Research Project on the manifestation of the High Arctic Large Igneous Province (HALIP) on Svalbard

© Harmon D. Maher Jr., Dept. of Geography and Geology, University of Nebraska at Omaha, Omaha, NE 68182-0199, U.S.A. 11/99

Fig. 1: Cretaceous sill in Carboniferous strata of Lomfjorden area, NW Spitsbergen with about 700 m of relief.

Background on the High Arctic Large Igneous Manifestation on Svalbard:

Major upper Cretaceous LIPs (e.g. the Kerguelen and Ontong Java Plateaus) show Aptian magmatic peaks, and are linked to global mantle overturning and anomalous surface environment conditions (Larson, 1991, Mahoney & Coffin, 1997). In this context, a widespread Cretaceous thermal event evident in the High Arctic has been identified as an LIP (Tarduno, 1998). Evidence for magmatic/thermal events of this age exists on Svalbard, Franz Josef Island, adjacent shelf areas, Axel Heiberg and Ellesmere Islands, and perhaps North


Fig. 2: Map showing present day position of HALIP localities. Arrows shoe Cretceous position of Franz Josef Island and Svalbard against the Lomonosov Ridge and adjacent to the Alpha Ridge. Base map source http://www.aquarius.geomar.de/omc/make_map.html.
Greenland, covering an area several hundred thousand square kilometers. These areas were peripheral during the development of the Amerasian (Canada) basin and Alpha Ridge, and together define the LIP. While very mild compression or platform stability initially characterized Svalbard and Franz Josef, extension characterized the Canadian Arctic. This is consistent with a large, diffuse plume superimposed on a complex and evolving stress field. Present evidence suggests magmatism was coeval in Svalbard and Franz Josef Land, inconsistent with a hot spot track hypothesis. Multiple pulses of magmatic activity could result from a deep and large plume.

This thermal/magmatic event has a distinct sedimentologic expression on Svalbard, and elsewhere.


Fig. 3: Stratigraphic section of black shales of the Rurikfjellet Fm. overlain by white sandstone of the Helvetiafjellet Fm.. This regression likely marks the first phase of HALIP related uplift. Overlying darker colored sands have a fair amount of volcanogenic debris, reflecting development of HALIP as a source to the N. Section from southern Midterhuken, Spitsbergen.
Given that much of the High Arctic LIP is either submerged, inaccessible, and has been tectonically dispersed and eroded, the sedimentologic record may provide important additional insight into this province.Effects attributed to the LIP include a slow regression evident towards the top of a thick black shale unit punctuated by locally abrupt uplift, development of a low angle unconformity, the production of new source terranes to the north, and more extensive diagenesis. On Spitsbergen a widespread transition from quartz arenites to lithic arenites and feldspathic sandstones marks the appearance of volcanic source terranes to the north and east. A Late Cretaceous low-angle unconformity likely represents the flank of thermal doming associated with the LIP. Towards the north associated erosion removed a minimum of 1 km and possibly several kilometers of platform cover sediments. The stratigraphic record can be viewed in light of two pulses of activity. Better understanding of the High Arctic LIP would help fill out the global picture of Cretaceous LIPs.

Description of research program:

Objectives of this project are: 1) to better characterize the geochemical signature of HALIP on Svalbard, 2) to develop a detailed model for the sedimentologic response to HALIP, 3) to significantly refine constraints on the duration of magmatism, and to possibly recognize pulses, 4) to test the idea of a hot spot track origin by comparison of our results with the published literature on Franz Josef Land (e.g. Dibner, 1998), and 5) to better characterize HALIP in the global superplume/overturn context.

People involved:

Ongoing work:

Future work

Dependent on funding, future work will concentrate on; 1) collecting diabase samples for trace element geochemical work to try and characterize the source character, degree of partial melting, and degree of any contamination involved in melt production, 2) collecting sandstone samples from appropriate stratigraphic levels for petrographic analysis and for Nd isotope analysis, and 3) comparison of our results with those from other parts of the HALIP.


Fig. 4: Well exposed and overturned section of Cretaceous strata in Hornsund, and a potential sampling locality in future work.

References

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