Paul Dennis edited discussion_temperature.tex  over 8 years ago

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\subsection{Temperature}  The data for the temperature at which calcite precipitated at Dirtlow Rake are the first measurements made for the southern Pennines using the clumped isotope technique. It's pertinent to ask if these temperatures are robust and representative of the hydrothermal fluid temperatures. We see a temperature range of 40$^{\circ}$C to 100$^{\circ}$C. The most direct comparison we can make is with fluid inclusion homogenization temperatures. Several fluid inclusion studies have been completed, largely using fluorite but also with a limited number of data points for calcite. Overall there is wide variation in the reported homogenization temperatures ranging from 60$^{\circ}$C to greater than 240$^{\circ}$C. Our temperature estimates fall towards the lower end of this range and are consistent with the homogenization temperatures reported for type 2 (62$^{\circ}$-82$^{\circ}$C), type 3 (64.9$^{\circ}$-98.9$^{\circ}$C), type 4 (63.4$^{\circ}$-106$^{\circ}$C) and type 5 (66.3$^{\circ}$-68.3$^{\circ}$C) inclusions in fluorite reported by Atkinson (1983). The type 1 inclusions reported on by Atkinson (1983) have higher homogenization temperatures of 119.5$^{\circ}$ - 157$^{\circ}$C. These are higher than the maximum temperatures we have observed for this part of the orefield. A difficulty in making a comparison is that the different types of inclusions are thought to relate to different stages in the mineral paragenesis and may not directly relate to the calcite veins at Dirtlow Rake.  The vein calcite at Dirtlow Rake is from zone 4 of the paragenetic sequence outlined by Walkden and xxxx. Hollis and Walkden have published limited fluid inclusion data for calcites from this zone.