphyric ignimbrite can be erupted rapidly. Heat flow, geophysical tomography, geochronology, geochemistry and petrology all provide observations, yet we are far from any consensus. The two most popular suggestions for forming ignimbrites, extraction of partial melt from a granitic upper crust reservoir or lower crustal hot zone melting, are each inconsistent with some observations/constraints. 100% melting of a granite mush, which may be consistent with many observations, was previously proposed1 but dismissed due to the large amount of latent heat needed to completely melt a mush. This work first presents new non-traditional isotope ratio data (Fe, Si) for plutonic and volcanic rocks suites showing that like Harker diagrams, volcanics and plutonics produce identical systematic behavior with differentiation. δ56Fe forms upwardly curving trends with increasing silica whereas δ30Si increases linearly. The logical deduction is that volcanics reflect 100% mobilization of a granite mush (not necessarily melting). While the origin of NTSI variations remains debated, the systematic NTSI trends are consistent with prediction of a top-down thermal migration zone refining (TMZR) process2. In part 2, we assume TMZR generates a granitic mush and propose that an instability in this mush leads to a runaway effect that results in eruption of aphyric ignimbrite. Experiments show that wet andesite evolves to granite at the cold (400°C) end of a thermal gradient3 with hydrous peralkaline melt existing interstitially. Previous work4 shows that such melts show retrograde immiscibility, segregating into a water rich melt and a water poor melt with temperature increase. Thus, as the mush builds down into hot crust, it crosses the immiscibility boundary triggering release of the water-rich phase; buoyant rise and

  9. Ordovician volcanic and plutonic complexes of the Sakmara allochthon in the southern Urals

    NASA Astrophysics Data System (ADS)

    Ryazantsev, A. V.; Tolmacheva, T. Yu.

    2016-11-01

    The Ordovician terrigenous, volcanic-sedimentary and volcanic sequences that formed in rifts of the active continental margin and igneous complexes of intraoceanic suprasubduction settings structurally related to ophiolites are closely spaced in allochthons of the Sakmara Zone in the southern Urals. The stratigraphic relationships of the Ordovician sequences have been established. Their age and facies features have been specified on the basis of biostratigraphic and geochronological data. The gabbro-tonalite-trondhjemite complex and the basalt-andesite-rhyolite sequence with massive sulfide mineralization make up a volcanic-plutonic association. These rock complexes vary in age from Late Ordovician to Early Silurian in certain structural units of the Sakmara Allochthon and to the east in the southern Urals. The proposed geodynamic model for the Ordovician in Paleozoides of the southern Urals reconstructs the active continental margin, whose complexes formed under extension settings, and the intraoceanic suprasubduction structures. The intraoceanic complexes display the evolution of a volcanic arc, back-, or interarc trough.

  10. A topaz- and amazonite-bearing leucogranite pluton in eastern Xinjiang, NW China and its zoning

    NASA Astrophysics Data System (ADS)

    Gu, Lian-xing; Zhang, Zun-zhong; Wu, Chang-zhi; Gou, Xiao-qin; Liao, Jing-juan; Yang, Hao

    2011-10-01

    The highly evolved Baishitouquan (BST) beryl-mineralised and topaz-bearing amazonite granite pluton is situated in the eastern Tianshan orogen of northwestern China. This pluton exhibits five well-exposed lithological zones, which, gradational from the lowest level, are leucogranite (zone-a), amazonite-bearing granite (zone-b), amazonite granite (zone-c), topaz-bearing amazonite granite (zone-d) and topaz albite granite (zone-e). The rocks are composed mainly of quartz, albite, and K-feldspar with varying amounts of topaz and amazonite. Quartz and topaz phenocrysts are the earliest phases that crystallised from the melt. Amazonite which replaced albite and K-feldspar was formed at the late magmatic stage or during the magmatic-hydrothermal transition. Geochemically, this pluton is characterised by high F (>2 wt.%) and Rb (499.5-1087.04 ppm), low P 2O 5 (⩽0.06 wt.%), Na 2O > K 2O, A/NKC = 1.00-1.11, low ratios of K/Rb, Al/Ga, Y/Ho, Zr/Ha and Nb/Ta, Σ14 REE = 28.6-231.9 ppm with gull wing-shaped distribution patterns (La CN/Lu CN = 0.11-0.68, Eu/Eu * = 0.0005-0.0110) and tetrad effects, and δ 18O = 9.75-7.32‰. Melt and fluid-melt inclusions coexist with liquid and vapour inclusions. The rocks were originated from a highly evolved granitic magma. The BST pluton exhibits transition in the following aspects from zone-a to zone-e: (1) As quartz and topaz phenocrysts progressively increase in size and crystal euhedral shape, rock textures change from equigranular to porphyritic. (2) Amazonite begins to appear in zone-b and becomes most concentrated in zone-c, whereas topaz begins to appear in zone-d becoming highly concentrated in zone-e. (3) Li and (Al + Ti) increase in white mica. (4) Petrochemically, there are general trends of increasing F, Al 2O 3 and Na 2O, and decreasing SiO 2, (Fe 2O 3 + FeO + MgO + MnO) and K 2O. Plots of normative compositions on the Qz-Ab-Or diagram move gradually towards the Ab apex. (5) Overall, Cr, Ni, Co, V, W, Nb, Zr, U, Th and Y

  11. Transport and Depositional Model for Large Country Rock Blocks Within the Searchlight Pluton, Southern Nevada

    NASA Astrophysics Data System (ADS)

    Perrault, D. S.; Furbish, D. J.; Miller, C. F.

    2006-05-01

    Searchlight pluton, a steeply tilted, 10 km thick Miocene intrusion in the Colorado River Extensional Corridor, exposes a zone with abundant, 5-400 m long blocks of Proterozoic gneiss. Blocks are present within a pair of subparallel horizons that make up a 2 km-thick zone and extend about 6 km laterally away from the pluton's north margin slightly oblique to the initially subhorizontal boundary between the pluton's middle unit (granite) and lower unit (qtz monzonite). Blocks are a variety of Precambrian metasedimentary gneisses, granitic gneisses, and mylonites. Blocks are commonly polylithologic and well foliated, with long and intermediate dimensions parallel to both their own foliation and that of the granitic host. Their average aspect ratio is ~ 4:1. Blocks within these horizons are interpreted as stoped (detached country rock that experience gravity- induced displacement) based on several lines of evidence. First, the distribution and abundances of blocks are not consistent with an isolated panel of wall rock (screen). The zone is laterally discontinuous (local abundances vary from ~ 0-40 %); transects a gradational (cm-m scale) internal contact at a slightly oblique angle; and tapers away from the pluton's margin. Second, while block foliations are homoclinal and show fairly consistent attitudes from block to block, block foliations are discordant with wall rock foliations at the same stratigraphic level (adjacent north wall). Third, mush disturbance features such as schlieren and enhanced feldspar foliation beneath blocks suggest a downward compaction. We interpret the blocks to have been emplaced after wall collapse events. We are using scaled settling experiments to clarify how blocks move within viscous fluids and interact with crystal mushes. The experiments, involving tabular ceramic blocks with density ρ = 1.75-2.20 g cm-3 settling in shampoo (ρ = 1.02 g cm-3) with viscosity μ = 20.35 Pa s, are scaled to order-of-magnitude by the particle Reynolds

  12. A Structural-Thermal Model of the Karkonosze Pluton (Sudetes Mountains, SW Poland) for Hot Dry Rock (HDR) Geothermal Use

    NASA Astrophysics Data System (ADS)

    Bujakowski, Wiesław; Barbacki, Antoni; Miecznik, Maciej; Pająk, Leszek; Skrzypczak, Robert

    2016-12-01

    The main objective of this study was to develop a spatial temperature distribution of the Karkonosze Pluton to indicate optimum locations for HDR systems at drillable depth. HDR geothermal technology makes it possible to extract heat from the Earth in areas where no hydro-geothermal resources are present. To produce electricity in a binary cycle, system temperatures of > 100°C are usually required. In this paper, the authors have analysed the potential opportunities for applying HDR technology in the area of the Karkonosze Pluton, which is regarded as an optimum location for the application of the HDR concept (due to the potential for stimulation offered by the mechanical properties of the granites, radiogenic heat production, modern tectonic activity, and the thickness of the pluton). The model used in the analysis, which takes into account a hypothetical assessment of the manner and paths of fluid migration within the pluton, provides an insight into the spatial distribution of subsurface temperatures. It thus allows the location of relatively shallow high-temperature zones, which are optimal for the efficient application of HDR technology, to be identified. With respect to this technology, the Szklarska Poręba area and the NE part of the pluton seem to be better targets than the Cieplice central area, where the model indicated much lower temperatures (e.g. at a depth of 5,000 m, estimated temperatures in the vicinity of Szklarska Poręba were about 185°C and in the vicinity of Cieplice they were about 140°C).

  13. Jurassic plutons in the Desolation wilderness, northern Sierra Nevada batholith, California: A new segment in the Jurassic magmatic arc

    SciTech Connect

    Sabine, C. . Quaternary Sciences Center)

    1993-04-01

    A 164[+-]7 Ma U-P zircon date establishes a Middle- to Late-Jurassic age for the Pyramid Peak granite and synplutonic dioritoids and hybrid rocks that comprise the Crystal Range suite, located southwest of Lake Tahoe. A Jurassic age is also assigned to the Keiths Dome quartz monzonite and the Desolation Valley and Camper Flat granodiorites (Loomis', 1983, Early Granitic Group) which are distinctly older than surrounding Cretaceous granitoids. The Keiths Dome quartz monzonite, the oldest pluton of the group, may be as old as 180 Ma and is distinguished by ductile shear zones and recrystallization textures which indicate an episode of deformation not undergone by other plutons. The Camper flat and Desolation Valley granodiorites are the youngest plutons of the group. ENE-trending microdiorite dikes filled extensional fractures, perpendicular to the direction of shortening, in all Jurassic plutons but on none of the Cretaceous bodies. Jurassic plutons may help constrain ages of metasedimentary and metavolcanic rocks and associated structures in the Mount Tallac roof pendant. The Pyramid Peak granite intrudes the Sailor Canyon Formation which bears Late Pliensbachian ammonites (Fisher, 1990), and the Keiths Dome quartz monzonite intrudes the overlying Tuttle Lake Formation and transects faults and shear zones in the pendant. Initial Sr isotope ratios for the Pyramid Peak granite range between 0.705427 and 0.706874, spanning the 0.706 value taken by some to mark the western limit of sialic lower crust. Data suggest an isotopically mixed source containing mantle and crustal components. Such an environment is not inconsistent with a passive continental margin where mafic magma invades rifted continental crust.

  14. Petrogenesis of the Late Eocene Tarom-e-`Olya shoshonitic plutonic rocks from the Alborz-Azarbayjan zone, NW Iran

    NASA Astrophysics Data System (ADS)

    Nazarinia, Asma; Rashidnejad Omran, Nematollah; Arvin, Mohsen; Ahmadi, Parham

    2017-04-01

    The Late Eocene Tarom-e-`Olya pluton is one of the plutonic bodies cropped out in the Alborz-Azarbayjan zone in the NW of Iran. The pluton, with NW-SE trend, is intruded into the Eocene Sedimentry- volcanic rocks and comprises mainly of monzonite and quartz monzonite rocks with subordinate monzogranite, monzodiorite and quartz monzodiorite. They are I-type metaluminous in nature and shoshonitic in composition, characterized by rather high total alkalies (K2O> Na2O, ranging from 0.9 to 2wt %). On primitive mantle normalized trace element spider diagrams the pluton shows strong enrichment of large-ion lithophile elements (LILE) and depletion in high-field strength elements (HFSE) such as Nb, Ta and Ti. The Chondrite- normalized REE patterns are characterized by slightly enrichments of LREE over MREE and flat heavy REE Patterns [(Gd/Yb) N = 0.80-1.87], high (La/Yb) N = 6.38-9.89 and negative Eu anomaly [(Eu/Eu*) N= 0.46 -1.38]. These are typical geochemical features of subduction related magmatic rocks. The negative Eu anomaly suggests an important role for plagioclase and K-feldespar during fractional crystallization. The geochemical features indicate that a small degree of partial melting (1-5%) of lithospheric mantle source, previously undergone metasomatism due to infiltration of fluids and melts released from the subducted Neotethyan slab, generated the parental magma in a post-Collisional tectonic setting. The melting resulted from slab roll back of the down going Neotethyan oceanic crust in the final stages of subdction beneath the Central Iran that facilitated upwelling of hot asthenospheric mantle which in turn caused lithospheric extension and promote decompression melting of the metasomatized mantle wedge. Later, extensive fractional crystallization accompanied by minor crustal assimilation led to evolution of the intermediate acidic composition of the Tarom-e-`Olya pluton. Key words: Tarom-e-`Olya, Shoshonitic, Alborz-Azarbayjan zone, Neotethys

  15. Spatially controlled Fe and Si isotope variations: an alternative view on the formation of the Torres del Paine pluton

    NASA Astrophysics Data System (ADS)

    Gajos, Norbert A.; Lundstrom, Craig C.; Taylor, Alexander H.

    2016-11-01

    We present new Fe and Si isotope ratio data for the Torres del Paine igneous complex in southern Chile. The multi-composition pluton consists of an approximately 1 km vertical exposure of homogenous granite overlying a contemporaneous 250-m-thick mafic gabbro suite. This first-of-its-kind spatially dependent Fe and Si isotope investigation of a convergent margin-related pluton aims to understand the nature of granite and silicic igneous rock formation. Results collected by MC-ICP-MS show a trend of increasing δ56Fe and δ30Si with increasing silica content as well as a systematic increase in δ56Fe away from the mafic base of the pluton. The marginal Torres del Paine granites have heavier Fe isotope signatures (δ56Fe = +0.25 ± 0.02 2se) compared to granites found in the interior pluton (δ56Fe = +0.17 ± 0.02 2se). Cerro Toro country rock values are isotopically light in both Fe and Si isotopic systems (δ56Fe = +0.05 ± 0.02 ‰; δ30Si = -0.38 ± 0.07 ‰). The variations in the Fe and Si isotopic data cannot be accounted for by local assimilation of the wall rocks, in situ fractional crystallization, late-stage fluid exsolution or some combination of these processes. Instead, we conclude that thermal diffusion or source magma variation is the most likely process producing Fe isotope ratio variations in the Torres del Paine pluton.

  16. U-Pb Zircon Geochronology of the Emigrant Gap Composite Pluton, Northern Sierra Nevada, California: Implications for the Nevadan Orogeny

    USGS Publications Warehouse

    Girty, G. H.; Yoshinobu, S.; Wracher, M.D.; Girty, M.S.; Bryan, K.A.; Skinner, J.E.; McNulty, B.A.; Bracchi, K.A.; Harwood, D.S.; Hanson, R.E.

    1993-01-01

    The undeformed Emigrant Gap composite pluton postdates the Lower to Middle Jurassic Sailor Canyon and Middle Jurassic Tuttle Lake Formations. According to earlier workers, these latterformations contain main and late phase Nevadan-aged (155 +/-3 Ma) spaced, slaty, phyllitic, and crenulation cleavage. Recently discovered fossils indicate that the upper part of the Sailor Canyon Formation can be no older than early Bajocian and no younger than Bathonian. The Tuttle Lake Formation stratigraphically overlies the Sailor Canyon Formation and thus probably includes middle to late Bajocian and/or Bathonian strata.The results of U-Pb work suggest that the Emigrant Gap composite pluton is composed of units that range in age from 168 +/-2 Ma (latest Bathonian to early Callovian) to 163-164 Ma (late Callovian). These new data, when combined with observations summarized above, imply that the Tuttle Lake Formation is older than the undeformed oldest unit of the Emigrant Gap composite pluton (i.e., latest Bathonian or early Callovian), and thus was probably deposited and deformed sometime between middle Bajocian and middle late Bathonian time. Hence, the cleavage contained within the Sailor Canyon and Tuttle Lake Formations could not have formed during the Late Jurassic Nevadan orogeny 155 +/-3 Ma as suggested by earlier workers.Within the foothills belt, just to the west of the Emigrant Gap composite pluton, a pronounced contractional deformation occurred sometime between 200 and 163 Ma (Early to Middle Jurassic). This middle Mesozoic deformation apparently was the result of a collision between an oceanic arc and continental North America. Because of the gross similarity in timing of structures produced during this collision and structures in the wall rocks of the Emigrant Gap composite pluton, we suggest that the latter Middle Jurassic structures are also the result of arc-continent collision, albeit a slightly more continentward expression.

  17. Europium mass balance in polymict samples and implications for plutonic rocks of the lunar crust

    SciTech Connect

    Korotev, R.L.; Haskin, L.A. )

    1988-07-01

    From correlations of SM concentration and Sm/Eu ratio with Th concentration for a large number of polymict samples from various locations in the lunar highlands and the value of 0.91 {mu}g/g for the mean Th concentration of the highlands surface crust obtained by the orbiting gamma-ray experiments. The authors estimate the mean concentrations of Sm and Eu in the lunar surface crust to be between 2 and 3 {mu}g/g Sm and 0.7 and 1.2 {mu}g/g Eu. The compositional trends indicate that there is no significant enrichment or depletion of Eu, on the average, compared to Sm relative to chondritic abundances, i.e., there is no significant Eu anomaly in average upper crust. Although rich in plagioclase ({approximately}70%), the upper crust does not offer evidence for a gross vertical separation of plagioclase from the final liquid from which it crystallized. This and the chondritic ratio of Eu/Al in average highlands material imply that the net effect of the processes that led to formation of the lunar crust was to put most of the Al and incompatible elements in the crust. Among plutonic rocks, only plagioclase in rocks from the magnesian suite can supply the excess Eu in the polymict rocks. Owing to the intermediate value of the mean Mg/Fe ratio of the crust, a significant fraction of the mafic rocks of the lunar highlands must have lower Mg/Fe ratios than the norites and troctolites of the magnesian-suite of plutonic rocks. A large fraction of the plagioclase in the lunar crust is associated not with ferroan anorthosite, but with more mafic rocks. There is little evidence in the Eu data that the lunar crust ever consisted of a thick shell of nearly pure plagioclase, as envisioned in some formulations of the magma ocean model of its formation.

  18. Metamorphism and plutonism around the middle and south forks of the Feather River, California

    USGS Publications Warehouse

    Hietanen, Anna Martta

    1976-01-01

    The area around the Middle and South Forks of the Feather River provides information on metamorphic and igneous processes that bear on the origin of andesitic and granitic magmas in general and on the variation of their potassium content in particular. In the north, the area joins the Pulga and Bucks Lake quadrangles studied previously. Tectonically, this area is situated in the southern part of an arcuate segment of the Nevadan orogenic belt in the northwestern Sierra Nevada. The oldest rocks are metamorphosed calcalkaline island-arc-type andesite, dacite, and sodarhyolite with interbedded tuff layers (the Franklin Canyon Formation), all probably correlative with Devonian rocks in the Klamath Mountains. Younger rocks form a sequence of volcanic, volcaniclastic, and sedimentary rocks including some limestone (The Horseshoe Bend Formation), probably Permian in age. All the volcanic and sedimentary rocks were folded and recrystallized to the greenschist facies during the Nevadan (Jurassic) orogeny and were invaded by monzotonalitic magmas shortly thereafter. A second lineation and metamorphism to the epidote-amphibolite facies developed in a narrow zone around the plutons. In light of the concept of plate tectonics, it is suggested that the early (Devonian?) island-arc-type andesite, dacite, and sodarhyolite (the Franklin Canyon Formation) were derived from the mantle above a Benioff zone by partial melting of peridotite in hydrous conditions. The water was probably derived from an oceanic plate descending to the mantle. Later (Permian?) magmas were mainly basaltic; some discontinuous layers of potassium-rich rhyolite indicate a change into anhydrous conditions and a deeper level of magma generation. The plutonic magmas that invaded the metamorphic rocks at the end of the Jurassic may contain material from the mantle, the subducted oceanic lithosphere, and the downfolded metamorphic rocks. The ratio of partial melts from these three sources may have changed with time

  19. Petrology and geochemistry of the Russian peak pluton, Klamath Mountains, northern California

    SciTech Connect

    Cotkin, S.J.

    1987-01-01

    The Jurassic Russian Peak pluton consists of an older peridotite-to-quartz diorite complex intruded by younger granodiorite. U-Pb ages of 159 Ma have been obtained for both units. The peridotite-to-quartz diorite complex consists principally of quartz diorite; however, cumulate ultramafic rocks occur where it is in contact with Ordovician serpentinite, and the following zonation from serpentinite to quartz diorite is present: peridotite, pyroxenite, hornblendite, eucrite, and diorite. In order to evaluate the petrogenesis of the pluton a combination of field, petrographic, microprobe, X-ray fluorescence, and instrumental neutron activation analysis, and Rb-Sr data have been collected. Major and trace element modeling indicates that quartz-rich quartz diorite formed by crystallization, quartz-poor quartz diorite by accumulation of crystals plus trapped liquid, and ultramafic rocks by assimilation of serpentinite. Granodiorite on the other hand can be modeled by crystallization alone, with the precipitation of plagioclase, amphibole, and biotite accounting for the major and minor element variations. REE modeling indicates that a garnet-clinopyroxene amphibolite is a plausible source. A variety of techniques have been used to decipher the conditions of crystallization in each unit, including a comparison of paragenesis with crystallization experiments, geological thermometry and barometry, and phase equilibria. Pressure of intrusion is considered to have been approximately 3 kbar. The peridotite-to-quartz diorite complex intruded at about 1000/sup 0/C and was completely crystalline at 790/sup 0/C. Granodiorite intruded at somewhat lower temperatures and was completely crystalline at about 700/sup 0/C. The oxygen fugacity for both units was slightly above QFM. At its solidus, granodiorite was saturated with H/sub 2/O, which may account for the pervasive deuteric alteration of this unit.

  20. Geology and geochemistry of the Mount Riley-Mount Cox pluton, Dona Ana County, New Mexico

    SciTech Connect

    Zimbelman, D.R.; Siems, D.F.; Kilburn, J.E.; Hubert, A.E.

    1985-01-01

    The Mount Riley-Mount Cox area is comprised of a relatively homogeneous pluton of rhyodacite rising some 1600 feet above the La Mesa surface. The pluton, of apparent Tertiary age, intrudes Cretaceous sedimentary rocks and Tertiary ( ) latite and tuff. The rhyodacite is holocrystalline, light gray to pinkish gray, porphyritic to microporphyritic, and locally banded. Phenocrysts include hornblende, quartz, biotite, and calcite. The phenocrysts range in size from 0.2 to 2 mm and make up one to fifteen percent of the rock. The phenocrysts often display a glomerophyric texture within a trachytic groundmass. The groundmass ranges from cryptocrystalline to very fine grained and is composed of plagioclase, quartz, potassium feldspar, hornblende/biotite, and iron-oxide material. Locally, the rhyodacite displays millimeter-scale banding and a poikilitic texture consisting of quartz oikiocrysts and plagioclase chadocrysts. The rhyodacite averages 68.74%, SiO/sub 2/, 0.39% TiO/sub 2/, 16.40% Al/sub 2/O/sub 3/, 2.87% Fe/sub t/, 0.10% MnO, 1.21% MgO, 2.56% CaO, 3.79% Na/sub 2/O, and 3.96% K/sub 2/O. The rhyodacite is cut by veins and veinlets of brown to white calcite. The veins attain a maximum thickness of one meter, are locally bordered by calcite-cemented breccia zones, and locally include pyrite. The veins trend north or northwest, consistent with regional trends for the Rio Grande rift and the Texas Lineament, respectively. Sixty-five samples of rhyodacite, breccia, and vein were analyzed for 31 elements by emission-spectrographic methods. Trace-element data suggestive of hydrothermal mineralization was not recognized.

  1. Alkaline and alkaline earth metal phosphate halides and phosphors

    DOEpatents

    Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

    2012-11-13

    Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

  2. Structural evolution of the Rieserferner Pluton: insight into the localization of deformation and regional tectonics implications

    NASA Astrophysics Data System (ADS)

    Ceccato, Alberto; Pennacchioni, Giorgio

    2016-04-01

    The Rieserferner pluton (RFP, Eastern Alps, 32.2±0.4 Ma, Romer et al. 2003) represents a relatively deep intrusion (12-15 km; Cesare, 1994) among Periadriatic plutons. The central portion of the RFP consists of dominant tonalites and granodiorites that show a sequence of solid-state deformation structures developed during pluton cooling and exhumation. This sequence includes: (1) quartz veins, filling two set of steeply-dipping joints trending respectively E-W and NW-SE, commonly showing a millimetric grain size and associated with strike-slip displacement. (2) Quartz- and locally epidote-filled shallowly E-dipping joint set, commonly exploited as discrete derived from both the quartz veins and the host tonalite. These mylonites show a composite sense of shear with a first stage of left-lateral strike-slip followed by a top-to-E dip-slip (normal) movement. The synmylonitic assemblage includes biotite + plagioclase + white mica + epidote ± sphene ± garnet. (3) Set of N-S-trending steeply-dipping joints. These joints are concentrated in zones 1-2 m wide, separated by otherwise un-jointed domains a few tens to hundred meters wide, and are commonly exploited as brittle-ductile faults with dominant dip-slip (normal) kinematics. The mineral assemblage of fault rocks includes white mica + calcite ± chlorite ± quartz. The joints/faults are locally involved in folding. (4) Mafic dikes, dated at 26.3±3 Ma (Steenken et al., 2000), locally injecting the N-S trending set of joints. (5) Cataclasite- and pseudotachylyte-bearing faults also forming a set of steeply-dipping N-S-trending structures. These faults are commonly associated with epidote veins surrounded by bleaching haloes. (6) Zeolite-bearing faults marked by whitish cataclasites, fault gouges and mirror-like surfaces. These faults have a complex oblique- to strike-slip kinematics with an overall N-S trending lineation. As observed in other plutons (e.g. Adamello; Pennacchioni et al., 2006), the network of

  3. Epithermal and plutonic gold mineralizations related to paleoproterozoic acid magmatism in the Tapajós Gold province, Amazonian craton, Brazil

    NASA Astrophysics Data System (ADS)

    Juliani, C.; Corrêa-Silva, R. H.; Monteiro, L. V.; Bettencourt, J. S.; dall Agnol, R.

    2003-04-01

    The Tapajós Gold Province (TGP) is part of the Tapajós-Parima geologic province, that includes ˜2.1 Ga volcano-sedimentary sequences (Jacareacanga Group) and the magmatic arcs of the Cuiú-Cuiú Complex (˜2.01 Ga), Creporizäo Intrusive Suite (1.97-1.95 Ga), Rio das Tropas Tonalite (˜1.90 Ga) and Parauari Intrusive Suite (˜1.88 Ga). Andesitic to rhyolitic volcanic and volcaniclastic rocks of the Iriri Group (1.88 Ga) overlie plutonic rocks and are cut by anorogenic Maloquinha Intrusive Suite (˜1.87 Ga). Paleoproterozoic fluvial to marine sequences (Buiuçú Formation), and several mafic intrusion events are also identified in the TGP. Paleoproterozoic gold mineralizations in the TGP are mainly classified as mesothermal orogenic lodes, intrusion-related gold systems, and epithermal and mesothermal lodes in shear zones. Recently, it was discovered a 1.869 Ga epithermal high-sulfidation (quartz-alunite) and low-sulfidation (adularia-sericite) gold and base metal mineralizations hosted in calc-alkaline volcanic and volcaniclastic rocks of the Iriri Group. In the high-sulfidation mineralization, hydrothermal breccias are strongly affected by high-temperature advanced argillic alteration, with alunite, natroalunite, woodhouseiite-svanbergite, andalusite, diaspore and enargite, besides argillic and propylitic hydrothermal alterations. Over the hydrothermal breccia pipe occurs a hematite-rich silica cap and in the deeper zones sericitic alteration is also present. The epithermal high- and low-sulfidation mineralizations are geneticaly linked to stocks of hydrothermalized granophyry, and rhyolitic and rhyodacitic porphyry dikes and are hosted by late ring composite volcanoes, related to evolution of nested ash-flow caldera complexes. The caldera genesis is atributed to emplacement of shalow late- to post-tectonic calc-alkaline batholits of the Parauari Intrusive Suite in back-arc rifts. The mesozonal relatively reduced Batalha Granite hosts gold mineralizations and

  4. Calc-alkaline mafic rocks of the Black Dyke Formation: Remnants of the final activity of a submerged Permian volcano

    SciTech Connect

    Blein, O.; Lapierre, H.; Pecher, A. ); Schweickert, R.A. . Dept. of Geological Science)

    1993-04-01

    The Permian Black Dyke Fm., which occurs as large tectonic slices within the Luning allochthon in the Excelsior Mountains, NV, forms an E-W trending anticline at Black Dyke Mountain. The 800-m thick stratigraphic succession consists of volcanic and pyroclastic rocks overlain conformably by volcaniclastic sediments. Along the northern limb of the anticline, the rocks consist of mafic porphyritic lavas, breccias, and graded and ungraded pyroclastic beds. The sedimentary unit consists of thick volcaniclastic turbidites overlain by conglomerates, sandstones, and mudstones. Along the southern limb of the anticline, the sequence is replaced by reworked breccia, tuffs, and sandstones. Mafic plutonic rocks occur as xenoliths in the lavas and breccias, and as coeval plugs intruding the section. Gabbros show cumulate or porphyritic textures and are composed of amph, cpx, and zoned plag. Their Ti/V (14.5--15) and Nb/Y (0.25--0.3) ratios fall in the range commonly found in calc-alkaline rocks. Diorite porphyry shows high Al[sub 2]O[sub 3], ZrO[sub 2], and REE abundances indicating that this rock is more fractionated. Basalts and andesites are plag-cpx-opx phyric. They often include glomeroporphyritic clots of cpx with amph coronas. Some rocks exhibit fluidal textures. Both volcanic and plutonic rocks show homogeneous geochemical features and similar crystallization sequences: Fe-Ti oxides---->plag---->opx + cpx----> brown zoned hbl, suggesting that they are cogenetic. Thus, the lower part of the Black Dyke Fm. likely represents the final products formed in a calc-alkaline magma chamber because pyroclastic rocks prevail over lava flows and abundant early crystal cumulates occur as plugs or as inclusions in the lavas and breccias.

  5. Geochemical and Isotopic Data for Oligocene Ignimbrites, Calderas, and Granitic Plutons, Southern Stillwater Range and Clan Alpine Mountains: Insights into the Volcanic-Plutonic Connection and Crustal Evolution in Western Nevada

    NASA Astrophysics Data System (ADS)

    John, D. A.; Colgan, J. P.; Watts, K. E.; Henry, C.; Cousens, B.

    2015-12-01

    Oligocene calderas and underlying plutons in the southern Stillwater Range (SSR) and Clan Alpine Mountains (CAM) in western Nevada were tilted (40->90°) by large-magnitude Miocene extension and unconformably overlain by 15-13 Ma intermediate and mafic lava flows. New geologic mapping, geochemistry, and Ar-Ar and U-Pb dating document 2 brief periods of magmatism resulting in 5 nested calderas and related plutons in sections locally ≥9 km thick. Early magmatism at ~29 Ma included the Deep Canyon caldera in CAM, and in the SSR, pre-caldera rhyolites, ~5 km of pre- and post-collapse intermediate lavas and rhyolite tuff that filled Job Canyon caldera (JC, ~29.4 to 28.8 Ma), and the >4-5 km thick IXL pluton (~28.5 Ma) that intruded JC and is compositionally similar to the tuff and lava flows. The second period included 3 ignimbrite units in 3 calderas: small-volume tuff of Louderback Mountains (LM, low-silica rhyolite; ≥600 m thick; ~25.3 Ma); multiple cooling units of tuff of Poco Canyon (PC, high-silica rhyolite; ≤4.5 km thick; ~25.3 Ma); and ≥2500 km3 of tuff of Elevenmile Canyon (EC, trachydacite to rhyolite; ≤4.5 km thick; 25.1 Ma) that covers ~1600 km2 and extends east from SSR to the northern Desatoya Mountains. The composite Freeman Creek pluton (granodiorite, ~25.0 Ma; granite, ~24.8 Ma) and Chalk Mountain rhyolite porphyry (~25.2 Ma) and granite (~24.8 Ma) plutons intruded LM, PC and EC calderas. Radiogenic isotopes in all caldera units are similar (Sri~0.7050, ΕNd~0.0), while oxygen isotope compositions are variable (δ18Oquartz=5.7-8.4‰, δ18Ozircon=4.1-6.3‰), corresponding to a magmatic range of 5.6-7.6‰, including <6‰ values for JC and lower PC rhyolites. U-Pb zircon dating shows homogeneous age populations and few/no xenocrysts or antecrysts. These data show that (1) thick plutons (>2-5 km) underlie compositionally and temporally related caldera-filling ignimbrites, (2) caldera-forming cycles are isotopically variable, requiring

  6. A paleomagnetic and magnetic fabric study of the Illapel Plutonic Complex, Coastal Range, central Chile: Implications for emplacement mechanism and regional tectonic evolution during the mid-Cretaceous

    NASA Astrophysics Data System (ADS)

    Ferrando, Rodolfo; Roperch, Pierrick; Morata, Diego; Arriagada, César; Ruffet, Gilles; Córdova, Maria Loreto

    2014-03-01

    The Illapel Plutonic Complex (IPC), located in the Coastal Range of central Chile (31°-33° S), is composed of different lithologies, ranging from gabbros to trondhjemites, including diorites, tonalites and granodiorites. U/Pb geochronological data shows that the IPC was amalgamated from, at least, four different magmatic pulses between 117 and 90 Ma (Lower to mid-Cretaceous). We present new paleomagnetic results including Anisotropy of Magnetic Susceptibility (AMS) from 62 sites in the plutonic rocks, 10 sites in country rocks and 7 sites in a mafic dyke swarm intruding the plutonic rocks.

  7. Anosmia in Alkaline Battery Workers

    PubMed Central

    Adams, R. G.; Crabtree, Norman

    1961-01-01

    The sense of smell of 106 alkaline battery workmen exposed at their work to cadmium and nickel dust has been compared with a control group of 84 men matched for age. The battery workers reported significantly more anosmia than the controls (15% to zero) and did less well in the phenol smelling test (27·3% to 4·8%). Cadmium proteinuria was found in 17 of the battery workers, 11 of whom showed virtual anosmia. Figures of recent concentrations of cadmium and nickel in the atmosphere are given. The noses of 85 battery workers and 75 controls were examined. Signs of non-specific chronic irritation were more frequent in the battery workers but no significant relationship was established between this appearance and the presence of anosmia. It is concluded that the anosmia is due to exposure to cadmium or nickel dust or a mixture of the two. PMID:13681418

  8. Closed type alkaline storage battery

    SciTech Connect

    Hayama, H.

    1980-06-10

    The alkaline storage battery employs a metallic hat shaped terminal closure which has a piercing needle as well as a puncturable metallic diaphragm positioned below the piercing needle. The needle is fixed by caulking at its peripheral edge portion to a edge of the closure. A comparatively thick and hard metal plate is placed on the inner surface of the diaphragm and is applied to an open portion of a tubular metallic container which has a battery element. A peripheral edge portion of the closure, the diaphragm and the metallic plate are clamped in airtight relationship through a packing between the caulked end portion and an inner annular step portion of the metallic container of the battery. A lead wire extends from one polarity electrode of the battery element and is connected to a central portion of the metallic plate.

  9. A 2 Million Year History of Plutonism and Volcanism in the Searchlight Magma System, Eldorado Mountains, Nevada (USA)

    NASA Astrophysics Data System (ADS)

    Miller, J.; Miller, C.; Wooden, J.; Perrault, D.; Hodge, K.; Faulds, J.; Cates, N.; Means, M.

    2006-12-01

    Subvolcanic plutons provide an important record of magma processing and solidification of upper crustal magma bodies but rarely can they be compared with volcanic output from the same magma system. In the Colorado River extensional corridor of southern Nevada, steep tilting caused by crustal extension has exposed outstanding examples of large intrusions that have complementary volcanic output. One of the best examples is the 12 km thick Searchlight pluton and its overlying volcanic cover. Earlier work in the pluton documented vertical growth, wherein crystal accumulation (mafic quartz monzonite cumulate) and roof-down solidification (upper quartz monzonite) resulted in segregation of evolved felsic melt in the chamber interior (middle granite). This general evolutionary sequence is mirrored by lava flow stratigraphy in steeply tilted volcanic sections that are structurally above the roof of Searchlight pluton. We have obtained more than 400 ion microprobe U/Pb zircon ages (Stanford/USGS SHRIMP-RG) on more than 20 samples for the pluton and overlying volcanic rocks in order to temporally link the volcanic rocks with the intrusive rocks. The oldest unit from Searchlight pluton is a gabbro pod near the northern margin of the lower Searchlight quartz monzonite that yielded a 206Pb/238U age of 17.7±0.3 Ma (all age errors reported are 1σ; MSWD ~1 or lower except where noted) but the main lower quartz monzonite from structurally deep has a 206Pb/238U age of 16.9±0.2 Ma. This age is the same age as trachydacite porphyry dikes and pods (16.6±0.3 Ma) that intrude upper Searchlight (but not lower Searchlight) and an identical trachydacite lava flow from near the base of a sequence of trachydacite flows above the pluton (16.9±0.4 Ma; MSWD 1.9). Samples of the middle granite and a gabbro that interacts with the granite are interpreted to be the last materials to solidify in the pluton and have 206Pb/238U ages ranging from 15.9-16.2 Ma but with MSWD's >3. Distinct age peaks

  10. Pediatric reference intervals for alkaline phosphatase.

    PubMed

    Zierk, Jakob; Arzideh, Farhad; Haeckel, Rainer; Cario, Holger; Frühwald, Michael C; Groß, Hans-Jürgen; Gscheidmeier, Thomas; Hoffmann, Reinhard; Krebs, Alexander; Lichtinghagen, Ralf; Neumann, Michael; Ruf, Hans-Georg; Steigerwald, Udo; Streichert, Thomas; Rascher, Wolfgang; Metzler, Markus; Rauh, Manfred

    2017-01-01

    Interpretation of alkaline phosphatase activity in children is challenging due to extensive changes with growth and puberty leading to distinct sex- and age-specific dynamics. Continuous percentile charts from birth to adulthood allow accurate consideration of these dynamics and seem reasonable for an analyte as closely linked to growth as alkaline phosphatase. However, the ethical and practical challenges unique to pediatric reference intervals have restricted the creation of such percentile charts, resulting in limitations when clinical decisions are based on alkaline phosphatase activity. We applied an indirect method to generate percentile charts for alkaline phosphatase activity using clinical laboratory data collected during the clinical care of patients. A total of 361,405 samples from 124,440 patients from six German tertiary care centers and one German laboratory service provider measured between January 2004 and June 2015 were analyzed. Measurement of alkaline phosphatase activity was performed on Roche Cobas analyzers using the IFCC's photometric method. We created percentile charts for alkaline phosphatase activity in girls and boys from birth to 18 years which can be used as reference intervals. Additionally, data tables of age- and sex-specific percentile values allow the incorporation of these results into laboratory information systems. The percentile charts provided enable the appropriate differential diagnosis of changes in alkaline phosphatase activity due to disease and changes due to physiological development. After local validation, integration of the provided percentile charts into result reporting facilitates precise assessment of alkaline phosphatase dynamics in pediatrics.

  11. Palaeomagnetic constraints from granodioritic plutons (Jiaodong Peninsula): New insights on Late Mesozoic continental extension in Eastern Asia

    NASA Astrophysics Data System (ADS)

    Charles, Nicolas; Chen, Yan; Augier, Romain; Gumiaux, Charles; Lin, Wei; Faure, Michel; Monié, Patrick; Choulet, Flavien; Wu, Fuyuan; Zhu, Rixiang; Wang, Qingchen

    2011-08-01

    Mechanism and kinematics of the Late Mesozoic continental extension event of Eastern Asia are still debated. In order to better constrain its evolution, two granodioritic plutons of the Jiaodong Peninsula have been chosen as targets for a time-constrained palaeomagnetic study. Indeed, plutons are devoid of visible deformation, did not experience rotation along horizontal axis and are precisely dated by U/Pb and 40Ar/ 39Ar methods. Multidomain (MD) magnetite has been identified as the principal magnetic remanent carrier. The interpolation of existing and new U/Pb and 40Ar/ 39Ar ages revealed that characteristic remanent magnetisation was acquired in a narrow range of 116 ± 2 Ma. Twenty out of 27 sites present stable magnetic directions calculated from high-temperature or high-coercive components. The observations of the solo normal magnetic polarity for this palaeomagnetic collection and of the magnetic remanent age consistent with the Cretaceous Normal Superchron (CNS) argue that the characteristic magnetic remanence may be considered as primary. Detailed field observations of the intrusive relationship between the plutons and country rocks and Anisotropy of Magnetic Susceptibility (AMS) study reveal the absence of the subsequent deformation of plutons, or rigid rotation of plutons along a horizontal axis. Two palaeomagnetic poles have been therefore calculated from these plutons. Among 12 out 15 Cretaceous palaeomagnetic poles, including the two new poles provided by this study, from the Jiaodong Peninsula and on both sides of Tan-Lu and Muping-Jimo faults are statistically consistent. As a result, the Jiaodong Peninsula behaved as a rigid block as internal deformation appears negligible. The remaining three derived poles are probably due to the secular variation or/and the vicinity of fault zones near of the palaeomagnetic sampling site. Thus, they can not be applied to the peninsula-scaled tectonics. Comparison of these time-constrained Cretaceous

  12. The role of felsic microgranular enclaves on the evolution of some Neoproterozoic granite plutons in SE Brazil

    NASA Astrophysics Data System (ADS)

    Alves, Adriana; Janasi, Valdecir A.; Pereira, Giovanna

    2010-05-01

    Recent studies of granite petrogenesis are strongly influenced by the finding that mafic microgranular enclaves (mme) witness frequent and volumetrically significant contribution of mantle-derived magmas to the origin and evolution of granitic melts, be it as a heat source and/or as a source compositional diversity. On the other hand, the origin of felsic microgranular enclaves (fme) is still a matter of debate; current hypotheses consider them as fragments of chilled margins, products of protracted hybridization between invading basic magmas and resident granite mushes or products of interaction between fairly similar melts. Felsic microgranular enclaves are widespread in various granite plutons from SE Brazil, in many cases surpassing mme in size and volume. Two groups of occurrences are studied in more detail illustrate different scenarios, with and without clear connections with mafic magmas. In the Mauá and Mogi das Cruzes plutons, made up of (muscovite)-biotite monzogranite, only fme occur, and the participation of more mafic melts is not evident from field structures or from whole rock and mineral chemical/isotope data. Our preferred model relate the fme to self-mixing events, suggesting mingling/mixing between highly viscous and chemically similar felsic endmembers. In the Itu Batholith, mme enclaves occur, albeit in very different volumes, in three chemically distinct plutons, all with A-type chemical affinities, In the rapakivi Salto Pluton, fme are large (dm to meter-sized) and widespread, except in a central body of porphyry granite. Scattered cm-sized mme of variable composition, some clearly brought as inclusions in the fme, are thought to represent different stages of hybridization, as indicated by disequilibrum features common also in the host syenogranites (rapakivi texture; mafic-rimmed quartz). The enclave assemblage of the Cabreúva Pluton is similarly dominated by fme, but larger mme and small diorite occurrences are evidence that basic magmas

  13. The generation of high Sr/Y plutons following Late Jurassic arc-arc collision, Blue Mountains province, NE Oregon

    NASA Astrophysics Data System (ADS)

    Schwartz, Joshua J.; Johnson, Kenneth; Miranda, Elena A.; Wooden, Joseph L.

    2011-09-01

    High Sr/Y plutons (Sr/Y > 40) occupy large areas in ancient and modern orogenic belts, yet considerable controversy exists regarding mechanisms of their generation, the tectonic settings in which they form, and their relationship to contractional deformation through time. In the Blue Mountains province (NE Oregon), a suite of Late Jurassic (148-145 Ma), high Sr/Y plutons intrude Middle Jurassic (162-157 Ma), low Sr/Y (< 40) arc-related lavas and plutons in the Dixie Butte area immediately after widespread Late Jurassic arc-arc collision (159-154 Ma). Early, pre- to syn-kinematic low Sr/Y lavas and plutons (162-157 Ma) have flat to slightly enriched light rare earth element (REE) abundances, low Sr (< 400 ppm) and Sr/Y values (< 40), and strongly positive initial epsilon Hf values (+ 10.1 to + 12.3: 2σ weighted average). Ce/Y values from basalts and gabbros yield a maximum crustal thickness of ~ 23 km. These geochemical and isotopic features suggest derivation from a depleted-mantle source and/or shallow-level (≪ 40 km) melting of pre-existing island arc crust with little to no evolved crustal input. In contrast, post-kinematic high Sr/Y plutons (148-145 Ma) are more compositionally restricted (tonalite-trondhjemite-granodiorite) and display depleted heavy REE abundances, an absence of Eu anomalies, elevated Sr (> 600 ppm) and Sr/Y values (> 40), and positive initial epsilon Hf values (+ 10.5 to + 7.8: 2σ weighted average). These geochemical and isotopic results are consistent with geochemical models suggesting derivation from partial melting of island arc crust in the presence of a plagioclase-poor to absent, clinopyroxene + hornblende + garnet-bearing source (depths > 35-40 km). We propose that the transition from low Sr/Y to high Sr/Y magmatism resulted from orogenic thickening of island arc crust in the Dixie Butte area during Late Jurassic arc-arc collision between the Olds Ferry and Wallowa island arcs at 159-154 Ma. This fundamental change in crustal

  14. Alkaline pH sensor molecules.

    PubMed

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range.

  15. Evolution of alkaline phosphatases in primates.

    PubMed Central

    Goldstein, D J; Rogers, C; Harris, H

    1982-01-01

    Alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] in placenta, intestine, liver, kidney, bone, and lung from a variety of primate species has been characterized by quantitative inhibition, thermostability, and immunological studies. Characteristic human placental-type alkaline phosphatase occurs in placentas of great apes (chimpanzee and orangutan) but not in placentas of other primates, including gibbon. It is also present in trace amounts in human lung but not in lung or other tissues of various Old and New World monkeys. However, a distinctive alkaline phosphatase resembling it occurs in substantial amounts in lungs from Old World monkeys but not New World monkeys. It appears that duplication of alkaline phosphatase genes and mutations of genetic elements controlling their tissue expression have occurred relatively recently in mammalian evolution. Images PMID:6950431

  16. Multisystemic functions of alkaline phosphatases.

    PubMed

    Buchet, René; Millán, José Luis; Magne, David

    2013-01-01

    Human and mouse alkaline phosphatases (AP) are encoded by a multigene family expressed ubiquitously in multiple tissues. Gene knockout (KO) findings have helped define some of the precise exocytic functions of individual isozymes in bone, teeth, the central nervous system, and in the gut. For instance, deficiency in tissue-nonspecific alkaline phosphatase (TNAP) in mice (Alpl (-/-) mice) and humans leads to hypophosphatasia (HPP), an inborn error of metabolism characterized by epileptic seizures in the most severe cases, caused by abnormal metabolism of pyridoxal-5'-phosphate (the predominant form of vitamin B6) and by hypomineralization of the skeleton and teeth featuring rickets and early loss of teeth in children or osteomalacia and dental problems in adults caused by accumulation of inorganic pyrophosphate (PPi). Enzyme replacement therapy with mineral-targeting TNAP prevented all the manifestations of HPP in mice, and clinical trials with this protein therapeutic are showing promising results in rescuing life-threatening HPP in infants. Conversely, TNAP induction in the vasculature during generalized arterial calcification of infancy (GACI), type II diabetes, obesity, and aging can cause medial vascular calcification. TNAP inhibitors, discussed extensively in this book, are in development to prevent pathological arterial calcification. The brush border enzyme intestinal alkaline phosphatase (IAP) plays an important role in fatty acid (FA) absorption, in protecting gut barrier function, and in determining the composition of the gut microbiota via its ability to dephosphorylate lipopolysaccharide (LPS). Knockout mice (Akp3 (-/-)) deficient in duodenal-specific IAP (dIAP) become obese, and develop hyperlipidemia and hepatic steatosis when fed a high-fat diet (HFD). These changes are accompanied by upregulation in the jejunal-ileal expression of the Akp6 IAP isozyme (global IAP, or gIAP) and concomitant upregulation of FAT/CD36, a phosphorylated fatty acid

  17. Composition of coarse-grained magnetite from pegmatite dikes related to plutons of quartz monzonite in the Jabal Lababa area, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Overstreet, William C.; Mousa, Hassan; Matzko, John J.

    1985-01-01

    Crystals of magnetite as large as 30 mm long and 7 mm thick are locally present in quartz-rich zones of interior and exterior pegmatite dikes related to plutons of quartz monzonite in the Jabal Lababa area. Niobium, tin, and yttrium are strongly enriched in six specimens of magnetite from interior pegmatite dikes in a small pluton where these elements form geochemical anomalies in nonmagnetic heavy-mineral concentrates from wadi sediment. Less abundant anomalous elements in the magnetite are molybdenum, lead, and zirconium, which also tend to be present in anomalous amounts in the nonmagnetic concentrates from the niobium-bearing pluton. The most anomalous trace element in the magnetite is zinc, which is at least 10 times as abundant as it is in the quartz monzonite plutons or in the nonmagnetic concentrates. The capacity of magnetite to scavenge molybdenum, zinc, niobium, lead, tin, yttrium, and zirconium suggests the possible utility of magnetite as a geochemical sample medium.

  18. The stages and duration of the Kieveiskoe and Fedorovskoe Pt-Pd deposits formation: U-Pb zircon data (Kola Peninsula)

    NASA Astrophysics Data System (ADS)

    Nitkina, Elena

    2010-05-01

    The Kola Peninsula is one of the unique geological provinces both in Russia and in the world, where Pt-Pd Kieveiskoe and Fedorovskoe deposits have been discovered (Mitrofanov, 2005). Several deposits within the Northern and Southern belts contain first hundreds of tons of estimated platinum metal resources, allowing us to ascribe the intrusions of the belts to the class of large igneous province (Schissel et al., 2002; Mitrofanov, 2005). The Kieveiskoe and Fedorovskoe deposits belong to the Pt-bearing Fedorovo-Pansky layered intrusion which is situated in the central part of the Kola Peninsula and is one of 14 major Early Proterozoic layered massifs of the Northern belt occurring at the border between Early Proterozoic volcano-sedimentary rift sequences and Archaean basement gneisses (Zagorodny, Radchenko, 1983; Bayanova, 2004). The aim of this report is to summarize all U-Pb data for Kieveiskoe and Fedorovskoe deposits including single grain dating with Pb205 tracer. At present, the following ages have been defined for the different stages of the massif evolution: 2526 - 2516 Ma - pyroxenite and gabbro of the Fedorovskoe deposit magma chamber (Nitkina, 2006), 2515 - 2518 Ma - Pt-bearing gabbro of Federovskoe stratiforme deposit; 2505 - 2496- 2485 Ma (Bayanova, 2004; Nitkina, 2006) - gabbro-norite and gabbro of the main phase of the Kieveiskoe deposit magma chamber and disseminated platinum-metal mineralization and relatively rich Cu-Ni sulphide mineralization in the basal part of the Kieveiskoe and Fedorovskoe non-stratiforme deposits; ca. 2470 Ma (Bayanova, 2004) - pegmatoid gabbro-anothosite and, probably, fluid-associated rich platinum-metal ores of the Lower Layered Horizon (Kieveiskoe deposit); ca. 2447+/-12 Ma (U-Pb zircon and baddeleyte (Bayanova, 2004)) - anorthositic injections and, probably, local lens-like rich Pt-Pd accumulations of the Upper layered Horizon (Kieveiskoe deposit). The U-Pb zircon ages of the massif evolution stages corroborate the

  19. Permeability of the rocks from the Kola superdeep borehole at high temperature and pressure: implication to fluid dynamics in the continental crust

    NASA Astrophysics Data System (ADS)

    Zharikov, A. V.; Vitovtova, V. M.; Shmonov, V. M.; Grafchikov, A. A.

    2003-07-01

    Permeability of the samples collected from the surface and from the depths of 8-11 km in the Kola SG-3 and from the depth of 3.8 in the KTB boreholes was studied at temperatures up to 600 °C and pressures up to 150 MPa. These PT correspond to in situ conditions of the deep parts of the superdeep boreholes and to the conditions of progressive and regressive metamorphism of the Kola series rocks. The experiments were carried out with fluid filtration parallel and normal to rock foliation and parallel to core axis. The temperature-permeability trend behavior depends on effective pressure and depth of sample collection. At low effective pressure, a temperature increase leads first to a permeability decrease and then to its increase. At higher effective pressure, inversions appear on all the temperature trends of the samples collected from great depths. In contrast, permeability of the samples selected at shallow depth (3.8 km) and on the surface decreases within the entire temperature range. As a rule, with flow parallel to foliation, the values of permeability are higher than with flow normal to foliation. The results of microstructure studies allow to conclude that microcrack initiation and closure, due to a competitive influence of temperature and pressure cause such permeability behavior. In the samples, there are two families of microcracks: with low aspect ratio and those with high aspect ratio. Their effect on rock permeability changes with temperature. On sample heating, the low aspect ratio microcracks close and, on the contrary, high aspect ratio ones open. The total effect is expressed by minima in the temperature-permeability trends. Permeability anisotropy increases with temperature, reaches a maximum at 200 °C and then decreases. Sample permeability decreases with different gradients at simultaneous increase of temperature and pressure, simulating in situ depth increase. Hence, the deep seat rocks can vary greatly in permeability and against the common

  20. Evolution of Mutnovsky Volcano, Kamchatka with Implications for Arc Pluton Growth

    NASA Astrophysics Data System (ADS)

    Simon, A.; Robertson, K.; Smith, E. I.; Kiryukhin, A. V.; Selyangin, O.; Mulcahy, S. R.; Walker, J. D.

    2011-12-01

    are consistent with the downward building of the sub-volcanic pre-eruptive magma plumbing system at Mutnovsky and have implications for the emplacement and iterative assembly of sub-volcanic plutons in arc environments. The model pressures yield calculated pre-eruptive magma storage depths that deepen from 13 km for Mutnovsky I and II, to 16 km for Mutnovsky III, to 30 km Mutnovsky IV. These data imply the potential for amalgamation of the residual magma chambers into a large pluton provided that the erupted volume of material from Mutnovsky I, II, III and IV represents a small fraction of the total pre-eruptive magma volume beneath each volcanic center.

  1. Temporal Evolution of Volcanic and Plutonic Magmas Related to Porphyry Copper Ores Based on Zircon Geochemistry

    NASA Astrophysics Data System (ADS)

    Dilles, J. H.; Lee, R. G.; Wooden, J. L.; Koleszar, A. M.

    2015-12-01

    Porphyry Cu (Mo-Au) and epithermal Au-Ag ores are globally associated with shallow hydrous, strongly oxidized, and sulfur-rich arc intrusions. In many localities, long-lived magmatism includes evolution from early andesitic volcanic (v) and plutonic (p) rocks to later dacitic or rhyolitic compositions dominated by plutons. We compare zircon compositions from three igneous suites with different time spans: Yerington, USA (1 m.y., p>v), El Salvador, Chile (4 m.y., p>v), and Yanacocha, Peru (6 m.y., v>p). At Yerington granite dikes and ores formed in one event, at ES in 2 to 3 events spanning 3 m.y., and at Yanacocha in 6 events spanning 5 m.y. At both ES and Yanacocha, high-Al amphiboles likely crystallized at high temperature in the mid-crust and attest to deep magmas that periodically recharged the shallow chambers. At Yanacocha, these amphiboles contain anhydrite inclusions that require magmas were sulfur-rich and strongly oxidized (~NNO+2). The Ti-in-zircon geothermometer provides estimates of 920º to 620º C for zircon crystallization, and records both core to rim cooling and locally high temperature rim overgrowths. Ore-related silicic porphyries yield near-solidus crystallization temperatures of 750-650°C consistent with low zircon saturation temperatures. The latter zircons have large positive Ce/Ce* and small negative Eu/Eu*≥0.4 anomalies attesting to strongly oxidized conditions (Ballard et al., 2001), which we propose result from crystallization and SO2 loss to the magmatic-hydrothermal ore fluid (Dilles et al., 2015). The Hf, REE, Y, U, and Th contents of zircons are diverse in the magma suites, and Th/U vs Yb/Gd plots suggest a dominant role of crystal fractionation with lesser roles for both crustal contamination and mixing with high temperature deep-sourced mafic magma. Ce/Sm vs Yb/Gd plots suggest that magma REE contents at <900°C are dominated by early crystallization of hornblende and apatite, and late crystallization (~<780°C) of titanite

  2. Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

    NASA Astrophysics Data System (ADS)

    Sato, M.; Yamamoto, S.; Yamamoto, Y.; Ohno, M.; Tsunakawa, H.; Maruyama, S.

    2015-12-01

    This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystal contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensity (MIRM) are larger than 4 × 10-12 Am2, while natural remanent magnetization (NRM) intensity (MNRM) are below 4 × 10-12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of MNRM ≥ 4 × 10-12 Am2 and MIRM ≥ 4 × 10-12 Am2, combining the rock-magnetic parameter, we proposed the sample selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high Bc values (>10 mT) or high MNRM/MIRM values (>~0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low Bc values (<10 mT) and low MNRM/MIRM values (<~0.1), main remanence carrier seem to be nearly pure magnetite with PSD grain sizes and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples of the zircon crystals satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM

  3. Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

    NASA Astrophysics Data System (ADS)

    Sato, Masahiko; Yamamoto, Shinji; Yamamoto, Yuhji; Okada, Yoshihiro; Ohno, Masao; Tsunakawa, Hideo; Maruyama, Shigenori

    2015-09-01

    This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. For 81 zircon crystals, IRM intensities ( M IRM) are larger than 4 × 10-12 Am2, while natural remanent magnetization (NRM) intensities ( M NRM) are below 4 × 10-12 Am2, indicating that these crystals are inappropriate for the paleomagnetic study. For the samples that had values of M NRM ≥ 4 × 10-12 Am2 and M IRM ≥ 4 × 10-12 Am2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity ( B c) values (>10 mT) or high M NRM/ M IRM values (>~0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM/ M IRM values (<~0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a

  4. Duality of magmatism in the plutonic sequence of the Sumail Nappe, Oman

    NASA Astrophysics Data System (ADS)

    Juteau, T.; Ernewein, M.; Reuber, I.; Whitechurch, H.; Dahl, R.

    1988-09-01

    Detailed field mapping of the crustal sequence in several areas of the Sumail Ophiolite Nappe, mainly in the Fizh, the Salahi and the Haylayn blocks, and comparisons with other well-studied areas, have shown that the crustal sequence was constructed by two distinct, although nearly contemporaneous, magmatic series: The first, a gabbroic series, was emplaced during the accretion stage at an oceanic spreading centre which formed the layered gabbro unit, the high-level isotropic gabbro unit and their by-products, the sheeted dyke complex and the lower extrusives. Fine-grained homogeneous, planar-laminated gabbros commonly occur at the top of the layered gabbro sequence. In some specific areas (Wadi Haymiliyah and Wadi Rajmi), these are strongly differentiated Fe-Ti-rich gabbronorites and norites, which coincide with large-scale discontinuities within the plutonic sequence, interpreted as axial discontinuities of the spreading magma chambers. The second series, an ultramafic wehrlitic series, is locally rooted in the upper mantle (i.e., the impregnated dunitic transition zone). This has intruded the whole crustal sequence up to the pillow lavas. Countless discordant and concordant wehrlitic bodies intruded the plutonic sequence, making up 20-40% of it in volume. We describe the various settings and forms of these intrusions, which were largely underestimated in previous studies. We also describe their mineralogy and textures, and show with chemical and mineralogical arguments that these bodies evolved as relatively closed systems, independently from each other. We infer from the study of the contacts that the gabbros were still hot and consolidated just at the moment of the wehrlitic intrusion. At the base of the crust however, indications of immiscibility between gabbros and wehrlites are common, suggesting that both magmatic series were quite contemporaneous. The wehrlites are commonly isotropic and may exhibit an internal layering of the dunite

  5. Review of ''Draft - Area Recommendation Report for the Crystalline Repository Project'', January 1986. [Rolesville pluton and Elk River complex

    SciTech Connect

    Butler, J.R.

    1986-03-13

    The Draft-Area Recommendation Report identifies portions of crystalline rock bodies as proposed potentially acceptable sites for consideration as repositories of high-level radioactive waste. The review is in three parts. Part I is a general summary of the main comments, written in semi-technical language and without detailed documentation or references. It includes summaries of comments on the two preliminary candidate areas for a nuclear-waste repository in North Carolina (Rolesville pluton and Elk River complex) and on the rest of the report. The following two parts are written in the technical language of a geological report and include both documentation and references for each of the points discussed: Part II - Rolesville pluton, Site SE-4; Part III - Elk River complex, Site SE-5.

  6. The distribution, geochronology and geochemistry of early Paleozoic granitoid plutons in the North Altun orogenic belt, NW China: Implications for the petrogenesis and tectonic evolution

    NASA Astrophysics Data System (ADS)

    Meng, Ling-Tong; Chen, Bai-Lin; Zhao, Ni-Na; Wu, Yu; Zhang, Wen-Gao; He, Jiang-Tao; Wang, Bin; Han, Mei-Mei

    2017-01-01

    Abundant early Paleozoic granitoid plutons are widely distributed in the North Altun orogenic belt. These rocks provide clues to the tectonic evolution of the North Altun orogenic belt and adjacent areas. In this paper, we report an integrated study of petrological features, U-Pb zircon dating, in situ zircon Hf isotope and whole-rock geochemical compositions for the Abei, 4337 Highland and Kaladawan Plutons from north to south in the North Altun orogenic belt. The dating yielded magma crystallization ages of 514 Ma for the Abei Pluton, 494 Ma for the 4337 Highland Pluton and 480-460 Ma for the Kaladawan Pluton, suggesting that they are all products of oceanic slab subduction because of the age constraint. The Abei monzogranites derived from the recycle of Paleoproterozoic continental crust under low-pressure and high-temperature conditions are products of subduction initiation. The 4337 Highland granodiorites have some adakitic geochemical signatures and are sourced from partial melting of thickened mafic lower continental crust. The Kaladawan quartz diorites are produced by partial melting of mantle wedge according to the positive εHf(t) values, and the Kaladawan monzogranite-syenogranite are derived from partial melting of Neoproterozoic continental crust mixing the juvenile underplated mafic material from the depleted mantle. These results, together with existing data, provide significant information about the evolution history of oceanic crust subduction during the 520-460 Ma. The initiation of subduction occurred during 520-500 Ma with formation of Abei Pluton; subsequent transition from steep-angle to flat-slab subduction at ca.500 Ma due to the arrival of buoyant oceanic plateaus, which induces the formation of 4337 Highland Pluton. With ongoing subduction, the steep-angle subduction system is reestablished to cause the formation of 480-460 Ma Kaladawan Pluton. Meanwhile, it is this model that account for the temporal-spatial distribution of these early

  7. Forceful emplacement of the Eureka Valley-Joshua Flat-Beer Creek composite pluton into a structural basin in eastern California; internal structure and wall rock deformation

    NASA Astrophysics Data System (ADS)

    Morgan, Sven; Law, Richard; de Saint Blanquat, Michel

    2013-11-01

    Anisotropy of Magnetic Susceptibility parameters have been analyzed at 311 locations in the Eureka Valley-Joshua Flat-Beer Creek (EJB) pluton of eastern California. The large amount of data has allowed for the AMS parameters to be contoured using techniques that both reveal map-scale trends and emphasize small-scale differences. The contour maps suggest that magnetic susceptibility is dominantly controlled by composition of the magma but may also be affected by emplacement-related strain as the magma chamber inflated and forced the wall rocks outward. Pluton construction involved two major pulses of different composition magmas that were emplaced sequentially but with overlapping periods of crystallization. The magmas initially intruded as sill-like bodies into a structural basin. The magnetic foliation of the pluton cuts across internal magmatic contacts on the map scale and is parallel to local contacts between the pluton and surrounding metasedimentary wall rocks. The magnetic fabric is similar in orientation and symmetry to intense flattening strains recorded in the aureole rocks. The metasedimentary wall r