Halloysite in Argentinian deposits: origin and textural constraints

Clay Minerals ◽  
2012 ◽  
Vol 47 (3) ◽  
pp. 329-340 ◽  
Author(s):  
F. Cravero ◽  
P. J. Maiza ◽  
S. A. Marfil
Keyword(s):  
Middle Eocene ◽  
Clay Mineralogy ◽  
Particle Morphology ◽  
Field Work ◽  
Time Range ◽  
Open Spaces ◽  
Chemical Methods ◽  
Rock Composition ◽  
Rio Negro ◽  
Geochemical Studies

AbstractIn Argentina, the only halloysite deposits found so far are located in the southwest of the province of Rio Negro. The areas are named Mamil Choique and Buitrera, separated by 50 km in a W–E direction. The deposits are located in pyroclastic rocks, rhyolitic tuffs and ignimbrites.The aim of this paper is to determine the origin of the alteration, any relationship between the processes in Mamil Choique and Buitrera, and the factors which controlled the halloysite formation. The work was based on field work, mineralogical and geochemical studies, form and distribution of the alteration. Fresh as well as altered rocks were collected. The first were studied by petrographic and chemical methods. In altered samples, the clay mineralogy was determined by XRD and textures by SEM and TEM. Chemical analyses on fresh and altered samples were used to characterize the alteration process and the rock composition.It was concluded that halloysite has been formed by weathering in a time range from Middle Eocene to Middle Oligocene and extended along 50 km in a W-E direction, independent of the source rock. Particle morphology depends on the original texture of the rock. Spheroidal halloysite is related to rocks with low porosity and tubular particles are related to rocks with open spaces.

Palynological and organic geochemical studies of the middle Eocene Siju Formation of Garo Hills, Meghalaya, India

2022 ◽  
Vol 131 (1) ◽  
Author(s):  
Y Raghumani Singh ◽  
Arka Rudra ◽  
Sh Priyokumar Singh ◽  
Suryendu Dutta ◽  
M Sapana Devi ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Garo Hills ◽  
Geochemical Studies

Oil and gas in Kurgan region

2021 ◽  
pp. 9-24
Author(s):  
A. A. Arsenyev ◽  
D. S. Leontiev ◽  
M. D. Zavatsky ◽  
V. V. Saltykov
Keyword(s):  
Oil And Gas ◽  
Field Work ◽  
Research Area ◽  
Petroleum Potential ◽  
Gas Recovery ◽  
History Of ◽  
And Migration ◽  
Active Processes ◽  
Geochemical Studies ◽  
High Degree

This article analyzes the prospects of petroleum potential in Kurgan region. The relevance of the work is due to the high degree of development of the traditional oil and gas recovery areas of Western Siberia, which leads to the need to organize search activities in areas with a low density of hydrocarbon resources. We have analyzed the results of exploratory drilling in the area of the Alabuga river in Kurgan region, and have studied the history of detections of onshore oil occurrences there. Based on the results of the retrospective analysis, the research area was determined, field work was performed to determine the state of search wells in the area, and a collection of geochemical soil and liquid samples was selected. The analysis of the samples revealed that all of them contain methane and its homologues up to and including pentane. The genesis of light methane homologs is related to the processes of catagenesis; their detection on the surface indicates active processes of generation and migration of petroleum hydrocarbons. Based on the analysis of archival materials and estimated ground-based geochemical studies, a conclusion is made about petroleum potential in Kurgan region.

New Uintasoricine (?Primates, Plesiadapiformes) From the Earliest Bridgerian, Latest Early Eocene of Wyoming

2012 ◽  
Vol 86 (6) ◽  
pp. 973-978 ◽  
Author(s):  
Gregg F. Gunnell
Keyword(s):  
North America ◽  
New Genus ◽  
Middle Eocene ◽  
Field Work ◽  
Biodiversity Hotspot ◽  
Individual Species ◽  
Early Eocene ◽  
New Genus And Species ◽  
Body Weights ◽  
New Form

Uintasoricines are diminutive plesiadapiforms that are found in the latest Paleocene through middle Eocene, predominantly in North America. They are not a diverse group but individual species may be locally abundant and they are a persistent element of the plesiadapiform radiation in North America surviving over a span of approximately 16 million years. Recent field work in southern Wyoming at South Pass has led to the discovery of a new genus and species of uintasoricine. The new form is smaller in tooth dimensions compared to other known uintasoricines, being slightly smaller thanUintasorex montezumicusfrom California. Both the newly described taxon andU. montezumicusare among the smallest plesiadapiforms yet known with body weights estimated to be 20 to 25 g. The sediments of the Cathedral Bluffs Tongue of the Wasatch Formation at South Pass contain a unique upland fauna—the presence of a distinctive uintasoricine in this assemblage adds further evidence to support the notion that this upland environment was a biodiversity hotspot during the latest early Eocene.

A Middle–Late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco; preliminary report: age and palaeobiogeographical implications

2010 ◽  
Vol 147 (6) ◽  
pp. 860-870 ◽  
Author(s):  
SYLVAIN ADNET ◽  
HENRI CAPPETTA ◽  
RODOLPHE TABUCE
Keyword(s):  
Middle Eocene ◽  
Field Work ◽  
Late Eocene ◽  
Close Relative ◽  
Evolutionary Trend ◽  
Western Sahara ◽  
Sedimentary Deposits ◽  
Marine Deposits ◽  
Bony Fishes ◽  
The City

AbstractRecent field work in the southern Moroccan Sahara (‘Western Sahara’), south of the city of ad-Dakhla, has led to the discovery of several new fossiliferous sites with fossil vertebrates in sedimentary deposits previously reported for the Mio-Pliocene. The sedimentology and geological setting of the studied area are briefly reported here, and at least three units have been identified in successive stratigraphical sequences according to their fossil content. The first preliminary list of vertebrate associations is reported and consists mainly of isolated teeth belonging to selachian and bony fishes, a proboscidean tooth currently assigned to ?Numidotherium sp. and many remains of archaeocete whales (Basilosauridae). At least 48 species of selachians are presently identified; many of them are new and others are recorded in the late Middle Eocene (Bartonian) and Late Eocene (Priabonian) of Wadi Al-Hitan (Egypt) or Wadi Esh-Shallala Formation (Jordan) as in other African localities (e.g. Otodus cf. sokolowi, ‘Cretolamna’ twiggsensis, Xiphodolamia serrata, Misrichthys stromeri, Hemipristis curvatus, Galeocerdo cf. eaglesomi, Propristis schweinfurthi), probably indicating a Late Eocene age for unit 2 of the bedrock successions. The evolutionary trend noticeable on the proboscidean tooth is in agreement with such an assumption, by comparison with the close relative species known from the Eocene of Egypt, Libya and Algeria. Indeed, the faunal associations from the Dakhla area clearly demonstrate the erroneous age of these deposits, previously thought to be Mio-Pliocene. It suggests a correlation in age (late Middle Eocene–Late Eocene) and a similar environment with the famous marine deposits from Egypt and Jordan. It opens new opportunities to understand the biogeography and the surprising similarity of landscape between West and Northeast Africa during the Bartonian–Priabonian period.

scholarly journals Geometric morphometrics of endophytic oviposition traces of Odonata (Eocene, Argentina)

2020 ◽  
Vol 7 (12) ◽  
pp. 201126
Author(s):  
Eugenia Romero-Lebrón ◽  
Raquel M. Gleiser ◽  
Julián F. Petrulevičius
Keyword(s):  
Geometric Morphometrics ◽  
Linear Models ◽  
Middle Eocene ◽  
Evolutionary Constraint ◽  
Mixed Linear Models ◽  
Lower Eocene ◽  
Rio Negro ◽  
Endophytic Oviposition ◽  
The Individual ◽  
First Time

The insertion of the Odonata ovipositor in the plant tissue generates a scar that surrounds the eggs (trace). In insects, individual egg traces are known to vary in size, but their variation in individual shape is mostly unknown. Twenty-four specimens were obtained from the Laguna del Hunco (Lower Eocene, Chubut) and Río Pichileufú (Middle Eocene, Río Negro), Argentina, which had 1346 oviposition traces (MEF Collection). For the first time, a study of the shape and size of a large number of individual Odonata endophytic egg traces was carried out using traditional (general and mixed linear models) and geometric morphometrics (Fourier elliptical series) to elucidate whether there are changes in size or shape of the individual endophytic egg traces associated with the substrate used at the time of oviposition, if the Lower Eocene traces have varied in relation to those of the Middle Eocene, and if the ichnological classification ( Paleoovoidus arcuatus , P. bifurcatus and P. rectus ) reflects such variations. We found differences in size ( p < 0.05), but not in shape, in relation to the variables studied. This could reflect that the shape of Odonata eggs (inferred from the traces), unlike their size, could have a strong evolutionary constraint already observed since the Eocene.

scholarly journals Further work on the early Archaean rocks of the Isukasia area, southern West Greenland

1982 ◽  
Vol 110 ◽  
pp. 49-54
Author(s):  
A.P Nutman
Keyword(s):  
Field Work ◽  
Regional Mapping ◽  
West Greenland ◽  
North East ◽  
The North ◽  
Starting Point ◽  
Supracrustal Belt ◽  
Geochemical Studies

Work in 1981 on the early Archaean rocks of the Isukasia area (Ailaart, 1976) was an integral part of GGU's mapping programme of northern Godthåbsfjord, Fiskefjord and adjacent areas to the north-east. Within the Isukasia area, there was dose co-operation with Minik Rosing who was making detailed studies of certain aspects of the Isua supracrustal belt. The object of this summer's field work was to complete the study of the supracrustal belt and the central gneisses that was started last year (Nutman et al., in press), and to see as much as possibIe of the gneisses between the supracrustal belt and 65°N (fig. 18). For the mapping of the supracrustal belt, manuscript maps drawn by J. H. Allaart were an invaluable starting point. Besides regional mapping, detailed studies were made of the nature of the lithological units and the relationships between them; see Table 4 for chronology. Suites of rocks were collected for isotopic and geochemical studies. In connection with this, H. Baadsgaard spent 10 days working with the author in the area, as a guest of GGu. The results reported here supplement those given by Nutman et al. (in press).

scholarly journals Rediscovery of Dendropsophus tintinnabulum (Anura: Hylidae) in the upper Rio Negro Drainage (Amazonas, Brazil), with a description of its advertisement call and external morphology

2016 ◽  
Vol 15 (2) ◽  
pp. 119 ◽  
Author(s):  
Bernardo Franco da Veiga Teixeira ◽  
Ariovaldo Antonio Giaretta
Keyword(s):  
Body Shape ◽  
Field Work ◽  
Morphological Features ◽  
External Morphology ◽  
Advertisement Call ◽  
Color Body ◽  
Rio Negro ◽  
Voucher Specimens ◽  
Genomic Results ◽  
Amazonas State

Dendropsophus tintinnabulum is one of six species of the genus unassigned to any group. Voucher specimens and recordings of this taxon obtained during field work in the municipality of São Gabriel da Cachoeira and elsewhere in the district of Cucuí in Amazonas state, Brazil, permit a description of the advertisement call and external morphological features. Based on overall similarities in size, dorsal color, body shape, advertisement call, and preliminary genomic results, D. tintinnabulum is tentatively assigned to the D. microcephalus Group

The middle Eocene Márkushegy subbituminous coal (Hungary): Paleoenvironmental implications from petrographical and geochemical studies

2007 ◽  
Vol 72 (1) ◽  
pp. 33-52 ◽  
Author(s):  
A. Bechtel ◽  
M. Hámor-Vidó ◽  
R.F. Sachsenhofer ◽  
D. Reischenbacher ◽  
R. Gratzer ◽  
...  
Keyword(s):  
Middle Eocene ◽  
Geochemical Studies

scholarly journals REE Geochemistry of Euphrates River, Turkey

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Leyla Kalender ◽  
Gamze Aytimur
Keyword(s):  
Middle Eocene ◽  
River Sediments ◽  
Volcanic Rocks ◽  
Tectonic Zone ◽  
Magmatic Complex ◽  
River Bank ◽  
Euphrates River ◽  
Lower Eocene ◽  
Western Asia ◽  
Geochemical Studies

The study area is located on the Euphrates River at 38°41°32.48′′N–38°14′24.10′′N latitude and 39°56′4.59′′E–39°8°13.41′′E longitude. The Euphrates is the longest river in Western Asia. The lithological units observed from the bottom to the top are Permo-Triassic Keban Metamorphites, Late Cretaceous Kömürhan Ophiolites, Upper Cretaceous Elazığ Magmatic Complex, Middle Eocene Maden Complex and Kırkgeçit Formation, Upper Pliocene and Lower Eocene Seske Formation and Upper Miocene, Pliocene Karabakır and Çaybağı Formations, Palu Formation, and Holocene Euphrates River sediments. The geochemical studies show that87Sr/86Sr and143Nd/144Nd isotopic compositions in the Euphrates River bank sediments are 0.7053, 0.7048, and 0.7057 and 0.512654, 0.512836, and 0.512775, respectively. These values indicate mixing of both carbonate-rich shallow marine sediment and felsic-mafic rocks from Elazığ Magmatic Complex into the stream sediments. The positiveεNd (0)values (0.35, 3.9, and 2.7) are higher downstream in the studied sediments due to weathering of the mafic volcanic rocks. The chondrite, NAS, and UCC normalized patterns show that the REE compositions of the Euphrates River sediments are higher than chondrite composition but close to NAS and UCC. The river sediments in the tectonic zone and the weathered granodioritic rocks of the Elazığ Magmatic complex affect upstream water compositions.

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