Cooling and exhumation history of the northeastern Gawler Craton, South Australia
Cooling and exhumation history of the northeastern Gawler Craton, South Australia
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DOI：
10.1016/j.precamres.2011.11.003
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发表时间：
2012-04
影响因子：
3.8
通讯作者：
C. J. Forbes;D. Giles;F. Jourdan;K. Sato;S. Omori;M. Bunch
中科院分区：
文献类型：
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作者：
C. J. Forbes;D. Giles;F. Jourdan;K. Sato;S. Omori;M. Bunch
我们展示了南澳大利亚高勒克拉通东北部古元古代至中元古代 Mount Woods Inlier 黑云母的 40Ar/39Ar 年龄。结合使用热历史程序的石榴石-黑云母 Fe-Mg 交换模型，这些数据用于约束峰后变质 P-T 路径、冷却速率和内点的温度-时间路径。黑云母40Ar/39Ar年龄谱在~1.53Ga处始终存在清晰的平台，表明此时岩石冷却至~300°C。从~1.59Ga到~1.53Ga的高温/低压变质峰峰值，内部区域内的冷却速率为~3–9°C/Ma。随后冷却速率降低至~4°C/Ma。冷却被认为是大量岩浆活动停止和地幔热量输入以及沿大约内陆西南边缘开始的折返作用的结果。 1.592–1.582Ga。内点的温度-时间路径具有凹形形状。伍兹内利尔的峰值变质和随后的冷却历史类似于附近的库纳莫纳省、南澳大利亚克拉通内的库伯佩迪山脊和梅布尔溪山脊。这些地体内部高级变质作用期间的变形被容纳在地壳中部，直到地体冷却并能够沿着离散的剪切带和断层以连贯的刚性块体形式被折返时，才会发生大规模的折返。
We present biotite40Ar/39Ar ages and from the Palaeo- to Mesoproterozoic Mount Woods Inlier in the northeastern Gawler Craton, South Australia. In combination with garnet–biotite Fe–Mg exchange modelling using the THERMAL HISTORY program, these data are used to constrain a post-peak metamorphic P–T path, cooling rates and a temperature–time path for the inlier. Consistently well-defined plateaus at ∼1.53Ga of biotite40Ar/39Ar age spectra indicate that the rocks cooled through ∼300°C at this time. Cooling rates within the inlier are ∼3–9°C/Ma from peak high-temperature/low-pressure metamorphism at ∼1.59Ga to ∼1.53Ga. Cooling rates subsequently decreased to ∼4°C/Ma. Cooling is suggested to be a function of cessation of voluminous magmatism and mantle heat input in conjunction with exhumation initiated along the southwestern margin of the inlier ca. 1.592–1.582Ga. The temperature–time path of the inlier has a concave shape. The peak metamorphic and ensuing cooling history of the Mount Woods Inlier are akin to the nearby Curnamona Province, Coober Pedy Ridge and Mabel Creek Ridge within the South Australian Craton. Deformation during high-grade metamorphism within these terranes was accommodated at mid-crustal levels, and large-scale exhumation did not occur until the terranes cooled and were able to be exhumed as coherent, rigid blocks along discrete shear zones and faults.