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A 50 m drill core (core no. 383-334) collected from the contact metamorphic aureole in the Mouat Ni-Cu prospect in the Mountain View area of Stillwater County, Montana, exhibits evidence of in situ fluid-absent biotite dehydration melting and local back reaction of melts derived from metasediments and metavolcanics. The drill core was investigated to characterize the mineral assemblages and their textures, to search for evidence of partial melting, and to determine mineral and whole-rock geochemistry to provide an understanding of the petrogenesis of the homfels close to the contact with the Stillwater Complex. The rocks investigated are predominantly quartz-plagioclase-cordierite-orthopyroxene-biotite [+ or -] spinel hornfels, Fe-Cu-Ni sulfides, and Fe-Ti oxides. One sample contains garnet ([Alm.sub.73-77][Pyr.sub.20-17][Sps.sub.3][Grs.sub.4]) in addition to cordierite. Three samples contain cordierite-hercynite symplectites surrounded by a narrow mantle devoid of orthopyroxene, plagioclase, and biotite that are roughly ovoid to lenticular in shape. Partially melted samples show back reaction between crystallizing melt and restite such that retrograde skeletal intergrowths of biotite and quartz in the mesosome were developed. Average T-P conditions of hornfels and melt genesis are 786 [degrees]C and 3.7 kbar. Back reactions that produced biotite occurred at somewhat lower temperatures. Whole-rock geochemistry suggests that the protolith of the hornfelsic rocks was likely a mixture of greywacke and additional intermediate to marie volcanogenic components. Keywords: Stillwater Complex, hornfels, partial melting, back reactions

A rare lithology consisting of garnet-tourmaline-sillimanite-biotite-ilmenite-quartz has been found within the granulite-facies region of south-central Massachusetts. The homogeneous, Ti-rich oxy-dravitic tourmaline, [X.sub.Mg] = Mg/(Mg + Fe) = 0.72-0.77, falls into the alkali group, and is similar in composition to lower grade tourmaline found in corresponding metapelitic rocks in Maine. Charge-balancing calculations and binary diagrams suggest that, like biotite in the region, tourmaline has undergone deprotonation by means of the exchange vectors AlO[R.sub.-1][(OH).sub.-1] and Ti[O.sub.2][R.sub.-1] [(OH).sub.-2], where R represents Fe + Mg. The restriction of a concordant tourmaline-rich horizon in otherwise tourmaline-free rocks of this granulite-facies region suggests that either: (1) B, released during prograde fluid-absent dehydration reactions of muscovite and biotite, was locally available in a fluid phase or melt for later crystallization near the peak of granulite-facies metamorphism along pathways that provided a conduit for fluid migration; or (2) that this is simply a B-rich compositional horizon (tourmalinite) that survived anatexis and granulite-facies metamorphism and that records the incipient conditions of tourmaline breakdown and subsequent recrystallization near or post-peak metamorphism. Keywords: Massachusetts, tourmaline, granulite-facies, partial melting, deprotonation

The Ti content of biotite can serve as a geothermometer for graphitic, peraluminous metapelites that contain ilmenite or rutile and have equilibrated at roughly 4-6 kbar. The relationship between Ti-content, temperature, and Mg/(Mg + Fe) value was calibrated empirically using an extensive natural biotite data set (529 samples) from western Maine and south-central Massachusetts in combination with the petrogenetic grid of Spear et al. (1999}. The calculated Ti-saturation surface is curved such that for a given Mg/(Mg + Fe) value, Ti concentration increases as a function of temperature in a nonlinear fashion, and for a given temperature Ti concentrations decrease with an increase in Mg/(Mg + Fe). The fit to the Ti-saturation surface can be reformulated as the geothermometric expression: T = [{[ln(Ti) - a - c[(X.sub.Mg).sup.3]/b}.sup.0.333], in which T is temperature in degrees Celsius, Ti is the number of atoms per formula unit (apfu) normalized on the basis of 22 O atoms, [X.sub.Mg] is Mg/(Mg + Fe), a = -2.3594, b = 4.6482 x [10.sup.-9] and c = 1.7283. The calibration range for this expression is [X.sub.Mg] = 0.275-1.000, Ti = 0.04-0.60 apfu, and T = 480-800 [degrees]C. Precision of the Ti-in-biotite geothermometer is estimated to be [- or +]24 [degrees]C at the lower temperature range and improves to [+ or -]12 [degrees]C at higher temperatures. Application of the Ti-in-biotite geothermometer to ilmenite- or rutile-bearing, graphitic, peraluminous metapelites equilibrated at 3-6 kbar is generally consistent with independent temperature determinations, but with some deviations that represent local reequilibration. Consequently, the Ti systematics in biotite can also serve as the basis of a very sensitive indicator of chemical equilibrium, or lack thereof. Application of the geothermometer to metapelites not containing the requisite mineral assemblages can lead to minor-to-significant errors in estimated temperatures. Biotite Ti-substitution mechanisms are controlled by several factors. Based on the biotite calibration data set, magnesian biotites {[X.sub.Mg] > 0.65) incorporate Ti in accordance with the exchange vector Ti[Al.sub.2][R.sub.-1][Si.sub.-2], where R is the sum of the divalent cations Mg + Fe + Mn. This substitution mechanism is primarily a response to misfit of the octahedral and tetrahedral layers in magnesian biotites. Intermediate biotites ([X.sub.Mg]

We examine the nature and temporal trends of science journal publishing, and seek to explain why some journals have higher Journal Impact Factors (JIF) than others. The investigation has implications for how we assess the importance of scientific contributions. National Laboratories run by the U.S. Department of Energy, for example, compare JIF across disciplines, while some academic institutions look at JIF when evaluating publication records. Problematic to these policies are several results, which have long been known in the medical and biological sciences, and are shown here to apply to the Earth sciences as well. In particular, citations are distributed almost logarithmically in any given issue of a journal, and so JIFs say nothing about the actual number of citations acquired by any given paper. In the area of mineralogy and petrology, for example, 25% of articles in a typical issue will capture >50% of all citations that accrue to that issue. For some issues the asymmetry is greater; we use such citation asymmetry to develop a classification for journals as "super elite," "elite," "influential," and "minor." We also find that JIFs are inherently larger for large disciplines, in part because as the size of a discipline increases (as measured by total papers published), the top journals benefit to a greater extent than other journals. For this and other reasons, JIF cannot be compared across disciplines. A heretofore unknown and disconcerting result is the incredible growth in JIFs for commercially published journals compared to their society-published counterparts--a growth that coincides with the advent of electronic distribution models (e.g., bundling) that were instituted by commercial publishers at the beginning of the 21st century. Journals, which only a decade ago had similar JIFs, and were viewed as being scientifically equivalent, now have very different JIFs. These contrasts may nucleate feedback loops (as authors look to higher JIF journals in which to publish) that threaten the health of society-published journals. Our analysis however, shows that in spite of growing contrasts in JIF, many society-published journals still provide a greater value (JIF/cost) compared to their commercially published counterparts. While we acknowledge that citations and citation rates can be useful tools to compare scientific influence and importance, the results of this and other bibliometric studies cause us to conclude that in the evaluation of science and scientists, it is a grave error to substitute numerical values for human judgment. And if professional societies are to continue to play a significant role in science publication, it is incumbent upon scientists--now more than ever--to send their best works to society-published journals. [ABSTRACT FROM AUTHOR]

A 50 m drill core (core no. 383-334) collected from the contact metamorphic aureole in the Mouat Ni-Cu prospect in the Mountain View area of Stillwater County, Montana, exhibits evidence of in situ fluid-absent biotite dehydration melting and local back reaction of melts derived from metasediments and metavolcanics. The drill core was investigated to characterize the mineral assemblages and their textures, to search for evidence of partial melting, and to determine mineral and whole-rock geochemistry to provide an understanding of the petrogenesis of the hornfels close to the contact with the Stillwater Complex. The rocks investigated are predominantly quartz-plagioclase-cordierite-orthopyroxene-biotite ± spinel hornfels, Fe-Cu-Ni sulfides, and Fe-Ti oxides. One sample contains garnet (Alm73-77Pyr20-17Sps3Grs4) in addition to cordierite. Three samples contain cordierite-hercynite symplectites surrounded by a narrow mantle devoid of orthopyroxene, plagioclase, and biotite that are roughly ovoid to lenticular in shape. Partially melted samples show back reaction between crystallizing melt and restite such that retrograde skeletal intergrowths of biotite and quartz in the mesosome were developed. Average T-P conditions of hornfels and melt genesis are 786 °C and 3.7 kbar. Back reactions that produced biotite occurred at somewhat lower temperatures. Whole-rock geochemistry suggests that the protolith of the hornfelsic rocks was likely a mixture of greywacke and additional intermediate to mafic volcanogenic components. [ABSTRACT FROM AUTHOR]