Features of ooids in the Middle Cambrian
Zhangxia Formation in the Western Hills, Beijing, and their environmental significance.
Caption: Figure 2: A stratigraphic column and core photos of Upper Ediacaran, Lower and Middle Cambrian
of Jiangye-1 well.
The occurrence of the Middle Cambrian
was clearly argued in the 1970s (Resheniya...
This interpretation means that Patagonia could have been accreted to East Antarctica during middle Cambrian
times, and that the Patuxent, El Jaguelito and Starshot formations and the Douglas Conglomerate could represent the synorogenic deformation associated with the collision.
The earliest stage of echinoderm evolution is represented by Ctenoimbricata from the early middle Cambrian
. These flattened stem echinoderms were completely covered on their lower side by calcite plates, but were largely uncalcified on their upper (dorsal) sides.
Earlier workers considered these rocks to be of Pennsylvanian age (e.g., Nichols 1956; Quinn 1971), until the discovery of Middle Cambrian
trilobites of Acado-Baltic affinities in the basal Jamestown Formation (Skehan et al.
The Technical Note concludes, interalia, that global correlations of Late Neoproterozoic and Middle Cambrian
source rock sequences from the Amadeus, Georgina and Wiso (Lander Trough) basins suggest that their potential for both conventional and unconventional hydrocarbon accumulations has been underestimated, considering the prolific hydrocarbon production from equivalent petroleum systems in Oman and on the Siberian Platform in Russia, and to some extent in the Sichuan Basin China.
2010), they have also been encountered much farther north, in the Early to Middle Cambrian
Mount Cap Formation of the Northwest Territories (Butterfield 1994; Butterfield and Nicholas 1996; Harvey and Butterfield 2008).
In addition to providing a more complete understanding of marine life at that time, the team's discovery upends a long-held belief that so-called Burgess Shale-type faunas, which are typical for the Early to Middle Cambrian
, disappeared at the end of the Middle Cambrian
epoch, some 499 million years ago.
the Lower-Middle Devonian (Parnu-Kemeri formations) and Middle Cambrian
aquifers buried to depths exceeding 800 m in the central and western parts of the Baltic basin (Fig.
The lobopod animal Aysheaia pedunculata Walcott, Middle Cambrian
, Burgess Shale, British Columbia.
Simon Conway Morris of the University of Cambridge in England reports that one type of Ediacaran organism, known as Charniodiscus, bears a close resemblance to a newly identified animal from the Burgess Shale, a fossil site dating to the middle Cambrian
period, roughly 520 million years ago.