Beyond whole-rock geochemistry of shales: The importance of assessing mineralogic controls for revealing tectonic discriminants of multiple sediment sources for the Ouachita Mountain flysch deposits

Totten, Matthew W.; Hanan, Mark A.; Weaver, Barry L.

doi:10.1130/0016-7606(2000)112<1012:bwgost>2.0.co;2

Cited by 64 publications

(11 citation statements)

References 30 publications

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“…12) are indicative of a mafic input involving oceanic crust, possibly obducted onto the continent during a collision event (Floyd, 1991; Totten, Hanan & Weaver, 2000). Their spiderdiagram, with a general correspondence to the continental arc and active-margin tectonic environment and the presence of a negative Sr anomaly similar to the passive-margin setting, is best described by mixing between a dominant passive-margin source and a sediment from an active margin setting (Totten, Hanan & Weaver, 2000). In Central Morocco, Carboniferous syntectonic flysch and catastrophic sediments were deposited in a compressional retro-foreland basin where interbedded basaltic lavas, doleritic dykes and gabbro sills were emplaced during thrusting (Ben Abbou et al .…”

Section: Discussionmentioning

confidence: 99%

Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)

2013

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In the Variscan fold belt of Morocco, the Jebilet massif is characterized by Palaeozoic metasedimentary rocks intruded by syntectonic magmatism that includes an ultramafic–granitoid bimodal association and peraluminous granodiorites emplaced c. 330 Ma, intruded by younger leucogranites c. 300 Ma. The mafic–ultramafic rocks belong to a tholeiitic series, and display chemical and isotopic signatures consistent with mixing between mantle-derived and crust-derived magmas or assimilation and fractional crystallization. The granites within the bimodal association are mainly metaluminous to weakly peraluminous microgranites that show characteristics of A2-type granites. The peraluminous, calc-alkaline series consists mainly of cordierite-bearing granodiorites enclosing magmatic microgranular enclaves and pelitic xenoliths. Detailed element and isotope data suggest that the alkaline and the peraluminous granitoids were formed in the shallow crust (<30 km) by partial melting of tonalitic sources at high temperatures (up to 900°C) and by partial melting of metasedimentary protoliths at relatively low temperatures (c. 750°C), respectively. Mixing between the coeval mantle-derived and crust-derived magmas contributed to the large variation of initial εNd values and initial Sr isotopic ratios observed in the granitoids. Further contamination occurred by wall-rock assimilation during ascent of the granodioritic plutons to the upper crust. The ultramafic–granitoid association has been intruded by leucogranites that have high initial Sr isotopic ratios and low initial εNd values, indicating a purely crustal origin. The heating events that caused emplacement of the Jebilet magmatism are related to cessation of continental subduction and convective erosion/thinning of the lithospheric mantle during plate convergence.

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Section: Discussionmentioning

confidence: 99%

Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)

2013

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“…Trace elements such as Th, Cr, Ni, V, La, Co, Sc, Nb, Zr, Hf, Y and REEs, are very important in interpreting of provenance and composition of the source area because they are immobile in the post-depositional processes [11,28]. According to the diagram of Hf versus La/Th [42], La/Sc versus Co/Th [11], Th/Sc versus Cr/Th [43], Y/Ni versus Cr/V [44] (Figure 8C-F), the studied sandstone shows that it is a felsic igneous source rock and basic mixed source rock. The ternary graph of Ni-V-Th*10 [45] showed that the Huanhe sandstones fall close to the V-Th*10 line, reflecting a mixed origin of felsic and mafic rock provenance (Figure 7).…”

Section: Geochemistrymentioning

confidence: 93%

Provenance and Tectonic Setting of Lower Cretaceous Huanhe Formation Sandstones, Northwest Ordos Basin, North-Central China

Luo

Yuqi

et al. 2021

Minerals

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In adjustment to fulfill the requirements of the investigation regarding the lower Cretaceous sandstone uranium deposit in the Naogaodai area within the northwest of Ordos Basin, twenty-seven sandstone samples obtained from the Lower Cretaceous Huanhe Formation were analyzed for major, trace and rare earth elements (REE). The source of clastic and tectonic background was additionally analyzed. The results show that Huanhe sandstone is feldspar rich sandstone, and also the mineral composition is principally quartz, albite and plagioclase; the ratio of light to heavy rare earth elements (LREE/HREE) is 9.25–10.83, with an average value of 10.00; (La/Yb)CN is 10.20–12.53, with an average value of 11.24, demonstrating that LREE is enriched and fractionated compared with HREE. REE distribution patterns are similar, which additionally reveals that Huanhe sandstone has a homogenous source; the Index of Compositional Variability (ICV) value is 1.17–1.73, with an average value of 1.35, both greater than 1, showing an immature property, which may be first-order cycle deposition. The average value of the Chemical Index of Alteration (CIA) is 50.29, suggesting that the source rock has encountered weak chemical weathering; sandstones are near-source first-cycle provenance, which is not significantly influenced by sedimentary sorting and recycling. The geochemical qualities further indicate that Huanhe sandstone was deposited in a passive margin and experienced moderate weathering.

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“…Sampling of the pelitic fraction was focussed on carbonate-poor layers to avoid the dilution effect that carbonates, with their typical fairly low trace-element content, have on trace elements that we intend to use as provenance tracers, such as the REE (Cullers et al, 1979;Taylor & McLennan, 1985;Cullers, 2002). The samples are well consolidated sedimentary rocks affected by quite strong and pervasive post-depositional modifications, hence taking into account the recrystallization processes and in analogy to other studies (van de Kamp & Leake, 1995;Fedo et al, 1996;Cullers, 2000;Totten et al, 2000) the chemical analyses were performed on the whole rock samples without separating the different grain size fractions. Twenty-six selected samples were analysed for both major and trace elements and the results are reported in Table 1, along with four samples from a previous work.…”

Section: Sampling Strategy Materials and Methodsmentioning

confidence: 99%

A snapshot of the Late Jurassic Western Tethys seafloor composition and morphology provided by the geochemistry of pelitic sediments (Corsica, Central Alps and Northern Apennines)

2013

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The chemical composition of fine-grained siliciclastic sediments is a powerful tool in provenance studies, either as a complement to other whole rock/single grain methods, or as a stand-alone method when other techniques are not applicable, and particularly in those cases where the coarser sediment fractions are not available or the regional-scale geologic framework is lost due major successive tectonic events. A comprehensive geochemical investigation of pelites from the post-rift deposits of the Ligurian-Piedmont ocean (sampled in tectonic units of the Alpine-Apennine orogen: Balagne Nappe, Corsica; Tuscan Nappe and Internal Ligurian units, Northern Apennines; Err-Platta units, Central Alps) has identified for the first time a major mafic-ultramafic input immediately following rifting. Key trace element ratios (e.g., LaN/YbN < 10; avg. Eu/Eu* = 0.73 ± 0.06, 1SD; Th/(Cr + Ni +V) < 0.03) show that the pelitic siliciclastic layers intercalated in the Radiolarite formation (the first post-rift deposits) are systematically enriched in a mafic-ultramafic source component as compared to the younger post rift sediments (Calpionella Limestone and Palombini Shale). Such a peculiar chemical fingerprint is interpreted as the result of erosion and distribution across the whole basin (even to continental domains) of intraoceanic ophiolitic debris by turbidity and bottom currents sweeping the sea floor at the time of deposition of the Radiolarite Formation. Exhumed mantle and gabbroic-basaltic rocks exposed at the morphologically articulated seafloor of the slow-spreading Ligurian-Piedmont ocean were available to erosion during the whole time-span of the deposition of the Radiolarite formation, whilst they became progressivey subordinate as a source as the basin floor was progressively covered by the siliciclastic input from the developing passive continental margins

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Beyond whole-rock geochemistry of shales: The importance of assessing mineralogic controls for revealing tectonic discriminants of multiple sediment sources for the Ouachita Mountain flysch deposits

Cited by 64 publications

References 30 publications

Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)

Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)

Provenance and Tectonic Setting of Lower Cretaceous Huanhe Formation Sandstones, Northwest Ordos Basin, North-Central China

A snapshot of the Late Jurassic Western Tethys seafloor composition and morphology provided by the geochemistry of pelitic sediments (Corsica, Central Alps and Northern Apennines)

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