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TitleLinking lithostratigraphy and chronostratigraphy at the mid to Late Triassic transition on Edgeøya, (Svalbard): the role of magnetostratigraphy
 
AuthorHounslow, M W; Harris, S E; Lucas, V A; Orchard, M JORCID logo; Mork, A; Lord, G S
Source2nd Boreal Triassic Conference, abstracts; 2015 p. 1
Image
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20160096
Meeting2nd Boreal Triassic Conference; Svalbard; NO; August 28 - September 1, 2015
Documentbook
Lang.English
Mediapaper
AreaEdgeøya; Norway
Lat/Long WENS 22.0000 23.0000 77.7667 77.7333
Subjectsstratigraphy; paleontology; geophysics; lithostratigraphy; chronostratigraphy; magnetostratigraphy; Ladinian; Carnian; sedimentary rocks; paleomagnetic interpretations; paleomagnetism; Botneheia Formation; De Geerdalen Formation; Mesozoic; Triassic
ProgramGSC Pacific Division
AbstractThe chronostratigraphy of the units close to the Ladinian-Carnian boundary is not understood in detail on Edgeøya because of the scarcity of ammonoids, and the lack of recent work on this interval. We address this by using conodont faunas and a linked magnetostratigraphy. A magnetostratigraphy has been obtained from sections on Edgeøya- from the Muen and Blanknuten sections on Edgeøya. These data are from the upper most part of the Botneheia Formation at Muen (TBnP unit of the Blanknuten Member), and the lower to mid parts of the De Geerdalen Formation at Blanknuten. The TBnP unit of the Botneheia Fm on Muen is productive for conodonts, and initial indications suggest some early Carnian faunas. On Edgeøya a fine-scale subdivision (units A to G) of the De Geerdalen Fm in the Blanknuten- Klinkhamaren area is constructed, based on cliff photographs and existing logs. This allows visual mapping of the obtained magnetostratigraphy onto units away from the sampled Blanknuten section.
The mean palaeomagnetic directions derived from the data pass the reversal test, and are consistent with other virtual geomagnetic palaeopole data from Svalbard, indicating a primary palaeomagnetic signal. The magnetostratigraphic and conodont data from the Muen section on Edgeøya is assessed for the indication of the likely position of the Ladinian-Carnian boundary within the Blanknuten Member of the Botneheia Fm. These data suggest the Carnian extends into the upper part of the Blanknuten Mbr, and contrasts with central Spitsbergen, where the earliest Carnian and latest Ladinian interval is missing. The magnetostratigraphic data indicate the base of the overlying Tschermakfjellet Fm is older (by ~0.5Ma) on Edgeøya than in central Spitsbergen.
The De Geerdalen Fm on Edgeøya begins in the mid parts of the Julian-1 substage (lower Carnian), and in central Spitsbergen begins in the basal part of the Julian-1. On Edgeøya the De Geerdalen probably extends into the lower to mid Tuvalian substage, whereas in central Spitsbergen at the Dalsnuten section, it is truncated by erosion in the Julian-2 substage (mid Carnian). Major channel sandstone units are not the same age on Edgeøya and central Spitsbergen, except perhaps for the first major channel sandstone (unit B on Edgeøya), whose age is mid Julian-1. The growth fault structures at Klinkhamaren are limited to the B-unit sandstones and the Tschermakfjellet Fm, and were probably initiated in a brief event (<0.4 Ma duration) in the late parts of the Julian-1 sub-stage. This event timing relates closely with the Carnian pluvial event, and probably relates to a period of very rapid sedimentation rate in the De Geerdalen channel systems, initiating the Klinkhamaren growth faults.
Summary(Plain Language Summary, not published)
To better understand the chronostratigraphy of the units close to the Ladinian-Carnian boundary on Edgeøya, Svalbard, we have studied conodont faunas and a linked magnetostratigraphy. The magnetostratigraphic and conodont data from the Muen section indicates the likely position of the Ladinian-Carnian boundary within the Blanknuten Member of the Botneheia Fm. Contrasts are made with the successions in central Spitzbergen where both formational boundaries and major channel sandstone units are not the same age. Local growth fault structures may relate closely with the Carnian pluvial event and a period of very rapid sedimentation rate.
GEOSCAN ID298858

 
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