 |
| Titel |
Tensor gradient field from GOCE as tool for gaining insight of the Amazon and the Solimões Basin, Brazil |
| VerfasserIn |
Everton Bomfim, Carla Braitenberg, Eder Molina |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250050825
|
|
|
|
|
|
| Zusammenfassung |
| We aim at gaining an improved understanding of the lithospheric structure beneath the
Solimões and Amazonas sedimentary basins by using the gradient tensor observations of the
GOCE mission.
The most direct way to detect density anomalies is the study of the gravity potential field and
its derivatives. The global availability and good resolution of the GOCE satellite data mission
coupled with the availability of data from terrestrial gravity and/or airborne gravity surveys
are ideal for the scope of intercomparison and classification of the two large-scale Amazon
and Solimões sedimentary basins.
In geological terms the Amazon and Solimões basins are very old and classified as
intracratonic Paleozoic basins; together they cover an area of almost 1,000,000 km2
separated by the Purus Arch. The basins belong to an intracontinental rift system that
straddles the border between Brazil and Guyana, covering some 4,500 km2 of the Brazilian
territory.
We consider the gravity gradient tensor components from global geopotential models as
EIGEN5C and EGM08 and the new fields recovered from the GOCE satellite.
We use various combinations of the gravity gradient components in order to enhance different
properties of the complex pattern of the field and to aid interpretation of the data. We use the
amplitude of the horizontal gradient of vertical gravity (gz); amplitude of the total gradient or
analytic signal of gz; and the differential curvature which is also known from the early
torsion balance literature as the horizontal directive tendency or HDT. The horizontal gradient
can be used as a detector of edges, or to map outlines of bodies. The analytical signal can be
used for interpretation of deeper masses. The magnitude of the differential curvature
strongly emphasizes the effects of shallower sources. The differential curvature
is proportional to the difference between the maximum and minimum curvature
of the geoid. It is an invariant under a rotation in the horizontal plane, and when
plotted as a vector it points towards high and low density. We present the different
quantities and compare them on the basis of a geological-geophysical database
which collects the known information in this area. Of particular interest in our study
is the linear positive signal that runs along the central axis of the Amazon basin:
we use the new observations to infer the origin of this signal, which is presently
unknown. |
|
|
|
|
|
|