In northern Vietnam, the Upper Devonian to Carboniferous Toc Tat Formation crops out along the frontier with China. The lower part of the formation is dominated by slope-and basin-marine carbonates consisting mainly of limestone breccia, slump beds, and turbidites. Hemipelagic marls and distal calciturbidites contain abundant Upper Devonian conodonts, ostracods and tentaculitoids. The Frasnian-Famennian stage boundary, well known as coincident with one of the five mass extinction events of the Phanerozoic, is identified by the first occurrence of the Famennian conodont species Palmatolepis triangularis. Carbon-rich black shales within the Devonian part of the Toc Tat Fm suggest the Lower and Upper Kellwasser anoxic events, the upper horizon coinciding with the F-F boundary. The Devonian succession of the Toc Tat Fm records a marked decline in the local biodiversity and abundance of tentaculitoids that is suggestive of extinction patterns in the eastern equatorial Palaeotethys region at this time.
Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian.
On Hideshima Island (Miyako area, Iwate Prefecture, northeast Japan), the Albian Hideshima Formation of the Lower Cretaceous (Aptian to Albian) Miyako Group consists mainly of alternations of turbidite sandstone and mudstone, thick sandstone, and conglomerate. It is also characterized by slump beds and debris flow deposits containing poorly preserved shallow-marine bivalves such as Glycymeris, Eriphyla, Nipponitrigonia, and rudists, representing typical allochthonous occurrences. Eleven genera of the benthic foraminifera have recently been identified in the mudstone of the middle part of the Hideshima Formation. The benthic foraminiferal assemblage is dominated by Bathysiphon spp., Recurvoides spp., and Haplophragmoides spp. Facies analysis and the composition of the benthic foraminifera indicate that the Hideshima Formation accumulated in a slope environment.
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