Tectonic Development of the Amerasian Basin with Implications for Surrounding Arctic Regions
The tectonic development of the Circum-Arctic region has long been debated due to its physical remoteness, complexity, scale and relative paucity of subsurface data. In particular, the Amerasian (Canada) Basin remains a geological enigma. Although most prevailing models favor a rotational movement of Arctic Alaska/E Siberia away from the Canadian Arctic Islands, the details and timing remain unclear and most resulting reconstructions fail to explain the evolution of the Chukchi Borderlands - a key element.
Using regional geology, seismic and well control with
newly compiled potential field data, a new tectonic model
is proposed that has
significant impact on timing and opening of the Amerasian (Canada) and
surrounding Circum Arctic regions. The
model
highlights the formation of the Amerasian Basin in the mid to late Jurassic when a continental block consisting
of northern Alaska and a portion of East Siberia rifted away from the Canadian
Arctic Islands around a pole of rotation in the onshore Richardson Mountains
region. This region has subsequently been overprinted by deformation in the NE
Brooks Range orogen. The Chukchi Borderlands consists of highly extended
continental crust that rifted away and rotated from East Siberia during this
Jurassic rifting event. An early Jurassic palinspastic restoration provides a
tight and compelling pre-rift fit of the two conjugate margins. Whereas
previous models invoked an Early Cretaceous opening of the Amerasian Basin
marked by the LCU (Lower Cretaceous Unconformity) defining the rift-drift
transition, the LCU represents a flexural unconformity related to Brookian
thrusting in our
model
to explain the observed magnetic anomaly data.
A selection of paleogeographic maps across the
Circum-Arctic are presented ranging from the early Triassic to Paleocene-Eocene
times. The maps were created using key stratigraphic and structural data
restored to their paleo-positions via PaleoGISTM. In addition, a Circum-Arctic
stratigraphic chart was compiled from various sources to validate and constrain
the proposed tectonic model
and resultant maps. This process facilitated
regional basin tectonic analysis and extrapolation of proven reservoir and
source rock trends into under-explored or data-poor areas highlighting potential
‘white-space’ areas for future exploration.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California