Thomas Stachel
University of Alberta
GeologyGeochemistryKimberliteDiamondMantle (geology)
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Publications 111
#1J. Czas (U of A: University of Alberta)
#2D. Graham Pearson (U of A: University of Alberta)H-Index: 22
Last. George H. ReadH-Index: 2
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Abstract The recently recognised Sask Craton, a small terrane with Archean (3.3–2.5 Ga) crustal ages, is enclosed in the Paleoproterozoic (1.9–1.8 Ga) Trans Hudson Orogen (THO). Only limited research has been conducted on this craton, yet it hosts major diamond deposits within the Cretaceous (~106 to ~95 Ma) Fort a la Corne (FALC) Kimberlite Field. This study describes major, trace and platinum group element data, as well as osmium isotopic data from peridotitic mantle xenoliths (n = 26) from th...
#1D. Howell (UNIPD: University of Padua)
#2Thomas Stachel (U of A: University of Alberta)H-Index: 26
Last. Pierre Cartigny (IPGP: Institut de Physique du Globe de Paris)H-Index: 35
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Abstract Diamonds are unrivalled in their ability to record the mantle carbon cycle and mantle fO2 over a vast portion of Earth’s history. Diamonds’ inertness and antiquity means their carbon isotopic characteristics directly reflect their growth environment within the mantle as far back as ∼3.5 Ga. This paper reports the results of a thorough secondary ion mass spectrometry (SIMS) carbon isotope and nitrogen concentration study, carried out on fragments of 144 diamond samples from various locat...
Yellow diamonds from the CH-7 (Chidliak) and the Misery (Ekati Mine) kimberlites in northern Canada are characterised for their nitrogen characteristics, visible light absorption, internal growth textures, and carbon isotope compositions. The diamonds are generally nitrogen-rich, with median N contents of 1230 (CH-7) and 1030 at.ppm (Misery). Normally a rare feature in natural diamonds, single substitutional nitrogen (C centres) and related features are detected in infrared absorption spectra of...
#1Mei Yan Lai (U of A: University of Alberta)
#2Christopher M. Breeding (Gemological Institute of America)H-Index: 12
Last. Richard A. Stern (U of A: University of Alberta)H-Index: 36
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Abstract High pressure high temperature (HPHT) treatment has long been applied in the gem trade for changing the body colour of diamonds. The identification of HPHT-treated diamonds is a field of on-going research in gemological laboratories, as different parameters of treatment will result in either the creation or the destruction of a variety of lattice defects in diamonds. Some features that exist in treated diamonds can also be found in natural diamonds, and consequently must not be employed...
#1Graham Pearson (U of A: University of Alberta)H-Index: 2
#2Margo E. Regier (ASU: Arizona State University)H-Index: 1
Last. Jeff W. Harris (Glas.: University of Glasgow)H-Index: 56
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#1J. C. M. De Hoog (Edin.: University of Edinburgh)H-Index: 4
#2Thomas Stachel (U of A: University of Alberta)H-Index: 26
Last. Jeff W. Harris (Glas.: University of Glasgow)H-Index: 56
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Trace-element concentrations in olivine and coexisting garnets included in diamonds from the Akwatia Mine (Ghana, West African Craton) were measured to show that olivine can provide similar information about equilibration temperature, diamond paragenesis and mantle processes as garnet. Trace-element systematics can be used to distinguish harzburgitic olivines from lherzolite ones: if Ca/Al ratios of olivine are below the mantle lherzolite trend (Ca/Al 300 µg/g Ca or > 60 µg/g Na are lherzolitic....
1 CitationsSource
#1Steven B. ShireyH-Index: 55
#2Karen V. SmitH-Index: 6
Last. Y. WeissH-Index: 9
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The authors thank the following institutions and individuals: our home institutions; SBS and EHH for support from the US National Science Foundation (EAR-104992); FN and PN for support from the European Research Council Starting Grant (#307322); Wuyi Wang and Tom Moses of the Gemological Institute of America (GIA) for the support of the research projects undertaken by KVS and EMS; and SCK for the support of De Beers Technologies.
#1Karen V. Smit (Gemological Institute of America)H-Index: 6
#2Thomas Stachel (U of A: University of Alberta)H-Index: 26
Last. Richard A. Stern (U of A: University of Alberta)H-Index: 36
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Abstract Here we present SIMS data for a suite of Zimmi sulphide-bearing diamonds that allow us to evaluate the origin and redox-controlled speciation of diamond-forming fluids for these Neoproterozoic eclogitic diamonds. Low δ 13 C values below −15‰ in three diamonds result from fluids that originated as carbon in the oceanic crust, and was recycled into the diamond-stable subcratonic lithospheric mantle beneath Zimmi during subduction. δ 13 C values between −6.7 and −8.3‰ in two diamonds are w...
1 CitationsSource
#1Kan Li (U of A: University of Alberta)H-Index: 1
#2Long Li (U of A: University of Alberta)H-Index: 15
Last. Thomas Stachel (U of A: University of Alberta)H-Index: 26
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Abstract A long-standing unresolved problem in understanding Earth's deep carbon cycle is whether crustal carbon is recycled beyond arc depths. While isotopic signatures of eclogitic diamonds and their inclusions suggest deep recycling of crustal material, the crustal carbon source remains controversial; seafloor sediment – the widely favored crustal carbon source – cannot explain the combined carbon and nitrogen isotopic characteristics of eclogitic diamonds. Here we examined the carbon and oxy...
3 CitationsSource
#1M.Y. Krebs (U of A: University of Alberta)H-Index: 2
#2David G. Pearson (U of A: University of Alberta)H-Index: 13
Last. J. KongH-Index: 3
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Abstract Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. “Planed” and “ribbed” trace element patterns characterize not only the high-densi...
5 CitationsSource