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首页> 外文期刊>Brazilian Journal of Geology >Metamorphic modeling and petrochronology of metapelitic rocks from the Luminárias Nappe, southern Brasília belt (SE Brazil)
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Metamorphic modeling and petrochronology of metapelitic rocks from the Luminárias Nappe, southern Brasília belt (SE Brazil)

机译：巴西利亚南部带（巴西东南部）LumináriasNappe的变质岩的变质建模和岩石年代学

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The Luminárias Nappe was formed in the agglutination of West Gondwana. A high-pressure metamorphic gradient oblique to the geological contacts is recorded in metapelitic rocks from this Nappe. In the northern portion, the metamorphic peak conditions are at high-pressure lower-amphibolite facies at 580 ± 4°C and ca. 0.9 GPa (Chl + Ky + St + Ms + Qtz + Rt); in the central portion, they are at high-pressure amphibolite facies at 600 ± 15°C and 1.1 ± 0.3 GPa (St + Bt + Grt + Ms + Qtz + Rt); and in the southern portion, they reach the eclogite facies at 630 ± 13°C and 1.4 ± 0.6 GPa (St + Ky + Grt + Ms + Qtz + Rt). Clockwise metamorphic P-T-t paths are registered in the studied rocks, with temperature and pressure increase followed by a strong decompression with retrograde phases as chloritoid (northern portion), chlorite and ilmenite (central portion) and biotite, chlorite and ilmenite (southern portion). U-Th-Pb T monazite ages range from 632 ± 4 Ma (southern portion) to 600 ± 8 Ma (northern portion included crystals in garnet and staurolite). The metamorphic age, the high-pressure conditions calculated in this paper and the clockwise metamorphic path indicate that the tectonic evolution of the Luminárias Nappe rocks is tightly associated with the subduction and collision processes of the southern Brasília belt. The overprint of the younger Ribeira belt is interpreted to be responsible for rock pile tilting, thus producing the oblique metamorphic gradient.
机译：Luminárias尿布形成于西冈瓦纳（West Gondwana）的凝集。斜向地质接触的高压变质梯度记录在该纳皮的变质岩中。在北部，变质峰条件是在580±4°C左右的高压下闪闪石相下。 0.9 GPa（Chl + Ky + St + Ms + Qtz + Rt）;在中部，它们处于600±15°C和1.1±0.3 GPa（St + Bt + Grt + Ms + Qtz + Rt）的高压闪石岩相;在南部，它们在630±13°C和1.4±0.6 GPa（St + Ky + Grt + Ms + Qtz + Rt）达到榴辉岩相。在研究的岩石中记录了顺时针变质P-T-t路径，随着温度和压力的增加，随后发生了强烈的减压作用，逆向相为类绿藻石（北部），绿泥石和钛铁矿（中央部分）以及黑云母，绿泥石和钛铁矿（南部部分）。 U-Th-Pb T独居石的年龄范围为632±4 Ma（南部部分）至600±8 Ma（北部部分包括石榴石和十字沸石中的晶体）。变质时代，本文计算的高压条件和顺时针变质路径表明，LumináriasNappe岩石的构造演化与巴西利亚南部带的俯冲和碰撞过程紧密相关。较年轻的Ribeira带的套印被解释为造成岩堆倾斜的原因，从而产生了倾斜的变质梯度。

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