Dresbachium

system	series	step	≈ age ( mya )
higher	higher	higher	younger
Cambrian	Furongium	10th stage	485.4 ⬍ 489.5
		Jiangshanium	489.5 ⬍ 494
		Paibium	494 ⬍ 497
	Miaolingium	Guzhangium	497 ⬍ 500.5
		Drumium	500.5 ⬍ 504.5
		Wuliuum	504.5 ⬍ 509
	2nd series	4th stage	509 ⬍ 514
		3rd stage	514 ⬍ 521
	Terreneuvium	2nd stage	521 ⬍ 529
		Fortunium	529 ⬍ 541
deeper

The Dresbachium is (or was) in the history of the earth a period in the hierarchical rank of a level in the Upper Cambrian of North America. The Dresbachium followed the Alberta series. The Franconium followed over or after the Dresbachium . The step is obsolete today and is no longer used, but it is very common in 20th century literature. Today the Dresbachium corresponds to the global levels of the Guzhangium and Paibium and extends into the Jiangshanium for a very short period of time . In geochronology and according to today's correlation (2012), the dresbachium corresponds to the period from 499.5 to 493.9 ma.

Naming and history

The term Dresbachium basically goes back to Newton Horace Winchell , who in 1884 spoke for the first time of a "Dresbach Stone". He reckoned this Dresbach Stone, however, to the St. Croix Formation or St. Croix Sandstone . From the context it is clear that Winchell merely introduced a lithostratigraphic unit within another formation. In 1886 and 1888 he referred to the unit as Dresbach Sandrock (within the St. Croix Formation). The term Dresbach Stone (or Dresbach Sandrock ) is named after the town of Dresbach in Winona County in the southeastern tip of Minnesota on the Mississippi . In 1924 Edward Oscar Ulrich defined the Dresbach Sandstone as a lithostraphic unit between the Franconia Sandstone and the Eau Claire Shale . Peterson introduced the Dresbach formation in 1929 and incorporated the Eau Claire Sandstone and Shale into the Dresbach formation. Trowbridge and Atwater expanded the Dresbach Formation again and set the beginning of the Dresbach Formation with the base of Mount Simon Sandstone. In 1938 the US Geological Survey severely restricted the Dresbach Sandstone again, excluding Eau Claire Sandstone and Mount Simon Sandstone. This lithological unit is now divided into the Mount Simon Formation , the Eau Claire Formation and Wonewoc Formation . The term Dresbach originally did not refer to a period.

Edward Oscar Ulrich named the period in question as Saint Croixan in his 1911 work Revision of the Paleozoic systems , although it is left open how long the Saint Croixan comprised (or should include). It was not until 1944 that BF Howell introduced the concept of time Dresbachian alongside Franconian and Tempealeauian.

Definition and correlation

In the original definition by Benjamin Franklin Howell et al. (1944) the Dresbachium comprised the Cedaria , the Crepicephalus and the Aphelaspis trilobite zones. In 1958 Christina Lochman-Balk and James Lee Wilson proposed the Dunderbergia faun zone. They limited the Dresbachian to the Cedaria and Crepicephalus zones. They wanted to propose a new stage at a later date that included the aphelaspis - and the Dunderbergia - trilobite zone. This suggestion did not prevail, but the Dunderbergia zone above the aphelaspis zone was added to the Dresbachium. These four zones correlate today with the upper two-thirds of the global Guzhangium stage, the entire global Paibium stage and a very short period in the lowest part of the global Jiangshanium stage. Ludvigsen & Westrup (1985) replaced the division of the Upper Cambrian into Dresbachium, Franconium and Tempealeauium with the new names Marjuman , Steptoean and Sunwaptan . Even these new levels could not prevail internationally or regionally. However, the limits of these new levels do not match the old levels. The Marjuman begins with the Ptychagnostus atavus zone, i.e. three trilobite zones lower than the Dresbachium and ends with the Crepicephalus zone, i.e. in the middle of the Dresbachium. The Steptoean above it includes the remaining two trilobite zones of the Dresbachium plus the Elvinia zone, the lower zone of the former Franconium.

Events in the Dresbachium

In the lower Dresbachian, a second extinction event in the Cambrian took place after the Upper Botomium . A third extinction event followed in the Tempealeauium and at the end of the Cambrian.

supporting documents

literature

• Bonem, Rena Mae 1971: Upper Cambrian (Dresbachian) Faunas of the Pilgrim Formation of Southwestern Montana. 204 p., Master Thesis, Faculty of the Department of Geology, New Mexico Institute o Mining and Technology, Socorro, New Mexico. PDF
• Gradstein, Felix M., Jim G Ogg, Mark Schmitz & Gabi Ogg 2012: The Geologic Time Scale 2012 2-Volume Set, Volume 2, pp. 437–1144, Amsterdam Online at Google Books (p. 464)
• Winchell, Newton Horace 1886: Fourteenth Annual Report for the year 1885: Minnesota Geological and Natural History Survey, 353 pp.
• Winchell, Newton Horace 1888: The geology of Minnesota: Minnesota Geological and Natural History Survey, 2: 696 S. Online at archive.org (S.XXII)
• Mossler, John H. 1992: Sedimentary rocks of Dresbachian age (Late Cambrian) Hollandale Embayment, southeastern Minnesota. Minnesota Geological Survey, Report of Investigations, 40: Saint Paul ISSN  0076-9177
• Rolf Ludvigsen, Stephen R. Westrop: Three new Upper Cambrian stages for North America . In: Geology . tape 13 , no. 2 , January 2, 1985, p. 139-143 , doi : 10.1130 / 0091-7613 (1985) 13 <139: TNUCSF> 2.0.CO; 2 .
• Keroher, Grace C. 1966: Lexicon of geologic names of the United States for 1936–1960, Part 1, A – F, US Geological Survey Bulletin, 1200: 1-1448, Washington, DC Online at Google Books (p. 1157, Dresbachian Stage)

Individual evidence

1. ^ Winchell, Newton Horace 1884: The geology of Minnesota. Minnesota Geological and Natural History Survey, 1: 697 pp., Minneapolis, Minnesota Online at archive.org (p. 180, p. 259)
2. ↑ Ulrich, Edward Oscar 1924: Transactions of the Wisconsin Academy of Sciences, 21: 71-93.
3. ^ Peterson, Eunice 1929: The Dresbach Formation of Minnesota. Bulletin of the Buffalo Society of Natural Sciences, 14 (2): 1-48, Buffalo, New York.
4. ^ Trowbridge, Arthur Carleton & Gordon Ingham Atwater 1934: Stratigraphic problems in the Upper Mississippi Valley. Bulletin of the Geological Society of America, 45: 21-79, New York.
5. ↑ Wilmarth, M. Grace 1938: Lexicon of geologic names of the United States: (including Alaska), Part 1 (AL). US Geological Survey Bulletin, 896: 1-1244, Washington, DC [1] (p. 631)
6. ^ Byers, Charles 2001: Sequence Stratigraphy at the Turn of the Century: EO Ulrich's Ozarkian System in Wisconsin. Geoscience Wisconsin, 18: 43–47, Madison, Wisconsin PDF  ( page no longer available , search in web archives )  Info: The link was automatically marked as broken. Please check the link according to the instructions and then remove this notice.  
7. ^ Ulrich, Edward Oscar 1911: Revision of the Paleozoic systems. Geological Society of America Bulletin, 22 (2): 281–680, New York Online at archive.org (p. 635)
8. ^ Howell, Benjamin Franklin (Chairman) et al. 1944: Correlation of the Cambrian formations of North America (Chart 1). Bulletin of the Geological Society of America, 55 (8): 993-1003, New York.
9. ↑ Lochman-Balk, Christina & James Lee Wilson 1958: Cambrian Biostratigraphy in North America, Journal of Paleontology, 32 (2): 312-350, stable URL
10. ^ Hallam, Anthony & Paul B. Wignall 1997: Mass Extinctions and Their Aftermath. 320 pp., Oxford University Press. ISBN 0-19-854917-2 Online at Google Books (p. 5)