Biostratigraphic Units and Tectonism in the Mid-Cretaceous Foreland of Wyoming, Colorado, and Adjoining Areas

1986 ◽  
Author(s):  
E. A. Merewether ◽  
W. A. Cobban
Keyword(s):  
Biostratigraphic Units

Late Glacial and Holocene history of Plešné Lake and its surrounding landscape based on pollen and palaeoalgological analyses

Biologia ◽  
2006 ◽  
Vol 61 (20) ◽  
Author(s):  
Vlasta Jankovská
Keyword(s):  
Late Glacial ◽  
Forest Steppe ◽  
Southern Europe ◽  
Pollen Diagram ◽  
History Of ◽  
The Bohemian Forest ◽  
Surrounding Landscape ◽  
Late Glacial And Holocene ◽  
High Degree ◽  
Biostratigraphic Units

AbstractPollen analysis has been carried out on a 549 cm thick sediment profile from lake Plešné jezero (Plešné Lake) in the Bohemian Forest (Šumava, Czech Republic; 1090 m a.s.l.; 48°47′ N; 13°52′ E). Analyses of 67 samples characterise the development of the lake biotope and the surrounding landscape during the last ca. 14,000 years. The pollen diagram shows a very distinct transition between the Late Glacial and the Holocene biostratigraphic units at a depth of ca. 312 cm. In the surroundings of Plešné Lake the vegetation was treeless during the entire Late Glacial. The alpine tree limit, formed by Betula and Pinus with undergrowth of shrubs, might have been at ca. 500 m a.s.l. Pollen transported from long distances was significant due to the openness of the landscape, coming from southern Europe and even Africa, and including high numbers of Artemisia, Poaceae, Chenopodiaceae, and some other herbs and shrubs from steppe and forest-steppe areas in southern Europe or Africa (likely Ephedra, certainly Lygeum spartum). The expansion of shrubs, particularly Juniperus, preceded the expansion of trees near the end of the Late Glacial. Afforestation of the region by thin stands of Betula and Pinus occurred during the Preboreal. Significant warming in the Boreal resulted in the expansion of Corylus, Quercetum mixtum (QM) trees, and probably also Picea and Alnus. Picea as well as QM trees were further expanding during the Early Atlantic. Picea was the dominant tree during the Late Atlantic and Fagus started to spread towards its end. Abrupt expansion of Abies marks the Subboreal. A high degree of afforestation (Abies, Fagus, Picea) was characteristic for the Early Subatlantic. During Late Subatlantic, pollen of synanthropic plants appears. Phases of the lake biotope development were defined on the basis of coccal green algae and Isoëtes.

Upper Homerian (upper Wenlock, Silurian) graptolites from arctic Canada

2002 ◽  
Vol 76 (2) ◽  
pp. 321-346 ◽  
Author(s):  
A. C. Lenz ◽  
A. Kozłowska-Dawidziuk
Keyword(s):  
New Species ◽  
Middle Part ◽  
Morphological Features ◽  
The Arctic ◽  
New Genera ◽  
Arctic Canada ◽  
Total Fauna ◽  
Biostratigraphic Units

An extraordinarily well-preserved upper Homerian (uppermost Wenlock) post-extinction (post-lundgreni Event) graptolite fauna is described from Arctic Canada. The fauna of dendroids, retiolitids and monograptids, predominantly of uncompressed and isolated material, demonstrates almost totally new morphological features in comparison with the pre-extinction fauna. The two species of the lowest post-extinction fauna are followed by a rapid proliferation in the middle part of the interval, resulting in the maximum diversity, 21 species, for the entire upper Homerian. The upper Homerian is divided into three biostratigraphic units: the lower nassadubius Biozone, middle praedeubeli-deubeli Biozone, and the upper ludensis Biozone. The total fauna consists of ten species of monograptids and 11 species of retiolitids; of the latter group, three (Baculograptus, Papiliograptus and Doliograptus) are new genera, and six (B. batesi, P. papilio,P.? petilus,D. latus,Doliograptus sp. A, and Spinograptus praerobustus) are new species. Among the recognized species of monograptids, only Colonograptus schedidoneus and Lobograptus? cornuatus are confined to the Arctic, while five species of retiolitids (B. batesi,P.? petilus,D. latus,Doliograptus sp. A, and Spinograptus praerobustus) appear to be endemic.

Biostratigraphy of the Bajocian-Bathonian boundary interval in northern Siberia: new data on belemnites from the Yuryung-Tumus peninsula

2017 ◽  
Vol 188 (1-2) ◽  
pp. 3 ◽  
Author(s):  
Benoît de Lagausie ◽  
Oksana S. Dzyuba
Keyword(s):  
European Russia ◽  
Northern Siberia ◽  
Central Russia ◽  
First Time ◽  
Ammonite Zones ◽  
Biostratigraphic Units

This paper presents a refined belemnite based biostratigraphy for the Bajocian-Bathonian transition in the Yuryung-Tumus peninsula (northern Siberia, Russia). A revision of the Siberian belemnite zonation is proposed. Herein two new belemnite biostratigraphic units are introduced: the Paramegateuthis subishmensis Zone (upper part of the Lower Bajocian) and the Paramegateuthis ishmensis Zone (Lower-Middle Bathonian boundary interval). Paramegateuthis subishmensis STOYANOVA-VERGILOVA, recorded for the first time in Siberia and previously only known from Bulgaria (Sub-Mediterranean domain), provides evidence for correlation of both the Boreal Boreiocephalites borealis and Cranocephalites gracilis ammonite zones with the standard Stephanoceras humphriesianum Zone. The new biostratigraphic data also result in an improved correlation based on belemnites for the Lower-Middle Bathonian of the Boreal (Siberia, North European Russia) and Subboreal (Central Russia) regions.

scholarly journals Biostratigraphy of Upper Jurassic of the Valy clay pit (Samarskaya Luka) by ammonites, ostracods and dinocysts

2021 ◽  
Vol 66 (3) ◽  
Author(s):  
Mikhail A. Rogov ◽  
◽  
Julia N. Savelieva ◽  
Olga V. Shurekova ◽  
◽  
...  
Keyword(s):  
Upper Jurassic ◽  
Ecological Analysis ◽  
Central Russia ◽  
Short Time ◽  
First Time ◽  
The Village ◽  
Upper Kimmeridgian ◽  
Biostratigraphic Units ◽  
Lower Kimmeridgian ◽  
Samarskaya Luka

The results of integrate biostratigraphic study of Upper Jurassic deposits of the clay pit near the village of Valy (Syzran district, Samara region) are presented. For the first time a bed-by-bed description was made and the subdivision of the section into zones, subzones and biohorizons by ammonites was established. Bauhini and Kitchini zones (Bayi subzone) are established in the Lower Kimeridgian, while Upper Kimmeridgian is represented by Autissiodorensis zone only. In the Lower Volgian Sokolovi and Pseudoscythica zones were recognized, while the Middle Volgian is represented by the Panderi zone. The age of the regionally developed unconformity at the base of the Trazovo Formation has been clarified. As in the sections located to the south from studied section, this unconformity is located in the base of the Autissiodorensis zone, overlying different Oxfordian and lower Kimmeridgian. For the first time for Kimmeridgian of Central Russia in the marlstone band of the Kitchini zone (bayi biohorizon) solitary corals conditionally attributed to the genus Trochocyathus were found. Along with corals other warm-water taxa (belemnites Hibolithes, rare ammonites Taramelliceras) were found in the same bed, suggesting deposition of this bed during the short-time warming event. 6 biostratigraphic units (zone and beds with fauna) were recognized by ostracods, along with 2 dinocyst-based units (assemblage and zone) which are compared with the stratigraphic subdivisions by these groups, previously proposed for the Kimeridgian and Volgian stages of the Russian Platform. The paleo-ecological analysis has allowed to assume, that sediments have accumulated in the conditions of warm shallow eutrophic basin with depth to 50 m, with gradual increase of eutrophy through time. At some levels, short-term episodes of severe shallowing or freshening are recorded by ostracods.

scholarly journals On the non-marine stratigraphy and floras of north-eastern Russia

2019 ◽  
Vol 27 (3) ◽  
pp. 40-52
Author(s):  
S. V. Shczepetov ◽  
A. B. Herman
Keyword(s):  
Floral Development ◽  
Facial Region ◽  
The Third ◽  
North Eastern ◽  
Stratigraphic Chart ◽  
Eastern Russia ◽  
Biostratigraphic Units

Some decisions of the Third Inter-departmental Regional Stratigraphic Meeting on Precambrian, Paleozoic and Mesozoic of North-eastern Russia (St. Petersburg, 2002) are analysed in the light of latest data obtained. It is shown that regional stratigraphic units (‘Horizons’) of non-marine Cretaceous recognised in this Meeting are in fact not the basic subdivisions, but rather specialised biostratigraphic units, namely ‘Beds with flora’. Ages of some of these units are specified, notably Beds with Arman Flora is Turonian–Coniacian, Beds with Amka Flora is Coniacian and Beds with Arkagala Flora is Santonian–Campanian. We recommend to keep the previous names for the Penzhina, Barykov and Koryak phases of floral development and for the corresponding stratigraphic units. An updated version of the non-marine Cretaceous stratigraphic chart of the Okhotsk-Chukotka structural-facial Region is proposed to discuss.

Conodonts from the lower Ordovician at Hunneberg, south-central Sweden

1993 ◽  
Vol 130 (2) ◽  
pp. 215-232 ◽  
Author(s):  
A. Löfgren
Keyword(s):  
Critical Part ◽  
Surface Samples ◽  
South Central ◽  
Lower Ordovician ◽  
Correlation Accuracy ◽  
Biostratigraphic Units

AbstractSix sections through lower Ordovician shale and limestone at Hunneberg have been sampled for conodonts. Forty-nine limestone horizons and 34 shale surface samples yielded over 40000 conodont elements. The degree of biostratigraphic resolution permitted further subdivision of the post-Tremadoc Paroistodus proteus Zone into four successive intervals. Preliminary studies of coeval rocks in other areas of Sweden show that this subdivision applies elsewhere as well. Comparison with published sections from, for example, Newfoundland, Estonia and Kazakhstan indicates that the fourfold subdivision of the P. proteus Zone proposed here could significantly increase the correlation accuracy, even internationally, within this critical part of the Ordovician. Graptolites and trilobites found together with the conodonts at Hunneberg indicated that the new subdivision could help to correlate biostratigraphic units based on these fossil groups. Thus the two lower intervals of the P. proteus Zone correspond to the M. (E.) armata trilobite Zone, and the upper two are approximately equal to the M. (V.) planilimbata Zone. The base of the T. phyllograptoides graptolite Zone at Hunneberg lies close to the boundary between the upper middle and uppermost intervals of the P. proteus Zone, but the graptolitic chronozonal boundary may be lower. The overlying Prioniodus elegans Zone is mainly represented by graptolitic shale at Hunneberg, but conodont faunas have been found in it, and co-occurrences of conodonts and graptolites have been noted.

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