Late Holocene Uplift of Shikine Island on the Northern Tip of the Philippine Sea Plate
Late Holocene Uplift of Shikine Island on the Northern Tip of the Philippine Sea Plate
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菲律宾海板块北端志根岛晚全新世隆起
DOI：
10.4294/zisin1948.36.4_587
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
H. Moriwaki
中科院分区：
文献类型：
--
作者：
Y. Ota;K. Ishibashi;H. Moriwaki
研究了日本中部太平洋沿岸五岛晚全新世的地壳抬升。Shikine是一个约3公里(EW)x2.5公里(NS)的小岛，位于伊豆-博宁弧北端，菲律宾海-欧亚板块边界以南，苏鲁加海槽和佐贺海槽。到目前为止，由于1498年或1605年或1703年的近海大地震，历史上岛上的同震隆起一直被怀疑是基于隆起的藤壶化石。在本研究中，对位于该岛北部和东部海岸的6个地点进行了观测，这些地点位于高达数十米的陡峭的海蚀崖脚下。在Loc.在2.6-4.3米的海拔范围内(大岛岛冈田的平均海平面以上)可以发现1个藤壶化石。Tetraclitella chinensis(采样高度3.2-3.6m amsl)、Megabalanus rosa(3.0-3.1m amsl)和Tetraclitella chinensis(2.6m amsl)的年龄分别为1980+130(Gak-9718)、1830+130(Gak-9717)和1350+100(Gak-9720)14CyB.P.，表明高度与日期有直接关系。然而，棘果牡蛎(Saccostrea Echinata)(2.6Mamsl)的14C年龄为2540+290yB.P.(Gak-9721)，与这一趋势不一致。这种异常可能是由于随后对较旧的外壳进行了重新处理。在该地区，淡水河床的生活上限表明，目前的潮位为1.0mamsl。在Loc.在海拔3.94.2m范围内发现2种藤壶和贝壳化石。然而，由于样本量较少，仅获得了不可靠的14C年龄1010+300yB.P.(GAK-9717)。在Loc.在3.9-6.1m海拔范围内有3个藤壶化石。散布在1.1米断面上的藤壶的~(14)C年龄
Late Holocene crustal uplift of Shikine Island, off the Pacific coast of central Japan, has been investigated. Shikine is a small island of about 3km(EW)x2.5km(NS), located on the northern tip of the Izu-Bonin arc, to the south of the Philippine Sea-Eurasian plate boundary of the Suruga and Sagami troughs. So far, historical coseismic uplift of the island, due to the 1498 or 1605 or 1703 great offshore earthquake, has been suspected based on raised fossil barnacles. In the present study, six localities on the northern and eastern coast of the island, which are situated at the foot of a steep sea cliff, several tens of meters high, have been observed. At Loc. 1 fossil barnacles can be found in the range of 2.6-4.3m amsl (above mean sea level at Okada, Oshima Island). Tetraclitella chinensis (sampling height, 3.2-3.6m amsl), Megabalanus rosa (3.0-3.1m amsl), and Tetraclitella chinensis (2.6m amsl) have been dated at 1980+ 130(GaK-9718), 1830+130 (GaK-9717), and 1350+100 (GaK-9720)14Cy.B.P., respectively, showing a direct relationship between height and date. The 14C date of 2540+290y.B.P.(GaK-9721) for Saccostrea echinata (2.6m amsl), however, is not in harmony with this tendency. This anomaly is probably due to subsequent reworking of the older shell. At this locality, the upper limit of living Tetraclita squamosa Japonica bed indicates that the present high tide level is 1.0m amsl. At Loc. 2 fossil barnacles and shells can be found in the range of 3.94.2m amsl. Here, however, due to a small amount of sample number, only an unreliable 14C date of 1010+300y.B.P. (GaK-9717) has been obtained for Tetraclita squamosa Japonica (4.2m amsl). At Loc. 3 fossil barnacles can be found in the range of 3.9-6.1m amsl. The 14C date of the barnacle Tetraclitella chinensis which are scattered throughout 1.1m at section