Download presentation
Presentation is loading. Please wait.
1
The Beauty and Economic Significance of Geologic Structures
2
Why study geologic structures? 1992 Landers, CA Earthquake (photo by Ramon Arrowsmith)
3
Understand and anticipate natural hazards (1995 Kobe Earthquake): (Slide by Ramon Arrowsmith) http://www.ngdc.noaa.gov/seg/hazard/slideset/21/21_slides.shtml
4
Mineral resources Energy & Mineral resources Magmatic segregation: gems in pegmatites: Hydrothermal solutions: important for concentating and precipitating ore deposits: Hot, metal-rich fluid migration as vein deposits or disseminated deposits (remobilized by faults) Crystallization in fluid-rich environment (Quartz Veins) (modified from slide by Ramon Arrowsmith)
5
Mucho oro!Mucho dinero!!
6
Los núcleos de perforadora diamante a la Zona Azul, Proyecto León
7
Types of oil traps (Keller, 2002)
8
Primary Geologic Structures Geometric features developed during formation of a rock body Microscopic to mountain scale Formed in sedimentary or igneous environments Provide clues about environment of rock formation
9
Sedimentary Structures Bedding Uncomformities Cross bedding Graded bedding Ripple marks Mud cracks Trace fossils Etc.
10
Bedding (stratificación) in the Grand Canyon (Cañón Grande): Sediments originally deposited in horizontal orientation Superposition: oldest layers on the bottom, youngest on top Major bedding planes separate sedimentary layers with contrasting properties (strength, porosity, permeability, resistance to erosion, etc)
11
Tilted bedding in Hawk Canyon (Cañada Halcón), December, 2008
12
Tilted bedding on San Miguel Island, May, 2004
14
San Miguel Island, May, 2004
16
Angular unconformity on San Miguel Island, May, 2004
17
Nonconformity in Cañada Halcón, February, 2007
18
Tilted nonconformity, Cañada Halcón, February, 2007
19
Proyecto León, Marzo, 2007
20
Proyecto León, Marzo, 2007(cross beds deposited originally non-horizontal)
21
Algadones Dunes (las dunas Algadones), January, 2007
22
Which way is the wind blowing?
23
Igneous Structures Flows Veins Dikes and Sills Chilled or baked margins Magmatic flow foliation Flow tops marked by vesicles Aa-aa vs. pahoehoe structure Stocks and batholiths Xenoliths or inclusions Magmatic segregations
24
Originally non-horizontal lava flow at Cerro Los Ojos, Sonora
25
Originally non-horizontal lava flow near Sierra Chocloduro, Sonora
26
Una vista mas cerca
27
Grand Canyon (photo by Ramon Arrowsmith)
28
San Antonio Canyon, March, 1998
29
Sierra la Salada, Marzo, 2007
31
Glendora Ridge Road, October, 2006
32
Culp Valley, November, 2007
33
Proyecto Colibri, Marzo, 2006
34
Zona Nopal, Deciembre, 2006
36
Mucho oro!
37
Este oro es mio!
38
Mis asistentes del campo, Proyecto León, Septiembre, 2007
39
Proyecto León, Septiembre, 2007
40
Proyecto León, Marzo, 2007
42
Mas núcleos de perforadora diamante a la Zona Azul, Proyecto León
43
Secondary Geologic Structures develop after formation of the rock body Folds Fractures and joints Faults and breccias Foliation and lineation Metamorphic fabrics like contact metamorphic aureoles and mylonitic S-C structures
44
Folds Photograph courtesy of Ramon Arrowsmith
45
Prince William Sound, Alaska, July, 2006
47
Palmer Canyon, San Gabriel Mountains, December, 2004
48
Palmer Canyon, San Gabriel Mountains December, 2004
49
Coastal Maine, July, 2007 (photo by Kayla Kroll)
51
Proyecto Colibri, Marzo, 2007
53
diagram from M.P. Searle Faults (mountain scale)
54
What is it? Moab normal fault, Utah (Slide courtesy of Greg Davis)
55
Whipple detachment fault, California (Slide from Greg Davis)
56
Younger on older, Low-grade (near surface) on High-grade (12 km) Ertomiao detachment fault, Lang Shan, China (Slide from Greg Davis)
57
σ 1 horizontal, σ 3 vertical — reverse faults σ 1 vertical, σ 3 horizontal — normal faults σ 1 horizontal, σ 3 horizontal — strike-slip faults (Slide designed by Greg Davis)
58
Hypothetically Reverse faults: should form at ~30° dip Normal faults: should form at ~60° dip Strike-slip faults: should form at ~90° dip Can you think of any exceptions?? (Slide designed by Greg Davis)
59
Common exceptions Thrust faults — mechanically unfavorable Low-angle normal faults — mechanically very unfavorable (Slide designed by Greg Davis)
60
Faults and Breccias at Outcrop Scale Manker Canyon, San Gabriel Mountains, October, 1994
61
Falla normal a Cañada Halcón, Deciembre, 2008
62
Mega Faults Sonoyta, Sonora, Jenero, 2006
65
Proyecto León, Marzo, 2007
66
Proyecto Ramaje Ardiente, Marzo, 2007
70
Proyecto Colibri, Jenero, 2006
72
Zona Nopal, Deciembre, 2006
73
Zona Nopal, Deciembre, 2006
74
Zona Nopal, Deciembre, 2006
75
Proyecto Elizabeth, Octubre, 2008
77
Diamond Drill Core from the Naranja Zone
78
Mylonites and Ductile Shear Zones
84
Foliation Planar fabric formed by ductile flow of minerals under directed stress Generally manifested as compositional layering Foliation plane generally oriented at high angle to maximum stress direction
85
San Gabriel Mountains, April, 2002
87
Arroyo Santa Felicita, Noviembre, 2008
92
Lineation
94
Arroyo Santa Felicita, Noviembre, 2008
95
What is the sense of shear? (Slide from Greg Davis)
96
Just how deformed is this rock? (Slide from Ramon Arrowsmith)
97
Or this one? What % extension has this rock experienced? (Photograph from Ramon Arrowsmith)
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.