Mantle Sulfides and their Role in Re–Os and Pb Isotope Geochronology

Harvey, Jason; Warren, J. M.; Shirey, Steven B.

doi:10.1515/9781501502095-012

Cited by 4 publications

(8 citation statements)

References 237 publications

(487 reference statements)

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“…The depleted mantle is thus poorer in sulfides than the primitive mantle (Lee et al, 2012). The crust in return is enriched in sulfides with respect to both the depleted and primitive mantle Patten et al, 2013;Harvey et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Sulfide enrichment at an oceanic crust-mantle transition zone: Kane Megamullion (23°N, MAR)

Ciążela

Koepke

Dick

et al. 2018

Geochimica et Cosmochimica Acta

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ABSTRACT:The Kane Megamullion oceanic core complex located along the Mid-Atlantic Ridge (23°30'N, 45°20'W) exposes lower crust and upper mantle directly on the ocean floor. We studied chalcophile elements and sulfides in the ultramafic and mafic rocks of the crust-mantle transition and the mantle underneath. We determined mineralogical and elemental composition and the Cu isotope composition of the respective sulfides along with the mineralogical and elemental composition of the respective serpentines. The rocks of the crust-mantle transition zone (i.e., plagioclase harzburgite, peridotite-gabbro contacts, and dunite) overlaid by troctolites are by one order of magnitude enriched in several chalcophile elements with respect to the spinel harzburgites of the mantle beneath. Whereas the range of Cu concentrations in spinel harzburgites is 7-69 ppm, the Cu concentrations are highly elevated in plagioclase harzburgites with a range of 90-209 ppm. The zones of the peridotite-gabbro contacts are even 2 more enriched, exhibiting up to 305 ppm Cu and highly elevated concentrations of As, Zn, Ga, Sb and Tl.High Cu concentrations show pronounced correlation with bulk S concentrations at the crust-mantle transition zone implying an enrichment process in this horizon of the oceanic lithosphere. We interpret this enrichment as related to melt-mantle reaction, which is extensive in crust-mantle transition zones. In spite of the ubiquitous serpentinization of primary rocks, we found magmatic chalcopyrites [CuFeS 2 ] as inclusions in plagioclase as well as associated with pentlandite [(Fe,Ni) indicate that the metal enrichment, increased sulfide modes, and potentially formation of small sulfide deposits could be expected globally along the petrological Moho.

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Section: Introductionmentioning

confidence: 99%

“…The estimated mode of sulfide in the primitive mantle is between 0.07 vol.% (Fellows and Canil, 2012) and 0.10 vol.% (Harvey et al, 2016). Sulfides melt in relatively low temperatures during partial melting of the mantle (Hart and Gaetani, 2006;Zhang and Hirschmann, 2016).…”

Section: Introductionmentioning

confidence: 99%

Sulfide enrichment at an oceanic crust-mantle transition zone: Kane Megamullion (23°N, MAR)

Ciążela

Koepke

Dick

et al. 2018

Geochimica et Cosmochimica Acta

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“…Their relative abundance may itself be informative for understanding diamond mineralisation where transient volatile-rich (C, H, O, N, S) metasomatic agents have been suggested as key to diamond formation (e.g., Deines and Harris, 1995;Westerlund et al, 2004;Thomassot et al, 2007Thomassot et al, , 2009Stachel and Luth, 2015). Thus studies of BMS inclusions within diamonds have become a major line of enquiry; for the timing and genesis of diamond growth, for models of crustal and mantle development during the Archaean and the Earth's deep carbon cycle (e.g., Hart et al, 1997;Pearson et al, 1998;Richardson et al, 2001Richardson et al, , 2009Shirey et al, 2004;Stachel and Harris, 2008;Dasgupta and Hirschmann, 2010;Harvey et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Advances in laser ablation ICP-MS (LA-ICP-MS) and in the development of sulphide standards for in situ analysis of PGE and Au in BMS have led to rapid advances in the study of mantle sulphides (see recent reviews by Luguet and Reisberg, 2016;Harvey et al, 2016). But aside from work primarily devoted towards Re-Os isotopes there have been comparatively few studies dedicated to analysing trace elements in diamond-hosted BMS since the 1990s.…”

Section: Introductionmentioning

confidence: 99%

“…Fleet et al, 1993;Barnes et al, 1997;Mungall et al, 2005;Helmy et al, 2007;Taylor and Liu, 2009;Holwell and McDonald, 2010). Because of this fractionation, it is incumbent that all of the mass of the inclusion be extracted intact to ensure a completely unbiased estimate for the composition of the original bulk sulphide Taylor and Liu, 2009;Harvey et al, 2016). However, the 'flaking' or disintegration of the sulphide during inclusion extraction by breaking open the diamond, is a frequently documented and inherent problem (e.g., Deines and Harris, 1995;Pearson et al, 1998;Richardson et al, 2001Richardson et al, , 2009Thomassot et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Homogenisation of sulphide inclusions within diamonds: A new approach to diamond inclusion geochemistry

McDonald

Hughes

Butler

et al. 2017

Geochimica et Cosmochimica Acta

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Base metal sulphide (BMS) inclusions in diamonds provide a unique insight into the chalcophile and highly siderophile element composition of the mantle. Entombed within their diamond hosts, these provide a more robust (closed system) sample, from which to determine the trace element, Re-Os and S-isotopic compositions of the mantle than mantle xenoliths or orogenic peridotites, as they are shielded from alteration during ascent to the Earth's crust and subsequent surface weathering. However, at temperatures below 1100°C some BMS inclusions undergo subsolidus re-equilibration from an original monosulphide solid solution (Mss) and this causes fractionation of the major and trace elements within the inclusions. Thus to study the subjects noted above, current techniques require the entire BMS inclusion to be extracted for analyses. Unfortunately, 'flaking' of inclusions during break-out is a frequent occurrence and hence the risk of accidentally under-sampling a portion of the BMS inclusion is inherent in current practices. This loss may have significant implications for Re-Os isotope analyses where incomplete sampling of a Re-rich phase, such as chalcopyrite that typically occurs at the outer margins of BMS inclusions, may induce significant bias in the Re-Os and 187 Os/ 188 Os measurements and resulting model and isochron ages. We have developed a method for the homogenisation of BMS inclusions in diamond prior to their break-out from the host stone. Diamonds are heated to 1100°C and then quenched to chemically homogenise any sulphide inclusions for both major and trace elements. Using X-ray Computed Microtomography (mCT) we determine the shape and spatial setting of multiple inclusions within a host stone and crucially show that the volume of a BMS inclusion is the same both before and after homogenisation. We show that the homogenisation process significantly reduces the inherent variability of in situ analysis when compared with unhomogenised BMS, thereby widening the scope for multiple methods for quantitative analysis, even on 'flakes' of single BMS inclusions. Finally we show that the trace elements present in peridotite (P-type) and eclogitic (E-type) BMS are distinct, with P-type diamonds having systematically higher total platinum-group element (particularly Os, Ir, Ru) and Te and As concentrations. These distinctions suggest that the PGE and semi-metal budgets of mantle-derived partial melts will be significantly dependent upon the type(s) and proportions of sulphides present in the mantle source.

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Mesoarchean melting and Neoarchean to Paleoproterozoic metasomatism during the formation of the cratonic mantle keel beneath West Greenland

Acken

Luguet

Pearson

et al. 2017

Geochimica et Cosmochimica Acta

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Mantle Sulfides and their Role in Re–Os and Pb Isotope Geochronology

Cited by 4 publications

References 237 publications

Sulfide enrichment at an oceanic crust-mantle transition zone: Kane Megamullion (23°N, MAR)

Sulfide enrichment at an oceanic crust-mantle transition zone: Kane Megamullion (23°N, MAR)

Homogenisation of sulphide inclusions within diamonds: A new approach to diamond inclusion geochemistry

Mesoarchean melting and Neoarchean to Paleoproterozoic metasomatism during the formation of the cratonic mantle keel beneath West Greenland

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