Stratigraphy, sediment dispersal and paleogeography of the lower Eocene San Jose Formation, San Juan Basin, New Mexico

Smith, Larry N.

doi:10.56577/ffc-43.297

Cited by 7 publications

(28 citation statements)

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“…1), we pick the base of the Cuba Mesa 250 m higher in elevation than did Stone et al (1983: sheet 4, well log 218) on the same well log. Based on our correlation of the base of the San Jose Formation along the axis of the San Juan Basin, the San Jose Formation reaches a maximum thickness of 608 m (Smith 1988: well log 177), which is significantly less than the 811 m thickness reported by Stone et al (1983: well log 219).…”

Section: Stratigraphy Of the San Jose Formation And Subjacent Strata ...contrasting

confidence: 50%

“…West-to-east tracing of a distinct sandstone interval at the base of the San Jose in Colorado is difficult because of vegetation cover (Barnes et al, 1954). The lack of matching strata between the Mesa Mountains and the H-D Hills (Barnes et al, 1954) suggests a pinchout in this area of an otherwise continuous basal sandstone (Smith, 1988). This region lies near the north-northwest-trending structural axis of the San Juan Basin and may be laterally equivalent to the northwest-trending pinchout of the Cuba Mesa Member described in our report.…”

Section: Regional Correlation Of Members Of the San Jose Formationsupporting

confidence: 49%

“…He also recognized an "unnamed member," composed mostly of mud-rock, north of the Llaves Member and suggested that it is time-and facies-equivalent of, but not laterally continuous with, the Regina Member (Baltz, 1967: 56). Stratigraphic data included in the present report and Smith (1988) indicate the necessity for some modifications to Baltz's work outside of the southeastern portion of the San Juan Basin (Fig. 4).…”

Section: Previous Studiesmentioning

confidence: 71%

“…The transitional nature of the contact from conformable to unconformable has not been analyzed or discussed in any detail. Contact relationships between the San Jose and Animas Formations in the northernmost San Juan Basin have been shown to be intertonguing (Smith, 1988). The presence of Tiffanian strata indicates that upper Paleocene strata are preserved below and/or laterally adjacent to the San Jose Formation in Colorado.…”

Section: Previous Studiesmentioning

confidence: 99%

“…In this paper we report on the stratigraphy and paleontology of that part of the San Jose Formation that lies between its southern and northern outcrop areas. We also include a discussion of the sedimentology of these strata, a subject which, except for Smith (1988), has not been reported for any part of the San Jose Formation. This study of the San Jose is part of an effort to decipher the basinwide stratigraphy of the unit, which will help to determine the (1) paleogeographic controls on the distribution of facies throughout the basin, (2) stratigraphic relationships between the contiguous Paleocene Animas and Nacimiento Formations and the San Jose, (3) stratigraphic relationships between members of the San Jose (Baltz, 1967: 56), (4) completeness of the rock record in the northern versus the southern San Juan Basin, and (5) physical stratigraphy of paleontological sites.…”

Section: Introductionmentioning

confidence: 99%

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Stratigraphy, sedimentology, and paleontology of the Lower Eocene San Jose Formation in the central portion of the San Juan Basin, northwest New Mexico

Smith¹,

Lucas²

1991

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The lower Eocene San Jose Formation in the central portion of the San Juan Basin of New Mexico consists of the Cuba Mesa, Regina, Llaves, and Tapicitos Members. Well-log data indicate that, from its 100 m thickness, the Cuba Mesa Member thins towards the center of the basin and pinches out to the northeast by latitude 36 deg. 40' N, longitude 107 deg. 19' W. The Regina Member crops out most extensively in the study area and decreases in sandstone-to-mudrock ratio to the north. The Llaves and Tapicitos Members occur only in the highest locales of the area, are thin due to erosion, and are not mappable as separate units.Well-log data and 1275 m of measured sections in the Regina, Llaves, and Tapicitos Members indicate that strata in the study area are made up of approximately 35% medium- to coarse-grained sandstone and 65% fine-grained sandstone and mudrock. Sedimentology and sediment-dispersal patterns in the study area suggest deposition by generally south-flowing streams that had sources to the northwest, northeast, and east. Low-sinuosity, sand-bedded, braided(?) streams shifted laterally across approximately 1 km wide channel belts to produce sheet sandstones that are prominent throughout the formation. Levees separated channel environments from floodplain and local lacustrine areas. Avulsion relocated channels periodically to areas on the floodplain, resulting in the typically disconnected sheet sandstones within muddy overbank sediments of the Regina Member.Fossil plants from lacustrine strata of the Regina Member at Santos Peak are the only flora described from the San Jose Formation. They indicate a humid, forested environment in the depositional basin. Fossil vertebrates from the Regina Member include the mammal taxa Phenacolemur praecox, Oxyaena forcipata, Ectoganus gliriformis, Esthonyx bisulcatus, Coryphodon molestus, Hyopsodus miticulus, Phenacodus primaevus, and Hyracotherium angustidens. These taxa support correlation with the Almagre local fauna of the Regina Member in the east-central San Juan Basin. They are thus indicative of a middle Wasatchian (Lysitean) age, about 53 Ma.

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Section: Stratigraphy Of the San Jose Formation And Subjacent Strata ...contrasting

confidence: 50%

Section: Regional Correlation Of Members Of the San Jose Formationsupporting

confidence: 49%

Section: Previous Studiesmentioning

confidence: 71%

Section: Previous Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stratigraphy, sedimentology, and paleontology of the Lower Eocene San Jose Formation in the central portion of the San Juan Basin, northwest New Mexico

Smith¹,

Lucas²

1991

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Sediment cores in a municipal drinking-water reservoir as a record of geochemical transport within a watershed, Farmington Lake, New Mexico, USA

et al. 2022

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Progradational‐to‐retrogradational styles of Palaeogene fluvial fan successions in the San Juan Basin, New Mexico

Zellman,

Plink‐Björklund,

Spangler

2023

Basin Research

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Basin‐scale outcrop analyses of fluvial architecture in the Palaeogene San Juan Basin, New Mexico, document lateral and vertical trends in channel, floodplain and palaeosol characteristics. Herein, the uppermost part of the Palaeocene Nacimiento Formation and lower Eocene Cuba Mesa and Regina Members of the San Jose Formation are identified as deposits of large fluvial fans based on trends observed across the basin. Stratigraphic trends suggest two packages originated by fluvial fan progradation. Progradation of the lower fan system provides a new explanation for the transitional nature of a disconformity at the Nacimiento–San Jose Formation contact, previously thought to be a low‐angle unconformity. The two fan systems are separated by a retrogradational interval that culminates in a depositional hiatus at the contact between the Cuba Mesa and Regina Members. This, combined with poor age constraints, indicates that the duration of the disconformity at the base of the Cuba Mesa Member may have been overestimated. Furthermore, the succession is interpreted as deposits of variable‐discharge rivers, based on the combined abundance of upper flow regime and high deposition rate sedimentary structures indicative of intense flooding events, preservation of in‐channel bioturbation and paedogenic modification indicating periods of prolonged dryness, lack of identifiable bar strata and alternations of poorly drained and well‐drained floodplain deposits with pedofacies indicating alternating wet–dry cycles. This dataset adds to a growing body of evidence linking the formation of large fluvial fans to discharge variability and thus to hydroclimates with significant inter‐ and intra‐annual precipitation variability and intense rainfall. A long‐term stratigraphic shift from poorly drained to well‐drained floodplain deposits across two progradational fan successions indicates that a predictive model suggesting downstream decreases in soil drainage conditions is not encompassing of all large fan systems, and instead suggests a transition to a more arid climate across the Palaeocene–Eocene boundary.

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Stratigraphy, sediment dispersal and paleogeography of the lower Eocene San Jose Formation, San Juan Basin, New Mexico

Cited by 7 publications

References 0 publications

Stratigraphy, sedimentology, and paleontology of the Lower Eocene San Jose Formation in the central portion of the San Juan Basin, northwest New Mexico

Stratigraphy, sedimentology, and paleontology of the Lower Eocene San Jose Formation in the central portion of the San Juan Basin, northwest New Mexico

Sediment cores in a municipal drinking-water reservoir as a record of geochemical transport within a watershed, Farmington Lake, New Mexico, USA

Progradational‐to‐retrogradational styles of Palaeogene fluvial fan successions in the San Juan Basin, New Mexico

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