| 词条 | Annona Chalk | |||
| 释义 |
| name = Annona Chalk | image = File:Bulletin_429_Plate_XVI_A_Annona_Chalk.jpg | caption = Outcrop east of Clarksville, TX (c. 1910) | type = Formation | age = Cretaceous | period = Cretaceous | prilithology = Chalk | otherlithology = | namedfor = Annona, Red River County, Texas[1] | namedby = Robert Thomas Hill | region = Arkansas | country = United States | coordinates = | unitof = | subunits = Austin Group | underlies = Ozan Formation, Marlbrook Marl | overlies = Brownstown Marl, Ozan Formation | thickness = 30 Meters | extent = | area = | map = | map_caption = }} The Annona Chalk is a geologic formation in Arkansas, Texas, Louisiana, and Oklahoma.[2] It preserves fossils dating back to the Cretaceous period. The formation is a hard, thick-bedded to massive, slightly fossiliferous chalk. It weathers white, but is blue-gray when freshly exposed. The unit is commercially mined for cement. Fossils in the Annona Chalk include coelenterates, echinoderms, annelids, bivalves, gastropods, cephalopods, and some vertebrate traces.[3] The beds range in thickness, up to over 100 feet in depth in some areas (such as the White Cliffs).[4] There is a gradual transition between the Annona chalk and the underlying Brownstown formation, where chalk and marl are interbedded.[5] ExposuresSee also{{Portal|Earth sciences|Arkansas|Paleontology|Cretaceous|Mesozoic}}
References1. ^{{cite journal|last1=Hill|first1=R.T.|title=Geology of parts of Texas, Indian Territory and Arkansas adjacent to Red River|journal=Bulletin of the Geological Society of America|date=1894|volume=5|page=308}} 2. ^USGS Geolex, Annona Chalk/Formation 3. ^{{cite web|author1=R. T. Hill|authorlink1=Geological Society of America Bulletin|title=ANNONA CHALK/FORMATION|url=http://www.geology.ar.gov/geology/ka.htm|website=Arkansas Geological Survey|publisher=Arkansas Geological Survey|accessdate=25 May 2015|archivedate=1894|location=v. 5|page=308}} 4. ^{{Cite book|title = Geology and Underground Water Resources of Northern Louisiana and Southern Arkansas|url = https://books.google.com/books?id=bGznAAAAMAAJ&pg=PA41&lpg=PA41&dq=Annona+Chalk&source=bl&ots=0GsNQA-jY-&sig=H5zTyv1SnjLPBeauAD_bEtN7gKk&hl=en&sa=X&ei=xTNjVcfWE8fr7Ab3mIGoDg&ved=0CD0Q6AEwCDgK#v=onepage&q=Annona%20Chalk&f=false|publisher = U.S. Government Printing Office|date = 1906|first = Arthur Clifford|last = Veatch}} 5. ^Matson, G. C., 1916, The Caddo Oil and Gas Field, Louisiana and Texas, USGS Bulletin 619
2 : Cretaceous Arkansas|Cretaceous geology of Texas |
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