Paleozoic Stratigraphy of Franklin Mountains, West Texas

Nelson, Lloyd Alvino

doi:10.1306/3d93319a-16b1-11d7-8645000102c1865d

Cited by 16 publications

(12 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thompson (1948) redefined the Derryan Series to include all rocks of post-Morrowan and pre-Desmoinesian age in south-central New Mexico. This correlation excluded the Morrowan "La Tuna Limestone" of Nelson (1940) from the Derryan, although the Derryan type section remained unchanged. Thompson (1948: 68) further stated that the Derryan may be almost the exact equivalent of the Atokan Series as proposed by Spivey & Roberts (1946).…”

Section: Previous Investigationsmentioning

confidence: 99%

Lower and Middle Pennsylvanian fusulinid biostratigraphy of southern New Mexico and westernmost Texas

Clopine¹

1992

View full text Add to dashboard Cite

This paper summarizes biostratigraphic and lithostratigraphic analyses of Lower and Middle Pennsylvanian strata in southern NM and westernmost TX. Fusulinid foraminifera offer the best means of subdivision and biostratigraphic correlation within this interval. Nineteen species in seven genera are documented, one new species is described, and eight biozones are correlated across the study area. Morrowan, Atokan, and early Desmoinesian sediments in the study area represent carbonate-shelf deposits. Shallow subtidal facies are dominant, but limited intertidal and supratidal deposits also occur. Fusulinid foraminifera occur in most carbonate lithologies, but are most abundant and best preserved in shallow subtidal biomicrite-wackestone, the dominant carbonate lithology encountered. Morrowan strata do not extend northward beyond the center of the Robledo Shelf. Earliest Morrowan deposits are restricted to the center of the Orogrande Basin. Morrowan strata thin rapidly to the northwest due to basal onlap above the pre-Pennsylvanian unconformity. Atokan and early Desmoinesian sediments (upper range of study) extend across the Robledo Shelf. The significant thickness variations in these strata across the study area reflect the lower subsidence rate of the Robledo Shelf relative to the Orogrande and San Mateo Basins during Atokan and early Desmoinesian time.Regional correlations indicate that the lower 0.95 m of the "Derryan Series" type section overlaps the Morrowan Series. However, fusulinid faunas from the remainder of the Derryan type section correlate closely with Atokan faunas from the mid-continent. The upper boundary of the Derryan type section falls just below the first occurrence of Beedeina and corresponds with most authors' concept of the Atokan/Desmoinesian Series boundary.The Atokan Series, as used in the midcontinent, and the Derryan Series, as defined in south-central NM, include approximately the same stratigraphic interval. Recent workers, however, have abandoned the term Derryan in favor of Atokan. The Atokan Series remains a controversial chronostratigraphic subdivision due in part to its lack of an adequate type section. This paper provides biostratigraphic and lithostratigrpahic analyses of Lower and Middle Pennsylvanian strata in southern NM and westernmost TX, which form a highly fossiliferous sequence of dominantly carbonate rocks. This sequence represents essentially continuous Morrowan through Desmoinesian deposition. These analyses were undertaken in order to better establish the relationships between Pennsylvanian chronostratigraphic units that are in current use but are not adequately defined.The study area is located in south-central NM and westernmost TX. Four sections have been measured within the study area along a roughly linear northwest-southeast trend stretching approximately 160 km. Pennsylvanian strata crop out along this trend in a series of discontinuous fault-block mountains.

show abstract

Section: Previous Investigationsmentioning

confidence: 99%

Lower and Middle Pennsylvanian fusulinid biostratigraphy of southern New Mexico and westernmost Texas

Clopine¹

1992

View full text Add to dashboard Cite

show abstract

“…The La Tuna, Berino, and Bishop Cap Formations of the Magdalena Group of the El Paso region are present in the Hueco and Franklin Mountains (Nelson, 1940). In the Sierra de Palomas and the Big Hatchet Mountains, the entire Pennsylvanian and lowermost Permian (lower Wolfcampian) are included in the thick Horquilla Formation (Zeller, 1965).…”

Section: Lithostratigraphymentioning

confidence: 99%

Lower and Middle Pennsylvanian strata in the Orogrande and Pedregosa Basins, New Mexico

Wilson¹

1989

View full text Add to dashboard Cite

Continued field work from 1955 to the present shows that Lower and Middle Pennsylvanian limestones crop out in various mountain ranges over most of southwestern New Mexico and northern Chihuahua, representing a once continuous sheet from 100 to 600 m thick. A regional NE-SW cross section from the Sacramento to the Big Hatchet Mountains shows detailed microfacies and fusulinid control and demonstrates that cyclic Lower Pennsylvanian (Morrowan) oolitic strata pinch out northward across southern New Mexico. The cross section also shows that Middle Pennsylvanian (Derryan and Desmoinesian) strata are widely represented by limestones with upward-shoaling cyclothems (generally upward-coarsening sequences) that number about a dozen at each location. Although the cyclothems are not correlative from section to section, they are generally present in all localities.Petrologic studies show that the limestones are exclusively open marine and dominantly bioclastic lime wackestones and packstones. Tectonic stability during Early Pennsylvanian time caused the deposition of shallow-marine carbonates over wide shelves east and west of the Pedernal Uplift. In the Delaware Basin and on the west flank of the Pedernal Uplift terrigenous clastics are present. Small channels on the carbonate shelves, far west of the Pedernal Uplift, contain polymictic limestone-chert conglomerates. Quartzose sandstones at the base of the Pennsylvanian contain variable amounts of matrix, are often channeled, and may contain abundant terrestrial-plant fossils.An isopach map of Lower and Middle Pennsylvanian strata shows that the Orogrande Basin is asymmetric in shape with marked subsidence along its eastern margin adjacent to the Pedernal Uplift. An anomalously thin area in the west-central part of the basin makes the basin narrower during Early and Middle Pennsylvanian time than in Late Pennsylvanian time. The Florida Uplift appears to transect thickness contours of the Lower and Middle Pennsylvanian, suggesting that uplift postdated development of the extensive carbonate sheet. The extent of carbonate deposition on the positive area, and the timing of the uplift, is difficult to prove since all Pennsylvanian and lowermost Permian (lower Wolfcampian) strata have been removed. The great thickness of Lower and Middle Pennsylvanian carbonates present in southwestern New Mexico and Arizona diminishes southward into Mexico (Chihuahua and Sonora). Two widely separated outcrops near Minas Plomosas, Chihuahua, and Bavispe, Sonora, contain only about 150 m of fusulinid-bearing shelf carbonates. Presumably these areas are located on opposite sides of the Pedregosa Basin. With sparse control at present, it is difficult to show whether or not the Pedregosa Basin, which should be between these localities, actually existed this early in Pennsylvanian time.

show abstract

“…The Canutillo Formation (Nelson, 1940;Laudon and Bowsher, 1949) was recognized at Bishop Cap and on Rattlesnake Ridge. It overlies massive Fusselman Dolomite on what has been described in the Franklin Mountains as a channeled surface marked by potholes (Harbour, 1972).…”

Section: Canutillo Formationmentioning

confidence: 99%

Geology of Organ Mountains and southern San Andres Mountains, New Mexico

Seager¹

1981

View full text Add to dashboard Cite

The Organ and southernmost San Andres Mountains in south-central New Mexico are part of a 150-mi long, west-tilted fault block extending from El Paso, Texas, northward to central New Mexico. The Organ Mountains tower nearly a mile above the floor of the Tularosa Basin on the east and the Rio Grande valley on the west. Oldest rocks exposed are Precambrian granite, overlain by as much as 8,500 ft of mostly marine Paleozoic and Cretaceous strata. In Laramide time, these rocks were deformed along the faulted margins of a basement-cored block uplift which was ancestral to the modern Organ-San Andres range. Lower Tertiary fanglomerate, at least 2,000 ft thick, records the erosional "unroofing" of the Laramide uplift and was sharply deformed as uplift progressed. Magmatism profoundly affected the area in middle Tertiary time. Intermediate composition lava and mudflow breccia of late Eocene or early Oligocene age buried the deeply eroded Laramide uplift. The Organ batholith (about 32.8 m.y. old) is interpreted to be an exposure of the upper, outer part of a magma chamber whose silicic cap erupted as pyroclastic flows and lavas 33.0-33.7 m.y. ago. The pyroclastic rocks, approximately 2 mi thick, subsided to form the Organ cauldron, only a piece of which is exposed in the Organ Mountains today. The pyroclastic rocks also formed the roof beneath which the batholith crystallized. Compositional zoning within the volcanics indicates that the erupted magma volume was also zoned, ranging from 77 percent SiO2 at the top to about 65 percent at lowest levels. The batholith represents deeper, less silicic (56-68 percent) levels of the magma chamber, and late-stage mineralized plutons within the batholith are interpreted to be products of the progressive crystallization of the magma chamber. Undated tristanite-trachybasalt flows interbedded with fanglomerate may indicate onset of late Tertiary block faulting in the area. Subsequent uplift of the modern ranges involved an early stage of closely spaced faulting associated with moderate west tilting or, locally, east downwarping. Some faults, initially steep, were rotated into low-angle positions as tilting progressed. The more recent stage of uplift is distinguished by development of the modern, widely spaced range-boundary faults and their associated horsts, west-tilted blocks, and grabens. Movement on the eastern range-boundary fault of the Organ and southern San Andres fault block has persisted to within the last 4,000-5,000 yrs. Several generations of alluvial fans, as old as middle Pliocene, are products of repeated movement on these faults. Mineral deposits related to the Organ batholith include base-metal deposits as replacements in limestone and dolomite, and as disseminations, vein fillings, and pegmatite minerals in the batholith.

show abstract

Paleozoic Stratigraphy of Franklin Mountains, West Texas

Cited by 16 publications

References 9 publications

Lower and Middle Pennsylvanian fusulinid biostratigraphy of southern New Mexico and westernmost Texas

Lower and Middle Pennsylvanian fusulinid biostratigraphy of southern New Mexico and westernmost Texas

Lower and Middle Pennsylvanian strata in the Orogrande and Pedregosa Basins, New Mexico

Geology of Organ Mountains and southern San Andres Mountains, New Mexico

Contact Info

Product

Resources

About