I heard it first hand from a geologist who works for the Danish Geological Survey. A paper will be published within a month or so....the Greenland impact is about 120% the size of the Sudbury impact.
I also found a few references here:
geologi.no
page 57:
The 2975 Ma Maniitsoq impact struc- ture in West Greenland: the oldest and most deeply exposed meteorite crater on Earth
Garde, A.A.
Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 Copenhagen K, Denmark
An outstanding impact structure at 65°15 ´N, 51°50 ´E south-east of Maniitsoq in West Greenland was dis- covered in September 2009. The discovery was based on: 100 km-scale aeromagnetic, gravity and geological map patterns, shock lamellae in plagioclase, and sup- porting evidence from superheated ultramafic– dioritic intrusions, widespread intrusion breccias, and a remarkable overlap of 2975 Ma geochronological data. The meteorite hit the Mesoarchaean Fiskefjord block, which was accreted between c. 3070 and 2975 Ma by oceanic island arcs merging into a microconti- nent. The northern part of the impact area itself is only poorly known from geological reconnaissance prior to 1980.
The impact produced the fourth multi-ring crater so far discovered on the planet, besides Chicxulub, Sud- bury and Vredefort. It is by far the oldest known im- pact structure on Earth and has been eroded over time to 20–25 km below the impacted surface. Fur- thermore, the meteorite plunged into an active accre- tional orogen, and the impact structure includes a large impact-triggered pluton in its centre.
The core of the structure is the 35–40 km large, 2975 Ma, remarkably homogeneous, heart- or drop-shaped, tonalitic–granodioritic Finnefjeld gneiss complex that partly overlaps with an aeromagnetic high of similar dimensions and a gravity low. The Finnefjeld gneiss complex is known from previous work to post-date the main episodes of regional deformation, except fi- nal localised shearing which affects its SW end. The above-mentioned shock lamellae in plagioclase have been found in granitoid host rocks just outside the southern margin of the pluton.
Surrounding the core there is a c. 30 km wide, inner belt of orthogneisses and supracrustal amphibolites
that outline an aeromagnetic low. The inner belt dis- plays widespread intrusion breccias of unknown true extent, with a proximal dioritic matrix (probably a mixture of crustal melts and an ultramafic melt of un- known origin) and more distally, a granitic matrix. In places both types of matrix occur together. Within the inner belt a 65 km long, banana-shaped field (plus outliers) occurs, consisting of elongate, late- to post- kinematic, syn-breccia, noritic–dioritic igneous bod- ies. These intrusions are characterised by extremely wide hybrid margins, common proto-orbicular tex- tures, and boninite-like chemical compositions with high SiO2, Mg and Cr. Their distribution suggests that most of them were emplaced along a semicircular crustal-scale fracture. One body has previously been dated at 2976 ± 13 Ma. It is presently not known if the ultrabasic component has been derived from the mantle, in which case the intrusions were emplaced upwards, or if they contain components of the initial impact melt and were emplaced downwards.
A more than 30 km wide outer belt coinciding with an aeromagnetic high comprises TTG gneisses and su- pracrustal rocks as well as several large, late- to post- kinematic, 2975 Ma crustal granites. It is currently uncertain how intensely the outer belt was affected by the impact; large areas are only known from geo- logical reconnaissance. However, a few small post- kinematic noritic–dioritic bodies have also been re- corded here, and the total overlap of granite ages ap- pears to be more than a coincidence.
The mere size and depth of exposure of the Maniitsoq impact structure will greatly improve our under- standing of the deep-crustal physical and chemical as- pects of large impact events. The timing of the impact into an active orogen is also unique, with its regional and instantaneous imprint on the middle and lower crust, and possibly the upper mantle. The structure furthermore holds a potential for preserved extra- terrestrial material that would increase our know- ledge of the earliest accretion of the Earth and early life.
stockhouse.com
The Greenland Geological Survey (GEUS) is currently investigating the possibility that the Finnefjeld gneiss complex lies at the centre of an extremely large, deeply eroded meteor impact structure and that the Maniitsoq norites may have been emplaced as a result of the impact. If so the Maniitsoq norites would be the only other known nickeliferous norites associated with an impact outside of the Sudbury Basin.
John Ferguson, a world expert in meteorite impacts, and John Rowntree of Hunter Minerals Pty Limited (“Hunter”) investigated the relevant geo-data base and concluded that the Maniitsoq structure is compatible with a large deeply eroded impact site. Hunter approached NAN with the opportunity to acquire the intellectual property and data developed by them and offered their assistance in connection with the acquisition of the Mineral License.
Adam Garde, a Danish Geological Survey geologist, also argues that the Maniitsoq area is an impact structure much like the Sudbury Basin in Ontario, Canada.
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