Results 11 to 20 of about 692 (139)

Chronostratigrahy of Acritarchs and Chitinozoans from upper Ordovician Strata from the Robat-e Gharabil Area, NE Alborz Mountains, Northern Khorassan Province: Stratigraphic and Paleogeographic Implications [PDF]

Journal of Sciences, Islamic Republic of Iran, 2018
The Palaeozoic rock units mainly, Ghelli, Niur, Padeha, Khoshyeilagh and Mobark formations are well-exposed in the north of Robat-e Gharabil village. 116 out of 157 surface samples were analyzed to determine aged relationships of Ghelli Formation.
M. Ghavidel-Syooki, S. Borji
doaj   +3 more sources

Biostratigraphy of the Ludlow chitinozoans from East Baltic drill cores [PDF]

Estonian Journal of Earth Sciences, 2009
The distribution of chitinozoans in the East Baltic Ludlow sequences was studied in the Ohesaare, Ventspils, Pavilosta, and Dubovskoye drill core sections.
Nestor, Viiu
doaj   +2 more sources

Early–Middle Ordovician chitinozoans from the Dawan Formation, Yichang area, Central China [PDF]

Journal of Micropalaeontology
The late Early to early Middle Ordovician is a key interval for chitinozoan macroevolution, during which chitinozoans diversified significantly, reaching their first enormous radiation later in the Darriwilian.
Y. Liang, S. Wu, S. Wu, X. Luan, R. Zhan, R. Zhan   +5 more
doaj   +3 more sources

LOWER TO MIDDLE ORDOVICIAN ACRITARCHS AND CHITINOZOANS FROM NORTHERN KARAKORUM MOUNTAINS, PAKISTAN

Rivista Italiana di Paleontologia e Stratigrafia, 2000
The lower Vidiakot section (Chitral, Pakistan) comprises the lower part (Yarkhun Formation and the base of the Vidiakot Formation) of the terrigenous complex transgressively overlying the crystalline basement of Northern Karakorum.
MARCO QUINTAVALLE, MARCO TONGIORGI, MAURIZIO GAETANI   +2 more
doaj   +2 more sources

Late Ordovician scolecodonts and chitinozoans from the Pin Valley in Spiti, Himachal Pradesh, northern India [PDF]

Acta Palaeontologica Polonica
The end of the Ordovician witnessed major perturbations in the ecosystem, seriously affecting global marine biodiversity. Nevertheless, some marine organism groups and their crisis-bound palaeogeographic distribution are still understudied.
PETRA TONAROVÁ, THOMAS J. SUTTNER, OLLE HINTS, YAN LIANG, MAREK ZEMEK, MICHAL KUBAJKO, TOMÁŠ ZIKMUND, JOZEF KAISER, ERIKA KIDO   +8 more
doaj   +3 more sources

The role of clay minerals in the preservation of Precambrian organic‐walled microfossils

Geobiology, Volume 21, Issue 6, Page 708-724, November 2023., 2023
Abstract Precambrian organic‐walled microfossils (OWMs) are primarily preserved in mudstones and shales that are low in total organic carbon (TOC). Recent work suggests that high TOC may hinder OWM preservation, perhaps because it interferes with chemical interactions involving certain clay minerals that inhibit the decay of microorganisms.
C. R. Woltz, R. P. Anderson, N. J. Tosca, S. M. Porter   +3 more
wiley   +1 more source

Expansion of Reducing Marine Environments During the Ireviken Biogeochemical Event: Evidence From the Altajme Core, Gotland, Sweden

Paleoceanography and Paleoclimatology, Volume 38, Issue 2, February 2023., 2023
Abstract New δ34Spy (pyrite) and δ34SCAS (carbonate‐associated sulfate) across the Llandovery‐Wenlock boundary (∼432 Ma) provide evidence for the expansion of reduced marine environments during the Ireviken Biogeochemical Event. This event consists of a major positive carbon isotope excursion, increased biotic turnover, and other major perturbations ...
Brittany M. Stolfus, Lindsi J. Allman, Seth A. Young, Mikael Calner, Emma R. Hartke, Stephan C. Oborny, Alyssa M. Bancroft, Bradley D. Cramer   +7 more
wiley   +1 more source

Geochemical Records Reveal Protracted and Differential Marine Redox Change Associated With Late Ordovician Climate and Mass Extinctions

AGU Advances, Volume 3, Issue 1, February 2022., 2022
Abstract The Ordovician (Hirnantian; 445 Ma) hosts the second most severe mass extinction in Earth history, coinciding with Gondwanan glaciation and increased geochemical evidence for marine anoxia. It remains unclear whether cooling, expanded oxygen deficiency, or a combination drove the Late Ordovician Mass Extinction (LOME).
Nevin P. Kozik, Benjamin C. Gill, Jeremy D. Owens, Timothy W. Lyons, Seth A. Young   +4 more
wiley   +1 more source

Silurian stratigraphy and graptolite faunas of the Mora 001 and Solberga 1 drill cores, Siljan District, central Sweden

Lethaia, Volume 54, Issue 5, Page 610-630, December 2021., 2021
The Mora 001 and Solberga 1 drill cores provide the best available overview on the early Silurian (Llandovery, Rhuddanian to Telychian) graptolite succession available for the Siljan Ring impact structure of central Sweden. The Solberga 1 succession includes a nearly complete graptolite succession from the Pernerograptus revolutus Biozone (late ...
Jörg Maletz
wiley   +1 more source

Upper Sandbian–lower Katian bio- and chemostratigraphy in the Pajevonys-13 core section, Lithuania [PDF]

Estonian Journal of Earth Sciences, 2016
The succession of five formations (Auleliai, Vilučiai, Alvitas, Šakiai, Jakšiai) corresponding to the upper Sandbian and lower Katian in southern Lithuania is dated based on new bio- and chemostratigraphical data from the Pajevonys-13 core section.
Linda Hints, Juozas Paškevičius, Tõnu Martma, Peep Männik, Jaak Nõlvak   +4 more
doaj   +1 more source