Earth and Planetary Sciences ETDs

Publication Date

12-1-2014

Abstract

The fluvial deposits of the early Paleocene Nacimiento Formation are comprised of variegrated mudstones with interbedded paleosols and channel sandstone bodies. This study documents these strata in a ~1 km2 outcrop area at Kutz Canyon, San Juan Basin, New Mexico, by employing fully georeferenced lidar intensity data collected from a terrestrial lidar scanner and an outcrop surface model constructed from the lidar data and calibrated digital field photographs. At this location, the lidar intensity data are responsive to lithology and distinct lidar facies are identified which correspond to facies types described in measured stratigraphic sections. One dimensional lidar intensity logs resemble subsurface gamma-ray logs in form and can be related with subsurface observations. Further, the structural dip of these strata was estimated by digitizing a key marker paleosol. We rotated the data along this dip using the scanner software, which provided more accurate correlations. Width-to-thickness ratios of a ribbon sandstone channel and a thick meter-scale sheet sandstone were also calculated. Wavelet analyses conducted on the lidar intensity data yielded a periodic signal at 6.5 m over a vertical thickness of 25 m. The recurrence interval of this signal is estimated to be approximately 34 kya and is interpreted as depositional products of successive avulsion episodes, or depositional lobe switching on a distributive fluvial system. Trenching through the weathering crust present on outcrop along two measured stratigraphic sections indicated that while gross lithology can be determined from the lidar intensity data, small-scale textural details cannot. As a result, a stacking-pattern analysis focused on identifying and then creating accommodation plots for fining-upward fluvial cycles was done exclusively on the measured sections. The cycle trends were only correlative when analyzed above the stratigraphic level that contained a thick sheet sandstone present in one of the sections. The results of this work illustrate the versatility of using lidar datasets in stratigraphy. A future project could potentially apply these methods to a larger area across Kutz Canyon and may have to ability to document indistinct stratal geometries on a multi-kilometer scale that could further be used to better understand the large-scale architecture of fluvial systems.

Degree Name

Earth and Planetary Sciences

Level of Degree

Masters

Department Name

Department of Earth and Planetary Sciences

First Advisor

Gary Weissmann

First Committee Member (Chair)

Maya Elrick

Second Committee Member

Louis Scuderi

Third Committee Member

Thomas Williamson

Language

English

Keywords

lidar, Paleocene, New Mexico, Fluvial, Nacimiento Formation

Document Type

Thesis

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