Low Melting Temperature of Anhydrous Mantle Materials at the Core-Mantle Boundary
Low Melting Temperature of Anhydrous Mantle Materials at the Core-Mantle Boundary
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DOI：
10.1029/2020gl089345
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发表时间：
2020-10-28
影响因子：
5.2
通讯作者：
Lee, Yongjae
中科院分区：
文献类型：
--
作者：
Kim, Taehyun;Ko, Byeongkwan;Lee, Yongjae
准确估计地幔熔融温度的核心挑战之一是探测固体层少量熔融的探测器的灵敏度。为了解决这个问题，我们使用了多通道准直仪来增强少量熔体的漫射x射线散射，并探测了共晶热解成分来增加固相处的熔体数量。通过对火成岩熔体的原位散射检测，确定了在119 +/- 6 GPa条件下的无水熔融温度为3302 +/- 100 K，在核心-地幔边界条件下的上限温度为3430 +/- 130 K。我们的CMB温度比以前的估计低了大约700 K，这意味着该地区的长期冷却速度更快，S、C、O和/或H的浓度更高，并且是非线性的，支持基底岩浆海洋假说。
One of the central challenges in accurately estimating the mantle melting temperature is the sensitivity of the probe for detecting a small amount of melt at the solidus. To address this, we used a multichannel collimator to enhance the diffuse X-ray scattering from a small amount of melt and probed an eutectic pyrolitic composition to increase the amount of melt at the solidus. Our in situ detection of diffuse scattering from the pyrolitic melt determined an anhydrous melting temperature of 3,302 +/- 100 K at 119 +/- 6 GPa and 3,430 +/- 130 K at the core-mantle boundary (CMB) conditions, as the upper bound temperature. Our CMB temperature is approximately 700 K lower than the previous estimates, implying much faster secular cooling and higher concentrations of S, C, O, and/or H in the region, and nonlinear, advocating the basal magma ocean hypothesis.