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Hi Mike, The impulse to chide you (and share it with the list) for clicking the "bonehead reply" button is overwhelming and irresistible. Your paper does sound good, however - hope nobody poaches the idea. Cheers, Bob T. Michael Brown wrote: > Dear Santosh: > > Thanks for the initiative to produce a Special Volume as a tribute to > Miyashiro's vision and contributions to various fields in the Earth > Sciences. I am interested in possibly contributing a paper with a > title something along the lines of "Paired Metamorphic Belts > Revisited". This paper would summarize prescient features of > Miyashiro's original contribution in 1960, how our understanding of > paired metamorphic belts has evolved during the subsequent half > century, and how the concept may be extended back through time given > due consideration to increased heat production and differences in the > style of metamorphism. > > I am very strongly motivated to contribute to this volume, since I > have a long-standing interest in paired metamorphic belts as well as > how the concept might be applied earlier in Earth history. However, I > would like to know the potential time frame for producing the volume > to ensure that I can meet the commitment. I look forward to hearing > from you further with respect to deadlines. > > My possible contribution is described in more detail below. > > With best regards, > Yours sincerely, > Mike > > > *Paired Metamorphic Belts Revisited > * > Michael Brown, Department of Geology, University of Maryland, College > Park, MD 20742-4211, USA > > Classic paired metamorphic belts in which an inboard high dT/dP > metamorphic belt is juxtaposed against an outboard low dT/dP > metamorphic belt along a tectonic contact are found in accretionary > orogens of the circum-Pacific. Generally, they appear to result from > tectonic juxtaposition of terranes with different metamorphic facies > series that may or may not be exactly contemporaneous and that may or > may not be far-traveled. This is an inevitable consequence of the > difference between contemporaneous subduction, generating low dT/dP > blueschists and eclogites in the subduction zone and extension in an > arc--backarc system with formation of depositional basins, compared > with the timing of events such as ridge subduction or deformation and > thickening of the arc--backarc system, generating high dT/dP metamorphism. > One issue to consider is whether to extend the concept of 'paired > metamorphic belts' more widely than accretionary orogens to > subduction-to-collision orogenic systems. The modern plate tectonics > regime is characterized by a duality of thermal environments, the > subduction zone and the suture zone of subduction-to-collision > orogens, and the backarc or orogenic hinterland, in which contrasting > types of regional-scale metamorphic belts are being formed > contemporaneously. I consider this duality to be the hallmark of > one-sided subduction, and the characteristic imprint of one-sided > subduction in the geological record will be the broadly > contemporaneous occurrence of two contrasting types of metamorphism > reflecting this duality of thermal environments. On this basis, I > define paired metamorphic belts as penecontemporaneous belts of > contrasting type of metamorphism that record different apparent > thermal gradient, one warmer and the other colder, juxtaposed by plate > tectonics processes. > By this definition, the combination of granulite-ultrahigh > temperature metamorphism with eclogite-high-pressure granulite > metamorphism from the Neoarchean Era to the Neoproterozoic Era may be > described as a paired metamorphic belt. This extends the original > concept of Miyashiro (1961) beyond the simple pairing of high dT/dP > and low dT/dP metamorphic belts in circum-Pacific accretionary > orogens, and makes it more useful in the context of our better > understanding of the relationship between thermal regimes and tectonic > setting. This is particularly useful in subduction-to-collision > orogenic systems, where an accretionary phase is overprinted by a > collision phase that will be registered by the imprint of > penecontemporaneous low-to-intermediate dT/dP and high dT/dP > metamorphism in the rock record. > > > > > At 12:17 AM 2/12/2009, you wrote: >> >> >> Dear Colleagues, >> >> Students, friends and colleagues of Late Prof. Miyashiro are planning >> a special volume as a tribute to his vision and contributions in the >> various fields of Earth Sciences. >> >> The special volume will assemble benchmark papers on different themes >> including metamorphism, thermodynamics, orogeny, exhumation >> processes, mantle dynamics (including geophysics), volcanic rock >> series, ophiolites, eclogites, and other related topics. >> Contributions under individual themes are expected to cover the >> historical outline, state-of-the-art and vision for the future. Among >> the contributors are Gary Ernst, Julian Pearce, Ned Brown, Surendra >> Saxena, Jibamitra Ganguly, Celal Sengor and Shun-ichiro Karato. >> >> Those who are interested to participate by contributing high quality >> papers to the volume as a tribute to Late Prof. Miyashiro, please >> e-mail us before March 10, 2009 together with the tentative title and >> a half page synopsis of the proposed contents. >> >> >> The special volume will be brought out in the multidisciplinary >> geoscience journal 'Gondwana Research' published by Elsevier. >> >> (Journal Home Page: www.elsevier.com/locate/gr >> <http://www.elsevier.com/locate/gr> ) >> >> (ScienceDirect page: >> http://www.sciencedirect.com/science/journal/1342937X) >> >> >> Thanks and best regards, >> >> Santosh >> >> ________________________________________________________ >> >> M. Santosh >> Professor of Geology & Editor-in-Chief, Gondwana Research >> Department of Natural Environmental Science >> Kochi University >> Akebono-cho 2-5-1, Kochi 780-8520, Japan >> Fax and phone: +81-88-844-8278 >> E-mail: [log in to unmask] <mailto:[log in to unmask]> >> > > __________________________________________________________ > > Michael Brown, Professor of Geology and Chair of > Department > > Department of Geology > Geology Building (#237) > University of Maryland > College Park > MD 20742-4211 > USA > > [log in to unmask] > http: www.geol.umd.edu > <http://www.geol.umd.edu/>Exec. asst.: 301 405 4065; Dept. office: 301 > 405 4082; Direct line: 301 405 4080 > Direct fax: 301 314 7970; Dept. fax: 301 314 > 9661 > > LABORATORY FOR CRUSTAL PETROLOGY (Information at: > http: www.geol.umd.edu/pages/faculty/BROWN/LCP/lcp.htm > <http://www.geol.umd.edu/pages/faculty/BROWN/LCP/lcp.htm>) > __________________________________________________________ > -- Dr. Robert J. Tracy Professor of Geosciences Department of Geosciences 5064 Derring Hall, Virginia Tech Blacksburg VA 24061-0420 Office Phone: 540-231-5980 Fax: 540-231-3386 e-mail: [log in to unmask]