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An isotope-geochronological study has been performed to examine the products of Late Cenozoic collision volcanism on the northern
coast of Lake Van, Turkey. We obtained 45 new K—Ar dates, based on which the principal time characteristics of volcanic activity
in the region have been determined. Volcanic activity in the northern coast of Lake Van has lasted ∼15 myr; it has had an
expressed discrete nature, when periods of intense volcanic activity alternated with long-lasting pose periods. Four stages
of Neogene—Quaternary volcanism have been identified: Middle Miocene (15.0—13.5 Ma), Late Miocene (10—9 Ma), Pliocene (5.8—3.7
Ma), and Quaternary (1.0—0.4 Ma). The average duration of the stages was 1—2 myr; the stages were separated from each other
with periods of inactivity of approximately equal lengths (∼3 myr). For each of the Pliocene and Quaternary stages, three
additional phases of volcanism have been identified, which were separated from each other with short time intervals (a few
hundred thousand years). The last burst of volcanic activity in the study area occurred ∼400 ka; similar to Quaternary volcanism
in general, it was not characterized by a high intensity. An important result of the studies performed was to confirm the
existence of a separate Middle Miocene stage of collision volcanism for the Caucasian—Anatolian Segment of the Alpine Fold
Belt. New geochronological data generated presented in this paper indicate that Neogene—Quaternary volcanism in this portion
of the belt started much earlier (∼15 Ma) than assumed by the majority of the previous researchers. 相似文献
2.
M. Keskin A. V. Chugaev V. A. Lebedev E. V. Sharkov V. Oyan O. Kavak 《Journal of Volcanology and Seismology》2012,6(6):352-360
This paper considers results from isotope-geochronological (K-Ar) studies of the products of Neogene-Quaternary volcanism in the Karacada? area, which is situated within the northern frontal part of the Arabian plate. It was found that magmatic activity has been evolving at this location for at least the last 11–10 Myr and was distinctly discrete in character. Three stages of volcanism have been identified: (I) Early or Miocene, ～11–6.7 Ma; (II) Middle or Pliocene-Early Quaternary, 4–1 Ma; and (III) Late or Late Quaternary, 0.4–0.1 Ma. The most recent manifestations of magmatic activity in the region date back to about 100000 years ago. An analysis of the spatial distribution of volcanic centers of different ages in the Karacada? neovolcanic area shows that the magmatism of that region involved a lateral migration of activity from northwest to southeast along a major regional tectonic fault. The migration was caused by the movement of local tension zones where the lithosphere was thinner and deep-seated mantle magmas were ascending. 相似文献
3.
Geochronology of Late Cenozoic volcanism in the area of Van Lake,Turkey: An example of development dynamics for magmatic processes 总被引：1，自引：0，他引：1
An isotope-geochronological study has been performed to examine the products of Late Cenozoic collision volcanism on the northern
coast of Van Lake, Turkey. We obtained 45 new K-Ar dates, based on which the principal time characteristics of volcanic activity
in the region have been determined. The total duration of magmatic activity in the area of the northern coast of Van Lake
has lasted ∼15 myr; it has had an expressed discrete nature, when periods of intense volcanic activity alternated with lasting
breaks in eruptions. Four stages of Neogene-Quaternary volcanism have been identified: Middle Miocene (15.0–13.5 myr), Late
Miocene (10–9 myr), Pliocene (5.8–3.7 myr), and Quaternary (1.0–0.4 Ma). The average duration of the stages has been 1–2 myr;
the stages were separated from each other with periods of inactivity of approximately equal lengths (∼3 myr). For each of
the Pliocene and Quaternary stages, three additional phases of volcanism have been identified, which were separated from each
other with short time intervals (a few hundred thousand years). The last burst of volcanic activity in the area in question
took place ∼400 ka; similar to Quaternary volcanism in general, it was not characterized by a high intensity. An important
result of the studies performed was to confirm the existence of a separate Middle Miocene stage of collision volcanism for
the Caucasian-Anatolian Segment of the Alpine Fold Belt. The data generated allow concluding that Neogene-Quaternary volcanism
in this portion of the belt started much earlier (∼15 Ma) than assumed by the majority of the previous researchers. 相似文献
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M. Keskin A. V. Chugaev V. A. Lebedev E. V. Sharkov V. Oyan O. Kavak 《Journal of Volcanology and Seismology》2012,6(6):361-382
A geochemical and isotope-geochemical (Sr-Nd-Pb) study has been carried out for the Karacada? neovolcanic area, which is situated within the frontal part of the Arabian plate. The obtained data and the results of petrological modeling show that the petrogenesis of parental magmas in the Karacada? neovolcanic area involved two compositionally different mantle sources; one consisted of garnet-bearing peridotites of the asthenosphere mantle and the other was spinel-bearing peridotites of the enriched subcontinental lithosphere mantle. During early stages in the evolution of the magmatic system, deep-seated asthenospheric magmas were ascending to the surface while intensively interacting with the melts that had been generated at upper mantle depths. The interaction gradually diminished, so that the later effusive rocks mostly have compositions that are similar to those of the primitive asthenospheric magmas. It is shown that a significant (up to 17–18 wt % of the mantle melt) assimilation of crustal material could take place only during the initial phases of the magmatism. Periodic replenishment of the magma chambers by primitive magmas, which resulted in an observable high degree of homogeneity in the composition of young effusive rocks, was also of importance in the petrogenesis of lavas during the evolution of volcanic activity. 相似文献
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