Juana Lopez Member: Difference between revisions
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== Description == |
== Description == |
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The Juana Lopez Member consists of sand with a large content of indistinguishable grains of fragmented coral, shells (especially [[Inoceramidae|inoceramid prisms]]), sharks teeth, bone, and other fragmented fossils. It smells of [[sulfur]] when freshly broken. It formed on wide, shallow [[Continental shelf|marine shelf]], with strong wave action, but with little sediment coming in from land. It was exposed on the land surface between the retreat of the [[Greenhorn cycle]] and the advance of the [[Niobrara cycle]] of the [[Western Interior Seaway]].<ref name="LewisR"/> |
The Juana Lopez Member consists of sand with a large content of indistinguishable grains of fragmented coral, shells (especially [[Inoceramidae|inoceramid prisms]]), sharks teeth, bone, and other fragmented fossils. It smells of [[sulfur]] when freshly broken. It formed on wide, shallow [[Continental shelf|marine shelf]], with strong wave action, but with little sediment coming in from land. It was exposed on the land surface between the retreat of the [[Greenhorn cycle]] and the advance of the [[Niobrara cycle]] of the [[Western Interior Seaway]].<ref name="LewisR"/> |
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== Fossils == |
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The unit is highly fossiliferous. Fossils identified in the unit include ''[[Prinocyclus]] wyomingensis'', ''[[Inoceramus]]'',<ref name=rankin>{{cite journal|last1=Rankin |first1=C.H., Jr. |year=1944 |title=Stratigraphy of the Colorado group, Upper Cretaceous, in northern New Mexico |journal=New Mexico Bureau of Mines and Mineral Resources Bulletin |volume=20 |url=https://geoinfo.nmt.edu/publications/monographs/bulletins/20/ |access-date=14 September 2021}}</ref> ''[[Ostrea]]'', and teeth of ''[[Ptychodus]]''.<ref>{{cite journal |last1=Ekren |first1=E.B. |last2=Houser |first2=F.N. |title=Geology and petrology of the Ute Mountains area, Colorado |journal=United States Geological Survey Professional Paper |date=1965 |volume=481 |doi=10.3133/pp481}}</ref> |
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== History of investigation == |
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The member was first designated in 1944 by C.H. Rankin, Jr., who recognized the member throughout northern New Mexico and western Colorado. Rankin established the correlation between the [[Mancos Shale]] and the [[Colorado Group]] and was able to identify most of the units of the Colorado Group within the Mancos Shale, and identified the top of the Juana Lopez Member as the top of the Carlisle Shale.<ref name=rankin/> |
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== References == |
== References == |
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Revision as of 20:40, 14 September 2021
| Juana Lopez Member | |
|---|---|
| Stratigraphic range: | |
| Type | Member |
| Unit of | Carlile Formation |
| Underlies | Niobrara Formation |
| Overlies | Codel Sandstone member of the Carlile |
| Thickness | 0–6 feet (0.0–1.8 m) |
| Lithology | |
| Primary | Sandstone with abundant carbonate fossil grains |
| Other | Gravel, Codel fragments |
| Location | |
| Coordinates | 35°29′12″N 106°12′04″W / 35.4866°N 106.2010°W |
| Country |  United States |
| Type section | |
| Named for | Mesita Juana Lopez Grant, six miles northwest of Los Cerrillos, New Mexico |
| Named by | Rankin |
| Year defined | 1944 |
  Juana Lopez Member (the United States)  Juana Lopez Member (New Mexico) | |
Juana Lopez refers to both the uppermost member of the Carlile Shale formation and to the environment that caused it to form. The Juana Lopez Member is calcareous sandstone dated to the Turonian age of the Upper Cretaceous and is exposed in the southern and western Colorado, northern and central New Mexico,[1] and northeastern Utah.[2] The unit has been described as "the most enigmatic" member of the Carlile Shale.[3]
Description
The Juana Lopez Member consists of sand with a large content of indistinguishable grains of fragmented coral, shells (especially inoceramid prisms), sharks teeth, bone, and other fragmented fossils. It smells of sulfur when freshly broken. It formed on wide, shallow marine shelf, with strong wave action, but with little sediment coming in from land. It was exposed on the land surface between the retreat of the Greenhorn cycle and the advance of the Niobrara cycle of the Western Interior Seaway.[1]
Fossils
The unit is highly fossiliferous. Fossils identified in the unit include Prinocyclus wyomingensis, Inoceramus,[4] Ostrea, and teeth of Ptychodus.[5]
History of investigation
The member was first designated in 1944 by C.H. Rankin, Jr., who recognized the member throughout northern New Mexico and western Colorado. Rankin established the correlation between the Mancos Shale and the Colorado Group and was able to identify most of the units of the Colorado Group within the Mancos Shale, and identified the top of the Juana Lopez Member as the top of the Carlisle Shale.[4]
References
- ^ a b Lewis, Russell K. (2013), Stratigraphy and depositional environments of the Late Cretaceous (Late Turonian) Codell sandstone and Juana Lopez members of the Carlile shale, southeast Colorado, Mines Theses & Dissertations, retrieved 2018-08-14
- ^ Molenaar, C.M.; Cobban, W.A. (1991). "Middle Cretaceous stratigraphy on the south and east sides of the Uinta Basin, northeastern Utah and northwestern Colorado". United States Geological Survey Bulletin. 1787-P. doi:10.3133/b1787P.
- ^ Lewis 2013.
- ^ a b Rankin, C.H., Jr. (1944). "Stratigraphy of the Colorado group, Upper Cretaceous, in northern New Mexico". New Mexico Bureau of Mines and Mineral Resources Bulletin. 20. Retrieved 14 September 2021.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Ekren, E.B.; Houser, F.N. (1965). "Geology and petrology of the Ute Mountains area, Colorado". United States Geological Survey Professional Paper. 481. doi:10.3133/pp481.
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