Estimating concentrations of heat producing elements in the crust near the Sudbury Neutrino Observatory, Ontario, Canada
Estimating concentrations of heat producing elements in the crust near the Sudbury Neutrino Observatory, Ontario, Canada
复制标题
估算加拿大安大略省萨德伯里中微子天文台附近地壳中产热元素的浓度
DOI：
10.1016/j.tecto.2014.03.001
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发表时间：
2014
期刊：
影响因子：
2.9
通讯作者：
J. Mareschal
中科院分区：
文献类型：
--
作者：
C. Phaneuf;J. Mareschal
由于铀和钍在地壳中的浓度必须确定精确的未来geoneutrino观测计划在萨德伯里中微子天文台，我们调查是否可以使用航空辐射测量来约束地壳的放射性。区域航空勘测覆盖的区域很广，空间分辨率高（< 250米），但只对非常薄的表层（25厘米）敏感。我们计算地壳产热在萨德伯里地区的航空辐射测量和测量露头和岩心样品，并与热流数据进行比较。放射性测量得到的铀、钍和钾的浓度与地质学有关，但产热估计值低于岩石样本的值。辐射测量给出了超过176，000个数值的平均产热为0.8 ± 0.6（σ）μW m− 3。在上级省沿沿着样带采集的露头样品产生的平均产热量为2.9 ± 2.4（σ）μW m− 3，钻孔岩芯样品产生的平均产热量为2.5 ± 0.8（σ）μW m− 3。岩石样本中的高热量生产与萨德伯里附近的表面热通量测量结果一致，平均值比加拿大地盾的平均值高12 mW m-2。这项研究表明，航空航磁测量提供了有用的信息，在地表产热的横向变化，但不太可能提供可靠的产热值需要计算地壳地中微子通量。地壳产热量最好根据热通量数据计算，并辅之以岩石样品的产热测量。萨德伯里火成杂岩样品的高平均产热量（1.5 μW m− 3）表明，熔融片的主要来源是上级省的放射性很强的上地壳，或者熔融片相对于下地壳来源而言是极其富集的。
Because the concentrations of uranium and thorium in the crust must be determined precisely for the future geoneutrino observations planned at the Sudbury Neutrino Observatory, we investigate whether airborne radiometric surveys can be used to constrain crustal radioactivity. The regional airborne surveys cover a wide area with high spatial resolution (< 250 m), but are only sensitive to a very thin (25 cm) surficial layer. We calculate crustal heat production in the Sudbury region from airborne radiometric surveys and compare with measurements on outcrop and core samples, and with heat flow data. The concentrations of uranium, thorium, and potassium from radiometric surveys are correlated with geology, but heat production estimates are lower than values from rock samples. The radiometric surveys give a mean heat production of 0.8 ± 0.6 (σ) μW m− 3for more than 176,000 values. The outcrop samples collected along a transect in the Superior Province yield an average heat production of 2.9 ± 2.4 (σ) μW m− 3and core samples from drill holes yield an average of 2.5 ± 0.8 (σ) μW m− 3. The high heat production in the rock samples is consistent with surface heat flux measurements near Sudbury with a mean value that is 12 mW m− 2higher than the average Canadian Shield. The study shows that airborne aeromagnetic surveys give useful information on lateral variations in surface heat production but are unlikely to provide the reliable values of heat production needed to calculate the crustal geoneutrino flux. Crustal heat production will be best calculated from heat flux data complemented by heat production measurements on rock samples. The high mean heat production in Sudbury Igneous Complex samples (≈ 1.5 μW m− 3) suggests that the main source of the melt sheet was the very radioactive upper crust of the Superior Province or that the melt sheet was extremely enriched relative to a lower crustal source.