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SUMMARY A detailed micropalaeontological analysis (foraminifera and calcareous algae) has been made of the Brigantian Basal Stratotype section at Janny Wood in the Stainmore Trough, and sections in the Rookhope, Allenheads, Feizor and Back Scar boreholes on the Alston and Askrigg blocks of northern England. The sections contain a complete composite succession from the upper Asbian to the Pendleian. Using the first appearances, last appearances and the acmes of the foraminiferal and algal taxa, it is possible to recognize eight assemblages in the shallow-water platform facies of the Alston and Askrigg blocks. Several taxa occur earlier in the Janny Wood section (Stainmore Trough) than in the boreholes on the adjacent blocks and many common taxa in what is currently regarded as the highest Asbian part of the Janny Wood section are more typical of the Brigantian. All the palaeontological data suggest that the Birkdale Limestone and possibly the Robinson Limestone in the Janny Wood section could be Brigantian, although there is an absence of basal Brigantian foraminiferal markers (e.g. Loeblichia and Janischewskina). Nevertheless, the basal Brigantian Stratotype boundary could be moved from its current position at the base of the Peghorn Limestone to a lower level, preferably at the base of the Birkdale Limestone.

The East China Sea basins, located in the West Pacific Continental Margin (WPCM) since the late Mesozoic, mainly include the East China Sea Shelf Basin (ECSSB) and the Okinawa Trough (OT). The WPCM and its adjacent seas can be tectonically divided into five units from west to east, including the Min‐Zhe Uplift, ECSSB, the Taiwan–Sinzi Belt, OT, and the Ryukyu Island Arc, which record regional tectonic evolution and geodynamics. Among those tectonic units, the ECSSB and the OT are important composite sedimentary pull‐apart basins, which experienced two stages of strike‐slip pull‐apart processes. In seismic profiles, the ECSSB and the OT show a double‐layer architecture with an upper half‐graben overlapping on a lower graben. In planar view, the ECSSB and the OT are characterized by faulted blocks from south to north in the early Cenozoic and by a zonation from west to east in the late Cenozoic. The faulted blocks with planar zonation and two‐layer vertical architecture entirely jumped eastward from the Min‐Zhe Uplift to the OT during the late Cenozoic. In addition, the whole palaeogeomorphology of the ECSSB changed notably, from pre‐Cenozoic highland or mountain into a Late Eocene continental margin with east‐tilting topography caused by the eastward tectonic jumping. The OT opened to develop into a back‐arc basin until the Miocene. Synthetic surface geological studies in the China mainland reveal that the Mesozoic tectonic setting of the WPCM is an Andean‐type continental margin developing many sinistral strike‐slip faults and pull‐apart basins and the Cenozoic tectonic setting of the WPCM is a Japanese‐type continental margin developing dextral strike‐slip faults and pull‐apart basins. Thus, the WPCM underwent a transition from Andean‐type to Japanese‐type continental margins at about 80 Ma (Late Cretaceous) and a transition in topography from a Mesozoic highland to a Cenozoic lowland, and then to below sea‐level basins. Copyright © 2013 John Wiley & Sons, Ltd.

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There is a continuing hot debate on whether the geodynamics in the West Pacific indicate either a marginal basin or back‐arc basin, since the nature, evolution and formation mechanism are not well known. Research on the Okinawa Trough (OT), which is an active back‐arc basin, has important scientific significance for discussing the opening and development of a marginal basin or back‐arc basin. This paper synthesizes data on the crustal thickness, heat flow, hydrothermal activity and fault patterns to determine the geological nature of the OT. By comparing the thicknesses of initial oceanic crusts of global passive continental margins and marginal basins in the West Pacific, the central and southern OT are interpreted to be at the early stage of seafloor spreading, generating new oceanic crust at the spreading centre, while the northern OT is at the mature stage of continental rifting, having the character of transitional crust. The NE‐ and NNE‐trending faults are dominant in the OT. The NE‐trending strike‐slip faults control the stratigraphic succession and structural framework of the OT. The NNE‐trending strike‐slip faults triggered the back‐arc rifting or extension and evolved into transform faults with the emergence of oceanic crust. The Cenozoic tectonic jumping in the East Asia Continental Margin, including the OT, indicates that the eastward movement of the mantle flow under the Eurasian Plate should be the main dynamic source. Because the Philippine Sea Plate is obliquely and passively subducted, the evolution of the OT can be divided into three stages. The first stage is the initial rifting, triggered by the back‐arc normal faulting. The second stage is the passive spreading, triggered by the strike‐slip pull‐apart process or transtensional faulting of NNE‐trending faults. The third stage is the initial divergence of the relic and Ryukyu island arcs, triggered by new‐born oceanic crustal spreading. Copyright © 2016 John Wiley & Sons, Ltd.