تقرير
Stratigraphic Change from Ca-Sulfate to Mg-Sulfate in the Sedimentary Bedrock of Gale Crater, Mars: Recent Results from Curiosity’s APXS
| العنوان: | Stratigraphic Change from Ca-Sulfate to Mg-Sulfate in the Sedimentary Bedrock of Gale Crater, Mars: Recent Results from Curiosity’s APXS |
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| المؤلفون: | Jeffrey Allan Berger, Ralf Kurt Gellert, Abigail Leigh Knight, Michael McCraig, Catherine O'Connell, John Spray, Lucy Margaret Thompson, Scott Joseph Victor Vanbommel, Albert S Yen |
| بيانات النشر: | United States: NASA Center for Aerospace Information (CASI), 2023. |
| سنة النشر: | 2023 |
| مصطلحات موضوعية: | Lunar and Planetary Science and Exploration |
| الوصف: | Curiosity’s APXS instrument has been quantifying sulfates over >30 km of traverse in Gale crater. The rover recently arrived at sedimentary strata where orbital data predicted hydrated Mg-sulfates that may record a change to a drier paleoenvironment. The sequence of strata is in the Marker Band Valley (MBV), the ~10-m-thick, metal-rich Marker Band (MB), and strata above the MB. Here, we report recent sulfate observations by the APXS and provide constraints on the occurrence of Mg-sulfate and the implications for paleoenvironment interpretations. In sedimentary strata below the MBV, Mg-sulfate enrichment (~5-10 wt%) is generally limited to larger diagenetic nodules (~1-3 cm). Ca is positively correlated with S at proportions consistent with Ca-sulfate addition to the bedrock matrix. S variation is thus controlled primarily by Ca-sulfate, which increases ~30% in transitional units below the MBV. The MBV contains the first evidence of Mg-sulfate enrichment in the bedrock matrix, confirmed by the detection of crystalline Mg-sulfate by CheMin. The MBV bedrock has the same overall bulk composition as the underlying Mt. Sharp gp. strata, but with an additional ~5-15 wt% Mg-sulfate. The MB has contrasting sulfate content: (1) targets with very high concentrations of MnO (1.5 wt%), FeO (47 wt%), and Zn (2.2 wt%) are depleted in S and (2) targets with lower metal content have evidence of Mg-sulfate addition. Strata above the MB have a bulk composition that is distinct from other rocks in Gale. For example, the bedrock has molar Fe/Mn (50-60) and Cr/Ti (0.4-0.7) similar to basaltic soil, but ~3X higher Zn and high Ge (50 ppm). Median SO3 above the MB (15 wt%) is higher than the MBV (14 wt%) as well as strata below the MBV (~8 wt%). S does not correlate with Ca or Mg above the MBV. MgO (~9 wt%) is higher than below the MBV (~5 wt%) and the SO3/MgO (1.7) is in the same range as the Mg-sulfate-bearing MBV, suggesting Mg-sulfate enrichment. APXS data indicate that the MBV and above the MB preserve a relatively sharp vertical transition (~5-10 m) from Ca-sulfate to Mg-sulfate in the rock matrix. The sharp contacts with the sulfate-depleted MB and the notable change in bulk composition above the MB may indicate a complex depositional and/or diagenetic history under conditions where enrichments in the highly soluble Mg-sulfates were ultimately preserved. |
| نوع الوثيقة: | Report |
| اللغة: | English |
| URL الوصول: | https://ntrs.nasa.gov/citations/20230015907 |
| ملاحظات: | J2-0092-2541-00004 857464 |
| رقم الأكسشن: | edsnas.20230015907 |
| قاعدة البيانات: | NASA Technical Reports |
| الوصف غير متاح. |