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

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.

scholarly journals Ichnofabrics of Eocene oil shales from central Jordan and their use for paleoenvironmental reconstructions

GeoArabia ◽  
2014 ◽  
Vol 19 (1) ◽  
pp. 85-112
Author(s):  
Mohammad Ali Hussein ◽  
Mohammad Alqudah ◽  
Olaf G. Podlaha
Keyword(s):  
Bottom Water ◽  
Middle Eocene ◽  
Trace Fossils ◽  
Total Thickness ◽  
Central Jordan ◽  
Depositional System ◽  
Rapid Changes ◽  
Oil Shales ◽  
Geochemical Studies ◽  
Paleoenvironmental Reconstructions

ABSTRACT The study of trace fossils is widely used in facies interpretation. It provides a crucial tool for reconstructing depositional paleoenvironments when used in combination with other sedimentological and paleontological proxies. Here we present the first detailed study of Eocene trace fossils from Jordan. Two sections of Early to Middle Eocene age, with a total thickness of 478.7 m, from central Jordan were cored and investigated. The results of individually occurring (isolated) or co-occurring (combined) ichnofabrics and bioturbation levels, in combination with results from biostratigraphic and geochemical studies, were used for stratigraphic and paleoenvironmental reconstructions. The bioturbation index (BI) was used to classify the burrowing density versus the preservation of the original sedimentary structures. The two cores show highly variable grades of bioturbation with BI ranging from 0 to 6. Four ichnogenera were identified: Thalassinoides, Chondrites, Teichichnus and Zoophycos. Both the ichnofabrics and the variations of the BI suggest a shallow, highly dynamic depositional system with rapid changes of water depth and degree of bottom-water oxygenation.

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.

Volcanoes of the southwestern extension of the active Mariana island arc: New swath-mapping and geochemical studies

Island Arc ◽  
1998 ◽  
Vol 7 (3) ◽  
pp. 596-607
Author(s):  
F RYER ◽  
S UJIMOTO ◽  
S EKINE ◽  
J OHNSON ◽  
K ASAHARA ◽  
...  
Keyword(s):  
Island Arc ◽  
Swath Mapping ◽  
Geochemical Studies ◽  
Mariana Island Arc

Genesis of crustal xenoliths from andesite in the Southeast Mátra Mts (Hungary) based on petrologic and geochemical studies

2006 ◽  
Vol 49 (4) ◽  
pp. 311-330
Author(s):  
Anita Jávor ◽  
Zuárd Ditrói-Puskás ◽  
Gábor Dobosi
Keyword(s):  
Crustal Xenoliths ◽  
Geochemical Studies
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