No / The Raman spectroscopic biosignatures of halotrophic cyanobacterial extremophiles from sabkha evaporitic saltpans are reported for the first time and ideas about the possible survival strategies in operation have been forthcoming. The biochemicals produced by the cyanobacteria which colonise the interfaces between large plates of clear selenitic gypsum, halite, and dolomitized calcium carbonates in the centre of the salt pans are identifiably different from those which are produced by benthic cyanobacterial mats colonising the surface of the salt pan edges in the intertidal zone. The prediction that similar geological formations would have been present on early Mars and which could now be underlying the highly peroxidised regolith on the surface of the planet has been confirmed by recent satellite observations from Mars orbit and by localised traverses by robotic surface rovers. The successful adoption of miniaturised Raman spectroscopic instrumentation as part of a scientific package for detection of extant life or biomolecular traces of extinct life on proposed future Mars missions will depend critically on interpretation of data from terrestrial Mars analogues such as sabkhas, of which the current study is an example.

The Middle Jurassic Entrada Sandstone of the Four Corners region, USA, is composed predominantly of very fine-grained, red, silty sandstone with poorly defined sedimentary structures. The origin of this facies is enigmatic, even though it is common both on the Colorado Plateau and globally, and is spatially situated between deposits recording unambiguous marine and aeolian environments. Eleven sections were measured along an 85 km transect from the Blanding Basin in southeastern Utah to the San Juan Basin in northwestern New Mexico. Outcrop and laboratory analyses distinguish eight facies: (1) silty shale, (2) shallow subaqueous reworked, fine- to medium-grained sandstone, (3) brecciated, very fine-grained sandstone, (4) crinkly laminated, very fine-grained sandstone with preserved wind ripples and abundant silty laminae, (5) weakly laminated, fine-grained sandstone with occasional silty laminae, (6) planar-laminated, fine-grained, wind-rippled sandstone, (7) cross-stratified, fine- to medium-grained aeolian cross-stratified sandstone, and (8) micritic limestone. Lateral and vertical relationships of these facies show a proximal to distal transition from cross-bedded wind-lain facies to loess-dominated sabkha facies with increasing abundance of water-lain facies basinward. The well known Todilto Limestone (facies 8) is situated stratigraphically below loess-dominated sabkha facies (facies 4 and 5) within the Entrada Sandstone, reinforcing previous interpretations that the unit represents a catastrophic flooding event and not a local groundwater flux. / text

In den UAE wurden in Salzböden N-Verbindungen, P, K, Mg, Ca, S, Na, Cl, EC, pH, Salzgehalt und Br, sowie in Salzpflanzen C, N, P, K, Mg, Ca, S, Na quantitativ bestimmt. Es sind 38 verschiedene Arten an 28 Standorten im Inland, am Ufer und in der Mangrove beprobt worden. Die Böden des Landesinnern waren am nährstoffärmsten. Die Böden der Uferbereiche besaßen einen höheren Nährstoffgehalt als die der Mangrovenstandorte. Die Arten zeigen eine von den angebotenen Nährstoffmengen fast unabhängige Aufnahme. Allgemein gilt, dass einige Chenopodiaceen verschiedene Makronährelemente anreicherten, während Gramineen dazu neigten verschiedene Makronährelemente auszuschließen. Die Küstenpflanzen hatten den höchsten Natriumgehalt. Die Pflanzen der Inlandsstandorte akkumulierten mehr Calcium. Arten wie Salsola imbricata reicherten Natrium an, andere Arten wie Cyperus conglomeratus oder Halopyrum mucronatum schränkten die Natriumaufnahme ein. Bei einigen Chenopodiaceen, wie Seidlitzia rosmarinus, Salsola schweinfurthii, Halopeplis perfoliata und Salsola imbricata könnte es sich um stickstofffixierende Arten handeln. Viele der untersuchten Halophyten akkumulieren S in den Blättern.Die Pflanzen konnten nach den Elementgehalten der Blätter, Äste und Wurzeln in Gruppen eingeteilt werden.Arthrocnemum macrostachyum und Avicennia marina vertrugen an ihren natürlichen Standorten Leitfähigkeitswerte bis zu 20 dS/m im Substrat.Nach den Ergebnissen dieser Arbeit kann vermutet werden, dass für Halophyten ein Wachstum auf versalzten Böden nur bei einem dem Salzgehalt angemessenen Nährstoffangebot möglich ist. Dabei muss das Nährstoffangebot mit dem Anstieg des Salzgehaltes zunehmen. Es wurde eine Liste mit etwa 2500 Halophyten erstellt. Die Elemente Mo, Na, Se, Cl, Br, Cd, Th, und U kommen in Halophyten in mindestens 10fach höherer Konzentration als in Nichthalophyten vor. Nur der Hg-Gehalt ist etwa 100fach niedriger.

First distinguished from other sedimentary successions in 1928, the Entrada Sandstone has been the subject of numerous studies. The western extent of the formation was initially described as laterally continuous "earthy" red beds, and categorized as sub- to supratidal marine-influenced sediments. Recent workers have reexamined the sedimentary facies hosted by the Entrada Sandstone, and findings suggest purely terrestrial depositional environments. Several outcrops of the upper Entrada hosted peculiar sedimentary features, including undulatory and convex-upward, parallel-laminated bedforms, reminiscent of hummocky cross-stratification- unexpected features in a terrestrial environment. The purpose of this study was to collect detailed outcrop measurements of these and other facies present in the upper Entrada Sandstone and to place them in context within a regional sedimentary system. Measured section data was analyzed and divided into sixteen primary facies based on textures, features, bedforms, grain size, and other characteristics. Surfaces were also noted and described. Each facies and surface was recognized to have developed under specific depositional or flow conditions, including eolian, paleosol, and fluvial subcritical, critical, supercritical, and waning flow. Primary facies were grouped into observed and interpreted facies associations. A depositional environment was then assigned to each facies association. These environments included sabkha, overbank splay/paleosol, distal terminal splay, and hyper-distal terminal splay. Ancient analogs were found in the Blomidon, Skagerrak, and Ormskirk Formations, which have been described as dryland fluvial systems that terminated onto saline mudflats (sabkhas). Modern analogs were found in the central Australian continent, in the form of fluvial terminal splays in ephemeral Lakes Eyre and Frome. The sedimentary system of the upper Entrada Sandstone of the San Rafael Swell is interpreted as an interfingering fluvial terminal splay and inland sabkha system. These are marked by a wide array of sedimentary structures representing stark extremes, from hyperarid to flash flooding conditions. During arid conditions, the only source of water was evaporative pumping of a high water table. During the rare occasions when surface water flowed through the system, flash flooding events produced the highest stage of supercritical flow described in geological literature. The succession of these facies reveals allogenic and autogenic processes active at the time of deposition, including episodes of tectonic uplift and fluvial avulsions.

The late Middle Jurassic (Callovian) Entrada Sandstone has been divided into two general facies associations consisting primarily of eolian sandstones in eastern Utah and "muddy" redbeds in central Utah. Sedimentary structures within the redbed portion are explained by the interfingering of inland sabkha, alluvial, and eolian depositional systems. A complete succession from the most basinward facies to the most terrestrial facies in the Entrada Sandstone consists of inland sabkha facies overlain by either alluvial or eolian facies. Where both alluvial and eolian facies interfinger, alluvial facies overlain by eolian facies is considered a normal succession. Sequence boundaries, often identified by more basinward facies overlying more landward facies, are observed in the Entrada Sandstone and are extrapolated for the first time across much of Utah, including both the eolian-dominated and redbed-dominated areas. Using these sequence boundaries as well as recent tephrochronologic studies, three time correlative surfaces have been identified in the Entrada. Based on the facies interpretations at each surface, five paleogeographic reconstructions and five isopach maps have been created, illustrating two major intervals of erg expansion and the location of the Jurassic retroarc foreland basin's potential forebulge. Eolian (erg-margin) sandstones pinch-out into muddy redbeds creating combination traps, as evidenced by dead oil (tar) and bleached eolian sandstone bodies within the Entrada. The Entrada Sandstone is a world-class analog for similar systems, such as the Gulf of Mexico's Norphlet Sandstone, where eolian facies grade into muddy redbed facies.