HR: 13:40h
AN: V13H-01 INVITED     [Abstracts]
TI: The McMurdo Dry Valleys Magmatic Laboratory Workshop of 2005 in Antarctica
AU: * Marsh, B D
EM: bmarsh@jhu.edu
AF: Morton K. Blaustein Department of Earth & Planetary Sciences, Johns Hopkins University, 3400 N. Charles St. Olin Hall, Baltimore, MD 21218 United States
AU: Simon, A
EM: Adam.Simon@ccmail.nevada.edu
AF: Morton K. Blaustein Department of Earth & Planetary Sciences, Johns Hopkins University, 3400 N. Charles St. Olin Hall, Baltimore, MD 21218 United States
AU: Charrier, A D
EM: charrier@jhu.edu
AF: Morton K. Blaustein Department of Earth & Planetary Sciences, Johns Hopkins University, 3400 N. Charles St. Olin Hall, Baltimore, MD 21218 United States
AU: Hersum, T G
EM: hersum@jhu.edu
AF: Morton K. Blaustein Department of Earth & Planetary Sciences, Johns Hopkins University, 3400 N. Charles St. Olin Hall, Baltimore, MD 21218 United States
AU: Eschholz, E
EM: erika.eschholz@usap.gov
AF: Raytheon Polar Services, McMurdo Station, McMurdo, Antarctica
AB: In January of 2005, twenty-five petrologists, volcanologists, geochemists, structural geologists, and magma dynamicists spent two weeks studying and discussing the Magmatic Mush Column represented by the 180 Ma Ferrar Dolerites of the McMurdo Dry Valleys, Antarctica. This exceptionally well-exposed system shows a series of massive interconnected sills culminating in a capping of regional flood basalts. The lowermost sill, the Basement Sill, contains a massive ultramafic tongue of large phenocrysts of orthopyroxene (Opx) with subordinate Cpx and much smaller plagioclase. The 3-D distribution of this Opx Tongue serves as a tracer for the filling dynamics and local motion of the magma. Ponding of the Basement Sill has resulted in a small (500 m), but exceedingly diversified and extensively layered ultramafic intrusion, the Dais Intrusion. Because of the relatively rapid cooling time of this body, the Dais textures have been preserved before extensive annealing, which presents the possibility of using these textures to understand those of much larger, slowly cooled bodies. The combination of seeing in detail a wide variety of exceptional field relations depicting layering, sill emplacement mechanics, internal ordering and crystal sorting in the Opx Tongue, dike and fissure distributions, wall rock thermal effects, and many other first order features of central interest to understanding magmatic processes and performing research in real time was a new challenge to all involved. Facilities were set up at McMurdo Station for rock cutting, thin-section making, map making, GIS analysis, petrographic analysis, and computer modeling using existing chemical and physical data on a spectrum of the representative rock types. At any one time half the group was housed in the field in Bull Pass near Wright Valley and the remaining group was shuttled in by helicopter each day. The principal groups were switched about every three days. Areas for daily field-work were decided upon by each individual through daily sign up sheets and field parties were shuttled to these locations each morning either from camp or directly from McMurdo. Even though this system presented unusually challenging logistical efforts, the system worked smoothly and routinely and the maximum possible science was carried out in the available time. Many new scientific insights were made into the formation, operation, petrogenesis, and dynamics of this magmatic system, which are directly applicable to planetary magmatism in general. Moreover, students were able to see in real time the process of research by groups of seasoned professionals. Hats off to the National Science Foundation, to the helicopter Pilots of PHI, to the support teams in McMurdo and Bull Pass, and to the participants for a safe and enormously productive scientific expedition.
DE: 3640 Igneous petrology
DE: 3699 General or miscellaneous
DE: 8499 General or miscellaneous
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005