The potential of detrital garnet as a provenance proxy in the Central Swiss Alps

Stütenbecker, Laura; Berger, Alfons; Schlunegger, Fritz

doi:10.1016/j.sedgeo.2017.02.002

Cited by 15 publications

(13 citation statements)

References 60 publications

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“…The exhumation of large slices of mid-crustal rocks from the European plate, the so-called external crystalline massifs, occurred relatively late in the Alpine evolution, probably during the late Miocene, although the exact timing is not well constrained. The external crystalline massifs are today characterized by high relief, intense glaciation, and some of the highest denudation rates in the Alps (up to 1.4 mm yr −1 ), which all contribute to their relevance as a sediment source (Kühni and Pfiffner, 2001;Wittmann et al, 2007;Stutenbecker et al, 2018). The exhumation is discussed as being related to crustal delamination in response to lithospheric mantle rollback (Herwegh et al, 2017), slab detachment (Fox et al, 2015), or erosional unloading (Champagnac et al, 2009), possibly due to increased precipitation rates in the Pliocene (Cederbom et al, 2004) or enhanced glacial erosion in the Pleistocene (Fox et al, 2015;Herman et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Miocene basement exhumation in the Central Alps recorded by detrital garnet geochemistry in foreland basin deposits

Stütenbecker¹,

Tollan

Madella³

et al. 2019

Solid Earth

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Abstract. The Neogene evolution of the European Alps was characterized by the exhumation of crystalline basement, the so-called external crystalline massifs. Their exhumation presumably controlled the evolution of relief, distribution of drainage networks, and generation of sediment in the Central Alps. However, due to the absence of suitable proxies, the timing of their surficial exposure and thus the initiation of sediment supply from these areas are poorly constrained. The northern Alpine foreland basin preserves the Oligocene to Miocene sedimentary record of tectonic and climatic adjustments in the hinterland. This contribution analyses the provenance of 25 to 14 Myr old alluvial fan deposits by means of detrital garnet chemistry. Unusually grossular- and spessartine-rich garnet is found (1) to be a unique proxy for identifying detritus from the external crystalline massifs and (2) to occur abundantly in ca. 14 Myr old deposits of the foreland basin. In contrast to previous assumptions, we therefore propose that the external massifs were already exposed to the surface ca. 14 Myr ago.

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Section: Introductionmentioning

confidence: 99%

Miocene basement exhumation in the Central Alps recorded by detrital garnet geochemistry in foreland basin deposits

Stütenbecker¹,

Tollan

Madella³

et al. 2019

Solid Earth

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“…While 15 geochemically distinct compositional end-members can be found in nature, there are 6 types that commonly form solid solutions, namely (in descending order of their abundance): almandine (Fe 3 Al 2 Si 3 O 12 ), spessartine (Mn 3 Al 2 Si 3 O 12 ), pyrope (Mg 3 Al 2 Si 3 O 12 ), grossular (Ca 3 Al 2 Si 3 O 12 ), andradite (Ca 3 (Fe,Ti) 2 Si 3 O 12 ), and uvarovite (Ca 3 Cr 2 Si 3 O 12 ). Garnets are usually formed in metamorphic rocks and it is the metamorphic history (temperature and pressure conditions) along with composition of the source rock that defines garnet geochemistry and, therefore, the end-member type (Krippner et al, 2014; Alizai et al, 2016; Stutenbecker et al, 2016). These source rock diagnostic geochemical characteristics combined with their rarity in igneous rock (von Eynatten and Dunkl, 2012) enable identification of the metamorphic setting, and make them very useful in provenance studies (Morton, 1991; Morton et al, 2004, 2011; Mange and Morton, 2007; Andò et al, 2013; Suggate and Hall, 2013; Krippner et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Insights into the provenance of the Chinese Loess Plateau from joint zircon U-Pb and garnet geochemical analysis of last glacial loess

et al. 2017

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The Chinese Loess Plateau, the world’s largest and oldest loess record, preserves evidence of Asia’s long-term dust source dynamics, but there is uncertainty over the source of the deposits. Recent single-grain detrital zircon U-Pb age analysis has progressed this issue, but debates remain about source changes, and the generation and interpretation of zircon data. To address this, we analyze different groupings of new and existing datasets from the Loess Plateau and potential sources. We also present the results of a first high resolution sampling, multi-proxy provenance analysis of Beiguoyuan loess using U-Pb dating of detrital zircons and detrital garnet geochemistry. The data shows that some small source differences seem to exist between different areas on the Loess Plateau. However, sediment source appears to be unchanging between loess and palaeosols, supporting a recent material recycling hypothesis. Our zircon and garnet data demonstrates, however, that Beiguoyuan experienced a temporary, abrupt source shift during the last glacial maximum, implying that local dust sources became periodically active during the Quaternary. Our results highlight that grouping data to achieve bigger datasets could cause identification of misleading trends. Additionally, we suggest that multi-proxy single-grain approaches are required to gain further insight into Chinese Loess Plateau dust sources.

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“…This appears fully justified because almost all chemical data used in this paper (both database and examples) are obtained by wave-length dispersive electron microprobe (EMP) techniques, which are very precise with respect to the elements considered. If the data to be analysed are obtained by other, less precise techniques (for comparison of, e.g., SEM-EDX vs. EMP see for instance Stutenbecker et al, 2017), the uncertainties with the calculated probabilities will be much higher, which is especially relevant if the decision of assigning a garnet to a specific group is somewhat ambiguous.…”

Section: Methodsmentioning

confidence: 99%

A multivariate discrimination scheme of detrital garnet chemistry for use in sedimentary provenance analysis

Tolosana‐Delgado

Eynatten

Krippner

et al. 2018

Sedimentary Geology

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Garnet chemistry provides a well-established tool in the discrimination and interpretation of sediment provenance. Current discrimination approaches, however, (i) suffer from using less variables than available, (ii) subjective determination of discrimination fields with strict boundaries suggesting clear separations where in fact probabilities are converging, and (iii) significant overlap of compositional fields of garnet from different host-rock groups. The new multivariate discrimination scheme is based on a large database, a hierarchical discrimination approach involving three steps, linear discriminant analysis at each step, and the five major host-rock groups to be discriminated: eclogite-(A), amphibolite-(B) and granulite-(C) facies metamorphic rocks as well as ultramafic (D) and igneous rocks (E). The successful application of statistical discrimination approaches requires consideration of the a priori knowledge of the respective geologic setting. This is accounted for by the use of prior probabilities. Three sets of prior probabilities (priors) are introduced and their advantages and disadvantages are discussed. The user is free to choose among these priors, which can be further modified according to the specific geologic problem and the level of a priori knowledge. The discrimination results are provided as integrated probabilities of belonging to the five major host-rock groups. For performing calculations and results a supplementary Excel® spreadsheet is provided. The discrimination scheme has been tested for a large variety of examples of crystalline rocks covering all of the five major groups and several subgroups from various geologic settings. In most cases, garnets are assigned correctly to the respective group. Exceptions typically reflect the peculiarities of the regional geologic situation. Evaluation of detrital garnets from modern and ancient sedimentary settings of the Western Gneiss Region (Norway), Eastern Alps (Austria) and Albertine Rift (Uganda) demonstrates the power to reflect the respective geologic situations and corroborates previous results. As most garnet is derived from metamorphic rocks and many provenance studies aim at reconstructing the tectonic and geodynamic evolution in the source area, the approach and the examples emphasize discrimination of metamorphic facies (i.e., temperature-pressure conditions) rather than protolith composition.

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The potential of detrital garnet as a provenance proxy in the Central Swiss Alps

Cited by 15 publications

References 60 publications

Miocene basement exhumation in the Central Alps recorded by detrital garnet geochemistry in foreland basin deposits

Miocene basement exhumation in the Central Alps recorded by detrital garnet geochemistry in foreland basin deposits

Insights into the provenance of the Chinese Loess Plateau from joint zircon U-Pb and garnet geochemical analysis of last glacial loess

A multivariate discrimination scheme of detrital garnet chemistry for use in sedimentary provenance analysis

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