Crust-formaticn processes in the Kontum Massif, Vietnam

越南昆嵩地块的地壳形成过程

• 批准号: 14340150
• 负责人: OSANAI Yasuhito
• 金额: $ 8.64万
• 依托单位: Kyushu University (2004)Okayama University (2002-2003)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340150/
• 关键词: Vitnam; Kontum Massif; ultrahigh-temperature metamorphism; ultrahigh-pressure metamorphism; metamorphic evolution; precise geochronology; collision metamorphism; super-continent formation; SHRIMP年代測定; 衝突型変成作用; 超高温泥質グラニュライト; 苦鉄質エクロジャイト; 時計回りの変成

The Kontum massif in central Vietnam consists of low-grade schists and amphibolite- to granulite-facies metamorphic rocks, that have been intruded by S-type and I-type granites. This terrane was formerly considered to be composed mainly of Archean granulites (the Kannak Complex), Proterozoic amphibolite-facies metamorphic rocks (the Ngoc Linh Complex) and low-grade schists (the Kham Duc Complex). They were thought to be the basement of the Indochina Craton in south-east Asia. The Kannak Complex is dominated by pelitic-semipelitic gneisses metamorphosed under high- to ultrahigh-temperature (UHT) conditions into granulite-facies. A minor amount of mafic and calcsilicate rocks are also intercalated within the gneisses. The highest-grade metamorphic condition is determined from garnet-orthopyroxene-sillimanite-cordierite gneiss, which indicates that multi-stage symplectite formation during retrograde stage started from isothermal decompression in UHT condition (1000 ℃<). On the other hand, … More the newly found garnet-clinopyroxene-orthopyroxene granulites (eclogitic ultrahigh-temperature mafic granulite) from the Ngoc Linh Complex shows a series of changes in divariant assemblages from garnet-clinopyroxene-quartz to hornblende-quartz through clinopyroxene-orthopyroxene- plagioclase-(garnet). It was identified that these rocks were formed as a result of their metamorphic evolution of isothermal decompression followed by nearly isobaric cooling.The ultrahigh-temperature metamorphic rocks in the Kontum massif, which are exposed along the Dac To Kan shear zone, show a clockwise pressure-temperature path with the peak metamorphic condition of ca. 1.2 GPa and ca. 1050 ℃ (M1 metamorphism). High-pressure M0 metamorphism (ca. 1.7 GPa<, ca. 1000 ℃) as part of the prograde metamorphism and low-pressure (but still ultrahigh-temperature) M2 metamorphism (0.9-1.0 GPa,ca. 1000 ℃) as part of the retrograde metamorphism during the clockwise pressure-temperature evolution are also recognized. The widely reported Permo-Triassic metamorphic event (ca. 240-260 Ma) from the ultrahigh-temperature metamorphic rocks would indicate a rapid metamorphic evolution from M0 stage to low-pressure and low-temperature retrograde stage (later M2 stage) during the continents collision in eastern Asia. The newly determined Sm-Nd internal isochron and SHRIMP ages from the Kannak and Ngoc Linh Complexes would also indicate that the Kontum massif had also undergone the Pan African metamorphic event (ca. 2.5,1.0 and 0.5 Ga). The present results of the metamorphic evolution of the Kontum massif including 41 journal papers indicate a strong constraint to consider the coninental evolution process in Eastern Asia. Less

越南中部的昆嵩地块由低品位片岩和角闪岩至麻粒岩相变质岩组成，这些变质岩已被 S 型和 I 型花岗岩侵入，该地体以前被认为主要由太古代岩组成。 Kannak 杂岩）、元古代角闪岩相变质岩（Ngoc Linh 杂岩）和低品位片岩（Kham Duc它们被认为是东南亚印度支那克拉通的粒状基底，也夹杂在片麻岩中。石榴石-斜辉石-硅线石-堇青石片麻岩，表明逆行阶段多期辛辉石的形成是在UHT条件下（1000℃<）等温减压开始的。 Ngoc Linh 杂岩中的榴辉岩超高温镁铁质麻粒岩）显示了一系列通过单斜辉石-斜辉石-斜长石-（石榴石）从石榴石-单斜辉石-石英到角闪石-石英的变化组合被确定为这些岩石是等温减压随后近等压冷却的变质演化的结果。昆嵩地块中的超高温变质岩，沿达克苏干河出露剪切带，显示出约 1.2 GPa 的峰值变质条件（M1 变质作用）（约 1.7 GPa<，约 1000 ℃）的顺时针压力-温度路径。渐进变质作用和低压（但仍超高温）M2变质作用（0.9-1.0 GPa，约1000 ℃）作为顺时针压力-温度演化过程中逆变质作用的一部分也被认为是来自超高温变质岩的二叠纪-三叠纪变质事件（约240-260 Ma）。东亚大陆碰撞期间从M0阶段到低压低温逆行阶段（后期M2阶段）的快速变质演化。从 Kannak 和 Ngoc Linh 杂岩中确定的 Sm-Nd 内部等时线和 SHRIMP 年龄也表明昆嵩地块也经历了泛非变质事件（约 2.5、1.0 和 0.5 Ga）。昆嵩地块包括 41 篇期刊论文，表明考虑东亚大陆演化过程存在很大的限制。

项目成果

Sajeev, K., et al.: "Geochronological evidence for multistage metamorphic events in ultrahigh-temperature granulites from central Highland Complex, Sri Lanka"Polar Geoscinece. 16. 137-148 (2003)

Sajeev, K. 等人：“斯里兰卡中部高地杂岩超高温麻粒岩多阶段变质事件的地质年代学证据”极地地球科学。

Decompression process of mafic granulite from eclogite to granulite facies under ultrahigh-temperature condition in the Kontum masif, central Vietnam

越南中部昆嵩地块超高温条件下镁铁质麻粒岩从榴辉岩到麻粒岩相的减压过程

• 发表时间: 2004
• 期刊: Jour.Mineral.Petrol.Sci. 99
• 作者: Nakano;N.
• 通讯作者: N.

Early Proterozoic tectonothermal events in the Napier Complex, East Antarctica : implication to the formation of East Gondwana.

南极洲东部纳皮尔杂岩的早元古代构造热事件：对东冈瓦纳形成的影响。

• 发表时间: 2003
• 期刊: Gondwana Research 6
• 作者: Owada;M.;Osanai;Y.;Toyoshima;T.;Tsunogae;T.;Hokada;T.;Crowe;W.A.;Kagami;H.
• 通讯作者: H.

地殻内変成作用の高温限界:超高温変成作用

壳内变质作用的高温极限：超高温变质作用

• 发表时间: 2002
• 期刊: 地質ニュース 573
• 作者: N.Sugiura;M.Hoshino;小山内康人
• 通讯作者: 小山内康人

Resetting and closing condition of Rb-Sr whole-rock isochron system : some samples of metamorphic and granitic rocks from・・・

铷-锶全岩等时线系统的复位和闭合条件：来自…的变质岩和花岗质岩的一些样品

• 发表时间: 2003
• 期刊: Polar Geoscinece 16
• 作者: Kagami;H.
• 通讯作者: H.