نتایج جستجو برای: upper devonian
تعداد نتایج: 206790 فیلتر نتایج به سال:
upper devonian sediments of the kuh-e zard area northwest of zefreh, central iran, arecomposed mainly of brown and grey limestones with sandstone and shale intercalations. they contain tracefossils such as chondrites isp., diplocraterion parallelum, fustiglyphus annulatus, lockeia isp., phycodesisp., and taenidium barretti. these trace fossils indicate a shallow marine environment
The Geirud Formation consists mainly of clastic sediments which are interbedded with limestone stringers. This rock unit is well-exposed along the Central Alborz Range in northern Iran. The Geirud Formation rests unconformably on the Mila Formation (Upper Cambrian) and is conformably overlain by the Mobarak Formation (Lower Carboniferous). This study was undertaken to determine the geologi...
about 35 samples were collected from lower and upper parts of the proposed frasnianamennian boundary in three sections of upper devonian marine sediments of the kerman province. the biostratigraphical and geochemical studies indicate that about 45% extinction of brachiopods probably caused by the frasnian-famennian bioevents, which is slightly higher than thr rate of devonian-carboniferous exti...
A single leafy stem from the Middle or lowermost Upper Devonian Campo Chico Formation, Sierra de Perija, western Venezuela, is the first record of the important Devonian herbaceous lycophyte Leclercqia from South America, usually considered as part of western Gondwana. The seemingly cosmopolitan distribution of this genus is discussed in relation to coeval assemblages and palaeocontinental reco...
In the Dusina area, which is built up of Lower Palaeozoic metasediments, Devonian carbonate complex and Upper Palaeozoic metarhyolites unconformably overlain by Upper Permian sediments, numerous ore occurrences have been investigated: (a) "stratabound" metamorphic hematite deposits in the pre-Devonian metasediments; (b) epigenetic veins and pipes of barite (& calcite) with accessory Hg-tetrahed...
Water and gas samples were collected from (1) nine shallow groundwater aquifers overlying Marcellus Shale in north-central West Virginia before active shale gas drilling, (2) wells producing gas from Upper Devonian sands and Middle Devonian Marcellus Shale in southwestern Pennsylvania, (3) coal-mine water discharges in southwestern Pennsylvania, and (4) streams in southwestern Pennsylvania and ...
Microgastropod fauna from the Upper Devonian Cephalopod Bed and overlying Lower Tournaisian strata of the original reference section of the Shishtu Formation have been examined. Twenty genera and one unknown genus have been identified. The original aragonite shells have been replaced either by pyrite or fluorapatite
About 35 samples were collected from lower and upper parts of the proposed Frasnianamennian boundary in three sections of Upper Devonian marine sediments of the Kerman province. The biostratigraphical and geochemical studies indicate that about 45% extinction of brachiopods probably caused by the Frasnian-Famennian bioevents, which is slightly higher than thr rate of Devonian-Carboniferous exti...
-Isotopic measurements (Sr, O, D) on formation waters from the Alberta Basin have been made, covering a stratigraphic range from Devonian to Upper Cretaceous. These measurements, combined with chemical compositional trends, give evidence for two distinct water regimes. One hydrological regime is composed of waters hosted in Devonian-Lower Cretaceous reservoirs, the other waters from Upper Creta...
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