Significant advances were made in the last century in the investigations of the Neogene stress history of the NE Japan arc. However, previous studies have failed to fully resolve middle Miocene post‐rift stress conditions owing to their assumption of Andersonian faulting and an inability to determine maximum and intermediate stress axes from dike orientations. We applied the latest methods of paleostress analysis in this study to igneous dikes and mesoscale faults in the Kakunodate area of the NE Japan arc to elucidate post‐rift stress conditions. Stratigraphic constraints and U–Pb dating indicate that the doleritic and dacitic dikes were formed at 16–12 Ma and 15–12 Ma, respectively. Dolerite and dacite dikes yielded NW–SE extensional stresses with intermediate and low stress ratios, respectively. Mesoscale faults in the middle Miocene formations of the studied area indicated similar stresses. We suggest the sluggish deformations resulting in the dike intrusion and faulting in the normal‐faulting stress regime after the termination of intra‐arc rifting at ca. 15 Ma.

中文翻译：

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日本东北角馆立地区的堤防和中尺度断层揭示了中新世后裂谷的应力状态

上个世纪，日本东北地区弧线的新近纪应力史研究取得了重大进展。但是，先前的研究由于假设安徒生断层并且无法根据堤​​的方位确定最大和中间应力轴，因此未能完全解决中新世后裂谷的应力条件。在这项研究中，我们将最新的古应力分析方法应用于日本东北部弧角地区火成岩和中尺度断层，以阐明裂谷后的应力条件。地层限制条件和U–Pb测年表明，背向堤坝和Dacitic堤坝分别形成于16-12 Ma和15-12 Ma。白云石和钠长石堤坝分别产生中等和低应力比的NW-SE拉伸应力。研究区中新世中层的中尺度断层显示了相似的应力。我们建议，弧形裂口的缓慢变形会导致堤坝的侵入，并在大约200毫米的弧内裂谷终止后，在正断层应力状态下断裂。15 Ma。