Pressure-temperature-fluid constraints for the Emmaville-Torrington emerald deposit, New South Wales, Australia: Fluid inclusion and stable isotope studies

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Lara Loughrey ◽  
Dan Marshall ◽  
Peter Jones ◽  
Paul Millsteed ◽  
Arthur Main
Keyword(s):  
Fluid Inclusion ◽  
New South ◽  
Two Phase ◽  
Quartz Veins ◽  
South Wales ◽  
Three Phase ◽  
Liquid Portion ◽  
Isotope Studies ◽  
Two Fluid ◽  
Metasedimentary Sequence

AbstractThe Emmaville-Torrington emeralds were first discovered in 1890 in quartz veins hosted within a Permian metasedimentary sequence, consisting of meta-siltstones, slates and quartzites intruded by pegmatite and aplite veins from the Moule Granite. The emerald deposit genesis is consistent with a typical granite-related emerald vein system. Emeralds from these veins display colour zonation alternating between emerald and clear beryl. Two fluid inclusion types are identified: three-phase (brine+vapour+halite) and two-phase (vapour+liquid) fluid inclusions. Fluid inclusion studies indicate the emeralds were precipitated from saline fluids ranging from approximately 33 mass percent NaCl equivalent. Formational pressures and temperatures of 350 to 400 °C and approximately 150 to 250 bars were derived from fluid inclusion and petrographic studies that also indicate emerald and beryl precipitation respectively from the liquid and vapour portions of a two-phase (boiling) system. The distinct colour zonations observed in the emerald from these deposits is the first recorded emerald locality which shows evidence of colour variation as a function of boiling. The primary three-phase and primary two-phase FITs are consistent with alternating chromium-rich ‘striped’ colour banding. Alternating emerald zones with colourless beryl are due to chromium and vanadium partitioning in the liquid portion of the boiling system. The chemical variations observed at Emmaville-Torrington are similar to other colour zoned emeralds from other localities worldwide likely precipitated from a boiling system as well.

Conditions for emerald formation at Davdar, China: fluid inclusion, trace element and stable isotope studies

2012 ◽  
Vol 76 (1) ◽  
pp. 213-226 ◽  
Author(s):  
D. Marshall ◽  
V. Pardieu ◽  
L. Loughrey ◽  
P. Jones ◽  
G. Xue
Keyword(s):  
Stable Isotope ◽  
Fluid Inclusion ◽  
Trace Element ◽  
Metasedimentary Rocks ◽  
Quartz Veins ◽  
Trace Element Chemistry ◽  
Stable Isotope Signatures ◽  
Swat Valley ◽  
Isotope Studies ◽  
Geological Work

AbstractPreliminary geological work on samples from Davdar in China indicate that emerald occurs in quartz veins hosted within upper greenschist grade Permian metasedimentary rocks including quartzite, marble, phyllite and schist. Fluid inclusion studies indicate highly saline fluids ranging from approximately 34 to 41 wt.% NaCl equivalent, with minimal amounts of CO2 estimated at a mole fraction of 0.003. Fluid inclusion, stable isotope and petrographic studies indicate the Davdar emeralds crystallized from highly saline brines in greenschist facies conditions at a temperature of ∼350°C and a pressure of up to 160 MPa. The highly saline fluid inclusions in the emeralds, the trace-element chemistry and stable isotope signatures indicate that the Davdar emeralds have some similarities to the Khaltaro and Swat Valley emerald deposits in Pakistan, but they show the greatest similarity to neighbouring deposits at Panjshir in Afghanistan.

scholarly journals Mathematical Functions to Model the Depth Distribution of Soil Organic Carbon in a Range of Soils from New South Wales, Australia under Different Land Uses

Soil Systems ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 46 ◽  
Author(s):  
Brian W. Murphy ◽  
Brian R. Wilson ◽  
Terry Koen
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Exponential Function ◽  
Depth Distribution ◽  
Soil Depth ◽  
New South ◽  
Exponential Functions ◽  
Two Phase ◽  
Mathematical Functions ◽  
South Wales

The nature of depth distribution of soil organic carbon (SOC) was examined in 85 soils across New South Wales with the working hypothesis that the depth distribution of SOC is controlled by processes that vary with depth in the profile. Mathematical functions were fitted to 85 profiles of SOC with SOC values at depth intervals typically of 0–5, 5–10, 10–20, 20–30, 30–40, 40–50, 50–60, 60–70, 70–80, 80–90 and 90–100 cm. The functions fitted included exponential functions of the form SOC = A exp (Bz); SOC = A + B exp (Cz) as well as two phase exponential functions of the form SOC = A + B exp (Cz) + D exp (Ez). Other functions fitted included functions where the depth was a power exponent or an inverse term in a function. The universally best-fitting function was the exponential function SOC = A + B exp (Cz). When fitted, the most successful function was the two-phase exponential, but in several cases this function could not be fitted because of the large number of terms in the function. Semi-log plots of log values of the SOC against soil depth were also fitted to detect changes in the mathematical relationships between SOC and soil depth. These were hypothesized to represent changes in dominant soil processes at various depths. The success of the exponential function with an added constant, the two-phase exponential functions, and the demonstration of different phases within the semi-log plots confirmed our hypothesis that different processes were operating at different depths to control the depth distributions of SOC, there being a surface component, and deeper soil component. Several SOC profiles demonstrated specific features that are potentially important for the management of SOC profiles in soils. Woodland and to lesser extent pasture soils had a definite near surface zone within the SOC profile, indicating the addition of surface materials and high rates of fine root turnover. This zone was much less evident under cropping.

Chronometric calibration of mid-Ordovician to Tournaisian conodont zones: a compilation from recent graphic-correlation and isotope studies

1992 ◽  
Vol 129 (6) ◽  
pp. 709-721 ◽  
Author(s):  
Barry G. Fordham
Keyword(s):  
High Resolution ◽  
High Precision ◽  
Time Scale ◽  
Lower Devonian ◽  
New South ◽  
Upper Ordovician ◽  
South Wales ◽  
Isotope Studies ◽  
Stratotype Section ◽  
Upper Silurian

AbstractThree available graphic-correlation analyses are used to calibrate mid-Palaeozoic conodont zonations: Sweet's scheme for the mid- to Upper Ordovician; Kleffner's for the mid- to Upper Silurian; and Murphy & Berry's for the lower and middle Lower Devonian. The scheme of Sweet is scaled by applying the high-precision U-Pb zircon date of Tucker and others for the Rocklandian and linked with that of Kleffner by scaling the graptolite sequence of the Ordovician-Silurian global stratotype section to fit two similarly derived dates from this sequence. The top of Kleffner's scheme, all of Murphy & Berry's, as well as standard zones to the Frasnian are calibrated by using tie-points of the latest Cambridge-BP time-scale (GTS 89). However, the recent microbeam zircon date by Claoué-Long and others for the Hasselbachtal Devonian-Carboniferous auxiliary stratotype is used to calibrate the standard Famennian zones. Also the similarly derived but preliminary determination reported by Roberts and others from the Isismurra Formation of New South Wales is tentatively taken as the top of the Tournaisian and so used to calibrate Tournaisian zones. Despite the considerable extrapolation required to compile these schemes and their inherent errors, the resultant time-scale closely agrees with other dates of Tucker and others from the Llanvirn as well as the GTS 89 Homerian-Gorstian tie-point. This suggests that stratigraphic methods can be usefully applied to geochronometry. The Llandovery appears to have lasted longer (16 m. y.) than usually envisaged and the Ordovician-Silurian boundary may need to be lowered to approximately 443.5 Ma. Certainly, chrons varied widely in duration and further stratigraphic studies to estimate their relative durations as well as high-resolution dating for their calibration will be crucial to more accurate biochronometries.

Contrasts in gem corundum characteristics, eastern Australian basaltic fields: trace elements, fluid/melt inclusions and oxygen isotopes

2006 ◽  
Vol 70 (6) ◽  
pp. 669-687 ◽  
Author(s):  
Khin Zaw ◽  
F. L. Sutherland ◽  
F. Dellapasqua ◽  
C. G. Ryan ◽  
Tzen-Fu Yui ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Melt Inclusions ◽  
Melt Inclusion ◽  
New South ◽  
Alkaline Basalt ◽  
South Wales ◽  
Basaltic Melt ◽  
Isotope Studies ◽  
Alkaline Fluid ◽  
Basaltic Melts

AbstractCorundum xenocrysts from alkaline basalt fields differ in characteristics and hence lithospheric origins. Trace element, fluid/melt inclusion and oxygen isotope studies on two eastern Australian corundum deposits are compared to consider their origins. Sapphires from Weldborough, NE Tasmania, are magmatic (high-Ga, av. 200 ppm) and dominated by Fe (av. 3300 ppm) and variable Ti (av. 400 ppm) as chromophores. They contain Cl, Fe, Ga, Ti and CO2-rich fluid inclusions and give δ18O values (5.1–6.2‰) of mantle range. Geochronology on companion zircons suggests several sources (from 290 Ma to 47 Ma) were disrupted by basaltic melts (47 ± 0.6 Ma). Gem corundums from Barrington, New South Wales, also include magmatic sapphires (Ga av. 170 ppm; δ18O (4.6–5.8‰), but with more Fe (av. 9000 ppm) and less Ti (av. 300 ppm) as chromophores. Zircon dating suggests that gem formation preceded and was overlapped by Cenozoic basaltic melt generation (59–4 Ma). In contrast, a metamorphic sapphire-ruby suite (low-Ga, av. 30 ppm) here incorporates greater Cr into the chromophores (up to 2250 ppm). Fluid inclusions are CO2-poor, but melt inclusions suggest some alkaline melt interaction. The δ18O values (5.1–6.2‰) overlap magmatic sapphire values. Interactions at contact zones (T = 780–940°C) between earlier Permian ultramafic bodies and later alkaline fluid activity may explain the formation of rubies.

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