 |
| Titel |
Early Holocene volcanism in CKD (Kamchatka) as a mechanical probe of the
stress level in the crust. |
| VerfasserIn |
Alexander Simakin, Olga Shaposhnikova |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129096
|
| Publikation (Nr.) |
 EGU/EGU2016-9164.pdf |
|
|
|
|
|
| Zusammenfassung |
| The last (late Pleistocene) glaciation in Kluychevskaya group of volcanoes (KGV) can be
considered as a large scale mechanical experiment allowing evaluation of the level of the
global geodynamic stresses in the crust of North Kamchatka. KGV is located in the
Central Kamchatka depression (CKD). Formation of the CKD can be connected with
accretion of Kronotsky paleoarc to the Kamchatka edge c.a. 5 Mys ago. At the
compression stage zone of the contact was thickened so that lower part can reach PT
parameters of basalt-eclogite transition. Suggested carbonates contamination of the
mantle wedge during accretion (Simakin et al., 2015) can became a source of CO2
facilitating eclogite formation. Dense eclogitic keel and trench retreat following
accretion can be the driving forces of the CKD rift formation. Extension is partially
accommodated (several mm/yr eastward motion) on the eastern border of CKD in
the zone of the normal faulting (Kozhurin et al., 2006). And partially extension is
accommodated by the formation of the series of dykes of submeridional direction
marked by monogenic cones on the surface. At the last phase of the Pleistocene
glaciation KGV was covered by the ice cap with 80 km diameter and above 1000 m
maximum thickness on the slopes. After the fast deglaciation surface uplift has produced
horizontal compression (Simakin and Muravyev, 2015; Pagli and Sigmundsson,
2008). Addition of the deglacial compression to the geodynamic extension turns s1
direction to the horizontal latitudinal one. Due to the horizontal compression areal of
eruptions was expanded towards edges of the former glacier. Numerical modeling
demonstrates that maximum level of the glacial stress is proportional to the ice
gravity load and is estimated to be 5.8-7.5 MPa. Initially principle compressive
stress due to the deglaciation was higher than geodynamic one abs(s1,glac) >
abs(s1,geod). Time of the volcanism return to the basic submeridional direction marked
the moment of viscous dissipation of the post glacial stresses: abs(s1,glac) <<
abs(s1,geod).
Literature. Kozhurin et al.(2006) Tectonophysics, 417(3-4), 285-304. Simakin et al.
(2015) J.Volcanol.Geotherm.Res., 307, 210-221. Simakin and Muravyev (2015) Volcanology
and Seismology, in press. Pagli and Sigmundsson (2008) Geophys. Res. Lett. 35. L09304. |
|
|
|
|
|
|