Pub Date : 2024-10-01Epub Date: 2024-08-25DOI: 10.1016/j.pgeola.2024.08.002
Yingshun Tang , Ming Li , Zhengyu Song , Honghe Xu , Hui Wang , Edmund A. Jarzembowski , Bo Wang
A new archostematan beetle, Brochocoleus sonidensis sp. nov. (Insecta: Coleoptera: Archostemata) is described based on a specimen preserved in the dorsal aspect from the Lower Cretaceous Damoguaihe Formation of Inner Mongolia, China. The new species is the first body species of the genus disinterred in China and can be distinguished from the other congeners based on its largest known size, not strong forward convergence of the lateral edges of the prothorax, and the unique combination of the aspect ratios of the pronotum and head.
{"title":"A new Early Cretaceous ommatine beetle (Insecta: Coleoptera: Archostemata) from Inner Mongolia, China","authors":"Yingshun Tang , Ming Li , Zhengyu Song , Honghe Xu , Hui Wang , Edmund A. Jarzembowski , Bo Wang","doi":"10.1016/j.pgeola.2024.08.002","DOIUrl":"10.1016/j.pgeola.2024.08.002","url":null,"abstract":"<div><div>A new archostematan beetle, <em>Brochocoleus sonidensis</em> sp. nov. (Insecta: Coleoptera: Archostemata) is described based on a specimen preserved in the dorsal aspect from the Lower Cretaceous Damoguaihe Formation of Inner Mongolia, China. The new species is the first body species of the genus disinterred in China and can be distinguished from the other congeners based on its largest known size, not strong forward convergence of the lateral edges of the prothorax, and the unique combination of the aspect ratios of the pronotum and head.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 528-532"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-09-27DOI: 10.1016/j.pgeola.2024.08.005
James B. Innes , Mairead M. Rutherford , David R. Bridgland , Ben R. Gearey , Malcolm C. Lillie , Wishart A. Mitchell , Charlotte E. O'Brien , Richard T. Jones , Gareth J. Thompson
Investigations at Pepper Arden Bottoms, a lake basin site on the interfluve between the rivers Tees and Swale in northeast England, have recovered lithostratigraphical, pollen and plant macrofossil sequences which have allowed the reconstruction of sedimentary and vegetation history from the Lateglacial Interstadial to the post-Ulmus Decline mid-Holocene. Although the calcareous nature of the sediment and lack of terrestrial plant macrofossils precluded radiocarbon dating of sediments pre-dating the Ulmus Decline, pollen analyses showed sediment accumulation from the middle of the Lateglacial Interstadial, with the lake catchment remaining poorly vegetated until the Holocene, with low values for woody taxa, and grasses and sedges dominant. The late Interstadial cold phase GI-1b is present in the pollen stratigraphy, with a major reduction in Betula frequencies, replaced by Juniperus, and an increase in cold-tolerant herbs, mainly grasses and sedges. Microcharcoal frequencies are consistently substantial throughout the Lateglacial levels, probably indicating a natural fire regime, but are absent from the Holocene, suggesting little Mesolithic or Neolithic activity nearby, which is confirmed by a lack of pollen indicators of disturbance. The Lateglacial (Loch Lomond) Stadial is entirely dominated by Cyperaceae and Poaceae pollen, with very few trees and shrubs. The successive migration of postglacial thermophilous trees is recorded in the Holocene and possible effects of the Preboreal Oscillation and the 8.2 ka BP cold events are recognised. An Ulmus Decline occurs near the top of the profile, after which the assemblage is dominated by Alnus as the lake became terrestrialised and was occupied by fen and then alder carr. The very open Lateglacial vegetation adds this site to a northern group in northeast England with poor Lateglacial woodland development, in contrast to sites to the south, in North Yorkshire, where Lateglacial Betula woodland was much better established.
在英格兰东北部蒂斯河和斯威尔河交汇处的一个湖盆遗址 Pepper Arden Bottoms 进行的调查发现了岩石地层、花粉和植物大化石序列，从而可以重建从大冰期间冰期到全新世中期乌尔姆斯衰退后的沉积和植被历史。虽然沉积物的钙质性质和陆生植物大化石的缺乏排除了对榆树衰退之前沉积物进行放射性碳测年的可能性，但花粉分析显示沉积物从腊肠冰期间冰期中期开始积累，湖泊流域直到全新世之前一直植被稀少，木本类群含量较低，禾本科植物和莎草占主导地位。花粉地层中出现了间冰期晚期的寒冷阶段 GI-1b，桦树的频率大幅下降，被杜松取代，耐寒草本植物（主要是禾本科和莎草）的频率上升。在整个拉特格拉冰期地层中，微炭的频率一直很高，这可能表明这里有自然的火灾机制，但全新世则没有微炭，这表明附近几乎没有中石器时代或新石器时代的活动，这一点也从缺乏扰动迹象的花粉中得到了证实。拉特格拉冰期（洛蒙湖）的花粉完全以桧柏科和禾本科花粉为主，很少有乔木和灌木。全新世记录了冰期后嗜热树木的陆续迁移，并确认了前生物涛动和 8.2 ka BP 寒冷事件可能造成的影响。在剖面顶部附近出现了榆树衰退现象，之后随着湖泊陆地化，湖泊被沼泽和桤木林所占据，桤木树群开始占据主导地位。非常开阔的腊特拉冰期植被使该地点跻身英格兰东北部腊特拉冰期林地发展较差的北部地区，与之形成鲜明对比的是，在北约克郡南部的地点，腊特拉冰期的桦树林地发展得要好得多。
{"title":"Lateglacial Interstadial to mid-Holocene stratigraphy and palynology at Pepper Arden Bottoms, North Yorkshire, UK","authors":"James B. Innes , Mairead M. Rutherford , David R. Bridgland , Ben R. Gearey , Malcolm C. Lillie , Wishart A. Mitchell , Charlotte E. O'Brien , Richard T. Jones , Gareth J. Thompson","doi":"10.1016/j.pgeola.2024.08.005","DOIUrl":"10.1016/j.pgeola.2024.08.005","url":null,"abstract":"<div><div>Investigations at Pepper Arden Bottoms, a lake basin site on the interfluve between the rivers Tees and Swale in northeast England, have recovered lithostratigraphical, pollen and plant macrofossil sequences which have allowed the reconstruction of sedimentary and vegetation history from the Lateglacial Interstadial to the post-<em>Ulmus</em> Decline mid-Holocene. Although the calcareous nature of the sediment and lack of terrestrial plant macrofossils precluded radiocarbon dating of sediments pre-dating the <em>Ulmus</em> Decline, pollen analyses showed sediment accumulation from the middle of the Lateglacial Interstadial, with the lake catchment remaining poorly vegetated until the Holocene, with low values for woody taxa, and grasses and sedges dominant. The late Interstadial cold phase GI-1b is present in the pollen stratigraphy, with a major reduction in <em>Betula</em> frequencies, replaced by <em>Juniperus</em>, and an increase in cold-tolerant herbs, mainly grasses and sedges. Microcharcoal frequencies are consistently substantial throughout the Lateglacial levels, probably indicating a natural fire regime, but are absent from the Holocene, suggesting little Mesolithic or Neolithic activity nearby, which is confirmed by a lack of pollen indicators of disturbance. The Lateglacial (Loch Lomond) Stadial is entirely dominated by Cyperaceae and Poaceae pollen, with very few trees and shrubs. The successive migration of postglacial thermophilous trees is recorded in the Holocene and possible effects of the Preboreal Oscillation and the 8.2 ka BP cold events are recognised. An <em>Ulmus</em> Decline occurs near the top of the profile, after which the assemblage is dominated by <em>Alnus</em> as the lake became terrestrialised and was occupied by fen and then alder carr. The very open Lateglacial vegetation adds this site to a northern group in northeast England with poor Lateglacial woodland development, in contrast to sites to the south, in North Yorkshire, where Lateglacial <em>Betula</em> woodland was much better established.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 569-588"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-09-24DOI: 10.1016/j.pgeola.2024.09.001
Nigel Banks
Data from over 80 boreholes have been used together with the surface geology to interpret the subsurface structure and stratigraphy of the Corallian to Gault (Upper Jurassic to Lower Cretaceous) sediments in the Vale of the White Horse, between Faringdon and Wantage in West Oxfordshire. The gentle regional dip to the SSE of the sediments in this area is interrupted by two major features. The first is the Faringdon Fault, first defined at outcrop just east of Faringdon. This has been traced SE from the outcrop extent for at least 8 km in the subsurface towards Wantage. It has an estimated maximum downthrow to the SW of ca 40 m. Contrary to previous interpretations, this fault was probably active during Kimmeridge Clay deposition.
The second feature is the Faringdon Trough, an erosional palaeovalley filled with at least 50 m of marine Lower Greensand sediments. The Trough trends SSE from Faringdon and cuts deeply through the Kimmeridge Clay to reach the underlying Corallian. A subtle structural feature, here named the Baulking Fault, has a throw of < 10 m and its movement was probably pre-Cretaceous, but it seems to have influenced the path and geometry of the Faringdon Trough, dividing it into two segments. Contrary to previous interpretations, subsurface mapping suggests that the main Trough has a broad U-shape in cross-section with a planar base where it rests on resistive Corallian limestone. Along its margins depositional dips of up to 9° have been widely recorded in the Lower Greensand sediments.
{"title":"The structural setting and geometry of the Faringdon Trough defined by subsurface mapping","authors":"Nigel Banks","doi":"10.1016/j.pgeola.2024.09.001","DOIUrl":"10.1016/j.pgeola.2024.09.001","url":null,"abstract":"<div><div>Data from over 80 boreholes have been used together with the surface geology to interpret the subsurface structure and stratigraphy of the Corallian to Gault (Upper Jurassic to Lower Cretaceous) sediments in the Vale of the White Horse, between Faringdon and Wantage in West Oxfordshire. The gentle regional dip to the SSE of the sediments in this area is interrupted by two major features. The first is the Faringdon Fault, first defined at outcrop just east of Faringdon. This has been traced SE from the outcrop extent for at least 8 km in the subsurface towards Wantage. It has an estimated maximum downthrow to the SW of <em>ca</em> 40 m. Contrary to previous interpretations, this fault was probably active during Kimmeridge Clay deposition.</div><div>The second feature is the Faringdon Trough, an erosional palaeovalley filled with at least 50 m of marine Lower Greensand sediments. The Trough trends SSE from Faringdon and cuts deeply through the Kimmeridge Clay to reach the underlying Corallian. A subtle structural feature, here named the Baulking Fault, has a throw of <<!--> <!-->10 m and its movement was probably pre-Cretaceous, but it seems to have influenced the path and geometry of the Faringdon Trough, dividing it into two segments. Contrary to previous interpretations, subsurface mapping suggests that the main Trough has a broad U-shape in cross-section with a planar base where it rests on resistive Corallian limestone. Along its margins depositional dips of up to 9° have been widely recorded in the Lower Greensand sediments.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 596-612"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-03-21DOI: 10.1016/j.pgeola.2024.03.003
The stratigraphical features and palaeoenvironmental conditions of the upper Cenomanian–lower Coniacian carbonates from the northern part of the Aures Range are described for the first time. Four formations have been recognised, namely the Arris, Adahri, Yabous, and Bou Ouali, respectively. Planktonic foraminifera enable us to assign the upper part of the Arris Formation and the lower part of the Adahri Formation to the Middle–Upper Cenomanian (Rotalipora sp. cf. R. cushmani Total Range Zone), the upper part of the Adahri Formation to the Cenomanian–Turonian Transition to the lower Turonian (Whiteinella archaeocretacea Partial Range Zone and Helvetoglobotruncana helvetica Total-Range Zone, respectively), the lower member of the Yabous Formation to the middle Turonian (Marginotruncana sigali Partial Range Zone), and the upper member of the Yabous Formation to the upper Turonian (Marginotruncana schneegansi Partial Range Zone). The Turonian–Coniancian boundary was dated approximately. This biozonation enables a correlation with several upper Cenomanian–lower Coniacian sections outside Algeria, mainly within the Tethyan and Boreal domains. Based on the field data, and microfacies studies, the strata of these formations are arranged into eleven microfacies types (MT 1 to MT 11) that are described in terms of depositional environments, and grouped into three main facies associations (FA 1, FA 2, and FA 3): (i) a deep shelf-basin facies zone; (ii) marginal sand shoals, an open-marine/restricted platform facies zone; and (iii) an outer platform and toe-of-slope/distal slope facies zone. Analysis of the sequence stratigraphy has allowed the recognition of three third-order depositional sequences grouped into two megasequences and correlated to a regional scale.
该报告首次描述了奥雷斯山脉北部上元古-下元古碳酸盐岩的地层特征和古环境条件。共确认了四个地层，分别为 Arris、Adahri、Yabous 和 Bou Ouali。浮游有孔虫使我们能够将 Arris 地层的上部和 Adahri 地层的下部归入中-上震旦纪（Rotalipora sp.cushmani Total Range Zone），将 Adahri Formation 的上部归入仙人漫纪-都龙纪过渡到下都龙纪（Whiteinella archaeocretacea Partial Range Zone 和 Helvetoglobotruncana helvetica Total-Range Zone、分别），雅布斯地层下统至都龙纪中统（Marginotruncana sigali 部分范围区），雅布斯地层上统至都龙纪上统（Marginotruncana schneegansi 部分范围区）。都元古代-康熙元年界线的年代大致确定。这种生物区系可与阿尔及利亚境外的几个上震旦纪-下震旦纪地段相关联，主要是在泰西和北方地区。根据野外数据和微成因研究，这些地层被划分为 11 个微成因类型（MT 1 至 MT 11），这些微成因类型根据沉积环境进行了描述，并分为三个主要成因组合（FA 1、FA 2 和 FA 3）：(i) 深陆架-盆地面带；(ii) 边缘沙滩、开放-海洋/限制平台面带；(iii) 外部平台和坡脚/斜坡面带。通过对地层序列的分析，可以确认三个三阶沉积序列，分为两个巨序列，并与区域尺度相关联。
{"title":"Stratigraphy and sedimentology of the upper Cenomanian–lower Coniacian in the Northern Aures Range (Algeria)","authors":"","doi":"10.1016/j.pgeola.2024.03.003","DOIUrl":"10.1016/j.pgeola.2024.03.003","url":null,"abstract":"<div><div><span><span>The stratigraphical features and palaeoenvironmental conditions of the upper Cenomanian–lower Coniacian carbonates from the northern part of the Aures Range are described for the first time. Four formations have been recognised, namely the Arris, Adahri, Yabous, and Bou Ouali, respectively. Planktonic foraminifera enable us to assign the upper part of the Arris Formation and the lower part of the Adahri Formation to the Middle–Upper </span>Cenomanian (</span><em>Rotalipora</em> sp. cf. <em>R. cushmani</em><span> Total Range Zone), the upper part of the Adahri Formation to the Cenomanian–Turonian Transition to the lower Turonian (</span><em>Whiteinella archaeocretacea</em> Partial Range Zone and <em>Helvetoglobotruncana helvetica</em> Total-Range Zone, respectively), the lower member of the Yabous Formation to the middle Turonian (<em>Marginotruncana sigali</em> Partial Range Zone), and the upper member of the Yabous Formation to the upper Turonian (<em>Marginotruncana schneegansi</em><span><span><span> Partial Range Zone). The Turonian–Coniancian boundary was dated approximately. This biozonation<span> enables a correlation with several upper Cenomanian–lower Coniacian sections outside Algeria, mainly within the Tethyan and Boreal domains. Based on the field data, and microfacies studies, the strata of these formations are arranged into eleven microfacies types (MT 1 to MT 11) that are described in terms of </span></span>depositional environments, and grouped into three main facies associations (FA 1, FA 2, and FA 3): (i) a deep shelf-basin facies zone; (ii) marginal sand shoals, an open-marine/restricted platform facies zone; and (iii) an outer platform and toe-of-slope/distal slope facies zone. Analysis of the </span>sequence stratigraphy<span> has allowed the recognition of three third-order depositional sequences grouped into two megasequences and correlated to a regional scale.</span></span></div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 613-630"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140282963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lacustrine depositional systems provide a valuable record of palaeoenvironmental conditions since they rely on a delicate balance between accommodation space and water-sediment supply controlled by tectonic activity and climatic conditions. This study presents new sedimentological and micropalaeontological information from the early Miocene lacustrine Oued Tilatou Formation, northeastern Algeria. Based on sedimentary facies and microfossil assemblages, the Oued Tilatou Formation (OTF) is divided into two discrete units, the Lower OTF and the Upper OTF. The Lower OTF is characterised by reddish clay-rich carbonate mudstone containing reworked foraminifera and ostracods interspersed by polymodal clast-supported conglomerates attributed to alluvial deposition. The Lower OTF was deposited under fluvial–palustrine conditions, marked by a notable terrigenous sediment influx. In contrast, the Upper OTF encompasses greenish charophyte-dominated (Sphaerochara sp.) carbonate mudstone interbedded with silty carbonate mudstone, and dolomitic wackestone containing charophyte thalli, several ostracod species, and stromatolites. The dominant ostracod taxa within this interval are Mediocypris sp. cf. M. candonaeformis, indicating freshwater–brackish water conditions. The transition in depositional facies from the Lower OTF to the Upper OTF is interpreted as reflecting changes in the environment from fluvial–palustrine to shallow water lacustrine with fluctuation in freshwater input during the Burdigalian (Early Miocene). This study provides new insights on the interplay between early Miocene climate conditions and the tectonic uplift of the Aurès Massif, and their implications for lacustrine palaeoenvironmental conditions.
{"title":"Early Miocene lacustrine deposits from the Oued Tilatou Formation (Aurès Massif, Eastern Algeria): Sedimentology, micropalaeontology, and palaeoenvironmental implications","authors":"Somia Khanfer , Fouad Djaiz , Josep Sanjuan , Lucas Silveira Antonietto , Bachir Lamouri , Amine Cherif , Hicham El Asmi , Cameron Manche","doi":"10.1016/j.pgeola.2024.08.003","DOIUrl":"10.1016/j.pgeola.2024.08.003","url":null,"abstract":"<div><div>Lacustrine depositional systems provide a valuable record of palaeoenvironmental conditions since they rely on a delicate balance between accommodation space and water-sediment supply controlled by tectonic activity and climatic conditions. This study presents new sedimentological and micropalaeontological information from the early Miocene lacustrine Oued Tilatou Formation, northeastern Algeria. Based on sedimentary facies and microfossil assemblages, the Oued Tilatou Formation (OTF) is divided into two discrete units, the Lower OTF and the Upper OTF. The Lower OTF is characterised by reddish clay-rich carbonate mudstone containing reworked foraminifera and ostracods interspersed by polymodal clast-supported conglomerates attributed to alluvial deposition. The Lower OTF was deposited under fluvial–palustrine conditions, marked by a notable terrigenous sediment influx. In contrast, the Upper OTF encompasses greenish charophyte-dominated (<em>Sphaerochara</em> sp.) carbonate mudstone interbedded with silty carbonate mudstone, and dolomitic wackestone containing charophyte thalli, several ostracod species, and stromatolites. The dominant ostracod taxa within this interval are <em>Mediocypris</em> sp. cf. <em>M. candonaeformis</em>, indicating freshwater–brackish water conditions. The transition in depositional facies from the Lower OTF to the Upper OTF is interpreted as reflecting changes in the environment from fluvial–palustrine to shallow water lacustrine with fluctuation in freshwater input during the Burdigalian (Early Miocene). This study provides new insights on the interplay between early Miocene climate conditions and the tectonic uplift of the Aurès Massif, and their implications for lacustrine palaeoenvironmental conditions.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 533-544"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-09-13DOI: 10.1016/j.pgeola.2024.08.001
Jonathan D. Radley , Robert A. Coram
Stromatolites in the essentially non-marine Purbeck Formation (Tithonian, Upper Jurassic) west of Aylesbury (Buckinghamshire, UK) cap an erosion surface truncating lacustrine–palustrine carbonates, previously documented from an exposure close to the site of the former Bugle Pit, Hartwell. The stromatolite occurrences in this area follow a regional northwest–southeast structural grain, evidenced by local normal faults, some demonstrably active during Late Jurassic–Early Cretaceous time. Observations from associated lithofacies and biota suggest a littoral lacustrine setting for the stromatolite ‘belt’. We hypothesise that the present-day stromatolite distribution reflects a fault-controlled palaeo-shoreline, and that growth of the stromatolites was linked to lacustrine transgression driven by syn-sedimentary movement on these faults. Littoral sand associated with the stromatolites was possibly reworked from older marine sediments undergoing erosion on a nearby fault footwall, or distally, on the western margin of the Anglo-Brabant Massif.
{"title":"A Tithonian (Upper Jurassic) lake shoreline in Buckinghamshire, UK: Evidence from stromatolite distribution in the Purbeck Formation","authors":"Jonathan D. Radley , Robert A. Coram","doi":"10.1016/j.pgeola.2024.08.001","DOIUrl":"10.1016/j.pgeola.2024.08.001","url":null,"abstract":"<div><div>Stromatolites in the essentially non-marine Purbeck Formation (Tithonian, Upper Jurassic) west of Aylesbury (Buckinghamshire, UK) cap an erosion surface truncating lacustrine–palustrine carbonates, previously documented from an exposure close to the site of the former Bugle Pit, Hartwell. The stromatolite occurrences in this area follow a regional northwest–southeast structural grain, evidenced by local normal faults, some demonstrably active during Late Jurassic–Early Cretaceous time. Observations from associated lithofacies and biota suggest a littoral lacustrine setting for the stromatolite ‘belt’. We hypothesise that the present-day stromatolite distribution reflects a fault-controlled palaeo-shoreline, and that growth of the stromatolites was linked to lacustrine transgression driven by syn-sedimentary movement on these faults. Littoral sand associated with the stromatolites was possibly reworked from older marine sediments undergoing erosion on a nearby fault footwall, or distally, on the western margin of the Anglo-Brabant Massif.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 518-527"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-08-02DOI: 10.1016/j.pgeola.2024.07.002
Lila Blake , Max Fursman , Christopher J. Duffin , Trevor Batchelor , Claudia Hildebrandt , Michael J. Benton
The Lower Greensand of southern England (early Aptian–early Albian; c., 120–110 Ma) has yielded diverse faunas of vertebrates, but these have not been reported in detail. Here, we present rich faunas, mainly comprising sharks, bony fishes, and crocodyliforms, from two localities to the north and south of the London–Brabant Massif. The first, Clophill Quarry, near Leighton Buzzard in Bedfordshire, has yielded fossils from the Brown Sands Formation, representing an inshore, tidally influenced environment, such as an estuary mouth. The second, Patteson Court Quarry, Nutfield, Surrey, has produced fossils from the Sandgate Formation (Redhill Sands Member). The faunas of both locations are similar, and they share a remarkable assemblage of at least 23 chondrichthyan taxa, one Edaphodon-like chimaeroid, ten hybodontiform sharks, and 12 neoselachian sharks. The hybodontiform sharks comprise two morphological groups, those with high-cusped piercing teeth, sometimes with lateral cusplets and a coronal ornament of vertical ridges, and those with low-crowned crushing teeth. The 12 species of neoselachian sharks include one representative of the extinct Synechodontiformes, as well as examples of the modern orders Hexanchiformes, Lamniformes, Carchariniformes, Squatiniformes, Heterodontiformes, and Orectolobiformes. Bony fishes are represented mostly by crushing teeth of Pycnodontiformes, Aspidorhynchiformes, Amiiformes, Lepisosteiformes, and Semionotiformes. Crocodyliforms are identified from seven morphotypes of elongate, goniopholid-like teeth. Based on these fossil teeth, the fauna is 53 % chondrichthyan and 21 % osteichthyan; neoselachians represent 32–45 % of the chondrichthyans, lower than figures from the underlying Wealden.
{"title":"Microvertebrates from the Lower Greensand Group (Lower Cretaceous) of Clophill, Bedfordshire, UK, and Nutfield, Surrey, UK","authors":"Lila Blake , Max Fursman , Christopher J. Duffin , Trevor Batchelor , Claudia Hildebrandt , Michael J. Benton","doi":"10.1016/j.pgeola.2024.07.002","DOIUrl":"10.1016/j.pgeola.2024.07.002","url":null,"abstract":"<div><div>The Lower Greensand of southern England (early Aptian–early Albian; <em>c.</em>, 120–110 Ma) has yielded diverse faunas of vertebrates, but these have not been reported in detail. Here, we present rich faunas, mainly comprising sharks, bony fishes, and crocodyliforms, from two localities to the north and south of the London–Brabant Massif. The first, Clophill Quarry, near Leighton Buzzard in Bedfordshire, has yielded fossils from the Brown Sands Formation, representing an inshore, tidally influenced environment, such as an estuary mouth. The second, Patteson Court Quarry, Nutfield, Surrey, has produced fossils from the Sandgate Formation (Redhill Sands Member). The faunas of both locations are similar, and they share a remarkable assemblage of at least 23 chondrichthyan taxa, one <em>Edaphodon</em>-like chimaeroid, ten hybodontiform sharks, and 12 neoselachian sharks. The hybodontiform sharks comprise two morphological groups, those with high-cusped piercing teeth, sometimes with lateral cusplets and a coronal ornament of vertical ridges, and those with low-crowned crushing teeth. The 12 species of neoselachian sharks include one representative of the extinct Synechodontiformes, as well as examples of the modern orders Hexanchiformes, Lamniformes, Carchariniformes, Squatiniformes, Heterodontiformes, and Orectolobiformes. Bony fishes are represented mostly by crushing teeth of Pycnodontiformes, Aspidorhynchiformes, Amiiformes, Lepisosteiformes, and Semionotiformes. Crocodyliforms are identified from seven morphotypes of elongate, goniopholid-like teeth. Based on these fossil teeth, the fauna is 53 % chondrichthyan and 21 % osteichthyan; neoselachians represent 32–45 % of the chondrichthyans, lower than figures from the underlying Wealden.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 493-517"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01Epub Date: 2024-09-13DOI: 10.1016/j.pgeola.2024.08.007
J. Benoit, S. Jirah, E.S. Lund, T. Lafferty, V. Buffa, L.A. Norton
Nythosaurus larvatus was one of the first cynodonts named and, for a long time, the only therapsid for which the endocranial cast was described. The holotype and only skull of this species is thus a landmark in the history of therapsid palaeontology. It is believed to have come from Commissie Drift 303 (Free State Province, South Africa), a locality that has been traditionally dated to the Lystrosaurus declivis Assemblage Zone. However, this age was mostly based on the synonymy between Nythosaurus larvatus and Thrinaxodon liorhinus, the former being the only fossil indisputably reported from this locality and the latter being an index taxon for the Lystrosaurus declivis Assemblage Zone. A recent revision of Nythosaurus larvatus also questioned the age of Commissie Drift. Here, we report the result of our fieldwork to re-assess the age of this locality. We find that the stratigraphy conforms to the lower Burgersdorp Formation and that the fossil tetrapod fauna does not match the Lystrosaurus declivis Assemblage Zone. The overall scarcity of fossil bones, absence of plants and dicynodonts, and relative dominance of amphibian remains all point to an assignation to the Langbergia–Garjainia Subzone of the Cynognathus Assemblage Zone, which is consistent with the stratigraphy. The discovery of new material attributable to cf. Nythosaurus bolsters the notion that this taxon is from the late Olenekian. Nythosaurus larvatus can safely be considered a valid taxon, and may in fact occur elsewhere in this subzone.
{"title":"Re-assessing the age of the type locality of Nythosaurus larvatus (Therapsida, Cynodontia) and implications on the evolutionary dynamics of cynodonts","authors":"J. Benoit, S. Jirah, E.S. Lund, T. Lafferty, V. Buffa, L.A. Norton","doi":"10.1016/j.pgeola.2024.08.007","DOIUrl":"10.1016/j.pgeola.2024.08.007","url":null,"abstract":"<div><div><em>Nythosaurus larvatus</em> was one of the first cynodonts named and, for a long time, the only therapsid for which the endocranial cast was described. The holotype and only skull of this species is thus a landmark in the history of therapsid palaeontology. It is believed to have come from Commissie Drift 303 (Free State Province, South Africa), a locality that has been traditionally dated to the <em>Lystrosaurus declivis</em> Assemblage Zone. However, this age was mostly based on the synonymy between <em>Nythosaurus larvatus</em> and <em>Thrinaxodon liorhinus</em>, the former being the only fossil indisputably reported from this locality and the latter being an index taxon for the <em>Lystrosaurus declivis</em> Assemblage Zone. A recent revision of <em>Nythosaurus larvatus</em> also questioned the age of Commissie Drift. Here, we report the result of our fieldwork to re-assess the age of this locality. We find that the stratigraphy conforms to the lower Burgersdorp Formation and that the fossil tetrapod fauna does not match the <em>Lystrosaurus declivis</em> Assemblage Zone. The overall scarcity of fossil bones, absence of plants and dicynodonts, and relative dominance of amphibian remains all point to an assignation to the <em>Langbergia</em>–<em>Garjainia</em> Subzone of the <em>Cynognathus</em> Assemblage Zone, which is consistent with the stratigraphy. The discovery of new material attributable to cf. <em>Nythosaurus</em> bolsters the notion that this taxon is from the late Olenekian. <em>Nythosaurus larvatus</em> can safely be considered a valid taxon, and may in fact occur elsewhere in this subzone.</div></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 5","pages":"Pages 589-595"},"PeriodicalIF":1.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142540287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-06-09DOI: 10.1016/j.pgeola.2024.05.004
The Cenomanian deposits of the Eastern Saharan Atlas are characterised by gypsum-dominated series interpreted as coastal sabkha deposits, indicating low-latitude, and tropical to subtropical settings. The evaporitic conditions are interrupted by rapid marine ingressions allowed the deposition of carbonate beds. In the Djebel Ousigna section, fine sandy limestone bed shows abundant burrows of Macaronichnus. These traces indicate the upper shoreface–foreshore contact, affected by storm events, which show similarities with recent huge tsunami waves that facilitated the proliferation of Travisia polychaete populations (Macaronichnus tracemaker). This Macaronichnus-suite represents the most proximal marine setting during a regressive phase. Also, this unique occurrence of Macaronichnus in the North African Cenomanian low-latitude, subtropical to tropical evaporites is interpreted as related to upwelling of cold nutrient rich-waters. The latter seemingly challenge the view that this trace fossil is restricted to colder climatic zones. From an ethological viewpoint, studied Macaronichnus specimens are considered to be a sequorichnial trace (exploratory behaviour) produced by polychaete annelids.
{"title":"Significance of the trace fossil Macaronichnus from the Cenomanian low-latitude nearshore deposits of the Saharan Atlas, Algeria","authors":"","doi":"10.1016/j.pgeola.2024.05.004","DOIUrl":"10.1016/j.pgeola.2024.05.004","url":null,"abstract":"<div><p><span>The Cenomanian<span> deposits of the Eastern Saharan Atlas are characterised by gypsum-dominated series interpreted as coastal sabkha deposits, indicating low-latitude, and tropical to subtropical settings. The evaporitic conditions are interrupted by rapid marine ingressions allowed the deposition of carbonate beds. In the Djebel Ousigna section, fine sandy limestone bed shows abundant burrows of </span></span><em>Macaronichnus</em><span>. These traces indicate the upper shoreface–foreshore contact, affected by storm events, which show similarities with recent huge tsunami waves that facilitated the proliferation of </span><em>Travisia</em> polychaete populations (<em>Macaronichnus</em> tracemaker). This <em>Macaronichnus</em>-suite represents the most proximal marine setting during a regressive phase. Also, this unique occurrence of <em>Macaronichnus</em><span> in the North African Cenomanian low-latitude, subtropical to tropical evaporites<span><span> is interpreted as related to upwelling of cold nutrient rich-waters. The latter seemingly challenge the view that this trace fossil is restricted to colder </span>climatic zones. From an ethological viewpoint, studied </span></span><em>Macaronichnus</em> specimens are considered to be a sequorichnial trace (exploratory behaviour) produced by polychaete annelids.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 369-376"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141399840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-01Epub Date: 2024-05-31DOI: 10.1016/j.pgeola.2024.05.003
Colin K. Ballantyne
Amongst the most neglected landforms in formerly glaciated mountain environments are the scars of major rock-slope failures where the displaced rock or runout debris has been removed by glacial erosion. The characteristics of 33 such debris-free failure scars (DFFSs) on Torridonian sandstone terrain were analysed. These range from 0.011 to 0.183 km2 in ground area, and scar volume implies removal of ~ 0.4–9.9 Mt of rock. Failure planes are planar or stepped at gradients of 37–50°, implying failure as ‘rough’ translational slides; most probably represent former rock avalanches or fragmented rockslides where shear through bedding planes resulted in runout fragmentation. Extension of 85 % to the slope crest is consistent with coseismic triggering during periods of glacio-isostatic crustal uplift. At least ten DFFSs demonstrably pre-date expansion of the last ice sheet at ~ 35 ka, and at least five probably represent failure that occurred in the Lateglacial interval of ~ 16–11.7 ka. Fourteen are located within cirques, confirming the importance of RSFs in cirque extension during ice-free interglacials or interstades; others have contributed to trough widening and the formation of arêtes. Older upper-slope cavities in Torridonian mountains are probably also the results of (possibly recurrent) rock-slope failures. It is concluded that the large-scale morphology of the Torridonian sandstone mountains reflects a long-term synergic relationship between alternating episodes of glacial erosion and rock-slope failure: reduction of rock-slope stability during each glacial-deglacial cycle has predisposed slopes to eventual failure, with subsequent glacial removal of displaced blocks and runout debris.
{"title":"Rock-slope failure scars on sandstone mountains in NW Scotland","authors":"Colin K. Ballantyne","doi":"10.1016/j.pgeola.2024.05.003","DOIUrl":"10.1016/j.pgeola.2024.05.003","url":null,"abstract":"<div><p>Amongst the most neglected landforms in formerly glaciated mountain environments are the scars of major rock-slope failures where the displaced rock or runout debris has been removed by glacial erosion. The characteristics of 33 such debris-free failure scars (DFFSs) on Torridonian sandstone terrain were analysed. These range from 0.011 to 0.183 km<sup>2</sup> in ground area, and scar volume implies removal of ~<!--> <!-->0.4–9.9 Mt of rock. Failure planes are planar or stepped at gradients of 37–50°, implying failure as ‘rough’ translational slides; most probably represent former rock avalanches or fragmented rockslides where shear through bedding planes resulted in runout fragmentation. Extension of 85 % to the slope crest is consistent with coseismic triggering during periods of glacio-isostatic crustal uplift. At least ten DFFSs demonstrably pre-date expansion of the last ice sheet at ~<!--> <!-->35 ka, and at least five probably represent failure that occurred in the Lateglacial interval of ~<!--> <!-->16–11.7 ka. Fourteen are located within cirques, confirming the importance of RSFs in cirque extension during ice-free interglacials or interstades; others have contributed to trough widening and the formation of arêtes. Older upper-slope cavities in Torridonian mountains are probably also the results of (possibly recurrent) rock-slope failures. It is concluded that the large-scale morphology of the Torridonian sandstone mountains reflects a long-term synergic relationship between alternating episodes of glacial erosion and rock-slope failure: reduction of rock-slope stability during each glacial-deglacial cycle has predisposed slopes to eventual failure, with subsequent glacial removal of displaced blocks and runout debris.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 355-368"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016787824000208/pdfft?md5=d791d011d347d7dc24948d6acecc9a46&pid=1-s2.0-S0016787824000208-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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