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March 2011 Master of Science in Geological & Mining Eng & Sciences
Plio-Quaternary kinematics and geometry of the Calama-Olacapato-El Toro fault zone across the Puna Plateau, Argentina
A brief overview of my MS Thesis project and INVOGE experience
Federica Lanza
UMB Supervisor: Prof. A. TibaldiAssistant supervisor: Prof. C. Corazzato
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University of Milano-Bicocca - Faculty of Mathematics, Physics and Natural Sciences and
Michigan Technological University – College of Engineering
MTUSupervisor: Prof. G. P. Waite
March 2011 Master of Science in Geological & Mining Eng & Sciences
PURPOSE OF THE WORK
Geological and structural field data were collected along The Calama-Olacapato-El Toro (COT) fault zone, where it crosses the Puna Plateau (Argentina).
Introduction
2
San Antonio De
Los Cobres
COT
Structural stations
Fault
After Jordan et al. (1983)
March 2011 Master of Science in Geological & Mining Eng & Sciences
To reconstruct the fault kinematics and the fault geometries through the individuation of striated fault planes and the offset of surface deposits and landforms.
To perform a stress analysis through time by
(I) reconstructing the paleostress tensor using stress-inversion methods
(II) determining stress orientations via study and new calculations of focal mechanisms
To connect faults with recent seismic events and provide information about the seismic risk of the region
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Principal Aims
March 2011 Master of Science in Geological & Mining Eng & Sciences
GEOLOGICAL AND STRUCTURAL SETTING
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The Calama – Olacapato – El Toro Fault Zone (COT)
Transversally crosses the Andean chain and the Puna Plateau at about 24° S.
NW-SE trending left-lateral trascurrent fault system
Can be considered the surface expression of ancient deep crustal trans-lithospheric structures, which have been periodically reactivated
Along with the Archibarca Transverse Zone, the COT is considered a bounding structure of regional importance
From Chernicoff et al. (2002)
March 2011 Master of Science in Geological & Mining Eng & Sciences
Creates favourable tectonic conditions for the locus of mineralizations.
Young volcanic activity (from Miocene to recent times) developed along this fault zone forming an important NW-SE trending volcanic belt constituted by several stratovolcanoes , monogenenitic cones and calderas. E.g: Tugzle, San Jeronimo, Negro De Chorrillos
The Calama – Olacapato – El Toro Fault Zone (COT)
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March 2011 Master of Science in Geological & Mining Eng & Sciences
WHAT I HAVE DONE
Field activities
Interpretation of satellite images
Field surveys:
- Faults measurements (dip direction, dip angle, pitch and kinematic indicators)- Geomorphological observations- Calculation of river offsets and associated slip rates- Logs of paleosismological sections
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March 2011 Master of Science in Geological & Mining Eng & Sciences
Example of paleoseismological section
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Fault gauge, pebble and boulder alignments
High density of fractures and secondary faults
Faulting occurred during multiple events with surface ruptures
March 2011 Master of Science in Geological & Mining Eng & Sciences
First Assumptions from structural data, and measurements collected in the field
The surface trace is rectilinear suggesting a vertical dip at least in the uppermost crust.
Considering the kinematics, a vertical component is usually present in the form of relative uplift of the northeastern tectonic block.
In the Chilean region, field evidence of Plio-Quaternary motions disappears and so the COT lineament should be older there.
Open fissures are only partially filled and are not located along or close to slopes. They might be interpreted as evidence of prehistoric/historic surface faulting.
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Faults offset Pliocene or Pleistocene volcanic deposits suggesting a Plio-Quaternary activity of the Puna Plateau segment of the COT fault zone.
March 2011 Master of Science in Geological & Mining Eng & Sciences
N=12
MP=
66.67%
4
N=6
MP=
83.33%
5
N=9
MP=
44.44%
6
N=7
MP=
71.43%
7
N=6
MP=
50%
22
10
MP=
100%
N=3
11
MP=
50%
N=6
19
MP=
100%
N=5
98
MP=
60%
N=5 N=8
MP=
50% MP=
100%
N=3
107 108 60
MP=
60%
N=5
21
MP=
57.14
%
N=7 N=7
MP=
42.86
% 28
N=23
MP=
52.17
%
N=19
MP=
47.37
%
W
E
82-104-105-
106
N=6
MP=
83.33%
30
First Results from Initial Processing: fault geometry as obtained by rose diagrams
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March 2011 Master of Science in Geological & Mining Eng & Sciences
457
6
22
10
11
19
98 107
108
60 21 28
30
82-104-105-
106
E
W
Direction of
compression
Direction of
extensionσ1 σ2 σ3
Stress Analysis (I): results from numerical inversion of striated fault planes
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March 2011 Master of Science in Geological & Mining Eng & Sciences
456722
10
11
19
98 107 108 60 21 28
W
E
82-104-105-
106
30
Compressive Tensile
Fault Plane Solutions: Right Dihedra Method of Angelier and Mechler (1977)
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March 2011 Master of Science in Geological & Mining Eng & Sciences
WHAT IS LEFT TO DO
Project developement
Stress Analysis (II)
- calculation of focal mechanisms in order to compare them to those derived from the inversion of striated fault planes
Research in seismic catalogs (CERESIS and IRIS) about the seismicity of the area in order to connect faults with recent seismic events and to provide information about the seismic risk of the region
Expected date of finishing: end of this summer (August 26th 2011)
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March 2011 Master of Science in Geological & Mining Eng & Sciences
Coursework and acquired skills
How to write a research paper
How to write a review paper
Interpret seismic signals fromvolcanoes, how to use MATLAB
Chance to learn physicalvolcanology and interpret volcanodeposits.
Field methods and seismic data processing
Volcanology
Global Geophysics and Geotectonics
Volcano Seismology (currently enrolled)
Research project
Volcanology Field trip to New Mexico (as Special Topic in Geology)
IRIS/PASSCAL Instrument Center and EarthScope USArray Array Operations Facility summer student internship at New Mexico Tech.
THE OVERALL INVOGE EXPERIENCE
… and what will happen before I leave for Italy
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March 2011 Master of Science in Geological & Mining Eng & Sciences
Highlights
Unique courses
Unique opportunities
Increase effectiveness by different learning approach
Implementation of new tools
Improve organizational competence
Development of personal skills
Inspiring, creative, and cosmopolitan environment
American culture
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March 2011 Master of Science in Geological & Mining Eng & Sciences
Questions?
Thank you!
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