Palaeoecology and palaeoenvironments of the Middle Jurassic to lowermost Cretaceous Agardhfjellet Formation (Bathonian–Ryazanian), Spitsbergen, Svalbard

IF 0.8 4区 地球科学 Q2 Earth and Planetary Sciences
M. Koevoets, Ø. Hammer, C. Little
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引用次数: 4

Abstract

We describe the invertebrate assemblages in the Middle Jurassic to lowermost Cretaceous of the Agardhfjellet Formation present in the DH2 rock core material of Central Spitsbergen (Svalbard). Previous studies of the Agardhfjellet Formation do not accurately reflect the distribution of invertebrates throughout the unit as they were limited to sampling discontinuous intervals at outcrop. The rock core material shows the benthic bivalve fauna to reflect dysoxic, but not anoxic environments for the Oxfordian – lower Kimmeridgian interval with sporadic monospecific assemblages of epifaunal bivalves, and more favourable conditions in the Volgian, with major increases in abundance and diversity of Hartwellia sp. assemblages. Overall, the new information from cores show that abundance, diversity and stratigraphic continuity of the fossil record in the Upper Jurassic of Spitsbergen are considerably higher than indicated in outcrop studies. The inferred life positions and feeding habits of the benthic fauna refine the understanding of the depositional environments of the Agardhfjellet Formation. The occurrence pattern of the bivalve genera is correlated with published studies of Arctic localities in East Greenland and Northern Siberia and shows similarities in palaeoecology with the former but not the latter. Ammonite biostratigraphy is used as a tool to date bivalve assemblage overturning events to help identify similar changes in other sections.
斯瓦尔巴群岛斯匹次卑尔根岛中侏罗世至下白垩世Agardhfjellet组(Bathonian-Ryazanian)的古生态与古环境
我们描述了中侏罗纪至白垩纪Agardhfjellet组最下层的无脊椎动物组合,这些无脊椎动物组合存在于中斯匹次卑尔根群岛(斯瓦尔巴群岛)的DH2岩芯材料中。先前对Agardhfjellet组的研究并不能准确反映整个单元无脊椎动物的分布,因为它们仅限于对露头处的不连续间隔进行采样。岩芯材料显示,底栖双壳类动物反映了牛津阶-基梅里阶下段的缺氧环境,表层双壳类的单特异性组合零星分布,Volgian的条件更有利,Hartwellia sp.组合的丰度和多样性显著增加。总的来说,岩心的新信息表明,斯匹次卑尔根上侏罗纪化石记录的丰度、多样性和地层连续性大大高于露头研究。推断的底栖动物的生活位置和进食习惯完善了对阿加德菲耶莱组沉积环境的理解。双壳类属的出现模式与已发表的对东格陵兰和北西伯利亚北极地区的研究有关,并在古生态学上与前者相似,但与后者不同。亚氨岩生物地层学被用作确定双壳类组合翻转事件日期的工具,以帮助识别其他部分的类似变化。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Norwegian Journal of Geology
Norwegian Journal of Geology 地学-地球科学综合
CiteScore
1.60
自引率
25.00%
发文量
0
审稿时长
>12 weeks
期刊介绍: The Norwegian Journal of Geology publishes high-quality, fully peer-review papers from all geoscientific disciplines. Papers are commonly based on regional studies and should emphasise the development of understanding of fundamental geological processes. More specialised papers can also be submitted, but should be written in a way that is easily understood by nonspecialists, and illustrate the progress being made within that specific topic in geosciences. We also encourage initiatives for thematic issues within the scope of the Journal.
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