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The Structural History of the Jan Mayen Micro-Continent (JMMC) and Its Role During the Rift “Jump” Between the Aegir to the Kolbeinsey Ridge

Anett Blischke1, Thorarinn S. Arnarson2, and Karl Gunnarsson3
1Energy Technology, Iceland Geosurvey, Akureyri, Iceland.
2Hydrocarbon Exploration, National Energy Authority, Reykjavik, Iceland.
3Geophysics and Reservoir Physics, Iceland Geosurvey, Reykjavik, Iceland.

In 2008 a structural and geological study was initiated in preparation for the first and second Icelandic petroleum exploration license calls in 2009 and 2011. A lot of research concerning the opening history of the North Atlantic has been ongoing using up to date information. The results of this study establish a basis for a re-evaluation of the Jan Mayen Ridge and its hydrocarbon potential. This structural interpretation has the aim to tie in and review existing studies conducted from the early seventies to present and primarily 2D seismic data sets acquired between 2001 and 2010. Traditionally the ridge has been subdivided into the Main- and Southern Ridge Complexes with associated listric and normal extensional fault patterns. The structural model indicates that the JMR itself is subdivided into smaller blocks with small highs and lows that most likely have been activated during the opening of the Aegir Ridge, and were influenced by the Jan Mayen Fracture Zone developments since. The western flank blocks especially show indications of uplift during the Tertiary, due to near complete erosion of the central highs in the Southern Ridge Complex with very thin deep basin sediment covers deposited during the post-rift time. It also could be suggested that two failed rift attempts reached into the southeastern and southern part of the Southern Ridge Complex during the early Middle Eocene, and during the transition between Late Eocene and Early Oligocene. Indications for this are not just presented in published work, but also would better explain mapped seaward dipping reflector areal lateral offsets, volcanic intrusive observations, fault mapping with their lateral offset comparisons on 2D seismic data, OBS velocity data anomalies between the JMR and Iceland, or explain structural features visible on high resolution bathymetry data. The newly derived structural model indicate that the JMR itself could be used as a part of the puzzle to better explain the transition from the Aegir Ridge to the Kolbeinsey Ridge during the opening of the North Atlantic between the Middle Eocene up to the Early Miocene. This transition history has implications for the structural history and timing of the ridge segments, and its geothermal influence on the JMR formations during the initial break-up of the North Atlantic and the extensive volcanism during the Late Paleocene to Early Eocene, and especially between the Middle Eocene and Early Miocene.

In 2008 a structural and geological study was initiated in preparation for the first and second Icelandic petroleum exploration license calls in 2008 and 2011. A lot of research concerning the opening history of the North Atlantic has been ongoing using up to date information. The last detailed study of the Jan Mayen Ridge (JMR) was conducted in 1985 to 1992 during a joint project between the National Energy Authority of Iceland (NEA) & the Norwegian Petroleum Directorate. This study has the aim to tie in newly acquired data sets, such as 2D seismic data, high resolution bathymetry, velocity estimates, or seafloor samples, and applicable research, in particular concerning the timing of the North Atlantic Opening and the Jan Mayen Fracture Zone. The results of this study establish a basis for a re-evaluation of the Jan Mayen Ridge and its hydrocarbon potential.

This structural interpretation has the aim to tie in and review existing studies conducted from the early seventies to present and primarily 2D seismic data sets acquired between 2001 and 2010, primarily focusing on 2D seismic data for structural modeling. A review of seismic- and OBS velocity data were included to tie the model to depth, and estimate possible ties to pre-Tertiary formations, outline the JMR's basement, and especially assist the interpretation of the volcanic formations within the ridge.

Traditionally the ridge has been subdivided into the Main- and Southern Ridge Complexes with associated listric and normal extensional fault patterns. The structural model indicates that the JMR itself is subdivided into smaller blocks with small highs and lows that most likely have been activated during the opening of the Aegir Ridge, and were influenced by the Jan Mayen Fracture Zone developments since. The western flank blocks especially show indications of major uplift during the Tertiary, due to near complete erosion of the central highs in the Southern Ridge Complex with very thin deep basin sediment covers deposited during the post-rift time.

It also could be suggested that two failed rift attempts reached into the southeastern and southern part of the Southern Ridge Complex during the early Middle Eocene, and during the transition between Late Eocene and Early Oligocene. Indications for this are not just presented in published work, but also would better explain mapped seaward dipping reflector areal lateral offsets, volcanic intrusive observations, fault mapping with their lateral offset comparisons on 2D seismic data, OBS velocity data anomalies between the JMR and Iceland, or explain structural features visible on high resolution bathymetry data.

The interpretation of the structural model for formation interval stratigraphic thickness changes also suggest the existence of two paleo-geographic lows striking more or less West-East that might have been present at the end of the Cretaceous, prior to the Late Paleozoic initial break-up episode and massive volcanic extrusive and intrusive depositions. These two lows appear to align with the general positioning of the JMMC to the Scoresby Sund just located south of the Liverpool Land high and Jameson Land prospective basin, with indications that pre-Tertiary deposits are still preserved underneath the Tertiary basalt cover, which could explain locally identified pre-Tertiary and sub-basalt unconformities and well visible layering on more recent 2D seismic data.
The newly derived structural model indicate that the JMR itself could be used as a part of the puzzle to better explain the transition from the Aegir Ridge to the Kolbeinsey Ridge during the opening of the North Atlantic between the Middle Eocene up to the Early Miocene. This transition history has implications for the structural history and timing of the ridge segments, and its geothermal influence on the JMR formations during the initial break-up of the North Atlantic and the extensive volcanism during the Late Paleocene to Early Eocene, and especially between the Middle Eocene and Early Miocene.

 

AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.