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首页> 外文期刊>Precambrian Research >Grenvillian-aged reworking in the North Australian Craton, central Australia: Constraints from geochronology and modelled phase equilibria
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Grenvillian-aged reworking in the North Australian Craton, central Australia: Constraints from geochronology and modelled phase equilibria

机译：在澳大利亚中部北澳大利亚克雷顿州的格林维利时代的返工：年代学和模拟相平衡的限制

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In situ LA-ICP-MS U-Pb monazite geochronology and garnet Sm-Nd geochronology, combined with calculated metamorphic phase diagrams, indicate that the eastern Warumpi Province along the southern margin of the North Australian Craton has undergone Grenvillian-aged reworking. Rocks in the eastern Warumpi Province are characterised by a pervasive flat lying fabric, with a NE trending lineation that is usually associated with top to the north shear sense. This flat lying fabric has been overprinted by regional-scale E-W trending upright folds. Calculated metamorphic phase diagrams based on garnet-staurolite-andalusite-bearing metapelites indicate a clockwise pressure-temperature (P-T) evolution involving decompression and heating from maximum pressures of 4 to 4.5 kbar at 530 °C to maximum temperatures of ~570 °C at 3.5 kbar. Sm-Nd isotopic analyses of prograde-zoned garnet within these metapelites yield ages of 1141 ± 22 Ma and 1100 ± 22 Ma. Monazite within the fabric that encloses these garnets yield LA-ICP-MS U-Pb ages in the range 1140-1109 Ma. The age data suggest that the flat lying fabric and regional folding in the eastern Warumpi Province is associated with Grenvillian-aged reworking of the late Paleoproterozoic protoliths. Dolerite dykes belonging to the 1080 Ma Stuart Dyke Swarm cross cut the upright folding, constraining the deformation to the interval 1140-1080 Ma. The late Mesoproterozoic timing of deformation and metamorphism contrasts with previous work, which attributes the tectonic architecture in the eastern Warumpi Province to early Mesoproterzoic (ca 1590 Ma) tectonism. The metamorphic conditions indicate a high geothermal gradient regime, associated with the formation of a regional, low-angle fabric and decompression which is suggestive of an extensional setting. The timing of the deformation in the eastern Warumpi Province is synchronous with the latter stages of high-T magmatism and metamorphism in the Musgrave Province, several hundred kilometres to the south. The similarity in age of high geothermal-gradient metamorphism in both regions implies that the effects of the Grenvillian-aged tectonism in central Australia are more extensive than previously understood. It also suggests that much of the basement to the intracratonic Amadeus Basin, which now separates the two provinces, also underwent deformation and metamorphism during this event.
机译：原位LA-ICP-MS U-Pb独居石年代学和石榴石Sm-Nd年代学，结合计算出的变质相图，表明北澳大利亚克拉通南部边缘的沃鲁比省东部经历了格林维尔时期的返工。沃鲁比省东部的岩石的特征是无处不在的平躺织物，其NE趋向线通常与从上到北的剪切力有关。这种平躺的织物被区域性的E-W趋势直立折叠叠印。基于石榴石-辉石-含铝辉石的变质岩的变质相图表明，顺时针压力-温度（PT）演化涉及减压和加热，从530°C的4至4.5 kbar的最大压力到3.5°C的最高温度〜570°C kbar。在这些变质岩中对正向带状石榴石进行Sm-Nd同位素分析，得出年龄为1141±22 Ma和1100±22 Ma。包围这些石榴石的织物中的独居石产生的LA-ICP-MS U-Pb年龄在1140-1109 Ma之间。年龄数据表明，瓦鲁比省东部的平躺织物和区域性折叠与晚古元古代原生石的格伦维利亚时代的改造有关。属于1080 Ma斯图尔特堤群的Dolerite堤切割了直立的褶皱，将变形限制在1140-1080 Ma的区间内。中元古代晚期的变形和变质时间与以前的工作形成了鲜明的对比，后者将东部沃伦比省的构造构造归因于中元古代（大约1590 Ma）构造。变质条件表明高地热梯度状态，与区域低角度织物的形成和减压有关，这暗示了伸展的环境。沃鲁比省东部的变形时间与南部几百公里的马斯格雷夫省的高T岩浆作用和变质作用的后期同步。在两个地区，地热梯度高变质时代的相似性表明，在澳大利亚中部格伦维利时期的构造运动的影响比以前理解的更为广泛。这也表明，现在将两个省分开的克拉通内阿玛迪斯盆地的许多地下室在这一事件中也经历了变形和变质作用。

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