Hydrocarbons associated with lead–zinc ores at Laisvall, Sweden

Rickard, David; Willdén, Mats; Mårde, Y.; Ryhage, Ragnar

doi:10.1038/255131a0

Cited by 30 publications

(11 citation statements)

References 2 publications

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“…Organic compounds (i.e., solid bitumen) are intergrown with sphalerite or included in barite (Saintilan et al, in press) and hydrocarbons were optically recognized in fluid inclusions in sphalerite (Lindblom, 1986). These observations are consistent with the results of the work by Rickard et al (1975), suggesting that the mineralizing fluids contained petroleum-like compounds.…”

Section: Strata-bound Sandstone-hosted Pb-zn Deposit In Autochthonoussupporting

confidence: 88%

“…Rickard, 1983; in press) involving hydrocarbons (cf. Rickard et al, 1975;Lindblom, 1986;Saintilan et al, in press). The sampling procedure avoided earlier-stage generations that formed by replacement of early diagenetic framboidal pyrite and euhedral diagenetic pyrite (δ 34 S values for these pyrite generations: from -11.0 to -6.0‰, and from 21.0 to 31.0‰, respectively; Saintilan et al, in press).…”

Section: Sample Selection For Rb-sr Isotope Systematics and Charactermentioning

confidence: 91%

“…Grip (1960) proposed a genetic relationship between epigenetic mineralization and Caledonian overthrusting with mineralizing solutions derived from the "inner part of the Caledonian range" (p. 158). Geologic and geochemical evidence led Gee (1972) and Rickard et al (1975Rickard et al ( , 1979 to propose that mineralization at Laisvall probably occurred after the deposition of the Middle Cambrian to Lower Ordovician Alum Shale Formation that represents an impermeable cap rock above the strata-bound mineralization in sandstone. Rickard et al (1979) related mineralization at Laisvall to Caledonian tectonics and suggested that mineralization predated the "great Caledonian nappes emplacement" (p. 1277) during the early Devonian.…”

Section: Introductionmentioning

confidence: 98%

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A Middle Ordovician Age for the Laisvall Sandstone-Hosted Pb-Zn Deposit, Sweden: A Response to Early Caledonian Orogenic Activity

Saintilan¹,

Schneider²,

Stephens³

et al. 2015

Economic Geology

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Ten sphalerite separates isolated from mineralized samples in proximal and distal positions relative to the proposed main feeder fault systems at the Laisvall deposit were used to obtain an absolute age determination of this world-class Pb-Zn deposit hosted by autochthonous Ediacaran to Lower Cambrian sandstone and located currently along the erosional front of the Scandinavian Caledonides in northern Sweden. Residue and leachate fractions of each separate were obtained using the crush-leaching technique. All samples correspond to sphalerite formed using reduced sulfur derived from thermochemical sulfate reduction, three of them from disseminated ore in the Lower Sandstone, two from the disseminated ore in the Upper Sandstone, and five from steeply dipping galena-sphalerite-calcite veinlets interpreted in previous works as remobilization of disseminated ores. The isotope dilution-thermal ionization mass spectrometry (ID-TIMS) data yield an overall complex Rb-Sr isotope pattern with two distinct trends in the 87 Sr/ 86 Sr vs. 87 Rb/ 86 Sr isochron diagram. The three sphalerite residues of disseminated mineralization from the Lower Sandstone orebody show Rb-Sr isotope systematics indicative of undisturbed primary precipitates, and yield an isochron model age of 467 ± 5 Ma (mean square weighted deviation, MSWD, 1.4). Since the isochron is based on three points, the obtained age is to be considered as preliminary. Yet, the obtained age is fully consistent with geologic evidence reported by previous authors and pointing to Middle Ordovician timing of ore formation.The ID-TIMS data were complemented by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) analyses on the same sphalerite samples. The data support the hypothesis that the measured ID-TIMS Rb and Sr contents in these sphalerite residues are held in the sphalerite structure itself and are not related to micro-inclusions. The most viable hypothesis, in agreement with published work, is that during rapid growth, sphalerite may incorporate Rb and Sr ions from the hydrothermal fluids in its structure, most probably in octahedral voids.By contrast, the second trend in the 87 Sr/ 86 Sr vs. 87 Rb/ 86 Sr space defined by most other sphalerite residues and corresponding inclusion fluid leachates from the Upper Sandstone orebody and the veinlet samples is too steep to account for a realistic isochron age determination. This steep linear trend is interpreted to represent a postmineralization disturbance involving fluids rich in Sr. This disturbance of the Rb-Sr isotope system is consistent with the presence of the steeply dipping galena-sphalerite-calcite veinlets and the fact that the Upper Sandstone is, in places, tectonically disrupted because of its proximity to the basal Caledonian décollement. The attempt to date the Granberget deposit, located in tectonically disrupted allochthonous units inside the Caledonian orogen, failed because the Rb-Sr isotope systematics of the three analyzed sphalerite samples are also disturbed.The obtained Middle Ord...

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Section: Strata-bound Sandstone-hosted Pb-zn Deposit In Autochthonoussupporting

confidence: 88%

Section: Sample Selection For Rb-sr Isotope Systematics and Charactermentioning

confidence: 91%

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

A Middle Ordovician Age for the Laisvall Sandstone-Hosted Pb-Zn Deposit, Sweden: A Response to Early Caledonian Orogenic Activity

Saintilan¹,

Schneider²,

Stephens³

et al. 2015

Economic Geology

View full text Add to dashboard Cite

show abstract

“…Although, it is tempting to suggest the high I/Cl ratios included in sulfide minerals were attained by fluids during interaction with organic matter at the site of mineralization. Organic matter has been reported within sphalerite fluid inclusions (Rickard et al, 1975) and is a potential reducing agent that could have triggered sulfide precipitation. The presence of similarly high I/Cl values in oxidized barite samples, cannot be explained by this process, and fluid mixing therefore remains the favored mechanism for mineralization.…”

Section: Fluid Mixingmentioning

confidence: 99%

“…of which up to one third is CaCl 2 (Roedder, 1968;Rickard et al, 1975;Rickard et al, 1979;Lindblom, 1986). Homogenization temperatures lie in the range 120 to 200°C and exhibit an overall cooling trend with cyclic changes through the paragenetic sequence (Lindblom, 1986).…”

mentioning

confidence: 98%