The Worcester Graben. Play Fairway Development in a Failed Rift System

Leckhampton Hill Aalenian Inferior Oolite megadunes, Dead Mans Quarry Inferior Oolite tidal cross sets, Frocester Quarry Pea Grit Oncoids, Leckhampton Hill, Aalenian Inferior Oolite Belemnite littered transgressive surface, Dead Mans Quarry Skolithos burrows in the Aalenian Inferior Oolite sandy beds Leckhamptonella Leckhampton Hill, Problemmatica algae Brachiopods, Aalenian Inferior Oolite Devils Chimney, Leckhampton Hill

Field seminar learning how to correlate using sequence stratigraphy in an oolitic Jurassic carbonate sequence where biostratigraphic markers are limited.

Objectives

The aim of this field seminar is to illustrate the evolution of a classic failed rift system.

Who Should Attend

This seminar will be of interest to geoscientists wanting to gain an understanding of the principals of play fairway analysis within failed rift systems.

Geological Setting

The Worcester Graben (Severn Basin of other authors) is a narrow N-S trending rift basin that links the Wessex-Channel Basin to the south with the Anglo-Dutch Basin to the north and east. The western edge of the graben is marked by a series of major faults that downthrow to the east, while the eastern margin is defined by a series of westward downthrowing faults that mark the western edge of the London-Brabant massif.

The central sector of the graben is markedly asymmetric, with the basin-fill thickening eastward to a maximum of ~2.8Km of Permian-Jurassic sediments. There is compelling seismic and depositional facies evidence for shallowing across N-S tending intrabasinal highs that interrupt an otherwise eastward dipping ramp profile.

The Worcester Graben is a classic failed-rift. The basin-fill commences with the Permian Bridgnorth Sandstone which thickens markedly across the western bounding faults. Faint offlapping reflectors immediately above basement probably represent alluvial fan deposits shed from the rift shoulders. These marginal facies pass basinward into age-equivalent aeolian sandstones up to 150m thick. The overlying Lower Triassic Sherwood Sandstone Group is predominantly fluvial, and is up to 800m thick in the Cleeve Hill Sub-basin. Outcrops of the Permian and Lower Triassic are largely confined to a small area on the western basin margin, and will be visited only briefly during the 3-day trip because of time constraints (though they could be included in more detail on an extended 4-day trip if desired). The bulk of the time will be spent examining the Jurassic basin fill which comprise offshore Liassic facies and Middle Jurassic shallow-water carbonates.

Course Format

A field-based workshop demonstrating the essential components of hydrocarbon play fair-way development within a failed rift system. Participants are provided with a detailed field guide, which presents outcrop and subsurface datasets and a geological overview of the area.

Course Details
  • Duration: 3 days

  • Proposed dates: to be arranged

  • Cost: By quotation, includes instruction, accommodation and a comprehensive field manual.

  • Clothing: Participants should be equipped with stout walking boots and waterproofs. Safety helmets are mandatory at quarry localities

  • Insurance: Participants should ensure that their employers liability insurance cover (including medical insurance) is in order, particularly for personal accident and loss or damage of equipment, as Oolithica Geoscience Ltd cannot accept responsibility for claims arising from this or any other field seminar.

  • Attendance Limit:  minimum 7, maximum 15 participants.