New paleomagnetic and paleointensity data from Pliocene lava flows from the Lesser Caucasus

被引:14
作者
Calvo-Rathert, Manuel [1 ]
Felicidad Bogalo, Maria [1 ]
Gogichaishvili, Avto [1 ,2 ]
Sologashvili, Jemal [3 ]
Vashakidze, Goga [4 ]
机构
[1] Univ Burgos, EPS, Dept Fis, Burgos 09006, Spain
[2] Univ Nacl Autonoma Mexico, Lab Interinst Magnetismo Nat, Mexico City 58098, DF, Mexico
[3] Caucasus Int Univ, GE-380192 Tbilisi, Georgia
[4] I Javakhishvili Tbilisi State Univ, Alexandre Janelidze Inst Geol, Tbilisi, Georgia
关键词
Paleomagnetism; paleointensity; Caucasus; Pliocene; WAISTED HYSTERESIS LOOPS; SOUTHERN GEORGIA; MAGNETIC-PROPERTIES; GEOMAGNETIC-FIELD; HIGHLAND; THELLIER; REVERSAL; TERTIARY; CRITERIA; FAILURE;
D O I
10.1016/j.jseaes.2013.04.039
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
A paleomagnetic, rock-magnetic and paleointensity study has been carried out on 14 basaltic lava flows from two Pliocene (K-Ar age between 3.09 +/- 0.10 Ma and 4.00 +/- 0.15 Ma) sequences (Apnia and Korxi) from the eastern Djhavakheti Highland in southern Georgia (Caucasus). Measurement of strong-field magnetisation versus temperature curves yielded three types of thermomagnetic curves: (i) Reversible curves with magnetite as only remanence carrier (type H); (ii) irreversible curves with magnetite as only carrier of remanence (type H-) and (iii) irreversible curves showing a low Curie-temperature phase and magnetite (type L). Analysis of hysteresis curves showed that samples were characterised by a mixture of single-domain and multi-domain grains. Paleomagnetic experiments allowed determining characteristic components for all flows and normal polarities (6 flows), reversed polarities (7 flows) and intermediate polarities (1 flow) were observed.. Paleomagnetic poles were calculated using only those sites unequivocally showing normal or reversed polarities. The paleomagnetic pole obtained from flows of both combined sequences (latitude lambda = 77.9 N, longitude phi = 152.1 degrees E, n = 13, A(95) = 11.8 degrees, k = 13.4) showed a good agreement with the 5 Ma window of the European synthetic apparent polar wander path of Besse and Courtillot (2002). The paleomagnetic direction of the combined Apnia-Korxi flows agrees well with the expected one, showing no significant tectonic rotation. The latter cannot be however, completely excluded in the Korxi section. In that section, analysis of the angular dispersion of virtual geomagnetic poles yields a much higher value than expected. Paleointensity experiments using the Coe method were performed on 31 specimens from 10 flows. After application of specific selection criteria, 19 samples from 8 flows were observed to provide successful determinations, with mean flow values showing a wide scatter. If only flows with more than one successful paleointensity determination are taken into account, virtual dipole moments (VDMs) vary between 3.5 x 10(22) A m(2) and 8.3 x 10(22) A m(2). In intermediate polarity site AP2 no weak transitional paleostrength values were observed. (C) 2013 Elsevier Ltd. All rights reserved.
引用
收藏
页码:347 / 361
页数:15
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