Age and associated stress field of middle Miocene back‐arc basalt magmatism in Northeast Japan
Age and associated stress field of middle Miocene back‐arc basalt magmatism in Northeast Japan
复制标题
日本东北部中中新世弧后玄武岩岩浆作用的年龄及相关应力场
DOI：
10.1111/iar.12379
复制
发表时间：
2021
期刊：
影响因子：
1.5
通讯作者：
Hirata Takafumi
中科院分区：
文献类型：
--
作者：
Hosoi Jun;Yamaji Atsushi;Iwano Hideki;Danhara Tohru;Hirata Takafumi
大量的中新世玄武岩广泛分布在日本东北部的弧后地区，包括出羽山脉周围。岩石学研究表明，出羽山周围的青泽组玄武岩是由于日本海的开放而生成的。为了确定中新世中期玄武岩岩浆作用的精确年龄，我们对构成青泽组最上部的流纹岩熔岩进行了 U-Pb 和裂变径迹 (FT) 测年。此外，我们还利用同一地层中玄武岩墙群的数据估计了火山作用的古应力场。流纹岩熔岩的U-Pb年龄为10.73 ±0.22 Ma（2σ），FT年龄为10.6 ±1.6 Ma（2σ），古应力分析表明正断层应力状态具有NW-SE向σ3轴、相对较高的应力比和相对较高的岩浆压力。我们的研究结果表明，青泽晚期岩浆活动发生在NW-SE拉伸应力下，结束于~11Ma。
A large volume of middle Miocene basaltic rocks is widely distributed across the back‐arc region of Northeast Japan, including around the Dewa Mountains. Petrological research has shown that basaltic rocks of the Aosawa Formation around the Dewa Mountains were generated as a result of the opening of the Sea of Japan. To determine the precise ages of the middle Miocene basaltic magmatism, we conducted U–Pb and fission‐track (FT) dating of a rhyolite lava that constitutes the uppermost part of the Aosawa Formation. In addition, we estimated the paleostress field of the volcanism using data from a basaltic dike swarm in the same formation. The rhyolite lava yields a U–Pb age of 10.73 ±0.22 Ma (2σ) and a FT age of 10.6 ±1.6 Ma (2σ), and the paleostress analysis suggests a normal‐faulting stress regime with a NW–SE‐trendingσ3‐axis, a relatively high stress ratio, and a relatively high magma pressure. Our results show that the late Aosawa magmatism occurred under NW–SE extensional stress and ended at ~ 11 Ma.