Hello everyone,
The Laacher See complex plinian explosive volcanic eruption (12.9 ky BP, East Eifel Volcanic Field, Germany) appears to be unique in having erupted both representative portions of the zoned chamber magmatic liquids as well as representative cumulates from chamber roof, sides and floor in what seems to be very large amounts.
In most plinian eruptions, it is inferred that less than 1% of the magma chamber volume is erupted in the end.
However at Laacher See this proportion is inferred to be at least an order of magnitude larger; and indeed much larger estimâtes are even quoted in the literature on LSE.
The Laacher See Eruption has been extensively studied for over 40 years and such case studies seem to fulfill the dream of volcanologists to understand eruptions as well as that of igneous petrologists to constrain the relation between cumulate pile developpement (crystal mush) and the magmatic liquid line of descent.
I wonder if anyone has systematically ploughed the literature to assess how "unique" Laacher See complex plinian explosive eruptions may actually be ?
I would be grateful for any pointers or insights into this.
Happy holidays to everyone, and very best wishes for the New Year,
Gerald
Mark,
Thank you.
As you know, there were 3 main phases and numerous explosive eruptions.
These were studied systematically and rigorously by Hans Schmincke and his eminent colleagues and they found that it was complex and with a big influence of external factors (external water in particular) during the opening and closing phases, as you suggest, but also that it also produced plinian airfall deposits, that have all the characteristics of plinian rather than phreatoplinian deposits. So, it was not just a phreatomagmatic eruption.
Actually, my question was not about how such a complex eruption should/could be called but about whether anyone was aware of other such eruptions that erupt an enormous volume of cumulate rocks together with the magmatic liquids.
I am still hoping for an answer from someone.
Thanks for any suggestion or insights.
Best,
Gerald
Thanks Martin.
Would you be so kind to attach the PDF directly or to email it to my mail:
Thanks, and I am still seeking additional examples.
Martin,
Many thanks for the PDF. It seems that the Albano Maar and Laacher See cases are closely complementary, with the Laacher See magma chamber into "schists" and the Albano Maar into "limestones". Clearly the Albano Maar is even more complex than the Laacher See case in that the country rocks generate a carbonate-rich melt and much CO2 which ultimately drive at least partially the explosive eruptions at Albano whereas at Laacher See external water - magma interactions drive the explosivity in the final stage in particular (once the magma chamber becomes under-pressured).
I do not have Hans Schmincke's PhD thesis on Gran Canaria and will look for papers that may cover the same topic. For Lesser Antilles, I'll try and look those up too.
Great many thanks,
Gerald
Hi everybody,
to me (and not only because I started science there), the Laacher See Tephra remains unique. Unlike the Alban Maar, that has had several eruptions separated by thousands of years and covering a large compositional range, the Laacher See Tephra is continuously zoned with much tighter compositional trends. At the final stages, the Laacher See erupted mafic phonolite together with basanite, that had just very recently mixing into the base of the magma chamber, and abundant cumulate and cognate syenite rocks, the latter suite contains hybrid syenite-carbonatite compositions, all have residual phonolitc interstitial glass. Together with Axel Schmitt and a student of mine, we have dated zircons in these rocks, verifying earlier indications by U-series dating, that the crystal-rich mush / carapace had existed at least 20 ka before the eruption. (
Wetzel F, Schmitt AK, Kronz A, Wörner G (2010) In situ U-Th disequilibrium dating of pyrochlore at sub-millennial precision. Am Min 95: 1353-1356
Schmitt AK, Wetzel F, Cooper KM, Zou HB, Wörner G (2010) Magmatic longevity of Laacher See Volcano (Eifel, Germany) indicated by intrusive carbonatites. J Pet 50: 1053-1085
I envisage that the eruption was fed from the remaining liquid core of an alkaline intrusive complex that was cooling outside in and was surrounded by crystal mush, syenites, carbonatite etc.
The final stage of the eruption was strongly phreatomagmatic and "excavated" right into the alkaline intrusive complex that was still just above its solidus. The abundance of cumulate and syenite lithics stems from the fact that the phreatomagmatic explosions probably occurred at the base of a diatreme right inside the shallow mush complex (but still at > 5 km depth).
Such a scenario is required by the observations and I am not aware of a similar case described in the literature.
Regards
Gerhard Wörner
Hallo Gerhard,
Thank you so much for sharing your research experience, and long expertise of Laacher See with us. Your answer confirms my prejudice that so far no one seems to have found a recently active volcano with the unique characteristics of the Laacher See or the opportunities it still offers to advance understanding of the link between an alkaline magma chamber system and its eruption dynamics or eruptive products.
It seems to me that it is worth seeking if such a Laacher See similar system may still exist somewhere in the world.
Perhaps slightly easier may be the search for a somewhat more ancient (earlier quaternary or tertiary ?) alkaline magma chamber system that could be considered closely analogue to the Laacher See magma chamber as you reconstructed it.
Are you aware of any you could recommend I read about ?
Thank you again for any insight,
Greetings to everyone,
Gerald
Dear Gerald,
regarding the publications: I was having problems uploading the files, I tried again and apparently it worked.
Older examples of "exploded" crystal mushes... , not any that I know of..
Gerhard
Interesting discussion! Some colleagues I know have some papers on cumulates erupted at another alkaline system (Tenerife) which may be of interest, not exactly the same as Laacher See, but there may be some parallels.
J. T. Sliwinski1,*, O. Bachmann1, B. S. Ellis1, P. Dávila-Harris2, B. K. Nelson3 and J. Dufek4 ‘Eruption of Shallow Crystal Cumulates during Explosive Phonolitic Eruptions on Tenerife, Canary Islands’ J. Petrology (2015) doi: 10.1093/petrology/egv068
And
MJ Stock, RN Taylor, TM Gernon (2012) Triggering of major eruptions recorded by actively forming cumulates Scientific reports 2
Hope these are of use!
Mike
Dear Gerhard, Many thanks for those. I have them now. Generally there seems to be a problem downloading some of your papers on RG, some of Hans papers also...
Dear Michael, could you also attach the PDFs to save us all time, if this is convenient to you.
Yes, I am enjoying the exchange too.
Many thanks to everyone,
Best,
Gerald
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