Journal of Petrology | Volume 39 | Number 10 | Pages 1787-1804 | 1998
© Oxford University Press 1998
Fluid-Absent Melting Behavior of a Two-Mica Metapelite: Experimental Constraints on the Origin of Black Hills Granite
Department of Geological Sciences, University of Oregon Eugene, or 97403-1272, USA
Received May 22, 1997; Revised typescript accepted April 17, 1998
 |
Abstract |
|---|
We have studied experimentally the vapor-absent melting behavior of a Proterozoic metapelite (HP-60-1) from the Black Hills, South Dakota, to assess whether the high-
18O, tourmaline-bearing granites of the Harney Peak suite resulted from muscovite-dominated dehydration-melting at 10 kbar. Samples were sealed with no added H2O in gold capsules, then run in a 0.5 inch (1.27 cm) piston-cylinder apparatus over the temperature interval 812–975°C. Experiments were conducted at 10 kbar to allow comparison with other metapelite melting studies. Mass balance calculations imply the melting reaction muscovite + biotite + plagioclase + quartz 
melt + alkali feldspar + aluminosilicate + garnet until muscovite is exhausted (<812°C), then the reaction biotite + plagioclase + quartz + alkali feldspar ± aluminosilicate melt + garnet. The inferred muscovite reaction is completed below 812°C and produces 1–2 wt % melt. Melt production of the continuous biotite reaction increases steadily with rising temperature, to 32 wt % in our highest temperature run. The low melt productivity of the muscovite reaction at 10 kbar suggests that melting at lower pressures may be necessary to generate mobile melt fractions by muscovite-dominated reactions in our starting material. In addition, melts of HP-60-1 are considerably more mafic than the tourmaline-bearing granites, with average combined TiO2 + MgO + FeO contents of 1.85 wt % and 0.84 wt %, respectively. In particular, melts of HP-60-1 are enriched in Ti, and would probably stabilize biotite rather than tourmaline upon cooling, arguing against HP-60-1 as a potential source rock for the tourmaline granites.
KEY WORDS: Black Hills; dehydration-melting; granite; metasediments; muscovite
* Corresponding author. Fax: 541-346-4692. e-mail: pick{at}darkwing.uoregon.edu
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  A. Acosta-Vigil, I. Buick, J. Hermann, B. Cesare, D. Rubatto, D. London, and G. B. Morgan VI Mechanisms of Crustal Anatexis: a Geochemical Study of Partially Melted Metapelitic Enclaves and Host Dacite, SE Spain J. Petrology, February 6, 2010; (2010) egp095v1. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J.D. Clemens The message in the bottle: "Melt" inclusions in migmatitic garnets Geology, July 1, 2009; 37(7): 671 - 672. [Full Text] [PDF]
|
|
|
|
|
|
F. Ferri, S. Poli, and D. Vielzeuf An Experimental Determination of the Effect of Bulk Composition on Phase Relationships in Metasediments at Near-solidus Conditions J. Petrology, May 8, 2009; (2009) egp026v1. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Stevens, A. Villaros, and J.-F. Moyen Selective peritectic garnet entrainment as the origin of geochemical diversity in S-type granites Geology, January 1, 2007; 35(1): 9 - 12. [Abstract] [Full Text] [PDF]
|
|