Wellheim Formation

{{Infobox rockunit

| name = Wellheim Formation

| period = Late Cretaceous

| age = upper Cenomanian to lower Turonian{{sfn|Niebuhr|Pürner|Wilmsen|2009|pages=17–19}} {{fossilrange|98|91}}

| image =Neuburg Siliceous Earth Mining 2006-06-24.jpg

| imagesize =

| caption =Siliceous earth quarrying of the Wellheim Formation near Neuburg

| prilithology = spiculitic silt, fine and medium sands, fine-grained silica (Kieselerde){{sfn|Niebuhr|Pürner|Wilmsen|2009|pages=17–19}}

| otherlithology = silicified conglomerate

| unitof = Danubian Cretaceous Group

| subunits = basal marine sandstone, Neuburg Kieselerde Member, Homsand facies{{sfn|Schneider et al.|2013|loc=figure 3}}

| underlies = Upper Freshwater Molasse Formation or Pleistocene loams

| overlies = Schutzfels Formation or Upper Jurassic limestone

| thickness = up to {{Convert|130|m|ft|-1}}

| area = southern Franconian Jura, Upper Bavaria{{sfn|Niebuhr|Pürner|Wilmsen|2009|pages=17–19}}

| map =

| map_caption =

| location =

| coordinates =

| region =

| country = Germany

| extent = {{convert|200|km2|sqmi|abbr=on}}

| namedfor = Wellheim

| namedby = B. Niebuhr, T. Pürner, and M. Wilmsen

| year_ts = 2009

| location_ts = open pit mines near Wellheim, Germany

| coordinates_ts =

| paleocoordinates_ts =

| region_ts =

| country_ts = Germany

| thickness_ts =

}}

The Wellheim Formation is a geological formation in southern Germany deposited during the Cenomanian to earliest Turonian stages of the Upper Cretaceous.

The Formation is subdivided into three member units: unnamed basal marine sandstone, the Neuburg Kieselerde Member, and an upper silicified conglomerate (Homsand facies).{{sfn|Schneider et al.|2013|loc=figure 3}}
Geographically, this formation is located in the central southernmost part of the Franconian Jura, on the left bank of the Danube, roughly between the towns of Wellheim and Neuburg in Bavaria.
The formation is commercially quarried for siliceous earth, which has a variety of applications.

Stratigraphy

The formation infills karstic voids found in Upper Jurassic limestones. Its upper contact is with either Miocene Upper Freshwater Molasse clays and marls or Pleistocene glacial deposits{{sfn|Salvador|Prieto|Mayr|Rasser|2016|page=129}} while the lower contact is with the Jurassic limestones, or the Lower Cretaceous Schutzfels Formation, a terrestrial unit which also infills the karstic terrain.

Depositional Environment

The Wellheim Formation was formed in a quiet water environment{{sfn|Wilmsen et al.|2010|page=274}} by deposition of pelagic sediments into a number of submerged karsts in the ocean floor over several million years.{{sfn|Schneider et al.|2013|pages=556–557}} Wilmsen et al (2010) identified the primary sediment composition as sandy and spiculitic sediments, with notably little terrigenous input.{{sfn|Wilmsen et al.|2010|page=274}} It consists of marine sediments classified as opoka. Opoka refers to Upper Cretaceous sponge spicule-rich, siliceous, marine limestones found in Poland and western Ukraine.{{Sfn|Machalski|Malchyk|2019|page=30}}

Lüttig (2007) called the scientific view of the formation of the Neuburg Kieselerde Member "contested"{{efn|{{langx|de|"nicht unumstritten"}},{{sfn|Lüttig|2007|page=156}} referring to the dissenting view of the sole exploiting company}}{{sfn|Lüttig|2007|page=156}} however that position has not been supported by subsequent authors.

Fossils

The Wellheim Formation is fossiliferous with the Neuburg Kieselerde Member having one of the most diverse invertebrate assemblages in the Danubian Cretaceous Group.{{sfn|Schneider et al.|2013|loc=abstract}} Schneider et al. (2013) mapped fossil yielding localities associated with this member in a rough triangle between Wellheim, Rennertshofen and Neuburg.{{sfn|Schneider et al.|2013|loc=figure 1}}

Age and correlation

It was deposited between about 93 to 98 million years ago during the Cenomanian, the lowest stage of the Upper Cretaceous.

The index fossil associated with these sediments is Inoceramus crippsi, a wing-shaped (pteriomorph) salt-water bivalve.{{sfn|Schneider et al.|2013|pages=555–610}}

Commercial exploitation

File:Neuburg Siliceous Earth on Spoon.jpg

Mining of Neuburg Kieselerde Member sediments takes place at an industrial scale around Neuburg an der Donau. The products are marketed under the umbrella term siliceous earth ({{langx|de|Kieselerde}}). The sediment is used as a filler material,{{sfn|Mushack|Bachmann|1996}}{{sfn|Heckl|Knör|2011}}{{sfn|Schönrock|2008}} an abrasive and polishing medium,{{sfn|Stork|2009}} a paint and varnish additive{{sfn|Roth|Reiter|Oggermüller|2020}} and as a nutritional supplement.{{sfn|Hoffmann Mineral GmbH|2010}}{{sfn|Lüttig|2007}}

It is generally composed of silicic acid (80 percent by weight or less) and kaolinite.{{sfn|Göske|Kachler|2008|pages=23–24}}

In 2015, 55,000 tons of the purified material were produced. This required the open-pit mining of 120,000 tons of raw siliceous earth.{{sfn|Elsner|2016|page=45}}

The producer has claimed a non-biogenic, mineral origin for their product,{{sfn|Göske|Kachler|2008|pages=23–24}} while most other sources assert a biogenic origin for the material.{{efn|For example, Schneider et al., 2013 have this statement as the first sentence of their article's abstract: "With approximately 100 species, the invertebrate macrofauna of the Neuburg Kieselerde Member of the Wellheim Formation (Bavaria, southern Germany) is probably the most diverse fossil assemblage of the Danubian Cretaceous Group."{{sfn|Schneider et al.|2013|loc=abstract}}}}{{sfn|Schneider et al.|2013|loc=abstract}}

Substances called siliceous earths are usually defined as having a biogenic origin,{{sfn|Meyers|1892}} with material of a similar composition usually being termed diatomaceous earth.

The producer also has repeatedly claimed a unique "one-of-a-kind worldwide" status of their product,{{sfn|Schanz|2016}}{{sfn|Baublatt|2019}} but Lüttig refuted this in 2007 for the material that is produced, saying that several similar material deposits are known, naming Heiligenhafen Kieselgestein as an example. On the other hand he agreed that the very special formation circumstances could indeed be called unique.{{sfn|Lüttig|2007|page=156}}

It has historically been used for the production of glass,{{sfn|Römpp|2015}} ceramics{{sfn|Lüttig|2007}} and color pigments like ultramarine.

Notes

References

Sources

{{Cite book|last=Elsner|first=Harald|title=Quarzrohstoffe in Deutschland|language=de|trans-title=Silica resources in Germany|date=28 January 2016|publisher=Deutsche Rohstoffagentur|url=https://www.bgr.bund.de/DERA/DE/Downloads/studie-quarz-2016|format=PDF|isbn=9783943566314}}
{{cite web|editor-last=Groteklaes|editor-first=Michael|work=RömppOnline|title=Kieselerde, RD-11-01037|accessdate=2 January 2015|url=https://roempp.thieme.de/lexicon/RD-11-01037|url-access=limited|ref={{sfnRef|Römpp|2015}}}}
{{cite journal|last1=Göske|first1=Jürgen|last2=Kachler|first2=Werner|title=Morphology, Physiochemistry and Phase Analysis of Neuburg Siliceous Earth|journal=Microscopy and Analysis|publisher=Wiley-VCH GmbH|url=https://www.hoffmann-mineral.com/asset/download/en/documents/general-documents/publications/morphology-physicochemistry-and-phase-analysis-of-neuburg-siliceous-earth-microscopy-and-analysis-9-2008.pdf|date=September 2008|location=Weinheim|volume=September 2008|pages=23–24}}
{{cite journal|last1=Heckl|first1=Siegfried|last2=Knör|first2=Nicole|title=Better filling of polyamides|journal=Kunststoffe International|publisher=Carl Hanser Verlag|location=Munich|volume=2/2011|year=2011|pages=70–73|issn=1862-4243|url=https://www.hoffmann-mineral.com/asset/download/en/documents/general-documents/publications/better-filling-of-polyamides-kunststoffe-international-2-2011.pdf}}
{{citation|type=trademark register entry|number=1056011|title=Aktisil|date=30 April 2010|author=Hoffmann Mineral GmbH|work=DPMAregister|publisher=German Patent and Trade Mark Office|url=https://register.dpma.de/DPMAregister/marke/registerIR?AKZ=1056011|accessdate=16 August 2021}}
{{cite web|title=Kieselsäuresalze - Kieselschiefer|work=Meyers Konversationslexikon|date=1885–1892|publisher=Verlag des Bibliographischen Instituts|location=Leipzig; Wien|edition=4th|url=http://www.retrobibliothek.de/retrobib/seite.html?id=109312|ref={{SfnRef|Meyers|1892}}}}
{{cite journal|title=Kieselerde ist nicht gleich Kieselgur - Naturwissenschaftliche Anmerkungen zu Heilerde-Präparaten|language=de|trans-title=Siliceous earth is not the same as kieselgur - Scientific remarks on "Healing earth" preparations|last=Lüttig|first=Gerd|journal=Erfahrungsheilkunde|volume=56|issue=3|issn=1439-4294|year=2007|pages=154–161|url=https://www.hoffmann-mineral.de/asset/download/de/dokumente/allgemeine-dokumente/veroeffentlichungen/kieselerde-ist-nicht-gleich-kieselgur-ehk-56-2007.pdf|archiveurl=https://web.archive.org/web/20210816030201/https://www.hoffmann-mineral.de/de/dokumente/allgemeine-dokumente/veroeffentlichungen/kieselerde-ist-nicht-gleich-kieselgur-(ehk-56-2007).pdf|archivedate=16 August 2021|doi=10.1055/s-2007-968058}}
{{cite journal |last1=Machalski|first1=M.|last2=Malchyk|first2=O.|year=2019 |title=Relative bathymetric position of opoka and chalk in the Late Cretaceous European Basin |journal=Cretaceous Research |volume=102 |pages=30–36|doi=10.1016/j.cretres.2019.05.007 |s2cid=181970561 |url=https://www.sciencedirect.com/science/article/pii/S0195667119300291|doi-access=free}}
{{cite journal|last1=Mushack|first1=R.|last2=Bachmann|first2=W.|title=Neuburger Kieselerde: natürliche, funktionelle Füllstoffe|language=de|trans-title=Neuburg siliceous earth: natural, functional filler substances|journal=GAK: Gummi, Fasern, Kunststoffe; Fachmagazin für die Polymerindustrie|publisher=Gupta|location=Ratingen|year=1996|volume=49|issue=8|pages=620–629|issn=0176-1625}}
{{cite journal|last1= Niebuhr|first1=B.|last2= Pürner|first2=T.|last3= Wilmsen|first3=M.|title=Lithostratigraphie der außeralpinen Kreide Bayerns.|journal=Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften|language=de|trans-title=Litho-stratigraphy of the ex-alpine Cretaceous of Bavaria|publisher=Schweizerbart Science Publishers|url=https://www.schweizerbart.de/publications/detail/isbn/9783510492114/Litho_und_Biostratigraphie_der_aueralpinen_Kreide_von_Bayern|date=2009|location=Stuttgart, Germany|volume=65|pages=7–58|url-access=subscription}}
{{cite journal|last1=Roth|first1=Meinhart|last2=Reiter|first2=Susanne|last3=Oggermüller|first3=Hubert|title=Neuburg Siliceous Earth as a functional extender for high performance road marking paints|journal=Asia Pacific Coatings Journal|publisher=dmg events|location=Dubai|volume=October 2020|date=October 2020|pages=45–47|issn=1468-1412|url=https://www.hoffmann-mineral.com/asset/download/en/documents/general-documents/publications/nse-in-road-marking-paints-apcj-october2020.pdf}}
{{cite journal|last1=Salvador|first1=R. B.|last2=Prieto|first2=J.|last3=Mayr|first3=C.|last4=Rasser|first4=M. W.|year=2016|title=New gastropod assemblages from the Early/Middle Miocene of Riedensheim and Adelschlag-Fasanerie, southern Germany|journal=Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen|volume=279|issue=2|pages=127–154|doi=10.1127/njgpa/2016/0546 }}
{{Cite news|last=Schanz|first=Sebastian|title=Neuburg: Eine weltweit einzigartige Ressource |language=de|trans-title=Neuburg: A globally unique resource |publisher=Donaukurier|location=Ingolstadt|date=1 July 2016|url=https://www.donaukurier.de/lokales/neuburg/art1763,3237755|archive-url=https://web.archive.org/web/20210609143445/https://www.donaukurier.de/lokales/neuburg/Neuburg-Eine-weltweit-einzigartige-Ressource;art1763,3237755|archive-date=9 June 2021}}
{{cite journal |last1=Schneider |first1=S. |last2=Jaeger |first2=M. |last3=Kroh |first3=A. |last4=Mitterer |first4=A. |last5=Niebuhr |first5=B. |last6=Vodrážka |first6=R. |last7=Wilmsen |first7=M |last8=Wood |first8=C. |last9=Zágoršek |first9=K. |year=2013 |title=Silicified sea life–Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to Lower Turonian Wellheim Formation, Bavaria, southern Germany) |journal=Acta Geologica Polonica |volume=63 |issue=4 |pages=555–610 |doi=10.2478/agp-2013-0025 |s2cid=54968776 |url=https://geojournals.pgi.gov.pl/agp/article/view/10370/8881|ref={{SfnRef|Schneider et al.|2013}}|doi-access=free }}
{{cite book|last=Schönrock|first=Dirk|title=Neuburger Kieselerde: Gewinnung, Veredelung, Anwendungen als funktioneller Füllstoff [Hoffmann Mineral]|language=de|trans-title=Neuburg siliceous earth: Excavation, refinement, uses as a functional filler substance [Hoffmann Mineral]|series=Die Bibliothek der Technik|publisher=Verlag Moderne Industrie|year=2008|location=Landsberg|volume=308|isbn=9783937889771}}
{{cite news|last=Stork|first=Stefanie|title=Von der Kieselerde zum Poliermittel|language=de|trans-title=From siliceous earth to polishing agent|publisher=Augsburger Allgemeine|date=25 August 2009|url=https://www.augsburger-allgemeine.de/neuburg/Von-der-Kieselerde-zum-Poliermittel-id6357946.html|archive-url=https://web.archive.org/web/20180326202828/https://www.augsburger-allgemeine.de/neuburg/Von-der-Kieselerde-zum-Poliermittel-id6357946.html|archive-date=26 March 2018}}
{{cite journal|last1=Wilmsen|first1=Markus|last2=Niebuhr|first2=Birgit|title=On the age of the Upper Cretaceous transgression between Regensburg and Neuburg an der Donau|year=2010|journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen|volume=256|issue=3|pages=267–278|doi=10.1127/0077-7749/2010/0051|ref={{sfnRef|Wilmsen et al.|2010}}}}
{{Cite web|title=Hoffmann Mineral baut Kieselerde ab – ein weltweit einzigartiges Vorkommen|language=de|trans-title=Hoffmann Mineral is mining siliceous earth – A globally unique deposit|publisher=Zeppelin Baumaschinen GmbH|date=27 August 2019|website=baublatt.de|url=https://www.baublatt.de/startseite/hoffmann-mineral-baut-kieselerde-ab-ein-weltweit-einzigartiges-vorkommen/|accessdate=17 June 2021|archive-url=https://web.archive.org/web/20210609143450/https://www.baublatt.de/startseite/hoffmann-mineral-baut-kieselerde-ab-ein-weltweit-einzigartiges-vorkommen/|archive-date=9 June 2021|ref={{sfnRef|Baublatt|2019}}}}