Dominika Niezabitowska, Thomas Stevens, Balázs Bradák, Martin Chadima, Yunus Baykal, Daniele Sechi, Ramona Schneider
{"title":"英格兰南部黄土中记录的矿物磁性和古环境","authors":"Dominika Niezabitowska, Thomas Stevens, Balázs Bradák, Martin Chadima, Yunus Baykal, Daniele Sechi, Ramona Schneider","doi":"10.1002/jqs.3620","DOIUrl":null,"url":null,"abstract":"<p>Extensive research has focused on the loess deposits in southern England, aiming to unravel their stratigraphic and palaeoenvironmental significance. However, no systematic mineral magnetic study on these deposits has yet been undertaken. Here we address this by investigating the magnetic mineral composition and alignment of loess at two sites in southern England, Lowland Point (LP) on the Lizard Peninsula of Cornwall, and Pegwell Bay (PB) in eastern Kent on the Isle of Thanet. A set of rock magnetic analyses was conducted to understand mineral magnetism within the studied sections. In addition, the primary depositional origin of the magnetic fabrics as well as their overprinting caused by various possible post-depositional processes were examined through anisotropy of magnetic susceptibility (AMS). The magnetic mineral composition is similar at both sites, derived from both sedimentary (aeolian) and post-depositional processes. The AMS results show magnetic foliation that varies between the two sites, aligning with the bedding plane, indicating deposition from gravitational dust fall at the PB site, and a stronger wind transport energy at the LP site. Although the magnetic lineation of bulk AMS is relatively weak, there is a noticeable tendency towards alignment in most samples, with flow directions from the SE indicated at both sections if a strong wind is assumed at LP, although with a possible SW direction if a weaker wind is assumed. These observations may imply the preservation of palaeowind directions during dust transport, with a substantial southerly component, which contradicts previous assertions of dominant northerly or northeasterly winds. Indeed, a possible dominant southeasterly wind direction between 25 and 18 ka would suggest a limited influence of katabatic, westerly or polar northeasterly winds during dust transport, and rather may imply the effect of low-pressure systems passing through the English Channel during that period.</p>","PeriodicalId":16929,"journal":{"name":"Journal of Quaternary Science","volume":null,"pages":null},"PeriodicalIF":1.9000,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3620","citationCount":"0","resultStr":"{\"title\":\"Mineral magnetism and palaeoenvironment recorded in loess in southern England\",\"authors\":\"Dominika Niezabitowska, Thomas Stevens, Balázs Bradák, Martin Chadima, Yunus Baykal, Daniele Sechi, Ramona Schneider\",\"doi\":\"10.1002/jqs.3620\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Extensive research has focused on the loess deposits in southern England, aiming to unravel their stratigraphic and palaeoenvironmental significance. However, no systematic mineral magnetic study on these deposits has yet been undertaken. Here we address this by investigating the magnetic mineral composition and alignment of loess at two sites in southern England, Lowland Point (LP) on the Lizard Peninsula of Cornwall, and Pegwell Bay (PB) in eastern Kent on the Isle of Thanet. A set of rock magnetic analyses was conducted to understand mineral magnetism within the studied sections. In addition, the primary depositional origin of the magnetic fabrics as well as their overprinting caused by various possible post-depositional processes were examined through anisotropy of magnetic susceptibility (AMS). The magnetic mineral composition is similar at both sites, derived from both sedimentary (aeolian) and post-depositional processes. The AMS results show magnetic foliation that varies between the two sites, aligning with the bedding plane, indicating deposition from gravitational dust fall at the PB site, and a stronger wind transport energy at the LP site. Although the magnetic lineation of bulk AMS is relatively weak, there is a noticeable tendency towards alignment in most samples, with flow directions from the SE indicated at both sections if a strong wind is assumed at LP, although with a possible SW direction if a weaker wind is assumed. These observations may imply the preservation of palaeowind directions during dust transport, with a substantial southerly component, which contradicts previous assertions of dominant northerly or northeasterly winds. Indeed, a possible dominant southeasterly wind direction between 25 and 18 ka would suggest a limited influence of katabatic, westerly or polar northeasterly winds during dust transport, and rather may imply the effect of low-pressure systems passing through the English Channel during that period.</p>\",\"PeriodicalId\":16929,\"journal\":{\"name\":\"Journal of Quaternary Science\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.9000,\"publicationDate\":\"2024-04-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jqs.3620\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Quaternary Science\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/jqs.3620\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOGRAPHY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Quaternary Science","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/jqs.3620","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOGRAPHY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
摘要
大量研究集中于英格兰南部的黄土沉积,旨在揭示其地层和古环境意义。然而,尚未对这些沉积物进行过系统的矿物磁性研究。为了解决这个问题,我们在英格兰南部的两个地点,即康沃尔蜥蜴半岛的低地点(Lowland Point,LP)和肯特郡东部塔内特岛的佩格韦尔湾(Pegwell Bay,PB),对黄土的磁性矿物成分和排列进行了研究。为了解所研究地段的矿物磁性,进行了一系列岩石磁性分析。此外,还通过磁感应强度各向异性(AMS)研究了磁性结构的主要沉积起源以及各种可能的沉积后过程造成的叠印。两个地点的磁性矿物成分相似,都来自沉积(风化)过程和沉积后过程。AMS 结果显示,两个地点的磁性褶皱各不相同,与基底面一致,这表明在 PB 地点的沉积来自重力尘降,而在 LP 地点的沉积来自更强的风力搬运能量。虽然大块 AMS 的磁力线相对较弱,但在大多数样本中都有明显的排列趋势,如果假定 LP 岩石的风力较强,则两个断面的流向均为东南方向,但如果假定风力较弱,则可能为西南方向。这些观察结果可能意味着在尘土飞扬的过程中保留了古风的方向,其中有很大一部分是偏南风,这与之前认为主要是偏北风或东北风的说法相矛盾。事实上,在 25 ka 至 18 ka 期间可能存在的东南风主导风向表明,在沙尘迁移过程中,卡塔巴特风、西风或极地东北风的影响有限,而可能意味着在此期间经过英吉利海峡的低压系统的影响。
Mineral magnetism and palaeoenvironment recorded in loess in southern England
Extensive research has focused on the loess deposits in southern England, aiming to unravel their stratigraphic and palaeoenvironmental significance. However, no systematic mineral magnetic study on these deposits has yet been undertaken. Here we address this by investigating the magnetic mineral composition and alignment of loess at two sites in southern England, Lowland Point (LP) on the Lizard Peninsula of Cornwall, and Pegwell Bay (PB) in eastern Kent on the Isle of Thanet. A set of rock magnetic analyses was conducted to understand mineral magnetism within the studied sections. In addition, the primary depositional origin of the magnetic fabrics as well as their overprinting caused by various possible post-depositional processes were examined through anisotropy of magnetic susceptibility (AMS). The magnetic mineral composition is similar at both sites, derived from both sedimentary (aeolian) and post-depositional processes. The AMS results show magnetic foliation that varies between the two sites, aligning with the bedding plane, indicating deposition from gravitational dust fall at the PB site, and a stronger wind transport energy at the LP site. Although the magnetic lineation of bulk AMS is relatively weak, there is a noticeable tendency towards alignment in most samples, with flow directions from the SE indicated at both sections if a strong wind is assumed at LP, although with a possible SW direction if a weaker wind is assumed. These observations may imply the preservation of palaeowind directions during dust transport, with a substantial southerly component, which contradicts previous assertions of dominant northerly or northeasterly winds. Indeed, a possible dominant southeasterly wind direction between 25 and 18 ka would suggest a limited influence of katabatic, westerly or polar northeasterly winds during dust transport, and rather may imply the effect of low-pressure systems passing through the English Channel during that period.
期刊介绍:
The Journal of Quaternary Science publishes original papers on any field of Quaternary research, and aims to promote a wider appreciation and deeper understanding of the earth''s history during the last 2.58 million years. Papers from a wide range of disciplines appear in JQS including, for example, Archaeology, Botany, Climatology, Geochemistry, Geochronology, Geology, Geomorphology, Geophysics, Glaciology, Limnology, Oceanography, Palaeoceanography, Palaeoclimatology, Palaeoecology, Palaeontology, Soil Science and Zoology. The journal particularly welcomes papers reporting the results of interdisciplinary or multidisciplinary research which are of wide international interest to Quaternary scientists. Short communications and correspondence relating to views and information contained in JQS may also be considered for publication.