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.
","abstract_html":"<p>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.</p>","abstract_has_math":false,"creators":["O'Hare, Daniel J."],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Thesis","degree_discipline":"Earth and Biological Sciences","degree_department":null,"school":null,"contributors":["Nick, Kevin E.","Brand, Leonard R.","Buchheim, H. Paul","Nalin, Ronald"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2015,"date_issued":"2015-12-01T08:00:00Z","date_published":"2015-12-01T08:00:00Z","updated_at":"2026-07-24T02:52:38Z","subjects":["Earth Sciences","Geology","Sedimentology","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","Lithology; Sedimentary structures; Paleoenvironmental model; Cross-stratification; Ripple laminations"],"languages":["English"],"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."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/333","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Nick, Kevin E.","Brand, Leonard R.","Buchheim, H. 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The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/333"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:title","label":"Title","values":["High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru"]}]}],"canonical_facts":{"dc:contributor":["Nick, Kevin E.","Brand, Leonard R.","Buchheim, H. Paul","Nalin, Ronald"],"dc:creator":["O'Hare, Daniel J."],"dc:description.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.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/333"],"dc:language":["English"],"dc: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."],"dc:subject":["Earth Sciences","Geology","Sedimentology","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","Lithology; Sedimentary structures; Paleoenvironmental model; Cross-stratification; Ripple laminations"],"dc:title":["High-Resolution Correlation of a Time-Bounded Unit of the Pisco Formation, Peru"],"thesis:degree_discipline":["Earth and Biological Sciences"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T02:52:38Z"}