Conodonts of the Barnett formation of Texas
Conodonts of the Barnett formation of Texas
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DOI：
10.3133/pp243f
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发表时间：
1953
期刊：
影响因子：
--
通讯作者：
W. H. Hass
中科院分区：
文献类型：
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作者：
W. H. Hass
得克萨斯州拉诺地区的巴内特组（密西西比期）包含两个牙形石动物群带。这两个带的上部被认为局限于在此被视为Meramec时代的地层部分，也可能局限于部分切斯特时代的地层部分;下部动物区系被认为局限于在此被视为Osage（Keokuk）时代的地层部分。在拉诺区域的所有象限都有属于上层动物区的岩石。在该区东部，这些岩石主要由橄榄灰色至黄褐色页岩组成，与少量薄泥质石灰岩互层;向西，上述岩石合并为石灰岩，其中一些非常海百合状。牙形刺在大多数标本中数量众多，但区系组合较小，在65个标本中仅识别出10属18种。其中一些牙形刺存在于俄克拉荷马州和阿肯色州的斯坦利页岩的下部，以及俄克拉荷马州的卡尼页岩中。提出了两个新属名：膝形属（Geniculatus）和圆形属（Roundya）。P. V. Roundy的牙形刺来自于巴内特组，已经被研究过，他的所有模式标本都被重新描绘。已知属于巴内特组下部动物区的岩石仅存在于拉诺地区的西南象限。该地区的动物群已被确认在20个集合，但没有被描述，因为它是保存不善。
The Barnett formation (Mississippian) of the Llano region, Texas, contains two conodont faunal zones. The upper of these two zones is believed to be restricted to that portion of the formation which herein is regarded as being of Meramec and possibly also partly of Chester age; and the lower faunal zone, to that portion of the formation which herein is regarded as being of Osage (Keokuk) age. Rocks assigned to the upper faunal zone are present in all quadrants of the Llano region. In the eastern part of the area, these rocks consist chiefly of olive-gray to yellowish-brown shales that are interbedded with a few thin argillaceous limestones; westward, the above-mentioned rocks merge into limestones, some of which are extremely crinoidal. Conodonts are numerous in most collections, but the faunal assemblage is small as only 10 genera and 18 species have been recognized in 65 collections. Some of these conodonts are present in the lower part of the Stanley shale of Oklahoma and Arkansas, as well as in the Caney shale of Oklahoma. Two new generic names, Geniculatus and Roundya are proposed. P. V. Roundy's conodonts from the Barnett formation have been studied and all of his type specimens have been refigured. Rocks assigned to the lower faunal zone of the Barnett formation are known to be present only in the southwest quadrant of the Llano region. The fauna of this zone has been recognized in 20 collections but has not been described as it is poorly preserved.