Hi Johannes,
Gas certainly may be present in fractures within halite eg.Terrinha et al.
1994. Smith (1996) records fractures, some of which are gas-filled in the
Permian Boulby Halite of NE England. In addition, Aptian age halite and
sylvinite in the Petromisa Mine of NE Brazil also contains gas-filled
fractures. This salt is at a depth of 300m with long range gas migration
occuring through the fractures - open fractures filled with methane gas are
also observed in the mine (Davison et al. 1996). Typically, rather than
being explosion-linked, fractures within sedimentary rocks adjacent to the
salt are related to near surface dissolution processes, thus encouraging
overburden collapse and brecciation. Such dissolution and collapse may
locally generate ~150m deep circular "sink hole" features eg Velaj et al.
1999.
Bestwishes
Ian Alsop
References
Terrinha, P., Ribeiro, A. & Coward, M.P. 1994. Mesoscopic structures in a
salt wall. The Loule salt wall diapir, Algarve Basin, south Portugal. Salt
Tectonics meeting, Geological society, London, 14-15th September 1994.
Abstract.
Smith, D.B. 1996. Deformation in the late Permian Boulby Halite (EZ3Na) in
Teeside, NE England. In: Alsop, G.I., Blundell, D.J. & Davison, I.
(Editors) Salt Tectonics, Special Publication of the Geological Society of
London 100, 77-87.
Davison, I., Alsop, G.I. & Blundell, D. 1996. Salt Tectonics: some aspects
of deformation mechanics. In: Salt Tectonics, Special
Publication of the Geological Society of London 100, 1-10.
Velaj, T., Davison, I., Serjani, A. & Alsop, .I. 1999. Thrust tectonics and
the role of evaporites in the Ionian Zone of the Albanides. Bulletin of
the American Association of Petroleum Geologists 83, 1408-1425.
>Hi everybody,
>I have encountered "buchites" in my work. To all: buchites are an old
>term for contact metamorphism-related glasses. Does anybody know modern
>analytical work on these guys? I am also interested in state-of-the-art
>studies of fenitization, brecciation related to fenitization.
>Did anybody read about dissolution of halite accompanied by explosions?
>I found a remark, that halite can host rather large quantities of gas
>(i.e. CO2), after pressure release, halite is supposed to dissolve and
>the expanding gas can fracture rocks (!?).
>
>thank you and best wishes
>Johannes H. Obenholzner
>NHM/Mineralogy-Vienna
>
>Ben Harte wrote:
>
>> Following the raising of the question concerning
>> an IUGS commission on metamorphic
>> nomenclature, I think I should give the following
>> additional information.
>>
>> There is a Subcommission on the Systematics of
>> Metamorphic Rocks (SCMR), which is a branch
>> of the IUGS Commission on systematics in
>> Petrology. The subcommission is in fact at an
>> advanced stage in its deliberations and plans to
>> produce a series of papers on different aspects of
>> the nomenclature of metamorphic rocks and a
>> comprehensive glossary. Although the completion
>> of these documents has been rather delayed, I
>> believe they will come forward in the next few
>> months.
>>
>> The website of the SCMR is at:
>> http://www.bgs.ac.uk/SCMR.
>> Its new executive chairman is Doug Fettes
>> <[log in to unmask]>; and the executive secretary is
>> Jacqueline Desmons <[log in to unmask]
>> nancy.fr>
>>
>> Regards all,
>> Ben
>>
>> Ben Harte
>> Dept Geology & Geophysics,
>> University of Edinburgh, King's Buildings,
>> Edinburgh EH9 3JW,
>> Scotland, UK
>> (FAX 44 131 668 3184)
>> FAX: [44] (0)131 668 3184
Dr. Ian Alsop
Crustal Geodynamics Group,
School of Geography & Geosciences,
University of St. Andrews,
St. Andrews, Fife, KY16 9AL UK.
Tel. (01334) 46 3937
FAX (01334 46 3949
e-mail [log in to unmask]
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