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GSA Penrose Conference on Ophiolites and Oceanic Crust

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No. 34 of the 1997 Series of E-mail Announcements from the InterRidge Office
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GEOLOGICAL SOCIETY OF AMERICA PENROSE CONFERENCE

OPHIOLITES AND OCEANIC CRUST:
NEW INSIGHTS FROM FIELD STUDIES AND OCEAN DRILLING PROGRAM
____________________________________________________________

A Geological Society of America Penrose Conference, "Ophiolites and Oceanic
Crust: New Insights from Field Studies and Ocean Drilling Program" will be
held September 13-17, 1998, at Marconi Center, Tamales Bay, California.
Ophiolites have been of particular importance in the reconstruction of
ancient plate boundaries ever since their recognition as on-land fragments
of oceanic lithosphere.  They are good structural analogues for oceanic
crust and provide 3-dimensional exposures and age relations to study the
nature of extensional tectonics and magmatic construction at oceanic
spreading environments.  They complement significantly our knowledge of the
architecture and generation of oceanic crust that is derived mainly from
seismic images and drill holes at mid-ocean ridges.  Recent
multidisciplinary studies of drilled core samples of modern oceanic crust
from the Mid-Atlantic Ridge, Costa Rica Rift, Hess Deep, Southwest Indian
Ridge, Lau Basin, Izu-Bonin-Mariana forearc, and Tonga forearc have provided
significant information on the mantle heterogeneity, magma chamber
processes, melt migration, structural and tectonic processes in deformation
of oceanic crust, and geochemical evolution of magma at these modern
tectonic settings.  The goal of this conference is to bring together a
multidisciplinary group of geoscientists from the communities of ophiolite
geology and marine geology/geophysics to re-evaluate the existing models on
ophiolite formation and oceanic crust generation, and to explore the
possibility of reaching a new consensus on the nature and significance of
ophiolites and oceanic crust for present plate tectonic processes and for
processes in the geological past.  The timing of this conference coincides
with the 25th anniversary of the first Penrose Field Conference on
ophiolites, during which an ophiolite pseudostratigraphy was formally
defined, and gives us a great opportunity to appraise our accumulated
knowledge during the last quarter of a century.

The main themes of the conference are : 
(1) Structure/tectonics of ophiolites and ophiolite-ocean crust analogy; 
(2) Structural and magmatic processes at spreading centers; 
(3) Hydrothermal alteration, serpentinization & mineralization; 
(4) Petrology and geochemistry of ophiolites and oceanic crust; 
(5) Sedimentation and sedimentary cover of ophiolites and oceanic crust; 
(6) Fracture zone tectonics in ophiolite/ocean crust geology; 
(7) Ophiolite emplacement, melange problem, and metamorphic soles; 
(8) Outstanding problems and future studies in ophiolite/ocean crust
geology, and drilling into oceanic crust in the 21st Century. 

 Thematic sessions will include short lecture(s), poster presentations, and
group discussions; poster presentations will be a significant component of
the conference to facilitate interactions and group discussions.  A one-day
field trip to the California Coast Ranges will explore the Late Jurassic
Coast Range Ophiolite and its sedimentary cover, the Franciscan melange, and
the structural relations between the ophiolite, melange, and forearc basin
(Great Valley Sequence).  The field trip is an integral part of the
conference and will serve as a catalyst to discuss most aspects of the theme
sessions by the outcrop.
	
The current interpretations of a typical ophiolite pseudostratigraphy and
oceanic crust-ophiolite analogy deviate significantly from that defined at
the first Penrose Conference on ophiolites, and a number of geological and
geophysical models have been put forward in recent years to explain the
deformed and "incomplete" nature of oceanic crust (as opposed to a
"layer-cake" model of the late 1970's).  An open discussion on these new
models and ideas by geologists, geochemists, and geophysicists in the
framework of this conference will help in their evaluation and will provoke
new research fields and questions on ophiolite-oceanic crust geology.
Furthermore, study of ophiolites and oceanic crust has become increasingly
multidisciplinary, as the interplay between tectonic and magmatic activities
during seafloor spreading and spatial and temporal relations between
deformation and hydrothermal alteration during the evolution of oceanic
crust necessitate this sort of collaborative approach between the
disciplines in quantitative studies of ophiolites and oceanic crust.  We
anticipate that this conference will provide an excellent forum for
cross-pollination of ideas from investigators working on ophiolites and
modern oceanic crust and from diverse approaches of structural geology,
petrology-geochemistry, and geophysics.  

Participation in the conference will be limited to 80 people.  Participants
will be selected to include broad representation of different relevant
disciplines, particularly from scientists participated in projects of the
Ocean Drilling Program, and researchers from the marine geology/geophysics
and ophiolite geology communities.  Graduate students are encouraged to
apply; a partial subsidy will be available to some graduate students.  The
registration fee, which will cover lodging, meals, field trips, and ground
transportation during the meeting, is not expected to exceed $700.

	Co-Conveners of the conference are:
Yildirim Dilek, Department of Geology, Miami University, Oxford, OH 45056;
Phone: (513) 529-2212; Fax: (513) 529-1542; E-mail: dileky at muohio.edu

Don Elthon, Division of Ocean Sciences, National Science Foundation,
Arlington, VA 22230; 	Phone: (703) 306-1586; Fax: (703) 306-0390; E-mail:
delthon at nsf.gov

Eldridge M. Moores, Department of Geology, University of California, Davis,
CA 95616; Phone: (530) 752-0352; Fax: (530) 752-0951; E-mail:
moores at geology.ucdavis.edu

Adolphe Nicolas, Laboratoire de Tectonophysique, Universite Montpellier II,
34095 Montpellier cedex 05, France; Phone: +33 (0)467 14 36 02; Fax: +33
(0)467 14 36 03; E-mail: tectono at dstu.univ-montp2.fr

The application deadline is March 16, 1998.  Formal invitation to
participants will be mailed by May 1, 1998.  Potential participants should
send a letter of application to Yildirim Dilek at the above address.
Applicants should include a brief statement indicating their area of
interest, the relevance of their recent work to the themes of the meeting,
and the subject of their presentation at this conference.

____________________________
Dr. Yildirim Dilek
Department of Geology
114 Shideler Hall
Miami University
Oxford, OH 45056
Phone: +1 (513) 529-2212
Fax: +1 (513) 529-1542
E-mail: dileky at muohio.edu
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