50. 40 AR- 39 AR ANALYSIS OF VOLCANIC ROCKS RECOVERED FROM THE JAPAN SEA FLOOR: CONSTRAINTS ON THE AGE OF FORMATION OF THE JAPAN SEA1
50. 40 AR- 39 AR ANALYSIS OF VOLCANIC ROCKS RECOVERED FROM THE JAPAN SEA FLOOR: CONSTRAINTS ON THE AGE OF FORMATION OF THE JAPAN SEA1
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发表时间：
1992
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影响因子：
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通讯作者：
I. Kaneoka;Y. Takigami;N. Takaoka;S. Yamashita;K. Tamaki
中科院分区：
文献类型：
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作者：
I. Kaneoka;Y. Takigami;N. Takaoka;S. Yamashita;K. Tamaki
利用~（40）Ar-~（39）Ar全岩分步加热实验对ODP航次127和128期间日本海的火山岩进行了分析。所有三个实验的样品从网站795在日本盆地显示干扰的年龄谱，但它们是一致的结晶年龄为15至25 Ma的样品。在大和盆地的797号现场，5个样品中有3个显示出18-19 Ma的高原年龄。在大和盆地北方的794站点，5个样品中有3个显示了20-21 Ma的一致年龄谱。放射性年龄结果与基于生物地层学的797站点最古老沉积物的估计年龄一致，但明显比794站点最古老沉积物的年龄更老。然而，放射性年龄是一致的，与以前推断的年龄为基础的日本海底的放射性年龄数据从日本海疏浚火成岩的形成。目前的研究结果表明，日本海底的形成至少开始于19-20 Ma前，并给出了更精确的年龄限制。
Volcanic rocks recovered from the Japan Sea during ODP Legs 127 and 128 were analyzed by 40Ar-39Ar whole-rock stepwise-heating experiments. All three experiments on samples from Site 795 in the Japan Basin revealed disturbed age spectra, but they are consistent with crystallization ages of 15 to 25 Ma for the samples. At Site 797 in the Yamato Basin, three of the five samples showed plateau ages of 18-19 Ma. At Site 794 in the northern Yamato Basin, three of the five samples revealed concordant age spectra of 20-21 Ma. The radiometric age results are consistent with the estimated ages for the oldest sediments at Site 797 based on the biostratigraphy, but are significantly older than those of the oldest sediments at Site 794. However, the radiometric ages are concordant with previously inferred ages for the formation of the Japan Sea floor based on radiometric age data from dredged igneous rocks from the Japan Sea. The present results indicate that formation of the Japan Sea floor started at least 19-20 Ma ago and give more precise age constraints.