High-resolution subsurface correlations of Hirnantian (Late Ordovician) through Sheinwoodian (Wenlock, Silurian) strata in southern and southeastern Ohio, USA Division of Geological Survey Phone: (614) 265-6627 Ohio Department of Natural Resources Christopher B. T. Waid Email: [email protected] 83°30'W 83°0'W 82°30'W 82°0'W Abstract Peebles Discussion and Conlusions !! B " 2 ! ! 39°30'N A " C ! ! ! ! ! ! ! «¬32 ! ! ! ! ! 1 Seaman Peebles ! In Ohio, Upper Ordovician and lower Silurian strata are a major source of aggregate and cement material, and contain extensive natural gas and " ! ! 1) The new Whippoorwill formation is proposed, with the Centerville and overlying Belfast as members. The term refers to the town in Adams ! !!!!! ! «¬32 !! !! ! ! !! !! ! ! !!!! ! ROSS ! !! ! ! Michigan ! ! ! ATHENS ! ! !! ! ! ! !! ! ! !! ! ! oil. Despite their importance, the ne-scale subsurface correlation of these units is poorly understood. Subsurface correlations are complicated Basin ! County, Ohio, where both members are well exposed along Lick Fork Creek (Table 1). The Centerville should be reduced to member rank ADAMS !! ch ! !! r # !! ! VINT !! ! A ON! !! n «¬781 ! ! i ! ! s ! ! 2 ! ! u West Union ! ! !! ! ! ! ! ! by several factors, particularly the use of several formal nomenclature schemes in dierent parts of the state, incorrect and/or inconsistent q d ! ! ! !! because it is too thin to be delineated at the scale (1:24,000) of geological mapping in the area. The Belfast Member should be removed from n ! ! Algo 1 ! !! !! !! n !! !! ! PIKE ! !MEIGS a ! !! l !! ! ! JACK !! ! SO h N !! application of formal unit terminology in subsurface studies, and diculty comparing log-based subsurface units with the lithologically and !! 39°0'N the Brasseld Formation, because it is separated from the rest of the Brasseld by a pronounced unconformity (Sullivan et al., 2016), and has g ! i ! ! ! ! ! ! Illinois Study Area in H ^ ! s !! ! ba c ! ! ! Basin h d i ¬41 paleontologically-dened surface units. To facilitate comparison between surface and subsurface units, a handheld gamma-ray spectrometer c « ! a distribution pattern distinct from the other Brasseld members. The Centerville and Belfast have long been thought to be basal Silurian, but r n n ADAMS la SCIOTO!! ! A e o GALLI i r ! A t o c Locations a f a " ! n n T Measley Ridge ! ! was used to create composite gamma curve of uppermost Ordovician and lower Silurian exposures in Adams County, Ohio. Core and a ! correlation to the Whirlpool Sandstone (Fig. 5) and Power Glen Formation (c.f. Ryder, 2000), respectively, of New York indicates that they are n i ! !! ! i ch Brush Creek Motorsport Complex !! c ! a ! l # Whippoorwill ! n a ! i p ! ! ! ! ! ! p ! C A !! º ^ LA! ! ! geophysical logs from the Aristech #4 well in southeastern Scioto County, Ohio provided additional lithological control for the units in deeper, - Geological Units A–A' ! WRENCE older. Schröer et al. (2016) recovered chitinozoans and scolecodonts indicating a Katian or Hirnantian position for the Whirlpool and Power o ! t Bisher & Lilley Fms, ! o B–B' r Peebles Dol undiv. Well 38°30'N p ! Estill Shale C–C' ! more clastic-rich environments. All of the members of the Brasseld, Noland, Alger Shale, and Bisher formations can be distinguished by Well in cross section !! Glen. Bergström et al. (2011) determined that the Manitoulin Dolomite, which interngers with the Whirlpool, is most likely Hirnantian, which Drowning Creek Formation D–D' 0 10 20 mi #1 3 0 1 E–E' ^ Adams County Composite geophysical logs, and were correlated in 140 wells throughout 10 counties in southern/southeastern Ohio. Five cross sections (two approximate 4### 2 mi Drakes Formation restricts the age of the overlying Power Glen to the Hirnantian as well. If the correlation of the Whippoorwill to the Whirlpool and Power Glen º 2 Fig. 6 ^ Aristech #4 Core 0 20 40 km 0 1 2 km º depositional strike, and three follow depositional dip) were created from these wells. These correlations place some commonly used subsurface is correct, then they too are most likely Hirnantian. Since the Centerville/Belfast are separated from the underlying Queenston and overlying FIGURE 3. (A) Paleogeographic map of eastern Laurentia. The study area spans basinal depositional settings in the east, to shallower ramp terminology into the more precise, surface-unit framework of southern Ohio. The “Medina sand” correlates to the Whirlpool Sandstone of New depositional settings in the west. Map modied from Blakey (2013). (B) Map showing the localities and sections used for creating the composite Brasseld by signicant unconformities, they should be removed from S-I. The term H-1 is tentatively proposed to reect their Hirnantian York, and to the Centerville Formation of southern Ohio. The lower Cabot Head extends from the top of the Brasseld Formation or Whirlpool gamma-ray log for the Silurian of Adams County, Ohio. Shading indicates topography. (C) County map of the study area showing the location of position, similar to the Cincinnatian third-order sequence designations (e.g. C1, C2) of Holland and Patzkowsky (1996). wells used for correlations and cross section lines. Sandstone to the base of the “red Clinton” sand. The “Clinton” sands interval in southeastern Ohio generally correlates with the thin-bedded and [K, U, Th] Chronostrat. shaly members of the Brasseld Formation. The upper Cabot Head spans from the top of the “stray Clinton” or “red Clinton” sand through the 0 10 20 30 ADAMS COUNTY SCIOTO COUNTY ATHENS COUNTY New York 2) The Drowning Creek Formation is abandoned, in favor of a revised Noland Formation (Fig. 3). The lowest member, the Rose Run iron ore 0 Lilley-Peebles transition Lockport Group ? nomenclature Plum Creek Shale. The “Packer Shell” in southern Ohio is equivalent to the Oldham Limestone where the Lulbegrud Shale is present, and to the Hm. (also termed upper massive Brasseld), is removed from the Brasseld Formation because it represents the base of S-II in central Kentucky and Lockport Group shaly Lilley mbr VI Seq. Lilley Sequence Decew Dol Oldham Limestone and Waco limestone where the Lulbegrud is thin or absent. The “Rochester Shale,” as generally used in most subsurface upper Lilley mbr Formation southern Ohio, and can be distinguished in the subsurface (Fig. 5), providing a useful marker for separating S-I from S-II. Similarly, the lower Lilley mbr Wenlock V Bisher Formation Rochester Sh correlations, corresponds to the base of the Lulbegrud to the top of the Estill Shale. Shnwd. Lulbegrud Member is removed from the overlying Alger Formation, and placed in the Noland, because it represents the uppermost part of S-II upper Bisher mbr Irondequoit Ls 50 V Seq. Bisher Rockaway Dol middle Bisher mbr Formation IV (Brett and Ray, 2005; also note truncation of Lulbegrud in Fig. 5). Silurian lower Bisher mbr Introduction Estill Shale Telychian III orange Waco II 3) The revised Alger Formation consists of the Waco and Estill Members, and represents S-III and S-IV in southern/southeastern Ohio. A Current work on the lower Silurian by the Ohio Geological Survey has two main goals. The rst is to revise the nomenclature used in southern Williamson Sh 100 Llandovery Aer. pronounced regionally angular unconformity separates the orange Waco from an underlying shale and carbonate unit (tentatively identied Ohio to reect the most current understanding of the biostratigraphy, chemostratigraphy, and sequence stratigraphy of the rocks (Fig. 1). The I thin bedded Brasseld lower Waco shale “Rochester Shale” Clinton Group Clinton Rhd. Seq. IV Seq. lower massive as the “white Waco”), the Lulbegrud Shale, and part of the Oldham Member. The white Waco, where present, is considered the base Clinton Group Clinton second is to correlate the surface units into the subsurface, and in doing so, place the traditional subsurface units (Fig. 2) into a more precise ) ft ( Belfast H1? h Alger shaly Brasseld t Estill Mbr Brasseld orange Waco upper Waco shale (transgressive sequence tract; TST) of the third-order S-III in southern Ohio and central Kentucky (Ettensohn et al., 2013; Sullivan et al., 2014, p Formation chronostratigraphic context. Facies vary considerably southern and southeastern Ohio, ranging from carbonate-dominated ramp e Wolcott Furn. D 150 Drakes Formation Lulbegrud Shale Saq. 2016), whereas the orange Waco is considered the TST of a 4th-order cycle in the middle of S-III. This interpretation is perplexing if the unit environments in the western part of the study area to clastic dominated, deeper-water environments in the east (g. 3a). Precise correlation of white Waco Wolcott Ls Hirnantian? Plum Creek Shale Oldham Limestone tentatively identied as the white Waco in Fig. 5 is in fact the white Waco, because the regionally-angular unconformity under the orange the surface units across such wide range of facies based on well logs requires hybrid allo- and litho-stratigraphic approach, particularly with the Rose Run iron ore Sodus Sh “stray Clinton ss” Packer Shell Waco appears more like a typical third-order sequence boundary. These contrasting interpretations may be a good example of the complex Medina Group. In general, formation-level units in this report are allostratigraphic (based on the sequence stratigraphy of Brett et al. (1990; u. Cabot Head Reynales Ls 200 Seq. Neagha Sh Waco shale III interplay between regional, tectonic sea-level change with eustatic sea-level variation. The white Waco may represent a eustatically-driven Waco Mbr orange Waco 1998), and member-level units are lithostratigraphic. II Seq. Thorold Ss Oldham Mbr Noland “red Clinton ss” Cambria Sh Plum Creek Mbr Formation Centerville Ordovician third-order TST, whereas the basin tilting and erosion under the orange Waco represents the rst eects of the Salinic Orogeny along the Rose Run Iron Ore shaly Brasseld mbr Medina Group Seq. I Seq. Upper Ordovician Katian Grimsby Fm Brasseld Queenston Shale western ank of the Appalachian Basin.