The Gedan floristic assemblage from the Late Cretaceous deposits of the Kholchan Formation of the Okhotsk-Chukotka volcanogenic belt

Palaeobotany ◽  
2014 ◽  
Vol 5 ◽  
pp. 73-93 ◽  
Author(s):  
L. B. Golovneva ◽  
S. V. Shczepetov
Keyword(s):  
River Basin ◽  
Late Cretaceous ◽  
Middle Part ◽  
Isotopic Data ◽  
Volcanogenic Belt ◽  
Stratigraphic Position ◽  
Cretaceous Deposits

The Gedan floristic assemblage occurs from upper layers of the Kholchan Formation of the Okchotsk-Chukotka volcanogenic belt (OCVB). The locality is situated at the Gedan River in the middle part of the Arman River basin. The Gedan assemblage is composed of 6 taxa: Cladophlebis sp., Sphenobaiera sp., Ginkgo ex gr. adiantoides (Ung.) Heer, Taxodium amguemensis (Efimova) Golovn., Metasequoia sp., Pagiophyllum sp. The similarity of the Gedan floristic assemblage with the Karamken and the Khirumki floristic assemblages from the Kholchan Formation of the Okhotsk sector of the OCVB allows us to join them in the Kholchan flora. This flora is distinct from more ancient Arman flora, which dated as the Turonian-Coniacian and from younger Ola flora, which dated as the Santonian-early Campanian. The age of the Kholchan flora is estimated as the Coniacian on the basis of stratigraphic position, presence of Podozamites, Metasequoia and Quereuxia and also isotopic data. This flora is equivalent with the Chaun flora of Central Chukotka, with the Aleeki flora from the Villigha and Toomahni Rivers interfluve and with the Ulya flora from the southern part of the Okhotsk-Chukotka volcanogenic belt.

The Envymaam floristic assemblage from the Upper Cretaceous deposits of the Okhotsk-Chukotka volcanogenic belt

Palaeobotany ◽  
2014 ◽  
Vol 5 ◽  
pp. 42-59 ◽  
Author(s):  
L. B. Golovneva ◽  
S. V. Shczepetov
Keyword(s):  
River Basin ◽  
Early Cretaceous ◽  
Upper Cretaceous ◽  
Isotopic Data ◽  
Basaltic Rocks ◽  
Volcanogenic Belt ◽  
The Poor ◽  
Palynological Assemblages ◽  
Systematic Composition ◽  
Cretaceous Deposits

The Envymaam floristic assemblage occurs from basaltic rocks of the Envymaam Formation in the Envymaam River basin, Central Chukotka segment of the Okhotsk-Chukotka volcanogenic belt. This assemblage consists of 18 taxa: Hepaticites sp., Coniopteris tschuktschorum (Krysht.) Samyl., Phoenicopsis ex gr. angustifolia Heer, Cupressinocladus enmyvaamensis Golovn., sp. nov., Araliaephyllum philippoviae Golovn., sp. nov. Among them, two species are fi rstly described. The Envymaam assemblage is characterized by presence of the Early Cretaceous relicts (Phoenicopsis), by rarity of angiosperms and by small sizes of their leaves. Age of the Envymaam floristic assemblage is determined as the late Campanian on the basis of systematic composition, palynological, paleomagnetic and isotopic data. Direct continuity between the Envymaam and the Ust’-Emuneret floristic assemblages from the subjacent Emuneret Formation it isn’t observed that is caused probably by the poor composition of the Envymaam floristic assemblage. Palynological assemblages from the Envymaam, Ust’-Emuneret, Ola and Arkagala Formations are very similar.

Ginkgophytes of the Ul’ya flora (the Ul’ya depresiion, the Okhotsk-Chukotka volcanogenic belt)

Palaeobotany ◽  
2016 ◽  
Vol 7 ◽  
pp. 80-95 ◽  
Author(s):  
L. B. Golovneva
Keyword(s):  
New Species ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Middle Part ◽  
Leaf Length ◽  
Volcanogenic Belt ◽  
Short Shoots ◽  
Volcanogenic Deposits

The Ul’ya flora comes from the Coniacian volcanogenic deposits of the Amka Formation (the Ul'ya depression, southern part of the Okhotsk-Chukotka volcanogenic belt). Ginkgoaleans are diverse in this flora and represented by three genera: Ginkgo, Sphenobaiera and Baiera. All specimens have no cuticle and were assigned to morphotaxa. Genus Ginkgo includes two species: G. ex gr. adiantoides (Ung.) Heer with entire leaves and G. ex gr. sibirica Heer with dissected leaves. Genus Sphenobaiera also consists of two species: S. ex gr. longifolia (Pom.) Florin with 4–8 leaf lobes and S. ex gr. biloba Prynada with two leaf lobes. Genus Baiera is represented by new species B. lebedevii Golovn., sp. nov.Leaves of this species are 25–30 cm long and 13–16 cm wide, narrowly wedge-shaped with flat slender petiole, dichotomously dissected 4–5 times into linear segments 3–6 mm wide with 6–12 veins. The length of ultimate segments is equal to about a half of leaf length. Leaves attached spirally to ovoid short shoots about 2 cm long. Among the Late Cretaceous floras similar diversity of ginkgoaleans was recorded only in the Turonian-Coniacian Arman flora from middle part of the Okhotsk-Chukotka volcanogenic belt (Herman et al., 2016). Four species of ginkgoaleans from the Ul’ya flora (except G. ex gr. adiantoides) are considered as the Early Cretaceous relicts.

New data about the Late Cretaceous floras of the Ulya depression (western coast of Sea of Okhotsk)

Palaeobotany ◽  
2013 ◽  
Vol 4 ◽  
pp. 148-167 ◽  
Author(s):  
L. B. Golovneva
Keyword(s):  
River Basin ◽  
Early Cretaceous ◽  
Late Cretaceous ◽  
Sea Of Okhotsk ◽  
Northeastern Russia ◽  
Western Coast ◽  
Fossil Plants ◽  
Sedimentary Deposits ◽  
Volcanogenic Belt ◽  
Systematic Composition

New investigation of fossil plants from volcanic-sedimentary deposits of the Amka Formation in Ulya River basin (southern part of the Okhotsk-Chukotka volcanogenic belt, Northeastern Russia) shows, that the Arinda, Uenma, Ust-Amka and Gyrbykan floristic assemblages from diff erent localities of this formation have very close systematic composition. We propose to joint these assemblages in the single regional flora, which is named the Ulya flora. The Ulya flora consists of almost 40 species. The majority of them are represented by new undescribed taxa. In this flora gymnosperms (Phoenicopsis ex gr. speciosa Heer, Ginkgo ex gr. adiantoides (Ung.) Heer, G. ex gr. sibirica Heer, Sphenobaiera sp., Podozamites sp., Elatocladus spp., Araucarites sp., Sequoia sp., Metasequoia sp., Cupressinocladus sp., Ditaxocladus sp., Pityophyllum sp., Pityostrobus sp.) predominate. Ferns (Asplenium dicksonianum Heer, Arctopteris sp., Cladophlebis spp. and several undescribed taxa) and angiosperms (Trochodendroides spp., undetermined Platanaceae, Dicotylophyllum spp., Quereuxia angulate (Newb.) Krysht. ex Baik.) are not abundant. This flora is characterized by presence of the Early Cretaceous relicts (Phoenicopsis, Sphenobaiera and Podozamites), by rarity of angiosperms and by high endemism. On the base of comparison of the Ulya flora with other floras from middle and northern parts of the Okhotsk-Chukotka volcanogenic belt, the age of the Ulya flora is estimated as the Coniacian.

New species of the genus Sequoia Endlicher (Cupressaceae) from the Late Cretaceous deposits of the Northeastern Russia

Palaeobotany ◽  
2015 ◽  
Vol 6 ◽  
pp. 80-95 ◽  
Author(s):  
D. A. Yudova ◽  
L. B. Golovneva
Keyword(s):  
New Species ◽  
River Basin ◽  
Late Cretaceous ◽  
Volcanic Belt ◽  
Northeastern Russia ◽  
Eastern Siberia ◽  
New Siberian Islands ◽  
Chukotka Volcanic Belt ◽  
Epidermal Features ◽  
Cretaceous Deposits

New species Sequoia ochotica Yudova et Golovn. (Pinopsida, Cupressaceae) from the Turonian-Coniacian deposits of the Arman and Chingandzha Formations of the Okhotsk-Chukotka volcanic belt is described based at morphological features of leaves and shoots. Two other Late Cretaceous species of this genus: S. minuta Sveshn. from the Vilyui River basin of Eastern Siberia and S. tenuifolia (Schmalh.) Sveshn. et Budants. from the New Siberian Islands have comparable shoot morphology, but these species were described based at epidermal features.

Late Cretaceous Kholokhovchan floral assemblage of the Okhotsk-Chukotka volcanogenic belt (North-Eastern Asia)

Palaeobotany ◽  
2013 ◽  
Vol 4 ◽  
pp. 116-147 ◽  
Author(s):  
S. V. Shczepetov ◽  
A. B. Herman
Keyword(s):  
Late Cretaceous ◽  
Eastern Asia ◽  
Plant Fossils ◽  
Volcanogenic Belt ◽  
North Eastern ◽  
Volcanogenic Deposits ◽  
Floral Assemblage ◽  
Eastern Russia ◽  
Comprehensive Study

Results of comprehensive study of the Kholokhovchan floral assemblage collection is summarized. These plant fossils were collected in 1978 by E. L. Lebedev from volcanogenic deposits in Penzhina and Oklan rivers interfluve, North-Eastern Russia. This assemblage was previously known as a list of Lebedev’s preliminary identifi cations only. He had suggested that the Kholokhovchan assemblage is correlative to the latest Albian — early Turonian Grebenka flora from the Anadyr River middle reaches. However, our study demonstrates that the Kholokhovchan assemblage is most similar to the presumably the Turonian-Coniacian Arman flora of the Okhotsk-Chukotka volcanogenic belt and, therefore, should be dated as the Turonian-Coniacian or Turonian.

Preliminary detrital zircon U-Pb Geochronology of the Wasatch Formation, Powder River Basin, Wyoming

2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock
Keyword(s):  
River Basin ◽  
Detrital Zircon ◽  
Middle Part ◽  
Detrital Zircons ◽  
Powder River Basin ◽  
Zircon Age ◽  
Lower Eocene ◽  
The North ◽  
Mountain Front ◽  
Fluvial Sandstone

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.

scholarly journals Coal petrology analysis and implications in depositional environments from upper Cretaceous to Miocene: a study case in the Eastern Cordillera of Colombia

2021 ◽  
Author(s):  
Clara Guatame ◽  
Marco Rincón
Keyword(s):  
Late Cretaceous ◽  
Foreland Basin ◽  
Late Eocene ◽  
Depositional Environments ◽  
Estuarine System ◽  
Eastern Cordillera ◽  
Stratigraphic Position ◽  
San Fernando ◽  
Coal Facies ◽  
Oil Sector

AbstractThe Piedemonte Llanero Basin is located on the eastern side of the Eastern Cordillera of the Colombian Andes. It has been the subject of numerous geological studies carried out for the oil sector, mainly. This study presents the coal-petrographical features of 15 coal seams of four geological formations from Late Cretaceous to Middle Miocene (Chipaque formation, Palmichal group, Arcillas del Limbo formation, and San Fernando formation). Analysis of 33 samples indicates enrichment in vitrinite, while liptinite and inertinite concentrations vary according to the stratigraphic position. Reflectance indicates that the coal range gradually decreases from highly volatile bituminous C (Chipaque formation) to subbituminous C (San Fernando formation). The microlithotypes with the highest concentrations are clarite and vitrinertoliptite. Maceral composition and coal facies indicate changes in the depositional conditions of the sequence. The precursor peat from Late Cretaceous to Late Paleocene accumulated under limnic conditions followed by telmatic in Late Eocene–Early Miocene. The coal facies indices show wet conditions in forest swamps with variations in the flooding surface, influxes of brackish water and good tissue preservation. The tectonic conditions along the Piedemonte Llanero basin is evident, from post-rift to foreland basin, evidenced by oxic and anoxic periods reflected in the maceral composition and its morphology. The coal environment corresponds to an estuarine system started in the Chipaque formation evolving to the lacustrine conditions in the San Fernando formation.

Late Cretaceous climatic trends, faunas, and hydrography in Britain and Ireland

1976 ◽  
Vol 113 (2) ◽  
pp. 115-128 ◽  
Author(s):  
R. E. H. Reid
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Water Masses ◽  
Relative Distribution ◽  
Isotopic Data ◽  
Climatic Trends

SummaryChanges in the Upper Cretaceous faunas of northeastern Ireland point to rising Cenomanian temperatures, and to progressive falls in temperatures from early Santonian to Maastrichtian times. At first sight, these changes fit the Cretaceous climatic trends claimed from isotopic data; but comparison with faunas seen in England suggests that this fit is illusory. It is suggested that faunas were more directly controlled by the influence of contrasting Atlanto-West Tethyan and Russo-Germanic water masses, and by changes in their relative distribution. Changes seen through the Irish Senonian may reflect the progressive submergence of a Scotland—Pennines barrier, permitting an increasing westward spread of the Russo—Germanic (‘boreal’) water and fauna.

Misinterpretation of zircon ages in layered intrusions

2021 ◽  
Author(s):  
R. Latypov ◽  
S. Chistyakova
Keyword(s):  
Phase Equilibria ◽  
High Precision ◽  
Bushveld Complex ◽  
Classical Model ◽  
Layered Intrusions ◽  
Isotopic Data ◽  
Magma Chambers ◽  
Stratigraphic Position

Abstract A recent re-interpretation of the Bushveld Complex and other layered intrusions as stacks of randomly emplaced, amalgamated sills is mostly fuelled by finding of zircon ages that are not getting progressively younger from the base upwards, as expected from a classical model for the formation of layered intrusions. Rather, they display several reversals from older to younger ages and vice-versa with moving up-section through the layered intrusions. Here, we show that the reported zircon ages are at odds with the relative ages of rocks as defined by cross-cutting relations in potholes of the Bushveld Complex. This indicates that interpretation of the zircon isotopic data as the emplacement age of the studied rocks/units is incorrect, making a new emplacement model for layered intrusions baseless. This conclusion is further buttressed by the phase equilibria analysis showing that regular cumulate sequences of layered intrusions are not reconcilable with a model of randomly emplaced sills. In this model, the late sills are free to intrude at any stratigraphic position of the pre-existing rocks, producing magmatic bodies with chaotic crystallization sequences and mineral compositional trends that are never observed in layered intrusions. There are thus no valid justifications for the re-evaluation of the current petrological model of the Bushveld Complex and other layered intrusions as large, long-lived and largely molten magma chambers. A fundamental implication of this analysis is that the current high-precision U-Pb TIMS ages from layered intrusions are inherently unreliable on the scale of several million years and cannot therefore be used for rigorous estimations of the timing of crystallization, duration of magmatism, and cooling of these intrusions.

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