Clastic metasediments of the Early Proterozoic Broken Hill Group, New South Wales, Australia: Geochemistry, provenance, and metallogenic significance

Slack, John F.; Stevens, B. P. J.

doi:10.1016/0016-7037(94)90155-4

Cited by 69 publications

(10 citation statements)

References 63 publications

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“…Plot of Eu/Eu* versus (Gd/Yb) N indicating that the analysed Sefwi phyllites and Lawra schists were derived from Proterozoic and Archaean provenances. Fields are after Taylor and McLennan (1985), Slack and Stevens (1994). Symbols are the same as in Figure 5 [Colour figure can be viewed at wileyonlinelibrary.com] evidences support the interpretation that the Sefwi and Lawra sediments were most likely derived from an active continental margin setting, presumably island arc setting.…”

Section: Figurementioning

confidence: 58%

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Geochemical and Sm–Nd isotopic evidence for the composition of the Palaeoproterozoic crust of the West African Craton in Ghana

Sakyi

Manu

et al. 2018

Geological Journal

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The metasedimentary rocks of the Sefwi and Lawra volcanic belts in Ghana respectively were analysed for their major and trace elements and Sr‐Nd isotopic compositions to constrain the provenance, palaeo‐weathering conditions, and tectonic setting of the rocks. Geochemical characteristics of the metasedimentary rocks show low to moderate chemical weathering in their source regions and the rocks are interpreted to have been derived from mixture of mafic and felsic rock components. The LREE show much enrichment in relation to the HREE (LaN/LuN, 4.67‐11.66). The εNd (2.1 Ga) values of −0.12 to +3.72 strongly suggest that the source of the sedimentary rocks was derived from a depleted mantle source and that they were most likely produced in an almost entirely oceanic environment with minor influence from the continental crust. The Nd model ages ranging from +2.05 to 2.41 Ga suggest possible contributions of a pre‐Birimian crustal material (or Archaean?) in the source material of the volcanic rocks. The rock types that contributed as detritus to the Birimian metasedimentary rocks were mainly pyroclastics and basalts, and their REE patterns suggest that the contribution to the phyllites can be modelled after 20% basalt, 13% andesite, and 67% dacite. Similarly, the schists can be modelled as a mixture of 16% basalt, 34% andesite, and 50% dacite. The Nd isotopic modeling implies that the bulk of the sedimentary detritus was supplied by the Palaeoproterozoic volcanic arc with contributions of less than 10% from the pre‐Birimian crust (Archaean?).

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Section: Figurementioning

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Geochemical and Sm–Nd isotopic evidence for the composition of the Palaeoproterozoic crust of the West African Craton in Ghana

Sakyi

Manu

et al. 2018

Geological Journal

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“…The lack of correlation between HFSE and Al 2 O 3 is consistent with these elements being generally contained in accessory phases in mudrocks (e.g. Slack & Stevens, 1994). We infer that these elements occur in the sediment mostly as resistate phases, supporting the idea that they efficiently record the provenance (McLennan, Hemming & Hanson, 1993 and many others).…”

Section: Whole-rock Geochemistrymentioning

confidence: 59%

Provenance signatures for the Miocene volcaniclastic succession of the Tufiti di Tusa Formation, southern Apennines, Italy

et al. 2011

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The Tufiti di Tusa Formation, a siliciclastic turbidite system of lower Miocene age in\ud southern Italy, is mainly composed of volcaniclastic and quartzolithic sandstones interbedded with\ud mudrocks. Sandstones are subdivided into four distinctive petrofacies, evolving from quartzolithic\ud to volcaniclastic lithofeldspathic and feldspatholithic, reflecting detrital evolution from growing\ud orogen (quartzolithic petrofacies) to active volcanism (volcaniclastic petrofacies). The mineralogical\ud composition of the associated mudrocks is predominantly characterized by phyllosilicates, mainly\ud illite/smectite mixed layers (I/S R1 associated with minor amounts of I/S R0 in the lower part of the\ud succession, and I/S R3 in its upper part), together with illite, detrital micas and chlorite, and minor\ud amounts of chlorite/smectite mixed layers and kaolinite, in addition to quartz, calcite and feldspars. The\ud most abundant phyllosilicates are I/S mixed layers, 10-Å minerals (illite and micas) and chlorite, while\ud kaolinite and chlorite–smectite mixed layers are present as a few per cent or in trace amounts. X-ray\ud diffraction patterns show the occurrence of the ordered I/S R1 mixed layers in most samples but, at the\ud top of the succession, some samples are characterized by I/S R3 mixed layers, whilst in the lower part\ud of the succession I/S R1 is associated with a lower amount of I/S R0. These features suggest that the\ud Tufiti di Tusa Formation experienced a medium diagenetic grade, and the occurrence of I/S R3 could\ud be explained by K-availability in samples in the upper part of the succession. The lithic fragments in\ud sandstones are metasedimentary rocks of Palaeozoic age, and andesite to dacite volcanic rocks of early\ud Miocene age. The associated mudrocks also contain trace element ratios (Cr/V, Y/Ni, La/Sc, Th/Sc,\ud Th/Co, Th/Cr, Cr/Th and Eu/Eu∗) consistent with a provenance containing intermediate to silicic\ud sources with scarce or absent basic rocks. The chemical index of alteration (63.2 to 71.6) suggests a\ud moderate degree of weathering in the source. Furthermore, the K/Cs ratios of sediments confirm likely\ud moderate rather than intense weathering. The index of compositional variability (ICV) values (from 1.2\ud to 2.5) are high enough to suggest the mudrocks are first-cycle sediments with little recycling. The Al–\ud Ti–Zr diagram and the Th/Sc v. Zr/Sc plot indicate poor sorting and rapid deposition of the sediments.\ud Detrital and sedimentary evolution of the Tufiti di Tusa Formation provides constraints, in terms of\ud relations between a growing orogenic system and active volcanism in the Central Mediterranean, to\ud contribute to geodynamic and palaeogeographic reconstructions of the earliest collision in the southern\ud Apennines region

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“…of Tourmaline from the Björkdal Deposit BJ-9-7 BJ-9-8 BJ-9-9 BJ-5-1 BJ-5-2 BJ-5-3 BJ-5-4 BJ-5-5 BJ-5-6 BJ-5-7 BJ-5-8 BJ-5-9 BJ-5-10 BJ-5-11 BJ-5-12 Although REE-complexing ligands and the redox state of the hydrothermal fluids can influence the REE chemistry of hydrothermal tourmaline (Slack, 1996), under low water-rock ratios the bulk rock composition of the host rock generally plays the major role (Slack and Stevens, 1994). The REE concentration of tourmaline from the Björkdal deposit is similar to that reported for tourmaline from granites and pegmatites, and in particular those from tin-bearing granite veins (Figs.…”

Section: Ree Systematicsmentioning

confidence: 99%

Sm-Nd and REE Characteristics of Tourmaline and Scheelite from the Bjorkdal Gold Deposit, Northern Sweden: Evidence of an Intrusion-Related Gold Deposit?

2006

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The Björkdal quartz vein-hosted gold deposit is located ~25 km northwest of Skellefte in northern Sweden, within a Paleoproterozoic volcanosedimentary sequence at the margin of a quartz-monzodiorite granitoid. Northeast-trending (030°-050°) quartz veins from the eastern open pit within the Björkdal deposit contain quartz, scheelite, tourmaline, calcite, and sulfides, with visible gold. Vein quartz shows undulatory extinction and sutured margins or is polycrystalline in form, features which suggest postcrystallization deformation. Coarse scheelite crystals (>5 mm) within the quartz veins are crosscut by thin veins of quartz, calcite, sulfides, and gold. The calcite in these crosscutting fractures is variably replaced by biotite or actinolite. Tourmaline from the quartz veins has low total REE contents (<1 × chondrite) and LREE-enriched patterns [(La/Sm)N = 2.8-4.5, (La/Yb)N = 1.8-5.1] with strong positive Eu anomalies (Eu/Eu* = 3.9-17.4). In contrast, the scheelite has a bell-shaped REE pattern, enriched in MREE, but also with positive Eu anomalies (Eu/Eu* = 1.4-2.4). The REE pattern of scheelite results from a strong crystallographic effect, largely due to the size of the Ca site and charge balance. Sm-Nd dating of scheelite from the Björkdal ore yields an age of 1893 ± 34 Ma, which coincides with a previously suggested age of the host intrusion. The εNd values of the scheelite (+1.8) and 87 Sr/ 86 Sr initial ratios of the tourmaline (0.7013-0.7014) are also consistent with derivation of REE and Sr in these minerals from the Jörn granitoids. Overall, the petrographic, geochemical, and isotopic data strongly suggest that Björkdal is an intrusion-related gold deposit, and that there is no requirement for involvement of external postmagmatic hydrothermal fluids.

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Clastic metasediments of the Early Proterozoic Broken Hill Group, New South Wales, Australia: Geochemistry, provenance, and metallogenic significance

Cited by 69 publications

References 63 publications

Geochemical and Sm–Nd isotopic evidence for the composition of the Palaeoproterozoic crust of the West African Craton in Ghana

Geochemical and Sm–Nd isotopic evidence for the composition of the Palaeoproterozoic crust of the West African Craton in Ghana

Provenance signatures for the Miocene volcaniclastic succession of the Tufiti di Tusa Formation, southern Apennines, Italy

Sm-Nd and REE Characteristics of Tourmaline and Scheelite from the Bjorkdal Gold Deposit, Northern Sweden: Evidence of an Intrusion-Related Gold Deposit?

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