Fourth order sequence and its distribution characteristics determined by well - seismic combination in Wuerxun depression

The high-porosity dolomite reservoirs of the Lower Ordovician Tongzi Formation (Fm.) were widely developed in the Sichuan Basin of southern China. The characteristics and developing mechanisms of the high-porosity dolomite reservoirs under the control of fourth-order sequence boundaries are discussed. In the Tongzi stage of the Early Ordovician, the Sichuan Basin was in a restricted platform facies in an evaporated shallow seawater environment. From the western to eastern regions of the basin, the Tongzi Fm. was serially developed in a tidal flat-lagoon-high-energy shoal depositional system. The evaporated seawater consequently led to dolomitization by way of the refluxing model. The Tongzi Fm. dolomites were subdivided into four coarsening-upward fourth-order sequences. Many tiny dissolution pores were formed in the dolomite beneath the four fourth-order sequence boundaries due to syn-sedimentation meteoric water erosion. Exposure above the seawater due to the short-term fall of the relative sea level consequently led to contemporaneous meteoric erosion. The Tongzi Fm. dolomites in the belt surrounding the Central Paleo-uplift were further subaerially dissolved by meteoric water due to tectonic uplift in the Guangxi Movement since the end of the Silurian period. Therefore, dolomitization, syn-sedimentation meteoric erosion under the fourth-order sequence boundaries, and meteoric karst during the Guangxi tectonic uplift jointly controlled the development of the Tongzi Formation high-porosity dolomite reservoirs. In the eastern and southeastern Sichuan Basin, the favourable reservoirs are the high-energy shoal dolomites that were eroded by meteoric water under fourth-order sequence boundaries. Around the Central Paleo-uplift, the favourable reservoirs are the dolomites dissolved by subaerial meteoric karst during the Guangxi Movement.

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Vertebrate track bed stratigraphy of the Röt and basal Lower Muschelkalk (Anisian) of Winterswijk (East Netherlands)

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/s0016774600022290 ◽

2001 ◽

Vol 80 (2) ◽

pp. 31-39 ◽

Cited By ~ 16

Author(s):

C. Diedrich

Keyword(s):

Fourth Order ◽

Nw Germany ◽

International Importance ◽

Stratigraphic Position ◽

Marine Influence ◽

Vertebrate Skeleton ◽

Order Sequence ◽

First Time ◽

Marker Beds ◽

Lower Muschelkalk

AbstractThe 35.5 m thick Anisian section of theWinterswijkse Steen- en Kalkgroeve (Eastern Netherlands) comprises the Upper Röt (Upper Röt Claystone Member) to the basal Lower Muschelkalk (Oolith Member). In the section 15 terrestrial or marine influenced parasequences are recognized. A fourth order sequence shows the increasing marine influence. New marker beds, ten vertebrate track beds, three bone beds and cephalopod remains have been documented. This enabled correlation to other sections in NW Germany. The tracks found in the Winterswijkse Steen- en Kalkgroeve at the boundary Röt/Lower Muschelkalk are linked to the oldest known vertebrate skeleton remains of the Germanic Basin. It is the first time that the exact stratigraphic position of these vertebrate remains has been established. In the terrestrial influenced section of the Winterswijkse Steen- en Kalkgroeve, the well preserved vertebrate track ways and vertebrate fauna will be of international importance and will provide new data of theTriassic carbonate tidal flat megatracksite concept and reptiles living in this environment.

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Children’s Recall of Approximations to English

Journal of Speech and Hearing Research ◽

10.1044/jshr.1602.201 ◽

1973 ◽

Vol 16 (2) ◽

pp. 201-212 ◽

Cited By ~ 3

Author(s):

Elizabeth Carrow ◽

Michael Mauldin

Keyword(s):

Language Development ◽

Fourth Order ◽

Third Order ◽

Memory Processes ◽

The Third ◽

General Index ◽

General Linguistic

As a general index of language development, the recall of first through fourth order approximations to English was examined in four, five, six, and seven year olds and adults. Data suggested that recall improved with age, and increases in approximation to English were accompanied by increases in recall for six and seven year olds and adults. Recall improved for four and five year olds through the third order but declined at the fourth. The latter finding was attributed to deficits in semantic structures and memory processes in four and five year olds. The former finding was interpreted as an index of the development of general linguistic processes.

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