geochronological analysis of the evolutional history of basement rocks in the Japanese Islands

日本列岛基底岩演化史的年代学分析

• 批准号: 09640568
• 负责人: SUZUKI Kazuhiro
• 金额: $ 1.98万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640568/
• 关键词: CHIME age; Monazite; Zircon; Granitoid; Metamorphic rocks; Nohi Rhyolite; Ryoke metamorphic belt; Denudation history; CHIMEage; アラナイト; 黒雲母変質; Pb-Pb年代; イオンマイクロプローブ; Monazite; Zircon; Granitoid; Motamorphic rocks; Denudation histong; T-P p

The evolutional history of basement rocks in the Japanese Islands was investigated on the basis of the CHIME dating and the XRF and EPMA analyses of igneous ; metamorphic and sedimentary rocks. The main results are as follows.(1)The CHIME zircon age is 85*5 Ma and the CHIME allanite age is 86*7 Ma for the Agigawa welded tuff sheet in the lowest volcanic sequence of the Nohi Rhyolite in central Japan. The Agigawa welded tuft sheet is chronologically identical with the post-tectonic Shinshiro Tonalite and Mitsuhashi Granodiorite in the Ryoke metamorphic belt. Acidic magmatism started simultaneously and widely at about 85 Ma after the denudation of the high T/P Ryoke belt metamorphosed at about 100 Ma.(2)Biotite from fresh rock shows a sharp 10 A basal reflection, but its Na-modification gives distinct 10 and 12.5 A reflections. This shows that biotite even from fresh rocks contains microdomains of K-poor biotite and vermiculite. The Fe2+/Fe3+ ratio is higher in K-rich biotite than in K-poor biotite and vermiculite. This suggests oxidation of iron in octahedral sheet causes the K-loss to maintain local electrostatic balance, and accounts for the deviation of K-Ar biotite ages from CHIME monazite ages.(3)The CHIME monazite ages for the Ryoke gneisses are concentrated between 102 and 98 Ma, and are interpreted as the time of monazite formation under lower amphibolite facies conditions. The peak metamorphism is contemporaneous with the geologically oldest plutons of at about 95 Ma in both the eastern and western parts separated by about 550 km. Plutonism continued from 95 Ma to 68 Ma in the eastern part, whereas in the western part it ceased at 85 Ma. These new age data do not support a current view that plutonism in the Ryoke belt becomes younger towards the east. The CHIME ages coupled with available geological data show that the western part was eroded rapidly (1.5mm/y) than the eastern part (0.8mm/y) over the time span from 91 Ma to 85 Ma.

在CHIME测年以及火成岩XRF和EPMA分析的基础上，研究了日本列岛基底岩的演化历史；变质岩和沉积岩。主要结果如下：(1)日本中部浓飞流纹岩最低火山层序Agikawa焊结凝灰岩片的CHIME锆石年龄为85*5 Ma，CHIME钠长石年龄为86*7 Ma。 Agikawa 熔接簇绒片在年代上与 Ryoke 变质带中的构造后 Shinshiro Tonalite 和 Mitsuhashi Granodiorite 相同。高T/P Ryoke带的剥蚀作用在约100 Ma变质之后，酸性岩浆作用在约85 Ma同时广泛开始。(2)来自新鲜岩石的黑云母显示出尖锐的10 A基底反射，但其Na改性给出了明显的10和 12.5 A 反射。这表明即使来自新鲜岩石的黑云母也含有贫钾黑云母和蛭石的微区。富钾黑云母中的 Fe2+/Fe3+ 比值高于贫钾黑云母和蛭石。这表明八面体片中铁的氧化导致K损失以维持局部静电平衡，并解释了K-Ar黑云母年龄与CHIME独居石年龄的偏差。(3)Ryoke片麻岩的CHIME独居石年龄集中在102之间和 98 Ma，被解释为下角闪岩相条件下独居石形成的时间。变质作用高峰期与东部和西部相距约 550 公里的地质最古老的岩体（约 95 Ma）同时发生。在东部地区，冥王论从95 Ma持续到68 Ma，而在西部，则在85 Ma停止。这些新时代的数据并不支持当前的观点，即 Ryoke 地带的岩成论向东变得更年轻。 CHIME年龄与现有地质数据相结合表明，在91 Ma至85 Ma的时间跨度内，西部地区的侵蚀速度（1.5毫米/年）快于东部地区（0.8毫米/年）。

项目成果

ENAMI,M., SUZUKI,K.and KATO,T.: "Pressure-temperature-time paths of metamorphism." Jour.Geogr.106. 689-698 (1997)

ENAMI,M.、SUZUKI,K. 和 KATO,T.：“变质作用的压力-温度-时间路径。”

IRIYAMA,J., SUZUKI,K.OGATA,Y.and IWATA,K.: "Residual 152Eu in a roof tile exposed to the Hiroshima Atomic Bomb." Bull.Nagoya Univ.Furukawa Museum.14. 1-14 (1998)

IRIYAMA,J.、SUZUKI,K.OGATA,Y. 和 IWATA,K.：“暴露于广岛原子弹的屋顶瓦片中残留的 152Eu。”

Kato,T., Suzuki,K., Morishita,T. and Yonezawa,C.: "CHIME ages of zircons in granitic gneiss and granite from Samilpo,southeastern Democratic Peaple′s Republic of Korea." Journal of Earth and Planetary Science,Nagoya University. 44. 61-69 (1997)

Kato, T.、Suzuki, K.、Morishita, T. 和 Yonezawa, C.：“朝鲜民主主义人民共和国东南部三日浦花岗质片麻岩和花岗岩中锆石的 CHIME 年龄，名古屋大学地球与行星科学杂志”。 . 44. 61-69 (1997)

SUZUKI,K.and ADACHI,M.: "Th, U and Pb analytical data of monazites used in the paper "Denudation history of the high T/P Ryoke metamorphic belt, southwest Japan : constraints from CHIME monazite ages of gneisses and granitoids"." J.Earth Planet.Sci., Nago

SUZUKI,K. 和 ADACHI,M.：“论文《日本西南部高 T/P Ryoke 变质带的剥蚀历史：来自片麻岩和花岗岩的 CHIME 独居石年龄的限制》中使用的独居石 Th、U 和 Pb 分析数据”

Nagasaki,A.& Enami,M.: "Sr-bearing zoisite and epidote in ultra high-pressure (UHP) metamorphic rocks from the Su-Lu province,eastern China: an important Sr-reservoir under UHP conditions" Am.Mineral. 83. 240-247 (1998)

长崎，A.