Abstract 1
Because of its high solubility in aqueous fluids as well
as silicate melts, the element B is a useful tracer of a
variety of geologic processes (Leeman and Sisson, 1996).
Examples are given below.
B is systematically depleted in progressively
metamorphosed rocks (e.g., Figure 1). This behavior helps
constrain formation of intraplate basaltic magmatism (Ryan
et al., 1966), granulite facies (Leeman et al., 1992) and
other styles of metamorphism (Woodford et al., 2000),
modification of subducted materials (Moran et al., 1992;
Bebout et al., 1993, 1999), evolution of granitic magmas
(Tonarini et al, 1997), and groundwater hydrology (Pennisi
et al., 2000)
Selected references:
Bebout, G.E., Ryan, J.G., and Leeman, W.P. (1993) B-Be
systematics in subduction-related metamorphic rocks:
characterization of the subduction component. Geochim
Cosmochim Acta, 57, 2227-2238.
Bebout, G.E., Ryan, J.G., Leeman, W.P., and Bebout, A.E.
(1999) Fractionation of trace elements by subduction-zone
metamorphism - Effect of convergent margin thermal
evolution. Earth Planet. Sci. Lett., 171, 63-82.
Leeman, W.P., Sisson, V.B., and Reid, M.R. (1992) Boron
geochemistry of the lower crust: evidence from granulite
terranes and deep crustal xenoliths. Geochim. Cosmochim.
Acta, 56, 775-788.
Leeman, W.P., Tonarini, S., Pennisi, M., and Ferrara, G.
(1995) Boron isotopic variations in volcanic exhalatives and
thermal waters from Vulcano Island, Italy: implications for
evolution of volcanic fluids. EOS 76, F655.
Leeman, W.P., and Sisson, V.B. (1996) Geochemistry of
boron and its implications for crustal and mantle processes.
In: E.S. Grew and L.M. Anovitz (eds.), BORON: Mineralogy,
Petrology and Geochemistry in the Earth's Crust, Reviews in
Mineralogy, v. 33, Mineral. Soc. Am., pp. 645-707.
Moran, A.E., Sisson, V.B., and Leeman, W.P. (1992) Boron
in subducted oceanic crust and sediments:effects of
metamorphism and implications for arc magma compositions.
Earth Planet. Sci. Lett., 111, 331-349.
Pennisi, M., Leeman, W.P., Tonarini, S., Pennisi, A., and
Nabelek, P.I. (2000) Boron, Sr, O, and H isotope
geochemistry of groundwaters from Mt. Etna (Sicily) -
hydrologic implications. Geochim. Cosmochim. Acta, 64,
961-974.
Ryan, J.G., Leeman, W.P., Morris, J.D., and Langmuir,
C.H. (1996) The boron systematics of intraplate lavas:
Implications for crust and mantle evolution. Geochim.
Cosmochim. Acta, 60, 415-422.
Tonarini, S., Dini, A., Pezotta, F., and Leeman, W.P.
(1998) Boron isotopic composition of zoned (schorl-elbaite)
tourmalines, Mt. Capanne Li-Cs pegmatites, Elba (Italy).
Eur. J. Mineral., 10, 941-951.
Woodford, D.T., Sisson, V.B., and Leeman, W.P. (2000)
Boron infiltration of the Alta Stock contact aureole, Utah:
Evidence from mineral chemistry and geochemistry. Amer.
Mineral., in press.
Abstract 2
Boron (and Li) isotopic composition is also useful in
constraining sources of B in various geologic reservoirs,
including sources of arc magmas (Smith et al., 1997; Chan et
al., 1999; Tonarini et al., 1997, 2000), and geothermal
systems (Leeman et al., 1992). Natural B isotopic variations
are illustrated in Figure 2.
Selected references:
Leeman, W.P., Vocke, R.D., and McKibben, M.A. (1992)
Boron isotopic fractionation between coexisting vapor and
liquid in natural geothermal systems. In. Y.K. Kharaka and
A.S. Maest (eds.), Water-Rock Interaction, v. 2,
1007-1010.
Chan, L.H., Leeman, W.P., and You, C.-F. (1999) Lithium
isotopic composition of Central American volcanic arc lavas:
Implications for modification of subarc mantle by
slab-derived fluids. Chem. Geol., 160, 255-280.
Smith H.J., Leeman W.P., Davidson J., and Spivack A.J.
(1997) The B isotopic composition of arc lavas from
Martinique, Lesser Antilles. Earth Planet. Sci. Lett. 146,
303-314.
Tonarini S., Pennisi M., Ferrara G., and Leeman W.P.
(1997) <FONT
FACE="Symbol">d</FONT><SUP>11</SUP>B
nelle lave di Volcano: implicazioni sulla petrogenesi dei
magmi. In: La Volpe L., Dellino P., Nuccio M., Privitera E.,
and Sbrana A. (eds.) Progetto Vulcano: Risultati delle
Attivita di Ricerca 1993-1995. Consiglio Nazionale delle
Ricerche, Gruppo Nazionale per la Vulcanologia, Pisa, Italy,
199-203.
Tonarini, S., Leeman, W.P., Pennisi, M., and Ferrara, G.
(2000) Boron isotopic variations in lava flows of the
Aeolian volcanic arc, Italy. J. Volcanol. Geotherm. Res., in
press.
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