Mineralogical and Chemical Zonation of the Laacher See Tephra Sequence (East Eifel, W. Germany)

Wörner, Gerhard; Schmincke, H.-U.

doi:10.1093/petrology/25.4.805

Cited by 137 publications

(76 citation statements)

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“…Arienzo et al, 2009;Eichelberger et al, 2000;Troll and Schmincke, 2002) with those putting more emphasis on in-situ fractional crystallization (e.g. Hildreth and Fierstein, 2000;Pappalardo et al, 2008;Worner and Schmincke, 1984). We propose a fractional crystallization-dominated scenario, in which pre-eruptive mixing with hotter recharge is essential to remobilize portions of the cumulate mush.…”

Section: Discussionmentioning

confidence: 95%

The origin of a zoned ignimbrite: Insights into the Campanian Ignimbrite magma chamber (Campi Flegrei, Italy)

Forni

Bachmann

Mollo

et al. 2016

Earth and Planetary Science Letters

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Caldera-forming eruptions, during which large volumes of magma are explosively evacuated into the atmosphere from shallow crustal reservoirs, are one of the most hazardous natural events on Earth. The Campanian Ignimbrite (CI; Campi Flegrei, Italy) represents a classical example of such events, producing a voluminous pyroclastic sequence of trachytic to phonolitic magma that covered several thousands of squared kilometers in the south-central Italy around 39 ka ago. The CI deposits are known for their remarkable geochemical gradients, attributed to eruption from a vertically zoned magma chamber. We investigate the relationships between such chemical zoning and the crystallinity variations observed within the CI pyroclastic sequence by combining bulk-rock data with detailed analyses of crystals and matrix glass from well-characterized stratigraphic units. Using geothermometers and hygrometers specifically calibrated for alkaline magmas, we reconstruct the reservoir storage conditions, revealing the presence of gradients in temperature and magma water content. In particular, we observe a decrease in crystallinity and temperature and an increase in magma evolution and water content from the bottom to the top of the magma chamber. We interpret these features as the result of protracted fractional crystallization leading to the formation of a cumulate crystal mush at the base of the eruptible reservoir, from which highly evolved, crystal-poor, water-rich and relatively cold melts were separated. The extracted melts, forming a buoyant, easily eruptible cap at the top of the magma chamber, fed the initial phases of the eruption, until caldera collapse and eruption of the deeper more crystalline part of the system. This late-erupted, crystal-rich material represents remobilized portions of the cumulate crystal mush, partly melted following hotter recharge. Our interpretation is supported by: 1) the positive bulk-rock Eu anomalies and the high Ba and Sr contents observed in the crystal-rich units, implying feldspar accumulation; 2) the positive Eu anomalies in the matrix glass of the crystal-rich units, testifying to the presence of liquid derived from partial melting of low temperature mineral phases within the crystal mush (mostly feldspars); 3) the Ba and Sr-rich rims in the feldspars and positive Eu anomalies in clinopyroxene rims, suggesting late rim growth from a locally enriched melt following cumulate mush remelting and 4) the occurrence of An-rich plagioclase, relict from a more mafic recharge, which acted as a heat source. Our model reconciles many observations made over the years on zoned deposits of such high-magnitude explosive eruptions, and provides a framework to understand magma chamber processes leading up to cataclysmic events.

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Section: Discussionmentioning

confidence: 95%

The origin of a zoned ignimbrite: Insights into the Campanian Ignimbrite magma chamber (Campi Flegrei, Italy)

Forni

Bachmann

Mollo

et al. 2016

Earth and Planetary Science Letters

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“…Wörner and Schmincke, 1984;Wilson et al, 1995). In conclusion, feldspar fractionation may have exerted the major control on the abundances of Ba, Sr and Eu in the most differentiated samples; the concomitant fractionation of amphibole and green sodic clinopyroxene had a competing effect on the Al 2 O 3 systematics.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Petrogenesis of rift-related tephrites, phonolites and trachytes (Central European Volcanic Province, Rhön, FRG): Constraints from Sr, Nd, Pb and O isotopes

Jung¹,

Mezger²,

Hauff³

et al. 2013

Chemical Geology

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“…This difference in chemical composition reflects the mineralogy of the two tephra layers. Phonolithic tephra was produced during the Laacher See eruption (W6rner and Schmincke, 1984), whereas the Ulmener Maar eruption resulted in nephelinitic tephra (Mertes and Schmincke, 1985). Comparing the trace element contents of LST, measured on the sedimentary record from Holzmaar, with published data (W6rner and Schmincke, 1984) for the lower LST (LLST), the middle LST (MLST) and the upper LST (ULST), it becomes evident that LST deposits from Holzmaar are related to the ULST (Table 3).…”

Section: Geochemistrymentioning

confidence: 87%

“…Phonolithic tephra was produced during the Laacher See eruption (W6rner and Schmincke, 1984), whereas the Ulmener Maar eruption resulted in nephelinitic tephra (Mertes and Schmincke, 1985). Comparing the trace element contents of LST, measured on the sedimentary record from Holzmaar, with published data (W6rner and Schmincke, 1984) for the lower LST (LLST), the middle LST (MLST) and the upper LST (ULST), it becomes evident that LST deposits from Holzmaar are related to the ULST (Table 3). This is in agreement with reconstructions of the LST distribution fan, confirming that only the final plume of the eruption was directed to the south-west (Bogaard and Schmincke, 1985).…”

Section: Geochemistrymentioning

confidence: 87%

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Sedimentological proof and dating of the Early Holocene volcanic eruption of Ulmener Maar (Vulkaneifel, Germany)

1995

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Mineralogical and Chemical Zonation of the Laacher See Tephra Sequence (East Eifel, W. Germany)

Cited by 137 publications

References 0 publications

The origin of a zoned ignimbrite: Insights into the Campanian Ignimbrite magma chamber (Campi Flegrei, Italy)

The origin of a zoned ignimbrite: Insights into the Campanian Ignimbrite magma chamber (Campi Flegrei, Italy)

Petrogenesis of rift-related tephrites, phonolites and trachytes (Central European Volcanic Province, Rhön, FRG): Constraints from Sr, Nd, Pb and O isotopes

Sedimentological proof and dating of the Early Holocene volcanic eruption of Ulmener Maar (Vulkaneifel, Germany)

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