TY - JOUR
T1 - Age and magnetism of lavas in Jokuldalur area, Eastern Iceland
T2 - Gilsa event revisited
AU - Udagawa, Saneyuki
AU - Kitagawa, Hajime
AU - Gudmundsson, Agust
AU - Hiroi, Osamu
AU - Koyaguchi, Takehiro
AU - Tanaka, Hidefumi
AU - Kristjansson, Leo
AU - Kono, Masaru
PY - 1999/9
Y1 - 1999/9
N2 - We present results of paleomagnetic measurements and K-Ar age determinations of 38 lava flows collected in five separate sections in the Jokuldalur area of Eastern Iceland, including one section previously studied by Watkins et al. [Watkins, N.D., Kristjansson, L., McDougall, I., 1975. A detailed paleomagnetic survey of the type location for the Gilsa geomagnetic polarity event. Earth Planet. Sci. Lett. 27, 436-444]. These sites are close to the type locality of the normal 'Gilsa event' in the Matuyama chron first identified by McDougall and Wensink [McDougall, I., Wensink, H., 1966. Paleomagnetism and geochronology of the Pliocene-Pleistocene lavas in Iceland. Earth Planet. Sci. Lett. 1, 232-236]. Using new experimental results as well as field observations, we could correlate the sequence of lava flows in the Jokuldalur area spanning the time interval between 1.8 and 0.5 Ma. The magnetic polarities and ages obtained in this study are quite consistent with the standard time scale for Brunhes-Matuyama ages given by Cande and Kent [Cande, S.C., Kent, D.V., 1995. Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic. J. Geophys. Res. 100, 6093-6095] based on marine magnetic anomalies, except that the Gilsa event needs to be added. Existence of Olduvai age lavas under Gilsa was inferred but not certain. Our results are fairly in good agreement with the former studies by Wensink [Wensink, H., 1964a. Secular variation of Earth magnetism in Plio-Pleistocene basalts of eastern Iceland. Geol. Mijnbouw 43, 403-413; Wensink, H., 1964b. Paleomagnetic stratigraphy of younger basalts and intercalated Plio-Pleistocene tillites in Iceland. Geol. Rund. 54, 364-384] and Watkins et al. [Watkins, N.D., Kristjansson, L., McDougall, I., 1975. A detailed paleomagnetic survey of the type location for the Gilsa geomagnetic polarity event. Earth Planet. Sci. Lett. 27, 436-444], but the assignment to the polarity zones is different because of the newly obtained K-Ar ages. Based on the present study, we propose that the Gilsa event is a short normal subchron in the Matuyama chron distinct from and above the more well-established Oldvai subchron.
AB - We present results of paleomagnetic measurements and K-Ar age determinations of 38 lava flows collected in five separate sections in the Jokuldalur area of Eastern Iceland, including one section previously studied by Watkins et al. [Watkins, N.D., Kristjansson, L., McDougall, I., 1975. A detailed paleomagnetic survey of the type location for the Gilsa geomagnetic polarity event. Earth Planet. Sci. Lett. 27, 436-444]. These sites are close to the type locality of the normal 'Gilsa event' in the Matuyama chron first identified by McDougall and Wensink [McDougall, I., Wensink, H., 1966. Paleomagnetism and geochronology of the Pliocene-Pleistocene lavas in Iceland. Earth Planet. Sci. Lett. 1, 232-236]. Using new experimental results as well as field observations, we could correlate the sequence of lava flows in the Jokuldalur area spanning the time interval between 1.8 and 0.5 Ma. The magnetic polarities and ages obtained in this study are quite consistent with the standard time scale for Brunhes-Matuyama ages given by Cande and Kent [Cande, S.C., Kent, D.V., 1995. Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic. J. Geophys. Res. 100, 6093-6095] based on marine magnetic anomalies, except that the Gilsa event needs to be added. Existence of Olduvai age lavas under Gilsa was inferred but not certain. Our results are fairly in good agreement with the former studies by Wensink [Wensink, H., 1964a. Secular variation of Earth magnetism in Plio-Pleistocene basalts of eastern Iceland. Geol. Mijnbouw 43, 403-413; Wensink, H., 1964b. Paleomagnetic stratigraphy of younger basalts and intercalated Plio-Pleistocene tillites in Iceland. Geol. Rund. 54, 364-384] and Watkins et al. [Watkins, N.D., Kristjansson, L., McDougall, I., 1975. A detailed paleomagnetic survey of the type location for the Gilsa geomagnetic polarity event. Earth Planet. Sci. Lett. 27, 436-444], but the assignment to the polarity zones is different because of the newly obtained K-Ar ages. Based on the present study, we propose that the Gilsa event is a short normal subchron in the Matuyama chron distinct from and above the more well-established Oldvai subchron.
KW - Gilsa event
KW - Lava
KW - Magnetism
UR - http://www.scopus.com/inward/record.url?scp=0033377766&partnerID=8YFLogxK
U2 - 10.1016/S0031-9201(99)00073-4
DO - 10.1016/S0031-9201(99)00073-4
M3 - Article
AN - SCOPUS:0033377766
SN - 0031-9201
VL - 115
SP - 147
EP - 171
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 2
ER -