Seismic Stratigraphy, Structure and Morphology of Makarov Basin and Surrounding Regions: Tectonic Implications
|Title||Seismic Stratigraphy, Structure and Morphology of Makarov Basin and Surrounding Regions: Tectonic Implications|
|Publication Type||Journal Article|
|Authors||Evangaletos, J, Mosher, DC|
|Date Published||April 1|
|Keywords||alpha-mendeleev ridge complex, arctic morphology, arctic stratigraphy, lomonsov ridge, Makarov Basin, seismic reflection|
The tectonic history of Amerasia Basin, Arctic Ocean, is not well known because of a paucity of data and complexities introduced by the Alpha–Mendeleev Ridge large igneous province. Makarov Basin, at the northern limit of Amerasia Basin and adjacent to Lomonosov Ridge, may provide a window into understanding the larger tectonic framework. The objective of this study is to decipher the sedimentary and tectonic history of northern Amerasia Basin by analysing the seismic stratigraphy, structure and morphology of Makarov Basin and surrounding regions (Alpha and Lomonosov ridges) of the central Arctic Ocean. The principal data sources for this study are a 400 km long multi-channel seismic line, extending from Alpha Ridge to the crest of Lomonosov Ridge via central Makarov Basin, and the Arctic bathymetric chart.
The seismic record within Makarov Basin is divided into five seismic units. The first unit overlying basement hosts Late Cretaceous (minimum age) slope to base of slope sediments. Some of these sediments are interbedded with volcanic or volcanoclastic rocks with a minimum age of 89 Ma. Makarov Basin becomes isolated from proximal sources of sediments after the onset of rifting that separated Lomonosov Ridge from the Barents Shelf, which may have occurred as early as the mid-Late Cretaceous, and led to the creation of Eurasia Basin. Sediments are largely pelagic to hemipelagic as a result of this isolation. This deposition style also applies to the draped sedimentary strata on Alpha and Lomonosov ridges. The uppermost seismic units within Makarov Basin arejump-correlatedto the stratigraphic record of the ACEX drill site on top of Lomonosov Ridge to provide age control. This correlation shows that the 44.4–18.2 Ma hiatus documented in the drill core is not apparent in the basin. Inter-ridge correlations and the absence of an obvious planate surface on Alpha Ridge also suggest that sedimentation was uninterrupted on this ridge during the hiatus.
Seismic data reveal a deep subbasin (~ 5 km thick) within Makarov Basin. This subbasin is immediately adjacent to Lomonosov Ridge within major bends in the general strike orientation of the ridge. The rhomboid shape of the deep subbasin, the straight and steep morphology of the Amerasian flank of Lomonosov Ridge and the presence of numerous sub-parallel ridges (e.g. Geophysicists and Marvin spurs) created by splay faulting are evidence of strike-slip (transtensional) tectonics. This interpretation supports the “rotational” model of opening of Amerasia Basin with a transform to transtensional margin at Lomonosov Ridge. As spreading continued, however, the tectonics became increasingly extensional perpendicular to Lomonosov Ridge. There is no evidence of major tectonic deformation in Makarov Basin beyond the late Paleocene.