Geol 470/770 – Neotectonics – Spring 2010 1
Death Valley Report
For the Death Valley project I would like you to put together summary reports for the
geology we encountered and discussed in the field for each of the three areas we
traversed during the trip: 1) the Southern Death Valley fault zone (SDVFZ) northeast of
the Noble Hills—Amargosa River area; 2) The Confidence Hills and SDVFZ—
Confusion Canyon area; and 3) the Northern Death Valley fault zone (NDVFZ)—area
north of Beatty Junction. For the first two parts, provide annotated versions of the NAIP
images we used in the field, field photos, figures and illustrations provided in class, and
perhaps sketches as figures to be included in the report. For the NDVFZ part of the report
you will be including an annotated surficial geology and fault map of the area we
traversed on the last day of the trip. To help facilitate the writing of the report I have
provided some suggested guidelines below.
Report Contents:
Introduction
geographic/tectonic setting (including a description of the Death Valley fault zone
and its principal components—e.g., the NDVFZ, the SDVFZ, and Black
Mountains fault zone)
dates of study and the areas examined during the trip
why the study was conducted (i.e., objectives)
what is being presented in the report
Southern Death Valley Fault Zone northeast of the Noble Hills—Amargosa River
area
Address the following:
Location of traverse with respect to the Southern Death Valley region and the
Southern Death Valley fault zone (SDVFZ)
Overall characteristics of the fault zone in general—general strike of the fault
zone, the type of fault, the map characteristics of the fault—is it composed of a
single strand or multiple strands?—are the fault traces linear—are the map traces
continuous or discontinuous—what are the estimated lengths the fault stands as
expressed in the southern part of SDV.
Characteristics of the fault zone specific to the traverse area—e.g., fault strands
exhibit a distinct left stepover—kind of structures expected along this type of
stepover along a RL slip fault.
Characteristics of the step over area— describe the age of strata that exhibits
intensive folding in this area—how do we know the age of the folded strata—
what is the general style and orientation of folding—is the orientation of folds in
the area what should be expected in this type of fault step over?—how has the
folding in this area been used to place limiting constraints on the amount of
displacement along the SDVFZ in this area.
Geol 470/770 – Neotectonics – Spring 2010 2
Descriptions of the tectonic geomorphology expressed along the fault where we
looked at it—e.g., mole tracks, offset/deflected stream channels
Summary of observations/measurements made of offset channels—mention what
offset measurements you felt most confident about and those you felt more
speculative about—did you walk away thinking you may have observed the
amount of fault offset associated with the most recent surface rupturing
earthquake on this part of the fault?
Use: 1) your best estimate of the amount of slip that was likely associated with the
most recent surface-rupturing event on the fault zone; and 2) the length of the
SDVFZ as expressed in the southern part of southern Death Valley (from the
southernmost part of the Noble Hills to the area of the traverse) to estimate the
earthquake magnitude that might be expected for this part of the fault. Use the
empirical data plots or regression equations (Wells and Coppersmith, 1994) to
estimate earthquake sizes from the two parameters (slip and fault length).
The Confidence Hills and SDVFZ—Confusion Canyon area
Address the following:
Location of the Confusion Canyon traverse with respect to the Southern Death
Valley region, the Confidence Hills (CH) and the Southern Death Valley fault
zone (SDVFZ)
Characterize the Confidence Hills geomorphically and with respect to the position
of the SDVFZ—e.g. long linear ridge between the Owlshead Mtns to the west and
the Black Mtns to the east—adjacent to and bound by the SDVFZ on the SW side
of the hills.
Charcterize the generalized stratigraphy of the CH as expressed along the
Confusion Canyon traverse—age of strata—how do we know the age of strata—
the types of strata (e.g., mainly highly deformed fine-grained lacustrine strata and
evaporites (the Confidence Hills Formation—CHF) overlain by fanglomerates
(the Captain)—describe the important stratigraphic relation between these two
units!
Characterize the generalized structure of the CH as expressed in the more highly
deformed strata of the CHF—the style of folding and what can we say about when
earlier folding occurred.
Characterize the SDVFZ similar to the previous section.
Estimate the expected earthquake magnitudes for the SDVFZ considering: 1) a
surface rupturing event on only the CH section of the SDVFZ; and 2) a surface
rupturing event on the entire SDVFZ from the southern part of the Noble Hills to
Shoreline Butte. Use the empirical data plots in Wells and Coppersmith (1994).
Geol 470/770 – Neotectonics – Spring 2010 3
Northern Death Valley Fault Zone—area north of Beatty Junction
The purpose of this exercise is to introduce you to aspects of mapping geomorphic
surfaces and tectonic geomorphic features, measuring offsets, and estimating slip rates
along strike-slip faults.
Surficial Geology and fault map of the Northern Death Valley fault zone just north of
Beatty Junction
1) From your field observations, produce an annotated map of the traversed section of the
Northern Death Valley fault zone. You should initially produce a map of the fault
trace, various fan units, and observations station numbers directly on the color
imagery and then transfer your mapped contacts (i.e., fault traces and fan unit
boundaries) onto the topographic base map provided.
2) All pertinent observations made in the field will ultimately be annotated directly on the
map such as: identifications of tectonic geomorphic features (e.g., shutter ridges,
pressure ridges) or measurements of right-laterally offset channel (in the annotations
make sure to identify the fan unit that offset channels are cut into).
3) Fault contacts: fault traces should be thin solid lines where the fault trace is actually
visible on the image or where you observed the fault trace in the field. Where the
fault is not expressed at the surface within younger fan units that have not experience
fault rupture, the fault trace should be shown as dotted (meaning concealed).
4) Fan unit contacts: fan unit boundaries should be drawn with very thin solid lines.
Once you have transfered and inked in you fan unit contacts use the following color
scheme (color units very lightly):
Q4a/b – light yellow
Q3c – amber
Q3b – light orange
Q3a – very light brown
Q2c – med brown
You might not interpret any of the units as Q2c. You may also not have reason to
separate Q4a from Q4b if you thought Q4a was faulted locally and Q4b was not. So
you may need to adjust your color scheme accordingly.
5) The map should have a title or caption and be accompanied by a ―Map Explanation‖
that includes ―Map Units‖ and ―Map Symbols‖ sections.
6) Include a brief summary in your report that addresses the following:
Geol 470/770 – Neotectonics – Spring 2010 4
Location of the traverse with respect to the Northern Death Valley region,
Furnace Creek, and the Northern Death Valley fault zone—also include the length
of part of the fault zone that was traversed
Characterize this section of the fault zone in general—is it a linear fault trace—
what type and general age of the deposits displaced by the fault in this area
Describe the stratigraphic nomenclature used for to distinguish different fan units
(include the table)
Summarize the tectonic geomorphology observed along the traverse—i.e., the
types of features observed—offset channel measurements—age constraints on
fault displacements based on the estimated ages of displaced fans.
Slip rate estimates? If so describe relations used to support these estimates.
Constraints on the age of the most recent surface rupturing event along this part of
the fault.
Similar to previous sections estimate the expected earthquake magnitudes for the
NDVFZ based on slip per event based on: 1) the amount of slip associated with
the most recent surface rupture event—if this info is available; and 2) the length
of the entire NDVFZ. As before use the empirical curves from Wells and
Coppersmith (1994).