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<title>UTas ePrints - Formation of the Denchai gem sapphires, northern Thailand: evidence from mineral chemistry and fluid/melt inclusion characteristics</title>
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<meta content="Limtrakun, P." name="eprints.creators_name" />
<meta content="Zaw, K." name="eprints.creators_name" />
<meta content="Ryan, C.G." name="eprints.creators_name" />
<meta content="Mernagh, T.P." name="eprints.creators_name" />
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<meta content="Formation of the Denchai gem sapphires, northern Thailand: evidence from mineral chemistry and fluid/melt inclusion characteristics" name="eprints.title" />
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<meta content="sapphire, Fluid and melt inclusions, alkaline magmatism, basalt, Thailand." name="eprints.keywords" />
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<meta content="The Denchai gem sapphire deposits in Phrae Province, northern Thailand are closely associated with
late Cenozoic alkaline basaltic rocks. The sapphires occur in alluvial placer deposits in palaeo-channels
at shallow depths. Electron microprobe analysis of minor and trace element contents (Fe, Ti, Cr, Ga
and V) of the sapphires indicate the following oxide abundances: Fe2O3 (0.32-1.98 wt.%), TiO2
(0.01-0.23 wt.%), Cr2O3 (<0.01 wt.%), Ga2O3 (0.01-0.03 wt.%) and V2O5 (<0.03 wt.%). Optical
studies of sapphires revealed three types of primary fluid/melt inclusions. CO2-rich inclusions (Type I)
contain three phases (LH2O + LCO2 + V) with the vapour phase comprising <10-15 vol.%. The presence of CO2 was confirmed by microthermometry and laser Raman analysis. Polyphase inclusions (Type II) (vapour + liquid + solid) contain a fluid bubble (20-30 vol.%), an aqueous phase (10-15 vol.%) and several solid phases. Silicate-melt inclusions (Type III) comprise vapour bubbles, silicate
glass and solid phases. Proton-induced X-ray emission (PIXE) analysis revealed high concentrations of
K (~4 wt.%) as well as Ca (~0.5 wt.%), Ti (~1 wt.%), Fe (~2 wt.%), Mn (~0.1 wt.%), V (<0.03 wt.%), Rb (~70 ppm) and Zr (~200 ppm) in the silicate glass. The Ga2O3 abundances and Cr2O3/Ga2O3 values (<1) of the sapphires favour their formation by magmatic processes. The presence of CO2-rich fluids and high K concentrations in the silicate melt inclusions link the origin of the Denchai gem sapphires
to CO2-rich alkaline magmatism." name="eprints.abstract" />
<meta content="2001-12" name="eprints.date" />
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<meta content="Mineralogical Magazine" name="eprints.publication" />
<meta content="65" name="eprints.volume" />
<meta content="6" name="eprints.number" />
<meta content="725-735" name="eprints.pagerange" />
<meta content="10.1180/0026461016560004" name="eprints.id_number" />
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<meta content="Aspen, P., Upton, B.G.J. and Dicken, A.P. (1990)
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GEOSEA, 3, M4 1-38." name="eprints.referencetext" />
<meta content="Limtrakun, P. and Zaw, K. and Ryan, C.G. and Mernagh, T.P. (2001) Formation of the Denchai gem sapphires, northern Thailand: evidence from mineral chemistry and fluid/melt inclusion characteristics. Mineralogical Magazine, 65 (6). pp. 725-735. ISSN 0026-461X" name="eprints.citation" />
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<meta content="The Denchai gem sapphire deposits in Phrae Province, northern Thailand are closely associated with
late Cenozoic alkaline basaltic rocks. The sapphires occur in alluvial placer deposits in palaeo-channels
at shallow depths. Electron microprobe analysis of minor and trace element contents (Fe, Ti, Cr, Ga
and V) of the sapphires indicate the following oxide abundances: Fe2O3 (0.32-1.98 wt.%), TiO2
(0.01-0.23 wt.%), Cr2O3 (<0.01 wt.%), Ga2O3 (0.01-0.03 wt.%) and V2O5 (<0.03 wt.%). Optical
studies of sapphires revealed three types of primary fluid/melt inclusions. CO2-rich inclusions (Type I)
contain three phases (LH2O + LCO2 + V) with the vapour phase comprising <10-15 vol.%. The presence of CO2 was confirmed by microthermometry and laser Raman analysis. Polyphase inclusions (Type II) (vapour + liquid + solid) contain a fluid bubble (20-30 vol.%), an aqueous phase (10-15 vol.%) and several solid phases. Silicate-melt inclusions (Type III) comprise vapour bubbles, silicate
glass and solid phases. Proton-induced X-ray emission (PIXE) analysis revealed high concentrations of
K (~4 wt.%) as well as Ca (~0.5 wt.%), Ti (~1 wt.%), Fe (~2 wt.%), Mn (~0.1 wt.%), V (<0.03 wt.%), Rb (~70 ppm) and Zr (~200 ppm) in the silicate glass. The Ga2O3 abundances and Cr2O3/Ga2O3 values (<1) of the sapphires favour their formation by magmatic processes. The presence of CO2-rich fluids and high K concentrations in the silicate melt inclusions link the origin of the Denchai gem sapphires
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<h1 class="ep_tm_pagetitle">Formation of the Denchai gem sapphires, northern Thailand: evidence from mineral chemistry and fluid/melt inclusion characteristics</h1>
<p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Limtrakun, P.</span> and <span class="person_name">Zaw, K.</span> and <span class="person_name">Ryan, C.G.</span> and <span class="person_name">Mernagh, T.P.</span> (2001) <xhtml:em>Formation of the Denchai gem sapphires, northern Thailand: evidence from mineral chemistry and fluid/melt inclusion characteristics.</xhtml:em> Mineralogical Magazine, 65 (6). pp. 725-735. ISSN 0026-461X</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/2085/1/Limtrakun.Zaw.Ryan.Mernagh.MM.2001.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" class="ep_doc_icon" border="0" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/2085/1/Limtrakun.Zaw.Ryan.Mernagh.MM.2001.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />1048Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input accept-charset="utf-8" value="2620" name="docid" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.1180/0026461016560004">http://dx.doi.org/10.1180/0026461016560004</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">The Denchai gem sapphire deposits in Phrae Province, northern Thailand are closely associated with
late Cenozoic alkaline basaltic rocks. The sapphires occur in alluvial placer deposits in palaeo-channels
at shallow depths. Electron microprobe analysis of minor and trace element contents (Fe, Ti, Cr, Ga
and V) of the sapphires indicate the following oxide abundances: Fe2O3 (0.32-1.98 wt.%), TiO2
(0.01-0.23 wt.%), Cr2O3 (<0.01 wt.%), Ga2O3 (0.01-0.03 wt.%) and V2O5 (<0.03 wt.%). Optical
studies of sapphires revealed three types of primary fluid/melt inclusions. CO2-rich inclusions (Type I)
contain three phases (LH2O + LCO2 + V) with the vapour phase comprising <10-15 vol.%. The presence of CO2 was confirmed by microthermometry and laser Raman analysis. Polyphase inclusions (Type II) (vapour + liquid + solid) contain a fluid bubble (20-30 vol.%), an aqueous phase (10-15 vol.%) and several solid phases. Silicate-melt inclusions (Type III) comprise vapour bubbles, silicate
glass and solid phases. Proton-induced X-ray emission (PIXE) analysis revealed high concentrations of
K (~4 wt.%) as well as Ca (~0.5 wt.%), Ti (~1 wt.%), Fe (~2 wt.%), Mn (~0.1 wt.%), V (<0.03 wt.%), Rb (~70 ppm) and Zr (~200 ppm) in the silicate glass. The Ga2O3 abundances and Cr2O3/Ga2O3 values (<1) of the sapphires favour their formation by magmatic processes. The presence of CO2-rich fluids and high K concentrations in the silicate melt inclusions link the origin of the Denchai gem sapphires
to CO2-rich alkaline magmatism.</p></div><table style="margin-bottom: 1em" cellpadding="3" class="not_ep_block" border="0"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Additional Information:</th><td valign="top" class="ep_row">Definitive version is available online at http://www.minersoc.org/pages/e_journals/minmag.html</td></tr><tr><th valign="top" class="ep_row">Keywords:</th><td valign="top" class="ep_row">sapphire, Fluid and melt inclusions, alkaline magmatism, basalt, Thailand.</td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/260100.html">260000 Earth Sciences > 260100 Geology</a></td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">2085</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Mrs Katrina Keep</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">11 Oct 2007 12:21</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">09 Jan 2008 02:30</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=2085;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&eprintid=2085">item control page</a></p>
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