Cretaceous Exhumation of Proterozoic Carbonatite on the Northern Margin of the North China Craton Constrained by Apatite Fission-Track and (U-Th)/He Geochronology
Cretaceous Exhumation of Proterozoic Carbonatite on the Northern Margin of the North China Craton Constrained by Apatite Fission-Track and (U-Th)/He Geochronology
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磷灰石裂变径迹及(U-Th)/He年代学约束的华北克拉通北缘白垩纪碳酸岩折返
DOI：
10.1086/693094
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发表时间：
2017-07
影响因子：
1.8
通讯作者：
Zhang Weibin
中科院分区：
文献类型：
--
作者：
Wu Lin;Liu Yan;Wang Fei;Zeng Liang;Yang Liekun;Tian Yuntao;Zhang Weibin
华北克拉通北方边缘发育有一些与元古代裂谷活动有关的碳酸岩，并与某些类型的矿化有密切的成因关系。我们获得了新的裂变径迹和（U-Th）/He年代学数据从伟晶磷灰石的碎片，共存于元古代火成岩碳酸盐岩沿着三省（河北，山西，内蒙古）的边界。20个碎片的裂变径迹中心年龄为124.1 ± 6.5Ma（1σ）。热历史反演和轨道长度分布表明，通过磷灰石部分退火带的快速早白垩世冷却。16个单碎片磷灰石（U-Th）/He年龄介于82.2 ± 1.8 ~ 109.6 ± 2.3Ma之间，年龄变化远大于分析不确定度。有几个原因可以解释这种分散。虽然α粒子再分布是由U和Th的不均匀性引起的，但化学变化和辐射损伤是最可能的原因。计算了所有分析碎片的平均年龄、中心年龄和等时线年龄，得到一致的统计年龄为100 Ma，可作为伟晶磷灰石冷却年龄的最佳估算值。这一结果还表明，元古宙碳酸盐岩在早白垩世晚期被折返至地下水平，此后埋藏深度不超过2-3 km，这种情况为某些矿床的保存提供了有利条件。元古代岩石的剥蚀与广泛的地壳伸展是一致的，表现为变质核杂岩和裂谷盆地的形成，正断层的复活，以及东亚大陆花岗岩的快速折返。这些新的低温地质资料对有关矿床的剥蚀和保存有一定的启示。
Some carbonatites related to Proterozoic rift activities developed on the northern margin of the North China Craton and have a close genetic relationship with certain types of mineralization. We obtained new fission-track and (U-Th)/He geochronological data from fragments of pegmatitic apatite that coexists with Proterozoic igneous carbonatite along the border of three provinces (Hebei, Shanxi, and Inner Mongolia). Twenty fragments yielded a fission-track central age of 124.1 ± 6.5 Ma (1σ). Thermal-history inversion and track-length distribution suggest rapid Early Cretaceous cooling through the apatite partial-annealing zone. Sixteen single-fragment apatite (U-Th)/He ages range between 82.2 ± 1.8 and 109.6 ± 2.3 Ma, with the age variation much larger than the analytical uncertainty. Several reasons could account for this dispersion. While alpha-particle redistribution resulted from U and Th inhomogeneties, chemical variations and radiation damage are the most probable causes. We calculated the mean age, central age, and isochron age of all the analyzed fragments and got a consistent statistical age of ∼100 Ma, which can be used as the best estimation of the cooling age for the pegmatitic apatite. This result also suggests that the Proterozoic carbonatite was exhumed to a subsurface level during the late Early Cretaceous and was not buried deeper than 2–3 km since then, a situation that provided favorable conditions for the preservation of some ore deposits. The denudation of the Proterozoic rocks was consistent with widespread crustal extension, represented by formation of metamorphic core complexes and rift basins, reactivation of normal faults, and rapid exhumation of granites on the eastern Asian continent. These new low-temperature geological data shed some light on the denudation and preservation of related mineral deposits.
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影响因子：
5
作者：
R. A. Wolf;K. Farley;L. Silver
通讯作者：
R. A. Wolf;K. Farley;L. Silver
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DOI：
10.1007/s11430-015-5259-3
发表时间：
2016-01
期刊：
Science China Earth Sciences
影响因子：
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通讯作者：
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DOI：
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发表时间：
2007
期刊：
--
影响因子：
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作者：
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通讯作者：
P. Reiners;S. Nicolescu
DOI：
10.1144/gsl.sp.2005.245.01.04
发表时间：
2005
期刊：
Geological Society, London, Special Publications
影响因子：
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作者：
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通讯作者：
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