Abstract

Correlation of beds in the Pisco Basin across significant distances is problematic and has not yet been effectively achieved. I chose to examine an interval bounded by two time markers, an 40Ar/39Ar-dated white tuff at the base and an 40Ar/39Ar-dated tuff couplet at the top. This interval was chosen because of the continuity and excellent exposure of the tuff beds at six distinct locations in a linear transect 30 km long. Correlation of units was achieved through 40Ar/39Ar dating, lithology, sedimentary structures, and magnetic susceptibility. The vertical and lateral variability in lithology, fossil assemblages, structures, and sequences was examined in detail and used to develop a paleoenvironmental model of the time-bounded sequence. Six distinct facies from the Pisco Formation were defined and used toward developing the paleoenvironmental model. Sedimentary structures associated with the facies, such as hummocky cross-stratification and ripple laminations, suggest wave reworking in a nearshore environment. The presence of clastics and coarse-grained sediments decrease from the northern outcrops to the southern outcrops, suggesting a decrease in energy levels and an increase of water depth away from the shore. This study provides the first secure correlation across a significant distance and a more comprehensive stratigraphy and paleoenvironmental interpretation of the Upper Pisco Formation.

LLU Discipline

Geology

Department

Earth and Biological Sciences

School

School of Medicine

First Advisor

Nick, Kevin E.

Second Advisor

Brand, Leonard R.

Third Advisor

Buchheim, H. Paul

Fourth Advisor

Nalin, Ronald

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2015

Date (Title Page)

12-2015

Language

English

Library of Congress/MESH Subject Headings

Sediments (Geology) - Peru - Pisco Formation; Sedimentation and deposition - Peru - Pisco Formation; Geology, Stratigraphic - Miocene; Geology, Stratigraphic - Pliocene; Stratigraphic correlation; Sequence stratigraphy; Magnetic susceptibility; Radioactive dating

Subject - Local

Lithology; Sedimentary structures; Paleoenvironmental model; Cross-stratification; Ripple laminations

Type

Thesis

Page Count

169

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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