|
Primary Author Information |
| Name |
Alejandro Alberto Tassone |
| Affiliation |
018270 |
| Co-Author
Information |
| Co-Author - 1 |
Name |
JUAN FRANCISCO VILAS |
| Affiliation |
009848 |
| Co-Author - 2 |
Name |
Maria Alejandra Comba |
| Affiliation |
018277 |
| Co-Author - 3 |
Name |
Horacio Francisco Lippai |
| Affiliation |
018273 |
| Co-Author - 4 |
Name |
Emanuele Lodolo |
| Affiliation |
019228 |
| Co-Author - 5 |
Name |
Marco Menichetti |
| Affiliation |
019233 |
| Co-Author - 6 |
Name |
Jose Luis Hormaechea |
| Affiliation |
019220 |
|
Abstract Information |
| Abstract Number |
3 |
| Abstract Title |
MAGNETIC AND GRAVITY MODELLING ON FUEGUINIAN
FOLD-AND-THRUST BELT. ARGENTINE |
| Presentation Style |
POSTER |
|
Abstract Submission |
| Speaker |
Co-Author1
|
| Abstract Body Preview |
| The studied area is localized in
the central northern side of the Fueguian Andes, where the structures of
the external thrust front propagate through to the Magallanes thin-skinned
foreland fold-and-thrust belt. A system of Oligocene-Quaternary E-W (the
Magallanes-Fagnano Fault System, MFS) left-lateral strike- slip faults
with an extensional component overprints the contractional structures and
is responsible for the main depression of the Lago Fagnano. A Quaternary
system of N-S faults with right-lateral strike-slip attitude crosses all
the previous structures and probably constitutes the present day
deformation strain field in the eastern part of the Island. Geophysical
field surveys allowed to acquire 440 DGPS-fixed data points where gravity,
magnetic and magnetic susceptibility measurements were performed. In the
surveyed area, the MFS segments have clear morphological expression, and
are associated with localized gravity minima in correspondence of their
unconnected ends. At the ESE tip of Lago Fagnano, the magnetic data
suggest the existence of several intrusive bodies in the subsurface. The
magnetic anomaly for each of these bodies indicates a rotation in relation
to the N-S direction. The geophysical modeling of an outcropping
monzodioritic body revealed a piston shape. A 2D numeric modeling was
performed (employing the IGMAS software) with the data of total Bouguer
anomaly. The model displays a N-S section of about 40 km through the upper
10 km. A 2D numeric modeling was performed with the data of total magnetic
anomaly using the Geomodel software. The model N-S cross-section through
the area combines the acquired gravity data with the field geological
information and the geometry of the deep structures derived from
industrial seismic reflection lines. A very good fitting was observed
between the measured and computed values for the basement depth whose
modelized geometry indicates a southward deepening from 5 km to 7 km. The
model geometry of the deep duplex with buried leading edge is
geometrically similar to the structures exposed in the western part of the
Island. The model geometry of passive roof thrusts and back-thrust that
develop the triangle zone north of the Lago Fagnano area is well
constrained with the geological field data and well marked by the seismic
reflectors of the shear zones. The lower detachment levels have up to 40%
of shortening, while the upper structures display less than 20% of
contraction. In the modelized section the MFS is related to a -49 miliGal
minimum. The offset of the strike-slip faults toward the plane of the
section constitutes one of the main incertitude for lack of geometrical
tags. Field geological data and regional considerations indicate that the
offset could be about few tens of km. |
|
Symposium or Workshop (First Preference) |
| Symposium or Workshop (First Preference)
|
JSA07 |
|
Symposium or Workshop (Second Preference) |
| Symposium or Workshop (Second Preference)
|
GAV.07 |
|
Keyword One |
| Keyword One |
0903 |
|
Keyword Two |
| Keyword Two |
8015 |
|
Keyword Three |
| Keyword Three |
9360 |
|
Is a Student Author presenting the paper? |
| Student Paper |
NO |
|
Equipment Requested for Presentation |
| Equipment Requested for Presentation
|
Overhead Projector |
|
Notes |
| Notes |
|