HR: 0830h
AN: V51A-01    [Abstracts]
TI: Evolution of the Icelandic Convective System: Correlation Between Numerical and Real Data
AU: * Rakhmenkulova, I
EM: iraida0205@yahoo.com
AF: Novosibirsk State University, 2 Pyrogova Street, Novosibirsk, 630090 Russian Federation
AU: * Rakhmenkulova, I
EM: iraida0205@yahoo.com
AF: Institute of Geology, 3 Koptyug Pr., Novosibirsk, 630090 Russian Federation
AU: Sharapov, V
EM: vik@uiggm.nsc.ru
AF: Novosibirsk State University, 2 Pyrogova Street, Novosibirsk, 630090 Russian Federation
AU: Sharapov, V
EM: vik@uiggm.nsc.ru
AF: Institute of Geology, 3 Koptyug Pr., Novosibirsk, 630090 Russian Federation
AU: Perepechko, Y
AF: Institute of Geology, 3 Koptyug Pr., Novosibirsk, 630090 Russian Federation
AU: Zhmodik, A
AF: Institute of Geology, 3 Koptyug Pr., Novosibirsk, 630090 Russian Federation
AB: The problem of hotspot existence under Large Igneous Provinces (LIP) is very disputable. However, the results of numerical modeling show that a `hotspot scheme' explains rather reasonably what we have in reality. In this work we take the existence of the hotspot under the Icelandic Convection System with a temperature 1920°C for granted. Convection in the upper mantle was taken as a mechanism for the melting zone development. Temperature distribution with depth in the upper mantle was taken in such a way that in the absence of a hot spot a convection cycle was well-developed. We tried to model the evolution of Iceland and to understand how the plate geometry influences such parameters as the 'asthenolens' existence time, the degree of melt and its chemical composition, the 'asthenonens' location and geometry. Several runs for various volcanic shield thicknesses, starting from oceanic crust, 7 km (when Iceland did not exist), to continental, 30 km, have been completed. In this way we modeled the evolution of Iceland from its origin to the present state. The results show that as the shield thickens from 7 to 30 km: 1) the existence time for the 'asthenolens' decreases from ~ 47 to 40 Ma 2) the maximum melt volume decreases from 4.784×10¹² kg/km³ to 2.546×10¹² kg/km³ 3) the degree of melt decreases from about 16% to 12% 4) the upper boundary of the 'asthenolens' deepens for more than about 10 km. Thus the results of our modeling show that the hotspot under the Icelandic Convection System is dying at present time. The model used will be developed to verify possible melting extents for the lithosphere rocks above the convection zone. Both the data for the melting zone extent and the system existence time are in rather good correlation with geologic and geophysical data. This work was supported by the RFBR (Grants No. 04-05-64276, No. 04-05-64107, and No. 04-05-64332).
DE: 8400 VOLCANOLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2005 Joint Assembly