A Review of the Research History of the Tjörnes Sequence, North Iceland

Eiríksson, Jón; Símonarson, Leifur A.

doi:10.1007/978-3-030-59663-7_4

Cited by 3 publications

(4 citation statements)

References 57 publications

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“…The bedrock in this region is the oldest of the Neogene series basalts with thin red and red‐brown interbedded clay layers, dated between 3.1–15 m.y.a. (Denk et al, 2005; Eiríksson & Símonarson, 2021; Sæmundsson, 1979) (Figure 3). The presently active rift zones in Iceland are located approximately 200 km from the study area, and there are no central volcanoes within it (Figure 3; Karson, 2017).…”

Section: Methodsmentioning

confidence: 96%

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Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Mastro,

Principato,

Sobel

et al. 2023

Earth Surf Processes Landf

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Glacial erosion rates on the Iceland landscape throughout the Pleistocene are not well quantified. Ice scour lakes provide an opportunity to investigate glacial erosive activity and relative intensity because they commonly form in areas beneath ice sheets due to intense quarrying. This study evaluates ice scour lake morphology and density as a potential proxy for paleo‐ice flow direction and basal thermal regime for parts of the Iceland Ice Sheet. Using GIS analysis, properties of ice scour lakes are examined in regions that experienced different rates of ice flow during and following the Last Glacial Maximum (LGM), as interpreted from streamlined subglacial landforms. The primary input datasets were topographic, hydrologic and bedrock data. Lake distribution and morphology were quantified for all natural lakes of Iceland (n = 30 169), with close examination of three 400 km2 sub‐regions in Vestfirðir (n = 904), Húnaflói (n = 69) and Bakkaheiði (n = 232). Lake distribution parameters include density, packing and centroid elevation. PolyMorph‐2D was used to quantify lake morphology including orientation, area and elongation ratio. Ice scour lake density, packing and elevation were all greatest on Vestfirðir. The high density and packing of lakes across Vestfirðir suggests unique ice dynamics relative to the other two sub‐regions, and multidirectional flow of lake axes supports the presence of an independent ice cap covering Vestfirðir. Differential intensity of glacial erosion interpreted from regions of high and low lake density on Bakkaheiði supports a proposed ice divide in Northeast Iceland. The orientation of lakes align with the flow directions of proposed LGM ice streams in Northern and Northeast Iceland. Ice scour lakes were most elongate on average on Bakkaheiði, which supports fast ice flow. Improving understanding of former ice sheet basal thermal regime and paleo‐ice flow velocity serves to inform modern controls on ice sheet stability and ice sheet basal processes.

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Section: Methodsmentioning

confidence: 96%

“…bedrock in this region is the oldest of the Neogene series basalts with thin red and red-brown interbedded clay layers, dated between 3.1-15 m.y.a (Denk et al, 2005;Eiríksson & Símonarson, 2021;Saemundsson, 1979). (Figure3).…”

mentioning

confidence: 99%

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Mastro,

Principato,

Sobel

et al. 2023

Earth Surf Processes Landf

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“…We use the Geomagnetic Polarity Time Scale of Ogg (2020) throughout. A comprehensive review of the available paleomagnetic data from the entire Tjörnes succession is provided by Eiríksson and Símonarson (2021) and Eiríksson et al. (2021a).…”

Section: Methodsmentioning

confidence: 99%

“…The Barmur Group sedimentary succession in north‐eastern Iceland, informally known as the Tjörnes beds, is an important archive of late Neogene palaeoenvironmental change in the high‐latitude North Atlantic (Figure 1a, Símonarson & Eiríksson, 2021a). The easily accessible, c. 600 m thick succession contains a variety of macrofossils and microfossils that have been studied for a century (Bárðarson, 1925; Eiríksson & Símonarson, 2021). Notably, the Barmur Group is a key outcrop for dating the first opening of the Bering Strait oceanic gateway, which established a trans‐Arctic marine connection between the Pacific and Atlantic Oceans (Marincovich & Gladenkov, 1999; Símonarson & Eiríksson, 2021a).…”

Section: Introductionmentioning

confidence: 99%

Timing and Consequences of Bering Strait Opening: New Insights From⁴⁰Ar/³⁹Ar Dating of the Barmur Group (Tjörnes Beds), Northern Iceland

Hall

Allison

Papadopoulos

et al. 2023

Paleoceanog and Paleoclimatol

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The Barmur Group (informally Tjörnes beds) sedimentary succession of northern Iceland is key to reconstructing the opening of the Bering Strait oceanic gateway because these rocks record migration of bivalve molluscs from the Pacific to the Atlantic via the Arctic. However, the timing of the migration event is poorly constrained owing to a lack of reliable absolute ages. To address this problem, we present the first Ar‐Ar radiometric dates from four basaltic lavas that underlie, are intercalated with, and overlie the Barmur Group, and integrate them with existing paleomagnetic records. We show that the Barmur Group has a latest Miocene to early Pliocene age range (c. 6.0–4.4 Ma; C3r–C3n.2n), older than all previous age models. Thus, the Barmur Group does not record the mid‐Piacenzian Warm Period, contra some previous suggestions. Abundant Pacific bivalve molluscs appeared in the Barmur Group during subchrons C3n.4n–C3n.3r at 5.235–4.896 Ma, over 1.3 million years earlier than previously suggested. Appearance of Pacific bivalves in the northern Atlantic occurred shortly after the 5.6–5.4 Ma age previously inferred for first appearance of Arctic bivalves in the Pacific. Thus, our data suggest that first opening of the Bering Strait gateway by the latest Miocene (c. 5.5 Ma) was soon followed by bidirectional trans‐Arctic faunal exchange, and argue against a hypothesized two‐stage faunal exchange process spanning c. 2 million years. Our results also confirm that first opening of the Bering Strait gateway was not directly associated with the growth of large northern hemisphere icesheets, which occurred several million years later.

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Valgarður: a database of the petrophysical, mineralogical, and chemical properties of Icelandic rocks

Scott

Levy²,

Covell

et al. 2023

Earth Syst. Sci. Data

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Abstract. The Valgarður database is a compilation of data describing the physical and geochemical properties of Icelandic rocks. The dataset comprises 1166 samples obtained from fossil and active geothermal systems as well as from relatively fresh volcanic rocks erupted in subaerial or subaqueous environments. The database includes petrophysical properties (connected and total porosity, grain density, permeability, electrical resistivity, acoustic velocities, rock strength, and thermal conductivity) as well as mineralogical and geochemical data obtained by point counting, X-ray fluorescence (XRF), quantitative X-ray diffraction (XRD), and cation exchange capacity (CEC) analyses. The database may be accessed at https://doi.org/10.5281/zenodo.6980231 (Scott et al., 2022a). We present the database and use it to characterize the relationship between lithology, alteration, and petrophysical properties. The motivation behind this database is to (i) aid in the interpretation of geophysical data, including uncertainty estimations; (ii) facilitate the parameterization of numerical reservoir models; and (iii) improve the understanding of the relationship between rock type, hydrothermal alteration, and petrophysical properties.

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A Review of the Research History of the Tjörnes Sequence, North Iceland

Cited by 3 publications

References 57 publications

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Timing and Consequences of Bering Strait Opening: New Insights From⁴⁰Ar/³⁹Ar Dating of the Barmur Group (Tjörnes Beds), Northern Iceland

Valgarður: a database of the petrophysical, mineralogical, and chemical properties of Icelandic rocks

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A Review of the Research History of the Tjörnes Sequence, North Iceland

Cited by 3 publications

References 57 publications

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

Timing and Consequences of Bering Strait Opening: New Insights From40Ar/39Ar Dating of the Barmur Group (Tjörnes Beds), Northern Iceland

Valgarður: a database of the petrophysical, mineralogical, and chemical properties of Icelandic rocks

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Product

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Timing and Consequences of Bering Strait Opening: New Insights From⁴⁰Ar/³⁹Ar Dating of the Barmur Group (Tjörnes Beds), Northern Iceland