Constraining the timing of brittle deformation and faulting in the Toki granite, central Japan
Constraining the timing of brittle deformation and faulting in the Toki granite, central Japan
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DOI：
10.1016/j.chemgeo.2013.05.005
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发表时间：
2013-08
期刊：
影响因子：
3.9
通讯作者：
S. Yamasaki;H. Zwingmann;Kunimi Yamada;T. Tagami;K. Umeda
中科院分区：
文献类型：
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作者：
S. Yamasaki;H. Zwingmann;Kunimi Yamada;T. Tagami;K. Umeda
断裂带形成时间的限制对于理解构造演化和脆性断裂过程具有基本的大地构造重要性。在这里，我们提出了自生伊利石K-Ar年龄数据从脆性断裂带，包括两个断层内的Toki花岗岩，日本中部。从米祖伊地下研究实验室的一个竖井中，在252.9和403.7米深处采集了断层泥样品，并将其分成五个粒度级（< 0.1、< 0.4、< 2、2-6、6-10 μm）。粘土组分的K-Ar年龄随粒度的增大而减小，表明富集了较新生成的自生伊利石的较细组分。各组分的K-Ar年龄为53.6 ~ 42.7Ma（古近纪-早始新世-中始新世）。< 0.1 μm组分的年龄分别为42.7 ± 0.9Ma和46.5 ± 1.0Ma。这一年龄范围与Toki花岗岩冷却历史中伊利石的稳定性场（即100-200 °C）和脆性变形的主要温度场（< 300 °C）相一致，并得到了寄主岩石大量热年代学数据的支持。
Constraining of the timing of fault zone formation is of fundamental geotectonic importance to understand structural evolution and brittle fault processes. Here, we present authigenic illite K–Ar age data from brittle fault zones comprising two gouges within the Toki granite, central Japan. The gouge samples were collected at depths of 252.9 and 403.7 m from a shaft at the Mizunami Underground Research Laboratory, and were separated into five grain-size fractions (< 0.1, < 0.4, < 2, 2–6, 6–10 μm). K–Ar ages of clay fractions decrease with grain size, suggesting enrichment in finer fraction of more-recently grown authigenic illites. The K–Ar ages of the fractions range from 53.6 to 42.7 Ma (Paleogene–Early to Middle Eocene). The < 0.1 μm fractions yield ages of 42.7 ± 0.9, and 46.5 ± 1.0 Ma. This age range is consistent with the stability field of illite (i.e. 100–200 °C) and the main temperature field of brittle deformation (< 300 °C) within the cooling history of the Toki granite, supported by extensive thermochronological data of the host rock.