¹Ziqing Li, ²Mengfan Zhang, ¹Bo Zhang, ³Yuqi Qian, ⁴Tao Long, ⁴Xiaochao Che, ¹Ao Su, ⁵James W. Head
Journal of Geophysical Research: Planets, 131, e2026JE009898 Open Source Link to Article [DOI: 10.1029/2026JE009898]
¹Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing, China
²School of Earth and Space Sciences and Institute of Energy, Peking University, Beijing, China
³Department of Earth and Planetary Sciences, NWU-HKU Joint Center of Earth and Planetary Sciences, The University of Hong Kong, Hong Kong, China
⁴Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
⁵Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
Published by arrangement with John Wiley & Sons

The cause of the observed mare basalt asymmetry between the lunar nearside and farside remains a long-lasting conundrum. In this study, we characterized the petrology and geochemistry of the Chang’e-6 low-Ti basalts from the lunar farside, performed petrological modeling of major elements and conducted Monte Carlo simulation of trace elements, for Chang’e-6 and Chang’e-5 basalts. The results from multiple approaches indicate that the young Chang’e-6 (2.8 Ga) and Chang’e-5 (2.0 Ga) basalts both originated from shallow, depleted ilmenite-bearing cumulate (IBC). Based on remote sensing and thermodynamic constraints, we estimated the mantle source ilmenite abundance for young shallow-source basalts (<3.0 Ga) globally. The modeling results indicate that the mantle sources of these basalts on the nearside generally contains ∼16–32 wt% ilmenite, especially beneath the PKT, whereas the mantle sources of these basalts beneath the farside SPA basin only has ∼13–24 wt% ilmenite. The phase equilibrium calculations show that the nearside mantle sources with higher ilmenite abundance leads to a significant decrease in melting point and tends to produce more melt compared to farside mantle sources. Therefore, asymmetric IBCs may play a key role in accounting for asymmetric nearside/farside volcanism.

¹F. Alberquilla (>10)
Journal of Geophysical Research: Planets, 131, e2026JE009742 Open Source Link to Article [DOI: 10.1029/2026JE009742]
¹University of the Basque Country (EHU), Leioa, Spain
Published by arrangement with John Wiley & Sons

Volcanic tubes provide stable environments where unique mineralogical assemblages can form and be preserved, making them valuable terrestrial analogs for Martian studies. This work investigates tree-like structures within two lava tubes on La Palma Island (Canary Islands, Spain) through a comprehensive geochemical and mineralogical characterization. Samples were analyzed using X-ray diffraction (XRD), micro Energy Dispersive X-Ray fluorescence (µ-EDXRF), Raman microscopy, Scanning Electron Microscopy Energy-Dispersive X-ray Spectroscopy (SEM-EDX), Short-Wave infrared (SWIR) hyperspectral imaging, and multivariate analysis Principal Component Analysis and Multivariate Curve Resolution-Alternating Least Squares (PCA and MCR-ALS) to identify primary mineral phases and assess potential organic matter preservation. The results reveal that these structures are predominantly composed of hydrated silica (opal-A), with secondary phyllosilicates, carbonates, sulfates, and iron oxides. Organic signatures were identified as spectral features consistent with microbial pigments such as β-carotene within the opal matrix, suggesting the potential encapsulation and preservation during silica precipitation. Hyperspectral analyses revealed spectral features consistent with the presence of opal-A, calcite, and nontronite, highlighting complex mineral associations. The comparison with CRISM observations from Jezero Crater revealed similarities in mineral assemblages and suggests that comparable alteration pathways may have affected basaltic substrates, with hydrated silica formation followed by carbonate precipitation under evolving fluid conditions. These findings underscore the relevance of terrestrial lava tubes as analogs for Martian volcanic environments and emphasize the potential of hydrated silica deposits to preserve biosignatures in extraterrestrial contexts.