Compositional End Members in Gale Crater, Mars

Geochemical data returned from the Mars Science Laboratory’s Curiosity rover over 1296 sols, has revealed a previously unforeseen martian geochemical complexity. Before Curiosity landed in Gale Crater, Martian SNC meteorite studies along with previous orbiter, rover and lander data showed Mars as being a predominantly basaltic planet with little magmatic differentiation. But through using ChemCam density contour plots to collate compositional data obtained by that instrument, we can identify 4 compositional end members in Gale sedimentary and igneous samples

Partial geometric designs and two-class partially balanced designs

AbstractIt is shown that a partial geometric design with parameters (r, k, t, c) satisfying certain conditions is equivalent to a two-class partially balanced incomplete block design. This generalizes a result concerning partial geometric designs and balanced incomplete block designs

Igneous compositions preserved in Gale crater's geological record

Gale crater’s geological record has two stratigraphic groups deposited in an early Hesperian fluviolacustrine system[1, 2]. The Bradbury Group (sols 1-750) is dominated by fluvial conglomerate and sandstone with lacustrine mudstone in Yellowknife Bay[1,2]. The Mt Sharp Group (Murray formation) is mainly well laminated lacustrine mudstone[2]. We have analysed NASA Curiosity rover ChemCam[3] observation point compositions for targets up to sol 1482 that have hit in situ host rock lacking obvious diagenetic features. ChemCam data are plotted on scatter and density contour plots for their associated stratigraphic units to replicate whole rock composition[4]. Our results show that coarse grained (>1 mm) targets are dominated by trachybasalt[5] and subalkaline basalt[5] igneous endmembers. Sandstone (0.062 – 1 mm) targets indicate a mixture of subalkaline basalt[5], trachybasalt[5] and potassic igneous[6] sources. Finally, mudstone units are dominated by the subalkaline basalt[5] at Yellowknife Bay, and a relatively silica-rich, subalkaline basalt endmember in most of the Murray formation[4], with an even more silica-rich volcanic component at Marias Pass[7]. This demonstrates that Gale crater sediments record a variety of igneous compositions, with subalkaline basalts dominant, but also including lesser amounts of alkaline and silica oversaturated igneous components. References: [1] Grotzinger et al. (2014) doi:10.1126/science.1242777, [2] Grotzinger et al. (2015) doi:10.1126/science.aac7575. [3] Wiens et al. (2012) doi:10.1007/s11214-012-9902-4. [4] Bedford et al. (subm.) GCA. [5] Edwards et al., (2017) MAPS, doi:10.1111/maps.12953. [6] Treiman et al. (2016) doi: 10.1002/2015JE004932. [7] Morris et al. (2016) doi: 10.1073/pnas.1607098113

Readiness exercise to combat avian influenza

10.1093/qjmed/hcn159QJM1022133-13