2003/12/01 by C. M. Rice, W. A. Ashcroft · 1 citation
Earth and Planetary Sciences · #Geological formations and processes #Geological and Geochemical Analysis #Paleontology and Stratigraphy of Fossils #Geology #Siltstone #Devonian #Structural basin #Paleontology #Bedrock #Andesite #Geomorphology #Geochemistry #Facies #Volcanic rock #Volcano
paper · doi:10.1017/s0263593300000705
openalex publication_date 2003/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
ABSTRACT A new geological map of the Early Devonian Rhynie Basin has been produced by traditional methods supplemented by trenching to bedrock and a ground magnetic survey. This shows that the basin margins are mostly fault-controlled and three trends are recognised: NE–SW, NNE–SSW and N–S. Three sets of open folds are distinguished with axial traces trending NE–SW, E–W and roughly NW–SE. The faults defining the basin margin and the folding may be related to basin formation within a regional strike-slip system of Early Devonian age. The stratigraphic succession comprises three mappable units: a lower mixed unit of sandstones, shales, conglomerates and andesitic lava (>700 m), a middle unit of laminated grey shale and siltstone (>300 m); and an upper unit of laminated sandstones and shales (>300 m). These correlate with the Tillybrachty Sandstone and Quarry Hill Sandstone Formations (lower unit), and the Dryden Flags Formation (middle and upper units). Small areas containing abundant chert float found outside the Rhynie SSSI may represent the surface expression of chert pods within the middle unit of laminated grey shale and siltstone, which also hosts the Rhynie cherts. The Windyfield cherts occur within the upper unit. No further centres of hydrothermal activity have been found in the northern half of the basin