Genesis and preservation of a uranium-rich Paleozoic epithermal system with a surface expression (Northern Flinders Ranges, South Australia): radiogenic heat driving regional hydrothermal circulation over geological timescales

The surface expressions of hydrothermal systems are prime targets for astrobiological exploration, and fossil systems on Earth provide an analogue to guide this endeavor. The Paleozoic Mt. Gee–Mt. Painter system (MGPS) in the Northern Flinders Ranges of South Australia is exceptionally well preserved and displays both a subsurface quartz sinter (boiling horizon) and remnants of aerial sinter pools that lie in near-original position. The energy source for the MGPS is not related to volcanism but to radiogenic heat produced by U-Th-K-rich host rocks. This radiogenic heat source drove hydrothermal circulation over a long period of time (hundreds of millions of years, from Permian to present), with peaks in hydrothermal activity during periods of uplift and high water supply. This process is reflected by ongoing hot spring activity along a nearby fault. The exceptional preservation of the MGPS resulted from the lack of proximal volcanism, coupled with tectonics driven by an oscillating far-field stress that resulted in episodic basement uplift. Hydrothermal activity caused the remobilization of U and rare earth elements (REE) in host rocks into (sub)economic concentrations. Radiogenic-heat-driven systems are attractive analogues for environments that can sustain life over geological times; the MGPS preserves evidence of episodic fluid flow for the past 300 million years. During periods of reduced hydrothermal activity (e.g., limited water supply, quiet tectonics), radiolytic H2 production has the potential to support an ecosystem indefinitely. Remote exploration for deposits similar to those at the MGPS systems can be achieved by combining hyperspectral and gamma-ray spectroscopy.Joël Brugger, Pierre-Alain Wülser and John Fode

Current strategies for the assessment and evaluation of genetic diversity in chicken resources

Chicken genetic resources comprise a wide range of breeds and populations including red jungle fowl (the assumed progenitor of all domestic breeds), native and fancy breeds, middle level food producers, industrial stocks and specialised lines. Based on the suggestion that the more distant a breed or population is the more likely it is to carry unique genetic features, the assessment of genetic distances by means of molecular marker information may provide useful information for initial evaluation of chicken genetic resources. During the last two decades several molecular marker classes have become available. Variable numbers of tandem repeat loci, in particular microsatellites, have been successfully used in chicken diversity studies. Genetic diversity measures using the highly polymorphic variable number of tandem repeat lociyield reliable and accurate information for the study of genetic relationships between chicken populations. First results of the European project on chicken biodiversity (AVIANDIV) obtained from microsatellite typing in DNA pools of 51 diverse chicken breeds showed that jungle fowl populations, traditional unselected breeds and broiler lines appear to be widely heterogeneous populations that may include a large portion of the genetic diversity of the tested breeds. In contrast, highly selected strains (layers and experimental lines) are characterised by a lower polymorphism. They behave as outliers from the set of breeds sampled. Single nucleotide polymorphism is a new and very promising molecular marker system which offers opportunities to assess the genetic diversity in farm animal species differently by investigating the mode and extent of changes in certain positions in the genome