Results 51 to 60 of about 6,336 (226)
Population structure of graptolite assemblages
, 1998 Graptolite rhabdosomes display a diverse suite of morphologies. The range of morphotypes present within most moderate to high diversity assemblages from the Ordovician and Silurian is similar, despite the different taxonomic composition of the faunas at ...
Underwood, Charlie J. +1 more
core +1 more source
Petroleum Research, 2017 Carbon and oxygen isotopes of marine carbonate rocks or fossil shells could indicate global sea-level relative change. Generally, heavier carbon isotopes or lighter oxygen isotopes reflected rise of global sea-level relative changes, and vice versa.
Zongju Zhao, Jianguo Wang, Peixi Wang
doaj +1 more source
Boreas, EarlyView.Map of Lower sediment (LS) thickness is a surrogate for the distribution of Thorncliffe Formation (TF) and ~75% of TF thickness from the slope of Niagara Escarpment east to Brighton. Inset images show the LS sequence at the Don Valleys brickyards (DVBY) and undeformed TF sand and gravel (~15 m) below Newmarket Till (NT) at sites L and Co.
David R. Sharpe +3 more
wiley +1 more source
Meteoritics &Planetary Science, EarlyView.Abstract The Tvären structure in southeastern Sweden has been listed as a confirmed marine‐target impact structure for decades. However, to date, no measurements and/or indexed data of planar deformation features in quartz grains from the structure have been published or any other unequivocal evidence of impact.
Katarzyna J. Gajewska +6 more
wiley +1 more source
Meteoritics &Planetary Science, EarlyView.Abstract We investigated the structural framework of the north–northwestern Paraná Basin in Brazil to test whether the pre‐impact structures in this region may have had any influence on the first‐order formation and morphostructure of the Araguainha impact structure (AIS).
Renato B. Bernardes +5 more
wiley +1 more source
The Skiddaw Group of Cumbria : early Ordovician Turbidite sedimentation and provenance on an evolving microcontinental margin. [PDF]
, 1992 During the Early Palaeozoic, the southern British Isles were part of a microcontinent Eastern Avalonia. In the early Ordovician Eastern Avalonia was close to the continent of Gondwana. in high southern latitudes.
Moore, Richard Maurice
core
Revisiting the Hummeln structure, Sweden—A shallow marine Cambrian impact structure
Meteoritics &Planetary Science, EarlyView.Abstract Hummeln is a simple impact structure located in south‐eastern Sweden. It is approximately 1.2 km in diameter and almost completely covered by a lake. Here, we present the first detailed investigation of impactites and mapping of the 164.25 m deep drill core Hummeln‐1 with a focus on impact metamorphism and the impact process.
S. Alwmark +8 more
wiley +1 more source
Sedimentology, EarlyView.ABSTRACT Aeolian deflationary events are erosive to static stages where sediment supply is insufficient to support bedform migration and preservation in the rock record. In the vicinity of shallow‐marine environments, inland rises of relative water table and associated generation of deflationary super surfaces may be driven by the onset of ...
Victor J. P. Hême de Lacotte +4 more
wiley +1 more source
Sedimentology, EarlyView.ABSTRACT Filamentous, anastomosing spar‐filled networks in Phanerozoic carbonates have been interpreted as the mineralised remains of keratose (non‐spiculate) sponges, yet their recognition remains contested because fabrics of broadly similar appearance may arise from microbial, diagenetic or physical processes. This study combines direct fossil–modern
Jeong‐Hyun Lee +2 more
wiley +1 more source
Upper Ordovician (Richmondian) cavity-dwelling (coelobiontic) organisms from southern Ontario
, 1980 Upper Ordovician (Richmondian) patch reefs in exposures of the Meaford Formation (Streetsville Member) in Mullett Creek, Mississauga, Ontario contain a preserved coelobiontic (cavity-dwelling) biota.
David R. Kobluk
core +1 more source