Aeromagnetics on the Lincoln Sea - A German Canadian Joint Project.

NRC publication: Ye

Some Preliminary Regional Tectonic Implications of Features from the Canada-Germany Polar Margin Aeromagnetic Program (PMAP) over the Canada-Greenland Margin.

NRC publication: Ye

Ross-age amalgamation of East and West Gondwana: evidence from the Shackleton range, East Antarctica

The structural setting of the northern Shackleton Range is dominated by west to south-west directed Ross-age thrusting leading to stacking of the following main units (I) remobilized northern basement, (II) ophiolite complex, (III-north) low-grade meta-sediments. The latter form a lithological link across the ice-covered centre (Fuchs Dome) to the southern Shackleton Range where similar lithologies occur in the south-westward transported Mt. Wegener nappe (III-south), which overrides unit (IV), a part of the East Antarctic Craton, consisting of the mid-Proterozoic basement of the Read Mountains plus an autochthonous Proterozoic sedimentary cover. Existing and new structural, petrological and geochronological data consistently support the interpretation of the Ross-age orogen in the Shackleton Range as a collisional belt formed by oblique sinistral collision of the East Antarctic Craton and the Kalahari Craton, and closure of an intervening oceanic basin (the traces in East Antarctica of the Mozambique Ocean?) through an initial NE-ward subduction. The formation of the collisional orogen in the Shackleton Range may be thus related to the final amalgamation of East and West Gondwana during late Precambrian-Cambrian time

Resistance to developing brain pathology due to vascular risk factors

Brain pathology develops at different rates between individuals with similar burden of risk factors, possibly explained by brain resistance. We examined if education contributes to brain resistance by studying its influence on the association between vascular risk factors and brain pathology. In 4111 stroke-free and dementia-free community-dwelling participants (62.9 ± 10.7 years), we explored the association between vascular risk factors (hypertension and the Framingham Stroke Risk Profile [FRSP]) and imaging markers of brain pathology (markers of cerebral small vessel disease and brain volumetry), stratified by educational attainment level. Associations of hypertension and FSRP with markers of brain pathology were not significantly different between levels of educational attainment. Certain associations appeared weaker in those with higher compared to lower educational attainment, particularly for white matter hyperintensities (WMH). Supplementary residual analyses showed significant associations between higher educational attainment and stronger resistance to WMH among others. Our results suggest a role for educational attainment in resistance to vascular brain pathology. Yet, further research is needed to better characterize determinants of brain resistance.</p

The subglacial geology of Wilkes Land, East Antarctica

Wilkes Land is a key region for studying the configuration of Gondwana and for appreciating the role of tectonic boundary conditions on East Antarctic Ice Sheet (EAIS) behavior. Despite this importance, it remains one of the largest regions on Earth where we lack a basic knowledge of geology. New magnetic, gravity and subglacial topography data allow the region's first comprehensive geological interpretation. We map lithospheric domains and their bounding faults, including the suture between Indo-Antarctica and Australo-Antarctica. Furthermore, we image subglacial sedimentary basins, including the Aurora and Knox Subglacial Basins, and the previously unknown Sabrina Subglacial Basin. Commonality of structure in magnetic, gravity and topography data suggest that pre-EAIS tectonic features are a primary control on subglacial topography. The preservation of this relationship after glaciation suggests that these tectonic features provide topographic and basal boundary conditions that have strongly influenced the structure and evolution of the EAIS

Subglacial geology and geomorphology of the Pensacola-Pole Basin, East Antarctica

The East Antarctic Ice Sheet (EAIS) is underlain by a series of low‐lying subglacial sedimentary basins. The extent, geology and basal topography of these sedimentary basins are important boundary conditions governing the dynamics of the overlying ice sheet. This is particularly pertinent for basins close to the grounding line wherein the EAIS is grounded below sea level, and therefore potentially vulnerable to rapid retreat. Here, we analyze newly acquired airborne geophysical data over the Pensacola‐Pole Basin (PPB), a previously unexplored sector of the EAIS. Using a combination of gravity, magnetic and ice‐penetrating radar data, we present the first detailed subglacial sedimentary basin model for the PPB. Radar data reveal that the PPB is defined by a topographic depression situated ~500 m below sea level. Gravity and magnetic depth‐to‐source modeling indicate that the southern part of the basin is underlain by a sedimentary succession 2–3 km thick. This is interpreted as an equivalent of the Beacon Supergroup and associated Ferrar dolerites that are exposed along the margin of East Antarctica. However, we find that similar rocks appear to be largely absent from the northern part of the basin, close to the present‐day grounding line. In addition, the eastern margin of the basin is characterized by a major geological boundary and a system of overdeepened subglacial troughs. We suggest that these characteristics of the basin may reflect the behavior of past ice sheets and/or exert an influence on the present‐day dynamics of the overlying EAIS