Geochronological constraints on the trans-Hudsonian tectono-metamorphic evolution of the pre-Athabasca basement within the Wollaston-Mudjatik Transition Zone, Saskatchewan
Geochronological constraints on the trans-Hudsonian tectono-metamorphic evolution of the pre-Athabasca basement within the Wollaston-Mudjatik Transition Zone, Saskatchewan
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萨斯喀彻温省沃拉斯顿-穆贾蒂克过渡带内阿萨巴斯卡前基底跨哈德逊纪构造变质演化的年代学限制
DOI：
10.1016/j.precamres.2017.07.019
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发表时间：
2017
影响因子：
3.8
通讯作者：
P. Ledru
中科院分区：
文献类型：
--
作者：
P. Jeanneret;P. Goncalvès;C. Durand;M. Poujol;P. Trap;D. Marquer;D. Quirt;P. Ledru
Wollaston-Mudjatik过渡带（WMTZ）前athabasca结晶基底（> ~ 1700 Ma）的Hudsonian压力-温度-变形-时间（P-T-D-t）演化突出了两个主要的构造变质事件M1-D1和M2-D2。这两个事件的年龄是通过原位LA-ICPMS U-Th-Pb定年和伟晶岩锆石U-Pb分析获得的，这些锆石分别来自含Grt-Crd的泥质片岩，并使用了Wolly-McClean勘探钻井项目的暴露基底和钻孔岩心。M1-D1事件发生在约1840 - 1813 Ma之间，被解释为在10 - 6 kbar的压力下向南冲断了变薄的赫恩边缘。M2-D2事件形成于约1813 - 1770 Ma的哈德逊斜碰撞晚期的左旋逆转构造体系，产生了西mtz的东北构造走向。M2-D2组合的热压估算表明，整个研究区域在约5 kbar和750-825℃的温度下重新平衡，反哈德逊浮晶岩被认为是富铀阿萨巴斯卡不整合型矿床的主要原矿。这些反哈德逊伟晶岩的形成、转移和分化在P-T-D-t演化过程中被取代。在1840-1813 Ma M1-D1部分熔融事件中，地壳深部产生的第一批熔体最有可能富集铀。1813 ~ 1770 Ma期间，由于地壳尺度急倾D2剪切带的发育，这些熔体向上转移至地壳上层，最终分化形成富铀伟晶岩。退变杂岩中的一些独居石和锆石颗粒记录了大约1720 Ma的后期事件，解释为最终冷却事件，温度降至300-400°C，导致变质组合部分退变。这个年龄为阿萨巴斯卡沉积的开始时间提供了新的见解，因此应该至少是1710 Ma或更年轻。
The Hudsonian Pressure-Temperature-Deformation-time-(P-T-D-t) evolution of the pre-Athabasca crystalline basement (>∼1700 Ma) of the Wollaston-Mudjatik Transition Zone (WMTZ) highlights two major tectono-metamorphic events M1-D1 and M2-D2. The ages of these two event have been obtained by in-situ LA-ICPMS U-Th-Pb dating of monazite from Grt-Crd bearing pelitic gneiss and U-Pb analyses performed on zircons from pegmatites, using both exposed basement and drill cores from the Wolly–McClean exploration drilling project. The M1-D1 event, interpreted as the burial of the thinned Hearne margin via southward thrusting to pressures varying from 10 to 6 kbar, occurred between ca.1840 and 1813 Ma. The M2-D2 event, producing the northeast structural trend of the WMTZ, was formed in a sinistral transpressional tectonic regime during the late stage of the Hudsonian oblique collision between ca. 1813 and 1770 Ma. Thermobarometric estimates on the M2–D2 assemblages show that the entire studied area was reequilibrated at about 5 kbar and 750–825 °C. trans-Hudsonian pegmatites are viewed as the main proto-ore of the uranium-rich Athabasca unconformity-type deposits. Formation, transfer and differentiation of these trans-Hudsonian pegmatites are replaced in this P-T-D-t evolution. During the 1840–1813 Ma M1-D1 partial melting event, the first batches of melt produced in the deep crust are the most likely enriched in uranium. Then, these melts were transferred upwards to the upper crustal levels owing to the development of crustal scale steeply-dipping D2 shear zones, and finally were differentiated to form uranium-enriched pegmatites between 1813 and 1770 Ma. Some monazite and zircon grains within retrogressed migmatites recorded a later event at ca. 1720 Ma, interpreted as the terminal cooling event down to 300–400 °C responsible for partial retrogression of metamorphic assemblages. This age provides new insights into the timing of the onset of the Athabasca sedimentation that should therefore be at least 1710 Ma old or younger.
影响因子：
3.4
作者：
G. Dumond;P. Goncalvès;Michael L. Williams;M. Jercinovic
通讯作者：
G. Dumond;P. Goncalvès;Michael L. Williams;M. Jercinovic