Results 21 to 30 of about 169 (141)

New biostratigraphically important chitinozoans from the Kukruse Regional Stage, Upper Ordovician of Baltoscandia [PDF]

Estonian Journal of Earth Sciences, 2015
Three new chitinozoan species, Conochitina savalaensis, Conochitina viruana and Belonechitina intonsa, are described. All these species are stratigraphically restricted to the Kukruse age (lowermost Sandbian, Laufeldochitina stentor chitinozoan Zone) and
Jaak Nõlvak, Garmen Bauert
doaj   +1 more source

Three‐Dimensional Morphology and Connectivity of Organic Pores in Shale from the Wufeng and Longmaxi Formations at the Southeast Sichuan Basin in China

Geofluids, Volume 2021, Issue 1, 2021., 2021
Organic pores play an important role in shale reservoirs. Organic pores occur where shale gas was produced and accumulated. However, there is little scientific understanding of the distribution and connectivity of organic pores. Organic pore types and their structural characteristics were studied using a total organic carbon (TOC), thin section ...
Tao Jiang, Zhijun Jin, Zongquan Hu, Wei Du, Zhongbao Liu, Jianhua Zhao, Kun Zhang   +6 more
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

Petrographic Characterization and Maceral Controls on Porosity in Overmature Marine Shales: Examples from Ordovician‐Silurian Shales in China and the U.S.

Geofluids, Volume 2021, Issue 1, 2021., 2021
The pore structure characterization and its controlling factors in overmature shales are keys to understand the shale gas accumulation mechanism. Organic matter in source rocks is a mixture of various macerals that have their own specific evolutionary pathways during thermal maturation. Pores within macerals also evolve following their own path.
Lin Wei, Shasha Sun, Dazhong Dong, Zhensheng Shi, Jia Yin, Shudi Zhang, Maria Mastalerz, Xiong Cheng, Kun Zhang   +8 more
wiley   +1 more source

Microfossils in the Ordovician erratic boulders from Southwestern Finland [PDF]

Bulletin of the Geological Society of Finland, 1995
Chitinozoans, ostracods and acritarchs found in four glacially transported limestone boulders from the south-western coast of Finland have been studied in order to test the usefulness of these microfossil groups in age determinations. Also rare specimens
J. Nõlvak, T. Meidla, A. Uutela
doaj   +1 more source

Geochemistry and correlation of volcanic ash beds from the Rootsiküla Stage (Wenlock–Ludlow) in the eastern Baltic [PDF]

Estonian Journal of Earth Sciences, 2011
Nine altered volcanic ash samples from the shoal and lagoonal sediments of the Rootsiküla Stage (Wenlock–Ludlow boundary interval, Estonia) were analysed, compared and correlated with five samples of deep sea environments from Latvia.
Tarmo Kiipli, Rein Einasto, Toivo Kallaste, Viiu Nestor, Helle Perens, Sven Siir   +5 more
doaj   +1 more source

New insights into the chemical composition of chitinozoans [PDF]

Organic Geochemistry, 2007
The chemical structure of isolated chitinozoan specimens extracted from Early Silurian marine rocks has been investigated by micro-FTIR, laser micro-Raman spectroscopy and laser micropyrolysis-gas chromatography/mass spectrometry (LmPy- GC/MS). The samples were subjected to relatively low thermal stress as attested by several indices.
Jacob, Jérémy, Paris, Florentin, Monod, Olivier, Miller, Meller A., Tang, Peng, George, Simon C., Bény, Jean-Michel   +6 more
openaire   +2 more sources

A summary and revision of the East Baltic Silurian chitinozoan biozonation [PDF]

Estonian Journal of Earth Sciences, 2012
The biostratigraphical data on the East Baltic Silurian chitinozoans are summarized. Based on the study of nine East Baltic drill cores, 28 regional chitinozoan zonal units, including 26 biozones and 2 interzones, are briefly characterized. In comparison
Viiu Nestor
doaj   +1 more source

Darriwilian (Middle Ordovician) conodont biostratigraphy in NW Estonia [PDF]

Estonian Journal of Earth Sciences, 2012
Darriwilian conodonts have been studied in numerous sections of Baltoscandia, but few data are available from the classical outcrop area in northern Estonia. In this paper we report the succession of Darriwilian conodonts and chitinozoans from the bed-by-
Olle Hints, Viive Viira, Jaak Nõlvak
doaj   +1 more source

Reconstructing Depositional Rates and Their Effect on Paleoenvironmental Proxies: The Case of the Lau Carbon Isotope Excursion in Gotland, Sweden

Paleoceanography and Paleoclimatology, Volume 35, Issue 12, December 2020., 2020
Abstract Variations in depositional rates affect the temporal depositional resolutions of proxies used for paleoenvironmental reconstructions; for example, condensation can make reconstructed environmental changes appear very abrupt. This is commonly addressed by transforming proxy data using age models, but this approach is limited to situations where
E. Jarochowska, T. Nohl, M. Grohganz, N. Hohmann, T. R. A. Vandenbroucke, A. Munnecke   +5 more
wiley   +1 more source