{"title":"Middle–Late Ordovician organic- walled phytoplankton from Sweden: diversity and early radiation","authors":"C. V. Rubinstein, V. Vajda","doi":"10.3176/earth.2023.42","DOIUrl":null,"url":null,"abstract":"The Borenshult-1 core, drilled in the vicinity of Motala, east of Lake Vättern in south central Sweden, comprises a well-dated and nearly complete succession of marine marly carbonates deposited relatively close to land. The 34 core samples analyzed for palynology encompass the upper part of the Darriwilian (Furudal Limestone), the entire Sandbian (Dalby Limestone, the Kinnekulle K-bentonite and the lower Skagen Limestone) and the lower part of the Katian (Skagen Limestone). The age of this interval is well-constrained to the late Darriwilian (Stage slice Dw3)– early Katian (Stage slice Ka1 ) , based on conodonts and 206Pb/238U dating of volcanic ash deposits. The samples yielded predominantly marine organic-walled phytoplankton, mainly acritarchs, with subordinate chitinozoans, scolecodonts and fragments of graptolites. Sparse terrestrial palynomorphs, represented by cryptospores and trilete spores, were also found in 23 of the samples. A total of 154 acritarch species corresponding to 53 genera were identified, as well as low percentages of abnormal forms ( teratological forms) of acritarch species at some levels. The strati graphic distribution of genera and species allowed for three palynological assemblages to be distinguished: Assemblage A of a late Darriwilian age, Assemblage B of a Sandbian age ( further subdivided into sub-assemblages B1 and B2 ) , and Assemblage C dated as Katian.","PeriodicalId":50498,"journal":{"name":"Estonian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.9000,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Estonian Journal of Earth Sciences","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.3176/earth.2023.42","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The Borenshult-1 core, drilled in the vicinity of Motala, east of Lake Vättern in south central Sweden, comprises a well-dated and nearly complete succession of marine marly carbonates deposited relatively close to land. The 34 core samples analyzed for palynology encompass the upper part of the Darriwilian (Furudal Limestone), the entire Sandbian (Dalby Limestone, the Kinnekulle K-bentonite and the lower Skagen Limestone) and the lower part of the Katian (Skagen Limestone). The age of this interval is well-constrained to the late Darriwilian (Stage slice Dw3)– early Katian (Stage slice Ka1 ) , based on conodonts and 206Pb/238U dating of volcanic ash deposits. The samples yielded predominantly marine organic-walled phytoplankton, mainly acritarchs, with subordinate chitinozoans, scolecodonts and fragments of graptolites. Sparse terrestrial palynomorphs, represented by cryptospores and trilete spores, were also found in 23 of the samples. A total of 154 acritarch species corresponding to 53 genera were identified, as well as low percentages of abnormal forms ( teratological forms) of acritarch species at some levels. The strati graphic distribution of genera and species allowed for three palynological assemblages to be distinguished: Assemblage A of a late Darriwilian age, Assemblage B of a Sandbian age ( further subdivided into sub-assemblages B1 and B2 ) , and Assemblage C dated as Katian.
Borenshult-1岩心是在瑞典中南部Vättern湖以东的Motala附近钻探的,包含了一个年代久远、几乎完整的海相碳酸盐岩序列,它们沉积在相对靠近陆地的地方。孢粉学分析的34个岩心样品包括达里威廉(Furudal灰岩)上部、整个沙边(Dalby灰岩、Kinnekulle k -膨润土和下斯卡根灰岩)和卡田(Skagen灰岩)下部。根据牙形刺和火山灰沉积物的206Pb/238U定年,该层序的年龄很好地限定在达里威廉晚期(Dw3阶段)-卡天早期(Ka1阶段)。样品中主要有海洋有机壁浮游植物,主要是水螅类,次要有几丁质动物、棘刺类和笔石碎片。在23份样品中还发现了稀疏的陆生孢子,以隐孢子和三孢子为代表。共鉴定出53属154种,在某些层次上有较低的畸形形态(畸形形态)。属和种的地层分布可区分出3个孢粉组合:晚达里威廉时代的组合A、沙边时代的组合B(进一步细分为亚组合B1和B2)和卡天时代的组合C。
期刊介绍:
The Estonian Journal of Earth Sciences is an international scientific open access journal published by the Estonian Academy of Sciences in collaboration with the Tallinn University of Technology, the University of Tartu, the Estonian University of Life Sciences and the Talllinn University.
The journal publishes primary research and review papers in the English language. All articles are provided with short Estonian summaries.
All papers to be published in the journal are peer reviewed internationally.
The journal is open for publications in all fields of Earth sciences, including besides different geological sensu lato disciplines, also geography and oceanography having certain connection with our part of the world, North Europe and the Baltic area in particular.