Impactites generally consist of target rocks subjected to a shock wave during an impact event, but theoretically can be composed of surficial materials such as soil or other unconsolidated surface materials. Frothy samples found in the impact melt-bearing breccia circum Lonar crater, India have a significantly lower density than shocked bedrock basalts. Analyses of petrographic and back-scattered electron images, along with mineralogical and geochemical comparisons between the target basalts and local Deccan soils suggest that these are shocked soils that were compressed and lithified during the impact event. Hyperspectral images reveal both unshocked and shocked silicates and glasses along with organics on a scale of millimeters. Shocked soils/regolith could hold tremendous value as recorders of ancient lithosphere-hydrosphere-atmosphere reactions on this planet as well as Mars.

Compositional stratigraphy, consisting of Al-rich kaolinite overlying Fe/Mg-richnontronite, is sporadically distributed within 40{degree sign}S to 30{degree sign}N on Mars. The compositional stratigraphy was considered a typical product of a warm and wet climate, and a window into understanding the atmospheric conditions of early Mars. However, the question remains as to whether the compositional stratigraphy was formed by chemical weathering or sedimentation. Variations in mineralogical/ geochemical properties along the compositional stratigraphy can provide important clues for interpreting the genesis of the compositional stratigraphy. Visible to near infrared (VNIR) reflectance spectroscopy has been used as an effective tool to quantitatively characterize the abundance of kaolinite, nontronite, and weathering intensity in a basaltic weathering succession, as demonstrated by a terrestrial regolith profile. Nevertheless, the VNIR spectra could be influenced by primary minerals and organics in a basalt succession. To test the effectiveness of spectral parameters, the stepwise transformation of nontronite to kaolinite was experimentally modeled and quantitatively investigated using thermogravimetric (TG) and VNIR. The correlation between BD1400 and the content of OH, BD1900 and the H2O content, and BD1400/BD1900 and the OH/H2O ratio were quantitatively constrained to demonstrate their effectiveness as spectral proxies. The obtained data set was also compared with the VNIR spectra from the compositional stratigraphy on Mars, and the continuous variations of the spectral proxies suggest the compositional stratigraphy is formed by a surface chemical weathering process. Accordingly, Mars likely had a warm and wet climate that could maintain liquid water on its surface over a geologic time span.

Global groundwater volumes in the upper 2 km of the Earth’s continental crust – critical for water security – are well estimated. Beyond these depths, a vast body of largely saline and non-potable groundwater exists down to at least 10 km —a volume that has not yet been quantified reliably at the global scale. Here, we estimate the amount of groundwater present in the upper 10 km of the Earth’s continental crust by examining the distribution of sedimentary and cratonic rocks with depth and applying porosity-depth relationships. We demonstrate that groundwater in the 2-10 km zone (what we call ‘deep groundwater’) has a volume comparable to that of groundwater in the upper 2 km of the Earth’s crust. These new estimates make groundwater the largest continental reservoir of water, ahead of ice sheets, provide a basis to quantify geochemical cycles, and constrain the potential for large-scale isolation of waste fluids.