Well-preserved miospore assemblages are recorded from the Late Ordovician (Katian-Hirnantian), Ghelli Formation in Pelmis-gorge at the north-eastern Alborz Mountain The palynomorphs were extracted from siliciclastic deposits which are well-dated by using of marine palynomorphs (acritarchs and chitinozoans). The encountered miospore assemblages consist of 14 genera (28 species: 26 cryptospores a...

Isotope data from bulk carbonates, micrite, marine calcite cements, non-skeletal grains and brachiopods indicate deposition of a wide spectrum of warm to cold water carbonates during the Ordovician and the Jurassic. This isotopic interpretation is supported by warm to cold climatic models proposed for the Ordovician and the Jurassic. These carbonates formed during the Greenhouse mode (condition...

for the first time, an assemblage of cryptospores, which includes 10 species belonging to nine genera, from the upper ordovicianstrata, is being reported, in iran. these cryptospore assemblages were recovered from the upper part of ghelli formation., from theeastern alborz mountain range. these peri-gondwanan cryptospores have been classified based on their morphology (monad, truedyad, pseudody...

isotope data from bulk carbonates, micrite, marine calcite cements, non-skeletal grains and brachiopods indicate deposition of a wide spectrum of warm to cold water carbonates during the ordovician and the jurassic. this isotopic interpretation is supported by warm to cold climatic models proposed for the ordovician and the jurassic. these carbonates formed during the greenhouse mode (condition...

Understanding ancient climate changes is hampered by the inability to disentangle trends in ocean temperature from trends in continental ice volume. We used carbonate "clumped" isotope paleothermometry to constrain ocean temperatures, and thereby estimate ice volumes, through the Late Ordovician-Early Silurian glaciation. We find tropical ocean temperatures of 32° to 37°C except for short-lived...

It has been hypothesized that predecessors of today's bryophytes significantly increased global chemical weathering in the Late Ordovician, thus reducing atmospheric CO2 concentration and contributing to climate cooling and an interval of glaciations. Studies that try to quantify the enhancement of weathering by non-vascular vegetation, however, are usually limited to small areas and low number...

animal life on land. The current benchmark for evidence of plants on land is about 450,000,000 years ago (Late Ordovician). Tantalizing microscopic fossils of chemically resistant spore walls occur in land-derived rocks around the world, and predate this Late Ordovician age by over 50,000,000 years (Upper Cambrian) and possibly beyond. Figuring out what kinds of organisms (algae, primitive plan...

Phyllite and quartzite, probably Precambrian, trend meridionally and dip steeply in the New River Gorge above the junction with the Salisbury River in southern Tasmania. Further upstream an association of silty dolomite and conglomerate is less deformed and may be younger. Siliceous conglomerate boulders occur in the New River below the gorge. Late Ordovician carbonates of the Gordon Group are ...

To geologists, the Ordovician System of Ohio is probably the most famous of the state's Paleozoic rock systems. The alternating shales and limestones of the upper part of this system crop out in southwestern Ohio in the Cincinnati region and yield an incredible abundance and diversity of well-preserved fossils. Representatives of this fauna reside in museums and private collections throughout t...