Plio-Quaternary kinematics and geometry of the Calama-Olacapato-El - - PowerPoint PPT Presentation

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. Tibaldi Assistant supervisor: Prof. C. Corazzato

1 University of Milano-Bicocca - Faculty of Mathematics, Physics and Natural Sciences and Michigan Technological University – College of Engineering

MTU Supervisor: 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

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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%

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N=6

MP= 83.33%

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N=9

MP= 44.44%

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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 %

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N=23

MP= 52.17 %

N=19

MP= 47.37 %

W E 82-104-105- 106

N=6

MP= 83.33%

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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 4 5 7 6 22 10 11 19 98 107 108 60 21 28 30 82-104-105- 106 E W Direction of compression Direction of extension

σ1 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

4 5 6 7 22 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 from

volcanoes, how to use MATLAB

• Chance to learn physical

volcanology and interpret volcano deposits.

• 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!