The Gulf of California and its surrounding land areas provide a classic example
of recently rifted continental lithosphere. The recent tectonic history of eastern Baja
California has been dominated by oblique rifting that began at ~12 Ma. Thus,
extensional tectonics, bedrock lithology, long-term climatic changes, and evolving
surface processes have controlled the tectono-geomorphological evolution of the eastern
part of the peninsula since that time. In this study, digital elevation data from the Shuttle
Radar Topography Mission (SRTM) from Baja California were corrected and enhanced
by replacing artifacts with real values that were derived using a series of geostatistical
techniques. The next step was to generate accurate thematic geologic maps with high
resolution (15-m) for the entire eastern coast of Baja California. The main approach that
we used to clearly represent all the lithological units in the investigated area was objectoriented
classification based on fuzzy logic theory. The area of study was divided into
twenty-two blocks; each was classified independently on the basis of its own defined
membership function. Overall accuracies were 89.6 %, indicating that this approach was
highly recommended over the most conventional classification techniques. The third step of this study was to assess the factors that affected the
geomorphologic development along the eastern side of Baja California, where thirty-four
drainage basins were extracted from a 15-m-resolution absolute digital elevation model
(DEM). Thirty morphometric parameters were extracted; these parameters were then
reduced using principal component analysis (PCA). Cluster analysis classification
defined four major groups of basins. We extracted stream length-gradient indices, which
highlight the differential rock uplift that has occurred along fault escarpments bounding
the basins. Also, steepness and concavity indices were extracted for bedrock channels
within the thirty-four drainage basins.
The results were highly correlated with stream length-gradient indices for each
basin. Nine basins, exhibiting steepness index values greater than 0.07, indicated a
strong tectonic signature and possible higher uplift rates in these basins. Further, our
results indicated that drainage basins in the eastern rift province of Baja California could
be classified according to the dominant geomorphologic controlling factors (i.e., faultcontrolled,
lithology-controlled, or hybrid basins).
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1518 |
| Date | 15 May 2009 |
| Creators | El-Sobky, Hesham Farouk |
| Contributors | Dorobek, Steven L., Tchakerian, Vatche P. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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