A new species of Glaphyromorphus (Reptilia : Scincidae) from Mt Elliot, north-eastern Queensland

Glaphyromorphus clandestinus, sp. nov., is described from granite-slab habitat on Mt Elliot, north-eastern Queensland. This species can be distinguished from its congeners by a combination of the following characters: large size (SVL 72 mm), adpressed limbs of adult separated by noticeably more than the length of the forelimb, 26 mid-body scale rows, and flanks patterned with dark flecks forming a series of longitudinal lines. The distribution, habitat preferences and habits of this species are poorly known. Currently G. clandestinus is known from a single locality where individuals have been found in an exposed area of exfoliating granite, set in a mosaic of rainforest and eucalyptus woodland. The discovery of this species brings to three the number of vertebrate species known to be endemic to Mt Elliot and highlights the evolutionary significance of this southerly outlier to the mountainous rainforest of the Wet Tropics.

Hydrothermal control on organic matter alteration and illite precipitation, Mt Isa Basin, Australia

Abundant illite precipitation, in Proterozoic rocks from Northern Lawn Hill Platform, Mt Isa Basin, Australia, occurred in organic matter-rich black shales rather than in sandstones, siltstones and organic matter-poor shales. Sandstones and siltstones acted as impermeable rocks, as early diagenetic quartz and carbonate minerals reduced the porosity-permeability. Scanning and transmission electron microscopy (SEM and TEM) studies indicate a relation between creation of microporosity-permeability and organic matter alteration, suitable for subsequent mineral precipitation. K-Ar data indicate that organic matter alteration and the subsequent illite precipitation within the organic matter occurred during the regional hydrothermal event at 1172 +/- 150 (2sigma) Ma. Hot circulating fluids are considered to be responsible for organic matter alteration, migration and removal of volatile hydrocarbon, and consequently porosity-permeability creation. Those rocks lacking sufficient porosity-permeability, such as sandstones, siltstones and organic matter poor shales, may not have been affected by fluid movement. In hydrothermal systems, shales and mudstones may not be impermeable as usually assumed because of hydrocarbons being rapidly removed by fluid, even with relatively low total organic carbon.