Geology topics

Merlynd K. Nestell

Publications and source records attributed to Merlynd K. Nestell.

7 recordsLinked to original sources

USGS2016

Awell-preserved conodont fauna from the Pennsylvanian Excello Shale of Iowa, U. S. A.

A superbly preserved discrete element conodont fauna has been recovered from carbonate concretions from the upper Desmoinesian (Pennsylvanian) Excello Shale at two localities in south-central Iowa. The multielement apparatuses for Gondolella wardlawi (new species), Idiognathodus acutus, Idioprioniodus conjunctus, and Neognathodus roundyi are reconstructed. Rare specimens of Idiognathodus tuberis (new species) also occur in the fauna.

Micropaleontology↗

USGS2016

Some contrasting biostratigraphic links between the Baker and Olds Ferry Terranes, eastern Oregon

New stratigraphic and paleontologic data indicate that ophiolitic melange windows in the Olds Ferry terrane of eastern Oregon contain limestone blocks and chert that are somewhat different in age than those present in the adjacent Baker terrane melange. The melange windows in the Olds Ferry terrane occur as inliers in the flyschoid Early and Middle Jurassic age Weatherby Formation, which depositionally overlies the contact between the melange-rich Devonian to Upper Triassic rocks of the Baker terrane on the north, and Upper Triassic and Early Jurassic volcanic arc rocks of the Huntington Formation on the south. The Baker terrane and Huntington Formation represent fragments of a subduction complex and related volcanic island arc, whereas the Weatherby Formation consists of forearc basin sedimentary deposits. The tectonic blocks in the melange windows of the Weatherby Formation (in the Olds Ferry terrane) are dated by scarce biostratigraphic evidence as Upper Pennsylvanian to Lower Permian and Upper Triassic. In contrast, tectonic blocks of limestone in theBaker terrane yield mostly fusulinids and small foraminifers of Middle Pennsylvanian Moscovian age at one locality.Middle Permian (Guadalupian) Tethyan fusulinids and smaller foraminifers (neoschwagerinids and other Middle Permian genera) are present at a few other localities. Late Triassic conodonts and bryozoans are also present in a few of the Baker terrane tectonic blocks. These limestone blocks are generally embedded in Permian and Triassic radiolarian bearing chert or argillite. Based on conodont, radiolarian and fusulinid data, the age limits of the meange blocks in the Weatherby Formation range from Pennsylvanian to Late Triassic.

Oregon↗

USGS2015

High influx of carbon in walls of agglutinated foraminifers during the Permian-Triassic transition in global oceans

The Permian – Triassic mass extinction is postulated to be related to the rapid volcanism that produced the Siberian flood basalt (Traps). Unrelated volcanic eruptions producing several episodes of ash falls synchronous with the Siberian Traps are found in South China and Australia. Such regional eruptions could have caused wildfires, burning of coal deposits, and the dispersion of coal fly ash. These eruptions introduced a major influx of carbon into the atmosphere and oceans that can be recognized in the wall structure of foraminiferal tests present in survival populations in the boundary interval strata. Analysis of free specimens of foraminifers recovered from residues of conodont samples taken at a Permian – Triassic boundary section at Lung Cam in northern Vietnam has revealed the presence of a significant amount of elemental carbon , along with oxygen and silica, in their test wall structure, but an absence of calcium carbonate . These foraminifers , identified as Rectocornuspira kalhori , Cornuspira mahajeri , and Earlandia spp. and whose tests previously were considered to be calcareous, are confirmed to be agglutinated , and are now referred to as Ammodiscus kalhori and Hyperammina deformis . Measurement of the 207 Pb/ 204 Pb ratios in pyrite clusters attached to the foraminiferal tests confirmed that these tests inherited the Pb in their outer layer from carbon -contaminated seawater. We conclude that the source of the carbon could have been either global coal fly ash or forest fire-dispersed carbon , or a combination of both, that was dispersed into the Palaeo-Tethys Ocean immediately after the end- Permian extinction event.

Ha Giang Province↗

USGS2015

An apparatus reconstruction of the conodont Caenodontus serrulatus Behnken 1975

The conodont species Caenodontus serrulatus Behnken is a rare coniform element first described in 1975 from Guadalupian strata exposed in the Guadalupe and Delaware Mountains of West Texas. Because it is rare, coniform, and occurs long after most coniform elements supposedly disappeared, it has been hauntingly mysterious. Based on new material containing a varied assemblage of coniform elements recovered from an outcrop of the Hegler Limestone (Guadalupian) in the Patterson Hills, West Texas, it is proposed that Caenodontusis comprised of a 6-7 membrate coniform apparatus and that this apparatus is very similar to the one proposed for the genus Ansella from the Ordovician.

Texas↗

USGS2015

Conodont biostratigraphy of the Permian-Triassic boundary sequence at Lung Cam, Vietnam

The occurrences of a few specimens of Clarkina and many specimens of Hindeodus at the Permian-Triassic boundary section at Lung Cam, Vietnam allow accurate graphic correlation to the P-T boundary stratotype at Meishan, China. One species of Clarkina, ten species and two subspecies of Hindeodus, and the apparatuses of Hindeodus latidentatus and Merrillina ultima are described and illustrated.

Micropaleontology↗

USGS2015

Conodont faunas from a complete basinal succession of the upper part of the Wordian (Middle Permian, Guadalupian, West Texas)

In the southern part of the Patterson Hills just to the west of the Guadalupe Mountains escarpment ofWest Texas, a 29m outcrop of alternating calcareous siltstone and silty limestone with a few thin fine sandstone interbeds displays the overlap occurrence of a narrowmorphotype of Jinogondolella nankingensis (herein named J. nankingensis behnkeni) with J. aserrata near its base. The transition of Jinogondolella aserrata to J. postserrata is present near the top of this section and marks theWordian-Capitanian boundary, therefore displaying a significant portion of the upper part of theWordian in one short continuous section. Pseudohindeodus brevis n. sp. and H. capitanensis n. sp. are described. Pseudohindeodus ramovsi, Caenodontus serrulatus, Hindeodus wordensis, Sweetina triticum, Jinogondolella palmata, and J. errata also occur in this succession.

Texas↗

USGS2009

Stratigraphy and conodont biostratigraphy of the uppermost Carboniferous and Lower Permian from the North American Midcontinent

Part A The uppermost Wabaunsee, Admire, Council Grove, and lower Chase Groups of Kansas, Oklahoma, and Nebraska are placed into three third-order depositional sequences: a Gzhelian late-highstand sequence set, a Council Grove transgressive and highstand sequence set, and a Chase transgressive sequence set. Sequences are defined by bounding maximum-exposure surfaces and are placed within the zone of exposure surfaces (typically, stacked paleosols). Conodonts are abundant in open-marine deposits and most marine units have a differing and characteristic faunal make-up. Eleven species are described as new: Streptognathodus binodosus , S. denticulatus , S. elongianus , S. florensis , S. lineatus , S. nevaensis , S. postconstrictus , S. postelongatus , S. robustus , S. translinearis , and S. trimilus . Part B Maximum-marine flooding levels and marine-condensed sections from uppermost Carboniferous and Lower Permian fourth-order (0.1-1 m.y.) depositional sequences of the North American midcontinent reveal a rich stratigraphic succession of species of Streptognathodus and Sweetognathus conodonts that permits high-precision correlation of the Carboniferous-Permian boundary as well as the Asselian-Sakmarian and Sakmarian-Artinskian boundaries. Eleven new species of Streptognathodus are described: Streptognathodus binodosus , S. denticulatus , S. elongianus , S. florensis , S. lineatus , S. nevaensis , S. postconstrictus , S. postelongatus , S. robustus , S. translinearis , and S. trimilus . Seventeen species are redescribed and clarified and include Streptognathodus alius , S. barskovi , S. bellus , S. brownvillensis , S. conjunctus , S. constrictus , S. elongatus , S. farmeri , S. flexuosus , S. fuchengensis , S. fusus , S. invaginatus , S. isolatus , S. longissimus , S. minacutus , S. nodulinearis , and S. wabaunsensis . The correlated level of the Carboniferous-Permian boundary is recognized in the lower part of the Red Eagle Depositional Sequence based on the introduction of Streptognathodus isolatus Chernykh, Ritter, and Wardlaw; Streptognathodus minacutus Barskov and Reimers; Streptognathodus invaginatus Reshetkova and Chernykh; Streptognathodus fuchengensis Zhao; and Streptognathodus nodulinearis Reshetkova and Chernykh. The correlated Carboniferous-Permian boundary occurs in the depositional sequence that represents the maximum-marine highstand of the Council Grove Composite Third Order Sequence. This level represents a significant marine-flooding event that should be correlatable in numerous shelfal sections throughout the world. Although the Asselian-Sakmarian boundary has not been rigorously defined, Sweetognathus merrilli has been informally utilized as a Sakmarian indicator. Due to the ecologically controlled distribution of species of Sweetognathus , we prefer to use a species of Streptognathodus as a defining species. We propose that Streptognathodus barskovi (Kozur) Reshetkova be considered as a potentially defining or ancillary defining species for the Sakmarian Stage. In the North American midcontinent, Streptognathodus barskovi appears in the same depositional sequence with Sweetognathus merrilli in the Eiss (Lower Bader) Depositional Sequence. Historically, Sweetognathus whitei has been used to mark the Sakmarian-Artinskian boundary. In our succession Sweetognathus whitei and Streptognathodus florensis appear in the basal part of the Barneston Depositional Sequence. We suggest that Streptognathodus florensis be further investigated as a possible defining or ancillary defining taxon for the base of the Artinskian Stage. This depositional sequence also forms the maximum-marine highstand of the Chase Third-Order Composite Depositional Sequence suggesting that this level is a significant marine-flooding event that should be widely traceable in numerous shelfal sections.

Kansas;Nebraska;Oklahoma↗