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·. " Pennsylvania Geological Survey: Trenton Black River Carbonates: Field Trip Guidebook Page 1 of2

PA STATE AGENCIES ONLINE

Trenton and Black River Carbonates in the Union Furnace Area of Blair and Huntingdon Counties, Pennsylvania

A Field Trip Guidebook for the Eastern Section AAPG Annual Meeting, September 10, 2003 and the PAPG Spring Field Trip, May 26, 2004

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Introduction carbonates in central Penns Ivania Geolo of the Union Furnace area Petroleum geochemistry Road log Stop 1 StoD2 Stop 3 Acknowledgements and references List offigures and plates

Christopher D. Laughrey, Pennsylvania Geological Survey Jaime Kostelnik, Pennsylvania Geological Survey David P. Gold, Professor Emeritus, Pennsylvania State University Arnold G. Doden, Consultant, State College John A. Harper, Pennsylvania Geological Survey

Edited by John A. Harper

Guidebook distributed by: Pittsburgh Association of Petroleum Geologists

For information on obtaining additional copies of this guidebook, contact:

John A. Harper Pennsylvania Geological Survey 400 Waterfront Drive Pittsburgh, PA 15222-4745 Phone: 412-442-4230 Fax: 412-442-4298

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PA STATE AGENCIES ONLINE

Ordovician Carbonates in Central Pennsylvania

I ntrod uction

Carbonate rocks of the Upper Ordovician Trenton and Black River Formations are the targets of active petroleum exploration in western and north central Pennsylvania (Figure 6), as well as the rest of the Appalachian basin. The potential reservoir targets are fractured dolostone or traps in narrow grabens that are related to basement structures (Avary, 2002). Although this is a seismic play searching for structural traps, the sedimentary geology of the Trenton and Black River Formations is also critical to exploration efforts. The distribution of porous and permeable carbonate facies undoubtedly influenced the subsurface fairways traveled by dolomitizing fluids; in many instances these fluids initially entered the Trenton and Black River rocks along vertical fractures related to faulting, but then spread out laterally through permeable grainstones (Colquhoun and Trevail, 2000). In these cases understanding the sedimentary history of the carbonates means understanding their reservoir storage capacity. The spatial distribution of reservoir seals, reservoir compartmentalization, and diagenetically controlled pore geometry are partially or wholly sedimentological features. The TrentonIBlack River play is basin wide in scope, and accurate stratigraphic correlations and analyses are necessary for rigorous petroleum exploration and development (Figure 7). Sequence stratigraphic analysis promises to provide such correlations and analyses (Cornell and others, 2001), but robust facies analyses must first be available before high-resolution surface and subsurface sequence stratigraphy can be accomplished (see Pope and Read, 1997). Finally, the sedimentary geology of the Trenton and Black River Formations has a direct bearing on understanding the petroleum source rocks of this play, as well as the migration and accumulation of oil and gas in these rocks (Ryder and others, 1998; Obermajer and others, 1999).

The primary purpose of this field trip is to acquaint geologists with the complex diversity of carbonate depositional facies that characterize the Trenton and Black River Formations in Pennsylvania. In addition to all of the reasons listed above, such an acquaintance can facilitate core and cutting sample interpretations in subsurface work. These rocks also have been the target of petroleum exploration here in the Valley and Ridge province. We will comment on the hydrocarbon potential of these rocks in the deep plateau and Ridge and Valley here in central Pennsylvania. We also wish to share with you the exciting economic geology of these rocks in this region, and hope you find the other uses people put these carbonates to as interesting as we do. Finally, as a side benefit to our excursion here today, we will casually examine some of the most spectacular karst features found in Pennsylvania, and learn a little bit of history concerning some remarkable underground explorations literally happening beneath our feet.

Setting

During Ordovician time, Pennsylvania comprised a tiny portion of the Laurentian craton, lying about 25° south of the equator (Figure 8). From Late through Middle Ordovician time, this region was part of an eastward-thickening, miogeoclinal basin that accommodated mostly carbonate platform (Thompson, 1999). These carbonate rocks constitute part of the "Great American Bank" (Ginsburg, 1982) that extended more than 3,000 km (1,864 mi) along nearly the entire length of what was the southern seaboard of the Laurentian continental mass (Figure 3). The platform prograded eastward through and Early Ordovician time, and its eastern terminus

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seaward was at a continental slope beyond which lay deep basin sediments. Beginning in the Middle Ordovician, the craton margin was uplifted during the Taconic orogeny (Faill, 1999). The platform was progressively submerged. The Appalachian basin changed from a miogeoclinal carbonate platform to an exogeosynclinal foreland molasses basin (Thompson, 1999). This basin received large amounts of terrigenous from eastern highlands, which were deposited in the foreland basin as the Taconian clastic wedge.

The distribution of landmasses and suggested for the late Middle and early Late Ordovician (Figure 9) should have affected global seasonal weather patterns essentially the same as we experience today (Wilde, 1991), but with the northern and southern hemispheres reversed. Summer months feature low pressure air masses developing over large landmasses, resulting in the flow of large amounts of moist air (monsoons). Because landmasses were essentially restricted to the southern hemisphere at this time (figures 8 and 9), monsoons would have occurred only in that hemisphere. Anti-trade monsoonal winds generated along the coast of drove warmer water northward between Siberia and Kazakhstan, countering the flow of cooler water from northern midlatitude high pressure systems. Because Pennsylvania lay on the southwest-facing coast of around 25° south latitude, the dominant winds would have been trades similar to Recent trade winds, with some variation due to continental configurations. Warm maritime air from the Iapetan embayment between Laurentia and Siberia (figure 9) would have provided abundant rainfall from the equator to about 35° or 40° south latitude.

The Ordovician stratigraphic record in Pennsylvania reflects the control of and paleogeography on sedimentation (Figure 10). Lower and Middle Ordovician rocks tell the tale of prolonged passive margin carbonate accumulation in semi-arid conditions. Upper Ordovician clastics reveal a history of basin filling by marine and terrestrial clastics on a subjected to moist air traveling westward in lower latitude. In between are the Upper Ordovician Trenton and Black River Formations, and their equivalents, which were deposited during the transition from passive margin carbonates deposited on the Great American Bank to foreland deposition of the Taconian clastic wedge, subjected to transitional climates. These carbonate rocks developed on a northeast-trending ramp that lay northwest of the Taconic foreland basin (Read, 1980). The Trenton and Black River Groups of central Pennsylvania reflect the transition from carbonate shelf to ramp in response to flexure and increasing down warping due to the growing Taconic orogeny to the southeast. Subjacent Cambrian carbonates, the Lower to Middle Ordovician , and the Middle Ordovician Loysburg Formation were deposited on a rimmed carbonate shelf, with restricted circulation and wave action, on which vast peritidal and shallow water carbonate facies flourished (Goldhammer and others, 1987; Faill, 1999). With the reversal of plate motion that stopped the spreading of Iapetus, compressional down warping of the Laurentian continental margin occurred as the Taconic thrust belt approached from the east. Subsidence rates increased markedly beginning 460 ma, and marked the termination of the "Great American Carbonate Bank" (Goldhammer and others, 1987) (Figure 11 ). This stratigraphic sequence reveals the passive margin history of the eastern part of the Laurentian craton from Early Cambrian to Middle Ordovician time, and the shift to down warping that led to terminal drowning of the platform during Late Ordovician time.

Stratigraphic Nomenclature

Stratigraphic nomenclature for the Middle and Upper Ordovician rocks of central Pennsylvania is somewhat controversial. The stratigraphic column shown in Figure 10 represents that of the

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Stratigraphic Correlation Chart of Pennsylvania (Berg and others, 1983), with some modification from Faill and others (1989). These authors replaced the name Nealmont Formation (Figure 7) with the name Rodman Formation (Figure 10). The Rodman is the upper member of the Nealmont Formation in previous schemes (see Rones, 1969 and Berg and others, 1983). Sudden, intricate facies changes, variations in stratigraphic thickness, and poor exposures make lithostratigraphic correlations outside of their type areas difficult. Leslie and Bergstrom (1997) showed that biostratigraphic studies based on graptolites and conodonts, and the use ofK-bentonite beds and sequence boundaries as stratigraphic markers helps to lessen the confusion, but serious correlation problems within the Middle and Upper Ordovician Series still exist.

The Hatter, Snyder, and Linden Hall Formations of central Pennsylvania are equivalent to the of western Pennsylvania (Figure 7). Likewise, the Nealmont, Salona, and Coburn Formations in the outcrop are equivalent to the of western Pennsylvania (.E.igy@ 1). Some workers have included the Hatter, Snyder, and Linden Hall Formations of central Pennsylvania in the , and the Nealmont, Salona, and Coburn Formations in the Trenton Group (Cullen-Lollis and Huff, 1986; Leslie and Bergstrom, 1997). We use these group names in this guidebook.

K-Bentonites

Kolata and others (1996) identified and described 29 K-bentonites from the Mohawkian rocks of central Pennsylvania. Nineteen K-bentonites are recognized and designated at the Union Furnace outcrop along PA 453. We have identified another possible K-bentonite near the top ofthe Hatter Formation. Cullen-Lollis (1986) and Berkheiser and Cullen-Lollis (1986) discussed the K-bentonite occurrences here at the Union Furnace exposure. Six of the K-bentonites in the Salona Formation have unique chemical signatures, and are particularly useful for regional correlations (Kolata and others, 1996). Two of these, the Deicke (Eigure 12) and Millbrig K-bentonites, have been especially useful in calibrating sequence stratigraphic correlations (Holland and Patzkowsky, 1996; Pope and Read, 1997).

There are several useful criteria for identifying the K -bentonites in the field (Kolata and others, 1996). The K-bentonites have a soapy, waxy texture when wet. They are light to dark gray, buff, orange, or tan in outcrop exposures. The variability is due to composition, variable oxidation due to ground water activity, and weathering. They appear greenish gray to bluish gray to white in cores. The K -bentonites may contain euhedral to anhedral flakes of biotite and relict glass shards. They also might contain euhedral crystals of zircon, feldspar, and apatite. The bentonites appear like fme­ grained clay bands that might extrude under compactionalloading by the carbonate rocks, but they weather and recess with exposure time. Chert bands in the often underlie thicker bentonites. Many bentonite layers are overgrown with trees and shrubs due to the moist, nutrient-rich clay. The bentonite beds are stratigraphically persistent.

Geochemical fingerprinting of these bentonites involves discriminant function analysis of 26 variables (elements) and four groups (beds) (see Kolata and others, 1996). The chemistry of the bentonite discerns a volcanic ash origin from a calc-alkaline destructive plate margin volcanic setting.

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http://www.dcm.state.pa.us/topogeo/tbr/ordcarb. aspx 1/29/2008 SYSTEM SERIES FORMATION

Monong.ohela Gr. PENNSYL­ Con...... G,. VANIAN Gr.

Upper

DEVONIAN

Middle

Lower

Upper

SILURIAN Lower

Upper

ORDOVICIAN

Middle

Lower

Upper

CAMBRIAN Middle

Lower

PRE· CAMBRIAN

EXPLANATION D Mixed clastics Limestone

Gray shale and D siltstone D Dolostone Dark gray to Chert • black.hale D

Mixed red clastics Evaporites

• Crystalline rocks

Figure 3. Generalized stratigraphic column representing the rocks exposed in the vicinity of the field trip route. E IN Y

\.:~~I 0 / Kastle Rosources • '. i ." '.... M .... n •• ~.._ ...... 11 Austin, .1 Blood. • ." o!.. ,... .. _ ...... _ r_., ...... ' Oom'.'~"wo,.... 11 Manheim. 110 Orthodox, 'ft. _ • • ; _ "._ . \ #1linder f#1 Mann / BeId and #2 Mahoney I • - •• - ... ~j f#1 RlGhard D' .... ", ••.• ;! ; . - ~;.. - .. ,... •• '-r" ._ .. _.."i Ba,.. ~..- • o ' ' • ,_ •• - CRAWFORD • * ; ; ! ! -"I-"~ • .....,..... I I ! . ." _ .... a_ . •. ..,.. ." . _. _. _ • .,... I• I ooA ' I , 1 -'-'r. 'I' ! .'.' • T~ .•. , .•.•." " i.. n' ;' BRADFORD ! !I ~.. I • O . I'" I I I ,...... • . • •• • • • • ' , "" " , ••••••• , •••• ; , I> .! • .!.,.., .•. , i"; ELK' i '.,!. •.••• ,'.! .'...'\ ; '.• o! ' r·····'· ... . " " '" . ! . • ! ~.• " I ; , •.•. _. !v. ! ,r " " ''; .1. '.I "'" ,.' .... J ' . . '''' I (.1 0 ! !', ! ! ' ....;!i! .(.' ". ,..'", ' /'i i-"""--"]..!' '-.' i.i" _a, • I ' . . •• , '...... ' .' .• • . •. I . "'" .',...... """'_ I ' •. , .••• " ' _.' • . " l' • ..,' ,.' ..~'den&BlakeC.... . !""._._._.!unionFuma.' "'. ,." -.; . !'. "1 .",;" ! I . I ..' -. & .1 Sta~a:.dgal_: ...... "'" deU! ' '.~ '.' .. .. rry & ,.' - ... .!.. i · ... ! i.,'" . . .: ', ' '\ , • ~~IiiI'" .' '. / . ! ...... i~'.• ...... -, .... /'. •.•. ! EW • • p' . , . '.' . • ' • -' ' 7.SEY · ..... ms._-. ',! . .'." ! .•. " " . reat Lak E • I • " & #2 MOS' ""'" : I • ' . * i,', ' , . " .' -::-"""",". . .' . •.' .,. ' ...... '. ,. '.. , ...... ,.-.. ' " ; .,.•. i" . ~~ r ·_-,·'·...... · .' . I ,'; G .' ...... B.. 1<0 I I ., , .. ; ..- ; .. .. , ...... , .. U.. p ,...... 'NGTON .•:. i .• "" .- : I .-" ,., .• ". ! ,( .... • J ._.... '-._., t·"· '. i" ,/ "~ :V' , .' i. I" ' '-.- ( . .' - ,. : \ \.,.' / ," ,/ •• - •• - •• - •• - ell - 1 ! .~ l" ../" WESt t.l SCALE ~ Ordovician outcrops o 10 20 30 40 50 Miles :;0 D I ,'i .. , e i'i " IT! II Cambrian outcrops o 20 40 60 80 Kilometers Permit only - no completion Old wells (before 1999) {* Gas in Beekmantown, New wells (1999 and later) *-Gas in TrentonIBlack River penetrating at least the "fC' Gatesburg, or UttJe Falls penetrating at least the top + . top of the Trenton Formation E) Dry in Trenton and deeper of the Trenton Formation Dry in TrentonIBlack RIVer 1* 011 and gas in Loysburg/Shadow Lake Figure 6. Location of Cambrian and Ordovician outcrops, wells that penetrate the top of the Trenton Group, and new permits for testing Trenton/Black River play in Pennsylvania. The location of the Union Furnace area is indicated. ::iw EASTERN EASTERN WESTERN I WEST-CENTRAL I CENTRAL I NORTHERN t; I SERIES OHIO PENNSYLVANIA NEW YORK PENNSYLVANIA o>

UPPER (in part)

z c( G I MIDDLE :> o IX I BEL.L,EFONTE c C) DOL ~I II I ze I ' - ..

iw W LOWER rBEEKMANTOWN ID BEEKMANTOWN FM.

:E· UPPER "ROSE RUN" ~ SS,

PRIMARILY PRIMARILY D PRIMARILY PRIMARILY D D DOLOSTONE LIMESTONE GRAY SHALE BLACK SHALE Figure 7. Regional lithostratigraphic correlation diagram for uppermost Cambrian and Ordovician rocks in the central Appalachian basin. We will examine the Coburn through Loysburg Formations of central Pennsylvania on this field trip. N

N

B

NP - North Polar Current landmass NSP - North Subpolar Current D NT - North Tropical Current Warm water current NE - North Equatorial Current ------I.~ D Warmwater M - Monsoonal Counter-Current ••••••• ~ Cool water current SE - South Equatorial Current Subtropical convergence Cool water ST • South Tropical Current Polar convergence SSP - South Subpolar Current Center of oceanic Coldwater SP • South Polar Current H high pressure

Figure 9. Paleoceanography of Earth during the Late Ordovician (modified from Wilde, 1991). A - Southern hemisphere summer and northern hemisphere winter. B - Southern hemisphere winter and northern hemisphere summer. Continents and seas are the same as those in Figure L-3. The red dot is the approximate location of the Union Furnace area. B­ Balto-Scandinavia. G - Gondwana. K - Kazakhstan. L - Laurentia. S - Siberia. CD~ ".tj c) -0I!- FORMATION CD O c~ CD: ~

c: .-ca - c: .-0) as J: .- In ....as e < C .-e,) ~ e e.CD .- e. 0 ::) Reedsville Formation e as .-e,) 0 "C ~ c ca ~E 0 !I.I. F e as .-e I C .- C ftI as ftI= -Q» -a. Milroy Mbr. .J~ E CD e ca -"C ca J: "C .-e t.) :t.- .-~ Bellefonte >t= Formation Tectonic Subsidence History

600 580 560 540 520 500 480 460 440 MA o I I ' , , , , , ,

E 1 I "' Power Oil well ~ ~~ c: " ~ 2 ...., I "RR Finch well D- ~ '" cC!) I ~ " Nittany Arch , 3 ,...... --...... - 1 3 4-1 , Great Valley " 6 cm/1000 yr

Figure 11. Ancient Appalachian tectonic subsidence history (modified from Goldhammer and others, 1987). Note the abrupt change in slope of the curves at approximately 460 rna. This time was the start of Black River sedimentation, and it marks the development of the carbonate ramp in response to the Taconic orogeny. Figure 12. Photograph of the Deicke K-bentonite at the exposure along Pennsylvania Route 456 near Union Furnace, Pennsylvania.