This file includes three folders containing GE lines, polygons,
annotated points, embedded imagery, and hyperlinks that help demonstrate
hypothetical, far-field crustal and body
strains occurring on Earth that developed in response to large,
hyper-velocity bolide (asteroid and comet) impacts. This is a working
hypothesis that has not yet been throughly scrutinized by
the general scientific community.
The strain effects are
separated into two folders for two
known and seven suspected impact events. The known impacts includethe
Chicxulub and Chesapeake events of ~65 Ma and ~35 Ma respectively,
located on the North American plate. The
seven suspected impact events reamin unproven, are located around the
Earth and their timing is interetped to span the Paleozoic to
late Cenzoic eras. Each of these events are hypothesized to
deeply fracture the lithosphere and some possibly perturb tectonic-plate
motions.
The far-field
body strains include circumferential crustal
welts and seismic zones, foreland shear fractures and thrust-faults,
and hinterland extension fractures and normal faults that are
systematically disposed about craters. Foreland compression paths are
illustrated using line that parallel
each bolide's descent trajectorys.
Many of these events are
thought to be single impacts, but others involve multiple
strikes, spalled projectiles, and strewn fields. Many of these
features were mapped
using Lambert equal-area, azimuthal projections
about each crater using a geographic
information system. Other strain features are
mapped using GE. Each crater is named and assigned an estimated age based on
preliminary geological studies including the use of data from deep-sea
(DSDP) and ocean-drilling
(ODP)
projects.
Ancillary data within a third folder inlcude plate boundary models,
continental geology by era imagery,
ocean-floor isochrons (Müller and others, 1997,
2008),
and
crustal-motion vectors from
global, ground-based GPS
data
(NASA JPL). Vector
size is scaled relative to velocity (factored by 0.1 degree for display
in geographic space).
This revision includes a report of newly suspected major impact
in the Amazon basin near the Xingu River, Brazil. This is the
7th, large one mapped, and it's delineation benefits greatly
from detailed studies of crustal thickness across the region (Tassara
and others, 2007).
Please read
Far-Field
Bolide-Impact Strains on
Earth for a brief
summary of prior work.
References
Müller, R.D.,
Roest, W.R., Royer, J.-Y., Gahagan, L.M. and Sclater, J.G., 1997. Digital
isochrons of the world's ocean floor. Journal of Geophysical Research, 102:
3211-3214.
o GE
Müller, R.D.,
Sdrolias, M., Gaina, C. and Roest, W.R., 2008. Age, spreading rates and spreading
asymmetry of the world's ocean crust. Geochem. Geophys. Geosyst., 9(Q04006):
doi:10.1029/2007GC001743.
Tassara A., Swain C., Hackney R.,
Kirby J., 2007, Elastic thickness structure of South America
estimated using wavelets and satellite
derived gravity data. Earth Pl. Sci. Lett., 253, 17-36. |
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