Paleomagnetic Stratigraphy of Volcanic Products in Southwestern Hokkaido, Japan : Paleomagnetic Studies of the Pliocene and Pleistocene Volcanic Products in Hokkaido, 2nd Report
Paleomagnetic Stratigraphy of Volcanic Products in Southwestern Hokkaido, Japan : Paleomagnetic Studies of the Pliocene and Pleistocene Volcanic Products in Hokkaido, 2nd Report
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日本北海道西南部火山产物的古地磁地层学：北海道上新世和更新世火山产物的古地磁研究，第二次报告
DOI：
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
S. Okada
中科院分区：
文献类型：
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作者：
Y. Fujiwara;S. Okada
作者Yoshiki Fujiwara和Shomei Okada(含5个图文和1个表)(北海道大学理学院地矿学系1634期供稿)对北海道西南部31个更新世火山产物发育地点的149个标本进行了古地磁研究。其中，两股火山碎屑流和一股熔岩流被反向磁化。布伦斯正常火山和松山火山之间的边界可能发生在日本北部北海道西南部东屋山和柴丘火山口周围火山产品喷发的某个时候。引言地球磁场可能并不总是像今天一样具有相同的极性，这一概念在本世纪初就已经被理解(布伦斯，1906年，松山，1929)。随着古地磁研究和K-Ar年龄测定的最新进展，地磁极性时间尺度在地质年代学中的适用性，特别是近4m.y。用于地层对比的古地磁方法称为古地磁地层学。地磁场以单极为主的时间间隔被称为纪元。它们的期限一般在10年左右。量级较短的事件发生在历元内。在K-Ar年龄测定的基础上对磁性地层学年龄的解释和时间刻度的结果如图5所示。用于该图的层序命名法是以Cox和Darymple(196 7)的命名法为基础的。北海道广泛发育从下更新世到全新世的各种类型的火山碎屑沉积，包括浮岩流沉积和瀑布沉积。我们长期与米纳托教授在野外合作，确定了这些火山碎屑沉积的地层序列，并试图将它们与目前的国际标准地层学进行对比(米纳托等人1970年，1972a，1972b)。除了这些地层调查外，我们还尝试在这些火山碎屑层序上应用古地磁方法，以确定更准确的地层位置。已经报道了北海道西南部和中部火山产物的一些磁性地层分析结果(Hashimoto et al 1968，Fujiwara 1972和Fujiwara et al 1975)。本文简要介绍了北海道西南部发育的火山碎屑岩沉积的古地磁分析结果，并讨论了与国际标准古地磁极性时标相对应的地层位置。·现地址：鸟取大学教育学院地球科学系，鸟取680 190 Y.Fujiwara&S.Okada
by Yoshiki Fujiwara and Shomei Okada' (with 5 text-figures and 1 table) (Contribution from the Department of Geology and Mineralogy, Faculty of Science, Hokkaido University , No. 1634) A paleomagnetic study was made on 149 specimens from 31 sites on Pleistocene volcanic products deve loping in .southwestern Hokkaido. Of them, two pyroclastic flows and one lava flow are reverse ly magnetized. The boundary between the Brunhes normal and the Matuyama reversed epochs probably took place sometime during the eruption of volcanic products developing around the Toya and also Shikotsu Caldera in southwestern Hokkaido, North Japan. Introduction The concept that the earth's magnetic field may not always had the same polarity as it has today had already apprehended early this century (Brunhes 1906, Matuyama 1929). The recent progress of paleomagnetic studies and also K-Ar age determinations have led the applicability of the geomagnetic polarity time scale to geochronology especially for the past 4 m.y. Paleomagnetic method applied to stratigraphic correlation is called paleomagnetic stratigraphy. Intervals, during which the geomagnetic field had predominantly one polar.ty have been termed epochs. They generally have durations of the order of 10 years. Events which have an order of magnitude shorter occur within epochs. The result of the interpretation of the ages of the magnetic stratigraphy followed by the time scale on the basis of K-Ar age determinations is shown in Fig. 5. The st ratigraphic nomenclature used for this figure is based on that of Cox and Darlymple (196 7). Various types of pyroclastic deposits including pumice flow and fall deposits ranging from the Lower Pleistocene to Holocene are widely develop in Hokkaido. We have long collaborated with Prof. Minato in field to settle the stratigraphic sequences of these pyroclastic deposits and tried to correlate them to the present international standard stratigraphy (Minato et al 1970, 1972a, 1972b). In addition to these stratigraphic investigations we have tried t~ applicate paleomagnetic methods on these pyroclastic sequence to settle more exact stratigraphic position. Some results of magneto-stratigraphic analysis of volcanic products in southwestern and also central Hokkaido were already reported (Hashimoto et al 1968, Fujiwara 1972 and Fujiwara et al 1975). In this paper, further results of paleomagnetic analysis on pyroclastic deposits developed in southwestern Hokkaido and discussions on their stratigraphic positions corellate to the international standard paleomagnetic polarity time scale are briefly given. • Present address: Department of Earth Science, Faculty of Education, Tottori University, Tottori 680 190 Y. Fujiwara & S. Okada
DOI：
10.1098/rspa.1953.0064
发表时间：
1953-01-01
影响因子：
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作者：
FISHER, R
通讯作者：
FISHER, R