Polychronous formation of the ophiolite association in the Tekturmas zone of Central Kazakhstan inferred from geochronological and biostratigraphic data
Tóm tắt
Plagiogranites and conodonts from chert intercalations in basalts of the ophiolite association in the Tekturmas zone of Central Kazakhstan were subjected to the U‒Pb geochronological and stratigraphic investigations, respectively. The age of plagiogranite crystallization is estimated to be 489 ± 8 Ma corresponding to the stratigraphic interval spanning from the uppermost Upper Cambrian to the lower Tremadocian. Conodonts from cherts of the Kuzek Formation are distributed along the section interval from the uppermost part of the Darriwilian (Middle Ordovician) to the lower part of the Sandbian (Upper Ordovician), which corresponds to the period of 457‒460 Ma. It is revealed that the formation of the ophiolite section in the Tekturmas zone was a multistage process lasting from the Late Cambrian to the initial Late Ordovician.
Tài liệu tham khảo
N. A. Gerasimova, M. Z. Novikova, L. A. Kurkovskaya, and A. S. Yakubchuk, Byull. Mosk. O-va Ispyt. Prir., Otd. Geol. 67 (3), 60–76 (1992).
M. Z. Novikova, L. L. German, I. E. Kuznetsov, and A. S. Yakubchuk, in Kazakhstan Magmatism and Ore Bearing (Gylym, Alma-Ata, 1991), pp. 92–102 [in Russian].
M. Z. Novikova, N. A. Gerasimova, L. A. Kurkovskaya, V. G. Stepanets, and A. S. Yakubchuk, Byull. Mosk. O-va Ispyt. Prir., Otd. Geol. 68 (6), 47–63 (1993).
K. M. Cohen, S. C. Finney, P. L. Gibbard, and J.-X. Fan, Episodes 36, 204–204 (2013).
T. E. Krogh, Geochim. Cosmochim. Acta 37, 494–494 (1973).
K. R. Ludwig, Isoplot 3.70. Berkeley Geochronol. Center Spec. Publ. No. 4 (Berkeley Geochronological Center, Berkeley, CA, 2003).
K. R. Ludwig, PbDat for MS-DOS. Ver. 1.21, U.S. Geological Survey Open-File Rep. No. 88-542 (1991).
J. M. Mattinson, Contrib. Mineral. Petrol. 116, 129–129 (1994).
J. S. Stacey and I. D. Kramers, Earth Planet. Sci. Lett. 26 (2), 207–221 (1975).
R. H. Steiger and E. Jager, Earth Planet. Sci. Lett. 36 (2), 359–362 (1976).