Sedimentary Infillings of Fossils and Cavities in Limestone at Treak Cliff, Derbyshire

Abstract

Observations of partial and complete sedimentary infillings of fossils and rock cavities at two localities on Treak Cliff, Castleton, Derbyshire, lead to the conclusion that at these localities the present dip of the limestones is largely or entirely depositional in origin. This conclusion agrees, more or less, with claims made in previous publications but, so far as the authors are aware, this is the first time that direct evidence of high initial dips at Treak Cliff has been recorded. PARTIAL and complete sedimentary infillings of fossils and rock cavities are common in the limestones at Treak Cliff (National Grid Reference SK 135832), 1-5 km west of Castleton, Derbyshire. Such infillings have been described and figured by Shrock (1948) and the partial sedimentary infillings have been described as " geopetal" (earthseeking) by Sander (1936). In many cases at Treak Cliff sedimentary infillings occur in isolation and conclusions concerning them are difficult to reach, but at two localities associations of several sedimentary infillings occur and these occurrences will be described in detail.At the cliff exposure approximately 290 metres N, 37 degrees W of the entrance to Treak Cliff Cavern (SK 13408337), well bedded limestone dipping at approximately 35 degrees towards the north-east is exposed. This is locality 6 of Parkinson 1953, fig. 2. The stratification of the limestone is conspicuous on account of differences in the limestone lithology (crinoidal, crinoidal and shelly, and shelly limestones) and in this respect this exposure differs from many others on Treak Cliff where the discrimination between bedding and jointing is frequently difficult. Fifteen fossils partially infilled with calcareous sediment (the upper part of the cavities is occupied by sparry calcite) and two cavities in the limestone completely infilled with calcareous sediment are visible. Although the bedding and the top surfaces of the sedimentary infillings must have been horizontal initially most of them are now observed (as apparent dips) to lie at an angle not only to the horizontal but also to the plane of the bedding in the limestone. Text- fig. 1 gives the details in diagrammatic form.Because the bedding of the limestone at this locality is regular and undisturbed it follows that the observed variation in the degree of inclination of the upper surfaces of the infillings in the fossils must result from rotation of the fossils after burial, possibly during

Unravelling evidence for global climate change in Mississippian carbonate strata from the Derbyshire and North Wales Platforms, UK

“…The dip angle of beds and the geopetal textures within slope facies from the northern margin of the Derbyshire Platform indicate a palaeo-dip on the platform slope of 30°. This is consistent with previous interpretations (Broadhurst and Simpson, 1967;Simpson and Broadhurst, 1969;Broadhurst and Simpson, 1973;Gutteridge, 1991;Harwood, 2005), but is shown here to have resulted from stabilisation of the remobilised debris, as well as microbial boundstones (Harwood, 2005), by syn-depositional radiaxial fibrous calcite cementation. These cements precipitate as a result of wave and storm-facilitated seawater flux (Kirkby, 1987;Kenter 1990;Della Porta et al, 2003;Bahamonde et al, 2004;van der Kooij et al, 2010).…”

Early fill of the Western Irish Namurian Basin: a complex relationship between turbidites and deltas

“…whilst on the Dinantian highs, they commonly rest disconformably on shallow-water limestones (e.g. Broadhurst & Simpson 1967;Stevenson & Gaunt 1971).…”

Bathymetry on a Carboniferous reef

“…Along parts of the western and northern margins of the inlier the shallow water 'shelf' limestones can be seen to pass laterally into limestones whose origin has generally been considered to have been in a reef environment. The transition is marked by a rapid increase in the dip of the strata to about 30" in a direction away from the 'shelf', and the presence of geopetal infillings of cavities provides evidence that these dips are largely depositional (Broadhurst & Simpson 1967). A further distinctive feature of the reef limestones is the abundance of well-preserved fossils of great variety.…”