HR: 08:20h
AN: T21E-02    [Abstracts]
TI: Strategies for Recovering the `Lost` Oceanic Large Igneous Province (LIP) Record of Paleozoic-Proterozoic Time
AU: * Ernst, R E
EM: Richard.Ernst@ErnstGeosciences.com
AF: Ernst Geosciences, 43 Margrave Ave., Ottawa, ON K1T 3Y2 Canada
AU: Buchan, K L
EM: kbuchan@NRCan.gc.ca
AF: Geological Survey of Canada, 601 Booth St., Ottawa, ON K1A 0E8 Canada
AB: During the past ca. 200 Myr the record of large igneous provinces (LIPs) indicates that they have occurred at a rate of about one per 10 Myr, about half of this due to oceanic LIPs. On the other hand, few oceanic LIPs have been identified in the Proterozoic and Paleozoic. This is undoubtedly due largely to poor preservation potential of oceanic LIPs during subduction. Because the average rate of continental LIP production throughout the entire Proterozoic and Phanerozoic period (including within the last 200 Myr) was approximately constant at about one per 20 Myr, then we can infer that the oceanic LIP production rate was also broadly constant throughout this time period. If we extrapolate the more recent oceanic LIP production rate of approximately one per 20 Myr to earlier times, we can infer that there are more than 100 unrecognized oceanic events in Proterozoic-Paleozoic time. Strategies for recovering this `lost' LIP oceanic record include: 1) recognizing which ophiolites and other accreted volcanic/plutonic packages are of LIP affinity, 2) tracing giant dyke swarms (up to 2500 km in length) that radiate from `lost' oceanic LIP centres onto formerly adjacent continental landmasses.
UR: http://www.largeigneousprovinces.org
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8137 Hotspots, large igneous provinces, and flood basalt volcanism
DE: 8140 Ophiolites (3042)
DE: 8178 Tectonics and magmatism
DE: 8416 Mid-oceanic ridge processes (1032, 3614)
SC: Tectonophysics [T]
MN: Fall Meeting 2005