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Stratigraphy, palaeoenvironments and palaeoecology of the Loch Humphrey Burn lagerstätte and other Mississippian palaeobotanical localities of the Kilpatrick Hills, southwest Scotland.
PeerJ. 2016; 4:e1700.P

Abstract

Background and Aims. The largely Mississippian strata of the Kilpatrick Hills, located at the western end of the Scottish Midland Valley, enclose several macrofossil floras that together contain ca 21 organ-species of permineralised plants and ca 44 organ-species of compressed plants, here estimated to represent 25 whole-plant species (Glenarbuck = nine, Loch Humphrey Burn Lower = 11, Upper = seven). The most significant locality is the internationally important volcanigenic sequence that is reputedly intercalated within the Clyde Plateau Lava Formation at Loch Humphrey Burn, where ca 30 m of reworked tuffs and other clastic sediments enclose one of the world's most important terrestrial lagerstätten of this period. We here explore the palaeoecology and palaeoenvironments of the locality, and elucidate its controversial age. Methods. Repeated re-excavation of key exposures allowed recognition of five main depositional units, differing in thickness from 4 m to 12 m. It also permitted detailed sampling for plant macrofossils and microfossils throughout the succession. Several approaches are integrated to re-assess the taphonomy and preservation of these exceptional plant fossils. Key

Results.

The deposits are rich in taxonomically diverse miospores and in toto contain at least six well-developed compression floras, together with two beds yielding nodules that enclose well-researched anatomically preserved plants permineralised in calcite. Bulk geochemistry shows that the upper nodules formed by migration of Ca with subordinate Mn and Na. Some phylogenetically important plant fossils recovered in the early 20th century have been traced to their source horizons. Trends in relative proportions of macrofossil and microfossil taxa through the sequence are only moderately congruent, perhaps reflecting the likelihood that microfossils sample the regional rather than the local flora.

Conclusions.

The Loch Humphrey Burn sequence encompasses a wide range of depositional environments that intercalates high-energy fluvial channels (possibly developed during flash floods in a seasonally arid environment) with lower energy flood plains and a brief lacustrine interval; all yield macrofloras typically dominated by allochthonous pteridosperms. The uppermost unit represents clastic swamps dominated by (hypo)autochthonous lycopsids and ferns s.l., and is tentatively correlated with the entire-reputedly mid-Visean-exposure at nearby Glenarbuck. Other nearby localities with rooted tree-lycopsids appear to have immediately pre-dated the onset of regional volcanism. These interpretations allow revised provenancing and dating of historical collections of key plant fossils. The late Tournaisian date previously attributed on palynological evidence to the lowest unit at Loch Humphrey Burn appears increasingly improbable when our re-appraisal of the macrofloras and microfloras is placed in the context of (a) statistical comparison with other permineralised Mississippian assemblages and (b) recent stratigraphic and geochronologic studies in the region; rather, we ascribe the entire Kilpatrick Hills sequence to the mid-Visean. Stratigraphic and palaeoenvironmental interpretations of the Mississippian rocks of the Kilpatrick Hills have especially profound implications for our understanding of the physical evolution of Scotland during the Variscan orogeny and formation of Pangea.

Authors+Show Affiliations

Royal Botanic Gardens Kew , United Kingdom.Earth Sciences, Natural History Museum, London, United Kingdom; School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom.School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham , United Kingdom.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

26925325

Citation

Bateman, Richard M., et al. "Stratigraphy, Palaeoenvironments and Palaeoecology of the Loch Humphrey Burn Lagerstätte and Other Mississippian Palaeobotanical Localities of the Kilpatrick Hills, Southwest Scotland." PeerJ, vol. 4, 2016, pp. e1700.
Bateman RM, Stevens LG, Hilton J. Stratigraphy, palaeoenvironments and palaeoecology of the Loch Humphrey Burn lagerstätte and other Mississippian palaeobotanical localities of the Kilpatrick Hills, southwest Scotland. PeerJ. 2016;4:e1700.
Bateman, R. M., Stevens, L. G., & Hilton, J. (2016). Stratigraphy, palaeoenvironments and palaeoecology of the Loch Humphrey Burn lagerstätte and other Mississippian palaeobotanical localities of the Kilpatrick Hills, southwest Scotland. PeerJ, 4, e1700. https://doi.org/10.7717/peerj.1700
Bateman RM, Stevens LG, Hilton J. Stratigraphy, Palaeoenvironments and Palaeoecology of the Loch Humphrey Burn Lagerstätte and Other Mississippian Palaeobotanical Localities of the Kilpatrick Hills, Southwest Scotland. PeerJ. 2016;4:e1700. PubMed PMID: 26925325.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Stratigraphy, palaeoenvironments and palaeoecology of the Loch Humphrey Burn lagerstätte and other Mississippian palaeobotanical localities of the Kilpatrick Hills, southwest Scotland. AU - Bateman,Richard M, AU - Stevens,Liadan G, AU - Hilton,Jason, Y1 - 2016/02/18/ PY - 2015/10/28/received PY - 2016/01/27/accepted PY - 2016/3/1/entrez PY - 2016/3/1/pubmed PY - 2016/3/1/medline KW - Anatomical preservation KW - Bulk geochemistry KW - Clyde Plateau lavas KW - Compressions KW - ICP-AES KW - Palaeobotany KW - Palaeoecology KW - Palaeoenvironments KW - Palynozones KW - Permineralisations KW - Spores KW - Stratigraphy KW - Tournaisian KW - Tuffs KW - Visean SP - e1700 EP - e1700 JF - PeerJ JO - PeerJ VL - 4 N2 - Background and Aims. The largely Mississippian strata of the Kilpatrick Hills, located at the western end of the Scottish Midland Valley, enclose several macrofossil floras that together contain ca 21 organ-species of permineralised plants and ca 44 organ-species of compressed plants, here estimated to represent 25 whole-plant species (Glenarbuck = nine, Loch Humphrey Burn Lower = 11, Upper = seven). The most significant locality is the internationally important volcanigenic sequence that is reputedly intercalated within the Clyde Plateau Lava Formation at Loch Humphrey Burn, where ca 30 m of reworked tuffs and other clastic sediments enclose one of the world's most important terrestrial lagerstätten of this period. We here explore the palaeoecology and palaeoenvironments of the locality, and elucidate its controversial age. Methods. Repeated re-excavation of key exposures allowed recognition of five main depositional units, differing in thickness from 4 m to 12 m. It also permitted detailed sampling for plant macrofossils and microfossils throughout the succession. Several approaches are integrated to re-assess the taphonomy and preservation of these exceptional plant fossils. Key Results. The deposits are rich in taxonomically diverse miospores and in toto contain at least six well-developed compression floras, together with two beds yielding nodules that enclose well-researched anatomically preserved plants permineralised in calcite. Bulk geochemistry shows that the upper nodules formed by migration of Ca with subordinate Mn and Na. Some phylogenetically important plant fossils recovered in the early 20th century have been traced to their source horizons. Trends in relative proportions of macrofossil and microfossil taxa through the sequence are only moderately congruent, perhaps reflecting the likelihood that microfossils sample the regional rather than the local flora. Conclusions. The Loch Humphrey Burn sequence encompasses a wide range of depositional environments that intercalates high-energy fluvial channels (possibly developed during flash floods in a seasonally arid environment) with lower energy flood plains and a brief lacustrine interval; all yield macrofloras typically dominated by allochthonous pteridosperms. The uppermost unit represents clastic swamps dominated by (hypo)autochthonous lycopsids and ferns s.l., and is tentatively correlated with the entire-reputedly mid-Visean-exposure at nearby Glenarbuck. Other nearby localities with rooted tree-lycopsids appear to have immediately pre-dated the onset of regional volcanism. These interpretations allow revised provenancing and dating of historical collections of key plant fossils. The late Tournaisian date previously attributed on palynological evidence to the lowest unit at Loch Humphrey Burn appears increasingly improbable when our re-appraisal of the macrofloras and microfloras is placed in the context of (a) statistical comparison with other permineralised Mississippian assemblages and (b) recent stratigraphic and geochronologic studies in the region; rather, we ascribe the entire Kilpatrick Hills sequence to the mid-Visean. Stratigraphic and palaeoenvironmental interpretations of the Mississippian rocks of the Kilpatrick Hills have especially profound implications for our understanding of the physical evolution of Scotland during the Variscan orogeny and formation of Pangea. SN - 2167-8359 UR - https://www.unboundmedicine.com/medline/citation/26925325/Stratigraphy_palaeoenvironments_and_palaeoecology_of_the_Loch_Humphrey_Burn_lagerstätte_and_other_Mississippian_palaeobotanical_localities_of_the_Kilpatrick_Hills_southwest_Scotland_ L2 - https://doi.org/10.7717/peerj.1700 DB - PRIME DP - Unbound Medicine ER -
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