نتایج جستجو برای: devonian
تعداد نتایج: 2127 فیلتر نتایج به سال:
Late Devonian (Frasnian) abiotic marine calcite has been microsampled and analyzed for R’Sr/*6Sr ratios, 6’*0 and d13C values, and minor element concentrations. Portions of marine cement crystals from the Alberta and Canning Basins have escaped diagenetic alteration and preserve original marine S180 values f-4.8%0 + 0.5, PDB), Si3C values (+2.0 to +3.0b, PDB), *‘Sr/*6Sr ratios (0.70805 + 3), an...
Past research on the emergence of digit-bearing tetrapods has led to the widely accepted premise that this important evolutionary event occurred during the Late Devonian. The discovery of convincing digit-bearing tetrapod trackways of early Middle Devonian age in Poland has upset this orthodoxy, indicating that current scenarios which link the timing of the origin of digited tetrapods to specif...
9. Gardiner, B. G. The relationships of the palaeoniscid ®shes, a review based on new specimens of Mimia and Moythomasia from the Upper Devonian of Western Australia. Bull. Brit. Mus. Nat. Hist. (Geol.) 37, 173±428 (1984). 10. Young, G. C. New information on the structure and relationships of Buchanosteus (Placodermi: Euarthrodira) from the Early Devonian of New South Wales. Zool. Jour. Linn. S...
In an earlier paper^ I described the new genus Brooksma from a series of sediments in southeastern Alaska tentatively referred to the upper Silurian. In that paper will be found a brief discussion of the faunal affinities of the series. A more detailed study of the Brooksina fauna together with the famias of lower and liighei horizons strengthens the belief that the formations in question shoul...
Chitinozoa from the Middle Devonian Columbus Limestone of central Ohio belong to eight species of the genera Alpenachitina, Ancyrochitina, Angochitina, Conochitina, Desmochitina, and Eisenackitina. Two new species, Ancyrochitina frankeli and Eisenackitina robusta, are described. The Chitinozoa occur in carbonate rocks such as mudstone, grainstone and packstone that represent well circulated ope...
The stratifi ed red beds of the Catskill Formation are conspicuous in road cut exposures on the Allegheny Plateau of north-central Pennsylvania. During this fi eld trip we will visit and explore several fossil localities within the Catskill Formation. These sites have been central to recent investigations into the nature of Late Devonian continental ecosystems. By the Late Devonian, forests wer...
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
Extraction of natural gas by hydraulic fracturing of the Middle Devonian Marcellus Shale, a major gas-bearing unit in the Appalachian Basin, results in significant quantities of produced water containing high total dissolved solids (TDS). We carried out a strontium (Sr) isotope investigation to determine the utility of Sr isotopes in identifying and quantifying the interaction of Marcellus Form...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید