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Eustatic controls on stratigraphy, chemostratigraphy, and water mass evolution preserved in a Lower Permian mudrock succession, Delaware Basin, West Texas, USA

Hardie S. Nance and Harry Rowe
Eustatic controls on stratigraphy, chemostratigraphy, and water mass evolution preserved in a Lower Permian mudrock succession, Delaware Basin, West Texas, USA (in Shale paleoenvironments, Bruce Hart (prefacer), Gilles Hennenfent (prefacer), Joe Macquaker (prefacer) and Harry Rowe (prefacer))
Interpretation (Tulsa) (February 2015) 3 (1): SH11-SH25

Abstract

Bone Spring (Leonardian) mudrock successions in Delaware Basin vary between silica- and carbonate-rich facies marking depositional responses to sea-level changes. Increased Mo, delta (super 15) N, and total organic carbon (TOC) record reduced oxygenation during sea-level lowstands. In a 91.4-m (300 ft) core from Sun No. 1 Houssels well and a 39.6-m (130 ft) core from Shell No. 1 Marsden well (Reeves Co., Texas), lower Bone Spring cycles comprised siliceous-calcareous mudrock couplets. The Marsden core was correlative to the upper part of the Houssels core. Cyclicity was interpreted from mineralogical calculations at numerous core horizons using energy-dispersive X-ray fluorescence (ED-XRF) measurements of elemental content. Elemental abundances enabled predicting mineralogy based on the stoichiometric relationships between elements and dominant minerals (calcite and quartz), and from average values of Si and K in published illite analyses. The average sample spacing for ED-XRF measurements was 0.24 m (0.8 ft) for the Houssels core and 0.15 m (0.5 ft) for the Marsden core. The measurements and interpretations provided: (1) information regarding comparisons in stratigraphic and geographic development of facies over the 10-km (6.2-mi) distance between wells and (2) guidance for petrographic, scanning electron micrograph, and organic matter analyses that address processes that produced different facies. Greater carbonate abundance in the Houssels core reflected the proximity to carbonate shelves on the Central Basin Platform (CBP); the greater siliciclastic abundance in the Marsden core was thought to reflect the greater distance from the CBP. Redox element (S and Mo) and TOC concentrations were greater, and delta (super 15) N values were higher in some siliciclastic-dominated intervals, suggesting that anoxia characterized sea-level lowstands when normal marine water flowing from the Panthalassa Ocean was inhibited through narrow interbasin channels or over sills. Carbon isotope (delta (super 13) C (sub TOC) ) variations suggested changes in organic matter characteristics, whereby greater (super 13) C-depleted organic matter was deposited during sea-level lowstands, marking: (1) reduction of shallow-marine sources or (2) increased terrigenous organic carbon contributions.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 3
Serial Issue: 1
Title: Eustatic controls on stratigraphy, chemostratigraphy, and water mass evolution preserved in a Lower Permian mudrock succession, Delaware Basin, West Texas, USA
Title: Shale paleoenvironments
Author(s): Nance, Hardie S.Rowe, Harry
Author(s): Hart, Bruceprefacer
Author(s): Hennenfent, Gillesprefacer
Author(s): Macquaker, Joeprefacer
Author(s): Rowe, Harryprefacer
Affiliation: Bureau of Economic Geology, Austin, TX, United States
Affiliation: Statoil, Houston, TX, United States
Pages: SH11-SH25
Published: 201502
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 32
Accession Number: 2016-007498
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. col., 1 table, sketch maps
Secondary Affiliation: Chevron, USA, United StatesExxonMobil, USA, United StatesBureau of Economic Geology, USA, United States
Source Note: Online First
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201604
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