Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Journal of the Geological Society

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Holness, M.B. Search for Related Content GeoRef GeoRef Citation

Textural immaturity of cumulates as an indicator of magma chamber processes: infiltration and crystal accumulation in the Rum Eastern Layered Intrusion

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK (e-mail: marian@esc.cam.ac.uk)

Textural maturity describes the extent to which rocks have approached textural equilibrium. For igneous rocks, this is a function of the time-integrated thermal history in the sub-solidus which, for cumulate rocks, generally translates to the cooling history via the rate of solidification of the accumulating crystal mush. The most straightforward way to quantify the textural maturity of orthocumulates (sensu lato) is to measure the angle subtended at the corners of interstitial grains. Texturally mature cumulates have angle populations with median values of c. 120°, whereas texturally immature cumulates have lower medians, inherited by the interstitial phase, which infills either an impingement texture in the accumulating mush or a texturally equilibrated pore topology. Textural observations of allivalites from the Rum Layered Suite demonstrate that stratigraphically localized excursions towards textural immaturity are the result of either transient, relatively rapid, solidification rates (perhaps a result of the arrival of cold crystal-laden bodies of fluid on the chamber floor) or late-stage infiltration of fully solidified cumulates by evolved liquids expelled upwards by compaction of underlying horizons. These two processes have distinct textural and compositional signatures.

This article has been cited by other articles:

				M. B. HOLNESS and B. WINPENNY The Unit 12 allivalite, Eastern Layered Intrusion, Isle of Rum: a textural and geochemical study of an open-system magma chamber Geological Magazine, May 1, 2009; 146(3): 437 - 450. [Abstract] [Full Text] [PDF]

				M. B. Holness, S. A. Morse, and C. Tegner Response to Comment by McBirney, Boudreau and Marsh J. Petrology, January 1, 2009; 50(1): 97 - 102. [Full Text] [PDF]

				M. B. Holness, C. Tegner, T. F. D. Nielsen, G. Stripp, and S. A. Morse A Textural Record of Solidification and Cooling in the Skaergaard Intrusion, East Greenland J. Petrology, December 1, 2007; 48(12): 2359 - 2377. [Abstract] [Full Text] [PDF]