GEOLOGIC MAP of the BOXLEY QUADRANGLE, NEWTON and MADISON COUNTIES, ARKANSAS ° 33 and Does Not Imply Endorsement by the U.S
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U.S. DEPARTMENT OF THE INTERIOR Prepared in cooperation with the SCIENTIFIC INVESTIGATIONS MAP 2991 U.S. GEOLOGICAL SURVEY U.S. NATIONAL PARK SERVICE Version 1.0 A 5 hhc 1620 Oe CORRELATION OF MAP UNITS Within the Ponca quadrangle, Hudson and Murray (2003) placed the contact above the level ACKNOWLEDGMENTS hbl 5 25 Mf 1515 hbl Lower part—Dominantly shale and siltstone with interbedded limestone and STRATIGRAPHY 1600 1540 5 3 5 thin beds of sandstone. Shale and siltstone are dark gray and fissile to thin, The study area preserves an approximately 1,600-ft-thick record of early and late of a thin coal bed approximately 250 ft above the base of the middle Bloyd sandstone. In Mf 1545 1530 4 This work was conducted in a cooperative project between the U.S. Geological Survey Mbv Qty the Boxley quadrangle, the Bloyd-Atoka contact is placed at a similar level within a shale 1940 5 Oe ripple bedded. Sandstone is tan, very fine to fine grained, thin bedded with Paleozoic deposition on what is now the southern margin of the North American continent. and the U.S. National Park Service. We thank D.L. Zachry for discussions about the hhg Qal Qc Ql QUATERNARY interval beneath an approximately 100-ft-thick interval of sandstone that underlies a 1550 ripple marks. Limestone includes medium to thick beds of red-brown Provincial series for Pennsylvanian and Mississippian units are from McFarland (1988). 51945 Mbv Qto Pennsylvanian stratigraphy. Helpful reviews were provided by Angela Chandler and Paul Mb 1500 conglomerate, with clasts of fossil fragments and subrounded sandstone and The Middle Ordovician Everton Formation is a heterogeneous sandstone and carbonate prominent topographic ledge. This sandstone sequence is typical of Atoka facies in being 1950 Mbv Carrara. h Unconformity siltstone. The Brentwood Limestone Member at the base of formation (not unit that Suhm (1974) interpreted to have been deposited in barrier island and tidal flat fine to very fine grained, thin to medium bedded with ripple laminations (fig. 3A) and being hc 5 2 2 h 1550 2 Mbs 5 mapped) is a 5- to 20-ft-thick limestone interval varying from massive gray laterally extensive across the quadrangle. An alternative contact that was considered, about hbu hg h depositional environments. The Everton Formation is unconformably overlain by the Upper REFERENCES CITED 5 Of a Atokan 50 ft lower, would shift the sandstone interval including fucoid trace fossils (fig. 3B) from the 5 1500 micrite to reddish-gray, coarse bioclastic limestone. Unit is conformable with Ordovician Fernvale Limestone. Angelier, Jacque, 1990, Inversion of field data in fault tectonics to obtain the regional hhg 1550 Mbs Of 2 upper Bloyd to the Atoka Formation (ha). This option was not favored because this Mp 5 1500 Unconformity underlying Hale Formation. Forms moderate to steep slopes and is poorly hhc 1950 5 1920 The Mississippian Boone Formation is widespread within the northern part of the stress—III, A new rapid direct inversion method by analytical means: Geophysical 5 1500 sandstone interval is more laterally variable in character and includes crossbedded, medium- 1900 5 exposed. Unit ranges from 40 ft thick in north to over 100 ft thick in south quadrangle. The phosphate-nodule-bearing sandstone at the base of the St. Joe Limestone hhc Oe 5 1950 Journal International, v. 103, p. 363–376. hbl 1500 hbu to coarse-grained sandstones with quartz pebbles that are more like the facies in the 1910 Mf Member (Mbs) is persistent throughout much of northern Arkansas (McKnight, 1935) and Henbest, L.G., 1953, Morrow Group and lower Atoka Formation of Arkansas: American 5 Hale Formation (Lower Pennsylvanian, Morrowan)—Interbedded sequence of underlying middle Bloyd sandstone. 1540 Unconformity was probably deposited in Early Mississippian time as a transgressive lag during sea-level rise Association of Petroleum Geologists Bulletin, v. 37, p. 1935–1953. 2 5 3 1960 sandstone, siltstone, shale, and thin limestone. Thickness 100–180 ft 4 (Horner and Craig, 1984). The contact of the main body of the Boone Formation with the 5 Qal 2 5 PENNSYLVANIAN STRUCTURAL GEOLOGY Horner, G.J., and Craig, W.W., 1984, The Sylamore Sandstone of north-central Arkansas, ha 1890 9 1880 h hbu 2 bl hhg Prairie Grove Member—Brown to reddish-brown, fine- to medium-grained, St. Joe Limestone Member is gradational and is based on the change to thin bedding and ° with emphasis on the origin of its phosphate, in McFarland, J.D., III, ed., Contributions 1880 5 7 5 1525 Mbv 1555 The dominant structural feature of the Boxley quadrangle is a N. 35 E.-trending fault 2 5 Morrowan 5 4 5 thick-bedded, calcite-cemented sandstone. Locally contains quartz pebbles at the generally chert-free lithology of the St. Joe Limestone Member. Near the top of the and fold zone that extends across the center of the quadrangle, aligning with parts of the to the geology of Arkansas, v. 2: Arkansas Geological Commission, p. 51–85. 2 5 2 hhg hbl 4 7 5 1480 formation an oolite interval as thick as 3 ft is present. The local presence of the Hindsville Mf Of base. Beds are planar or crossbedded, and crossbeds may have Buffalo River valley in the north and Beech and Edgemon Creeks in the south. Structure Hudson, M.R., 1998, Geologic map of parts of the Jasper, Hasty, Ponca, Gaither, and 5 3 2 11 2 hhg 6 1940 5 1480 Unconformity Limestone Member of the Batesville Sandstone (Mbv), containing angular chert fragments 51905 ha 5 bi-directional dips. May contain interbeds of reddish-brown coarse bioclastic contours on the top of the Boone Formation and the base of the middle Bloyd sandstone Harrison quadrangles in and adjacent to Buffalo National River, northwestern Arkansas: 1900 5 hbl 1535 5 1900 limestone. Weathered sandstone forms rounded surfaces with elliptical that were probably derived from the underlying Boone Formation, demonstrates a are more closely spaced and swing into northeast trends along this zone. The 4.5-mi-long, U.S. Geological Survey Open-File Report 98–116, scale 1:24,000. 4 Qc 1480 h 3 5 hc depositional hiatus between the Boone Formation and Batesville Sandstone. Batesville 2 5 7 cavities as long as 1 ft. Sandstone forms steep slopes but may be covered northeast-striking Edgemon Creek fault is in the southwestern part of the zone and has Hudson, M.R., 2000, Coordinated strike-slip and normal faulting in the southern Ozark 7 3 1550 5 1480 Mp hbu by a colluvial mantle derived from overlying units. Thickness 20–60 ft Sandstone thins and the proportion of limestone increases to the south in the quadrangle, down-to-the-southeast throw of as much as 60 ft; a component of dextral strike-slip offset is dome of northern Arkansas: Deformation in a late Paleozoic foreland: Geology, v. 28, Mp 1550 5 1880 Unconformity Mp 6 2 3 5 Mbv 5 2 suggesting a decreasing sand supply in a marine setting. also indicated by kinematic data discussed below. Rocks on both sides of the Edgemon p. 511–514. 5 4 3 Qty ha hhc 5 1530 5 2 Mp Cane Hill Member—Interbedded sequence of shale, siltstone, and sandstone. The onset of Morrowan deposition reflects sea-level rise following a terminal 5 h Creek fault dip gently toward a syncline axis just southeast of the fault, marking the low Hudson, M.R., and Cox, R.T., 2003, Late Paleozoic tectonics of the southern Ozark dome, 1860 a 3 hhc 5 1520 Upper part mostly composed of fissile to rippled, thin-bedded, dark-gray Mississippian sea-level drop (Sutherland, 1988; Manger and Sutherland, 1992) and as a Mp h 2 7 5 point of an approximately 1-mi-wide structural zone having an overall structural relief of as in Cox, R.T., compiler, Field trip guidebook for Joint South-Central and Southeastern 51870 hg h 1500 Mf Chesterian shale and siltstone but locally contains rippled, thin-bedded, very fine grained bl 1510 consequence the base of the Morrowan Cane Hill Member (hhc) of the Hale Formation much as 200 ft. The Edgemon Creek fault dies out to the northeast but down-to-southeast Sections: Geological Society of America, Tennessee Division of Geology Report of 3 3 3 4 1910 5 3 Mb 51860 5 sandstone interval as thick as 5 ft. Upper part of unit is poorly exposed and 4 hhc 5 5 represents a significant unconformity within the map area. The thinning of the Pitkin throw continues across a northeast-trending monocline that is broken by several shorter Investigations 51, p. 15–32. Mf 1500 1525 Mbv 4 1450 forms gentle to moderately steep slopes. Lower part is a 10- to 20-ft-thick 3 2 Qto MISSISSIPPIAN Limestone (Mp) beneath the unconformity in the northern part of the quadrangle likely is faults. This structural zone aligns, and is likely continuous, with a zone of faulted northeast- Hudson, M.R., and Murray, K.E., 2003, Geologic map of the Ponca Quadrangle, Newton, hbu 6 6 51910 1910 5 1475 5 3 Unconformity sandstone interval that generally changes downward from olive-brown, very related to Late Mississippian-Early Pennsylvanian erosion, a conclusion supported by the 3 5 1840 5 2 trending monoclines farther to the northeast within the Ponca quadrangle (Hudson and Boone, and Carroll Counties, Arkansas: U.S. Geological Survey Miscellaneous Field 5 1870 5 6 fine grained to fine-grained, thin-bedded sandstone with ripple cross- common presence of probable Pitkin Limestone clasts within basal conglomerate lenses of 6 4 Meramecian- Murray, 2003) that together comprise the southwestern part of the Ponca lineament of Studies Map MF–2412, scale 1:24,000.