Denudation of the Ryoke metamorphic belt ; timing of ductile deformation revealed by CHIME monazite dating of granitic veins

Ryoke 变质带的剥蚀；

• 批准号: 16340153
• 负责人: SUZUKI Kazuhiro
• 金额: $ 5.18万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340153/
• 关键词: Ryoke metamorphic belt; CHIME dating; denudation history; ductile deformation; burittle deformation; granitic vein; monazite; 領家変成帯; 変形花崗岩質岩脈; 非変形花崗岩質岩脈

The Ryoke metamorphic belt is a typical high T/P metamorphic belt in southwestern Japan, and consists mainly of paragneisses and associated granitoids. The paragneisses show CHIME monazite age of c. 100Ma (Suzuki & Adachi, 1989), and are injected by numerous deformed and non-deformed granitic veins of several to 30cm in thickness. The deformed veins are largely concordant with the tectonic foliation but are locally folded and boudinaged. The boudin necks are filled with the same minerals as found in the matrix. This suggests that the host gneisses were still ductile and recrystallization continued after the injection of the deformed vein. The non-deformed veins are largely discordant with straight and sharp boundaries, and seem to have formed through permeation of granitic melt into brittle fractures. This suggests that paragneisses had changed from ductile to brittle deformation conditions before the injection of the non-deformed vein. Ages of individual granitic veins with distinct d … More eformation histories can, therefore, be used to constrain the timing of the ductile-brittle transition in the Ryoke metamorphic belt. Monazites were analyzed with a JEOL JXA-733 electron microprobe equipped with 4 wavelength-dispersive spectrometers (radius of Rowland circle=140mm) through spot by spot mode. The instrument was operated at 15kV acc. voltage, 0.2μA probe current and defocused 4-6μm probe diameter. The ThMα, UMβ, PbMα and YLα lines were measured simultaneously with PET crystals and sealed Xe X-ray detectors. CaKα, SKα, PKα and NbLβ1 lines were also measured. The spectral interferences of YLγ, ThMζ and NbLβ on PbMα and ThMγ and KKα on UMβ were corrected. An U-poor young monazite was used for evaluation of correction factors of Th interferences. The detection limits at a 2σ confidence level are 0.009, 0.011 and 0.006wt.% for ThO_2, UO_2 and PbO, respectively. Relative errors are about 10% for 0.03wt.% PbO, 2% for 0.6wt.% UO_2 and 0.5% for 7.0wt.% ThO_2. All analytical data for spots containing detectable amounts of S, K and Nb were discarded for CHIME age calculation.The deformed veins show CHIME monazite ages of 93.6±6.2-89.7±5.3Ma, and the non-deformed veins show ages of 86±6-75±5Ma. The ductile deformation in the Ryoke metamorphic belt continued beyond 90Ma and ended before c.85Ma. Less

Ryoke变质带是日本西南部典型的高T/P变质带，主要由副片麻岩和伴生花岗岩组成，副片麻岩的年龄约为100Ma(Suzuki & Adachi，1989)，并由大量变形岩注入。厚度数至30厘米的未变形花岗岩脉。与构造叶理一致，但布丹颈部充满了与基质中相同的矿物质，这表明在变形脉注入后，主体片麻岩仍然具有延展性，并且再结晶仍在继续。很大程度上与笔直而尖锐的边界不一致，并且似乎是通过花岗岩熔体渗透到脆性裂缝中而形成的。在注入未变形矿脉之前，副片麻岩已从韧性变形条件变为脆性变形条件，因此，具有不同变形历史的单个花岗岩脉的年龄可用于限制 Ryoke 中韧性-脆性转变的时间。使用配备 4 个波长色散光谱仪的 JEOL JXA-733 电子探针对变质带进行了分析（半径为罗兰圆=140mm）通过点对点模式操作，仪器在15kV加速电压、0.2μA探头电流和散焦4-6μm探头直径下与PET晶体同时测量并密封。 Xe X 射线探测器还测量了 YLγ、SKα、PKα 和 NbLβ1 线的光谱干扰。 PbMα 上的 ThMz 和 NbLβ 以及 UMβ 上的 ThMγ 和 KKα 被用于评估 Th 干扰的校正因子，ThO_2 的检测限为 0.009、0.011 和 0.006wt.%。 、UO_2 和 PbO 的相对误差分别约为 10%。 0.03wt.% PbO、2%（0.6wt.% UO_2）和 0.5%（7.0wt.% ThO_2） 含有可检测量 S、K 和 Nb 的点的所有分析数据均被丢弃用于 CHIME 年龄计算。变形的静脉显示 CHIME。独居石年龄为93.6±6.2-89.7±5.3Ma，未变形Ryoke变质带的脉体年龄为86±6-75±5Ma，延性变形持续到90Ma以上，并在约85Ma之前结束。

项目成果

Quantitative chemical analysis of rocks with X-ray fluorescence analyzer XRF1800.

使用X射线荧光分析仪XRF1800对岩石进行定量化学分析。

• 发表时间: 2004
• 期刊: Bulletin of the Nagoya University Museum 20
• 作者: Nakazaki;M.;Tsuboi;M.;Kanagawa;K.;Kato;T.;Suzuki;K.
• 通讯作者: K.

R Biochemical signatures preserved in ancient siliceous sediments; new perspectives to Triassic radiolarian bedded chert composition

R 古代硅质沉积物中保存的生化特征；

• 发表时间: 2006
• 期刊: Geochemical Journal 40
• 作者: Takiguchi;T.;Sugitani;K.;Yamamoto;K.;Suzuki;K.
• 通讯作者: K.

Role of partial melting in the evolution of the Sulu (eastern China) ultrahigh-pressure terrane

• DOI: 10.1130/g20991.1
• 发表时间: 2005-02
• 期刊: Geology
• 影响因子: 5.8
• 作者: S. Wallis;M. Tsuboi;Kazuhiro Suzuki;M. Fanning;Laili Jiang;Tsuyoshi Tanaka

電子プローブマイクロアナライザを用いたCHIME年代測定

使用电子探针显微分析仪进行 CHIME 测年

• 发表时间: 2005
• 期刊: 地質学雑誌 111
• 作者: Wallis;S.;Tsuboi;M.;Suzuki;K.;Fanning;M.;Laili;J.;Tanaka;T.;鈴木和博
• 通讯作者: 鈴木和博

CHIME dating of granites exposed in the Huanggoushan area of the Julin province, China.

中国莒林省黄沟山地区出露花岗岩的 CHIME 测年.

• 发表时间: 2004
• 期刊: Bulletin of the Nagoya University Museum 20
• 作者: Sun;D.Y.;Suzuki;K.
• 通讯作者: K.