Sound velocities of Anorthite at high pressures and temperatures: Implications for estimating porosity in upper lunar crust

IF 3 2区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Icarus Pub Date : 2025-09-09 DOI:10.1016/j.icarus.2025.116808

Peng Chen , Duojun Wang , Nao Cai , Rui Zhang , Junsheng Ma , Baocun Wang , Yinan Sun , Chunyin Zhou , Ke Yang

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Abstract

The porosity of the lunar crust serves as the key to deciphering crucial geological processes such as the Moon's impact history, volcanic activity, space weathering, and the formation and evolution of its internal structure. In this study, we conducted ultrasonic interferometry experiments on polycrystalline anorthite samples under high pressures and temperatures (up to 5.7 GPa and 873 K) using synchrotron radiation technology. We obtained the relationships between the compressional wave velocity (V_P) and shear wave velocity (V_S) of anorthite with varying pressure and temperature. The elastic properties of anorthite were fitted as follows:

K_{S 0} = 94.71 (7) GPa, K_{S}^{'} = 1.60 (5), \partial K_{S} / \partial T = - 0.004 (7) GPa / K, G_{0} = 46.37 (3) GPa, G^{'} = 0.87 (1), \partial G / \partial T = - 0.007 (1) GPa / K

. By integrating these results with the lunar velocity model derived from the Apollo missions, we constructed a porosity model for the upper lunar crust, using anorthite as a representative mineral. The results indicate that the thickness of the lunar regolith (weathered surface layer) is approximately 30 km. Within the top 1 km of the lunar surface, porosity ranges from 30 % to 90 %. At the depth of 1–30 km, porosity ranges from 0 % to 50 %. At the depth of 30–50 km, porosity is less than 10 %. This study provides constraints on the porosity of the lunar surface and offers scientific guidance for the safety and design of future lunar exploration missions.

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高压和高温下钙长石的声速：对估算月球上地壳孔隙度的意义

月球地壳的孔隙度是破译关键地质过程的关键，如月球的撞击历史、火山活动、太空风化以及其内部结构的形成和演化。在本研究中，我们利用同步辐射技术在高压和高温（高达5.7 GPa和873 K）下对多晶钙长石样品进行了超声干涉测量实验。得到了不同压力和温度下钙长石纵波速度（VP）和横波速度（VS）的关系。对钙长石的弹性性质进行拟合：KS0=94.717GPa,KS′=1.605,∂KS/∂T= - 0.0047GPa/K,G0=46.373GPa,G′=0.871,∂G/∂T= - 0.0071GPa/K。通过将这些结果与来自阿波罗任务的月球速度模型相结合，我们构建了月球上地壳的孔隙度模型，并以钙长石为代表矿物。结果表明，月球风化层（风化表面层）的厚度约为30 km。在月球表面上方1公里的地方，孔隙率从30%到90%不等。在深度1 ~ 30km处，孔隙度为0% ~ 50%。在30 ~ 50 km深度，孔隙度小于10%。该研究提供了月球表面孔隙度的约束条件，为未来月球探测任务的安全和设计提供了科学指导。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Icarus 地学天文-天文与天体物理

CiteScore

6.30

自引率

18.80%

发文量

356

审稿时长

2-4 weeks

期刊介绍： Icarus is devoted to the publication of original contributions in the field of Solar System studies. Manuscripts reporting the results of new research - observational, experimental, or theoretical - concerning the astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of our Solar System or extrasolar systems are welcome. The journal generally does not publish papers devoted exclusively to the Sun, the Earth, celestial mechanics, meteoritics, or astrophysics. Icarus does not publish papers that provide "improved" versions of Bode''s law, or other numerical relations, without a sound physical basis. Icarus does not publish meeting announcements or general notices. Reviews, historical papers, and manuscripts describing spacecraft instrumentation may be considered, but only with prior approval of the editor. An entire issue of the journal is occasionally devoted to a single subject, usually arising from a conference on the same topic. The language of publication is English. American or British usage is accepted, but not a mixture of these.