Carbonate Rocks of Cambrian and Ordovician Age in the Lancaster Quadrangle Pennsylvania
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Carbonate Rocks of Cambrian and Ordovician Age in the Lancaster Quadrangle Pennsylvania By HAROLD MEISLER and ALBERT E. BECHER CONTRIBUTIONS TO STRATIGRAPHY GEOLOGICAL SURVEY BULLETIN 1254-G Prepared in cooperation with the Pennsylvania Geological Survey Department of Internal Affairs Commonwealth of Pennsylvania UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director U.S. GOVERNMENT PRINTING OFFICE WASHINGTON : 1968 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 10 cents CONTENTS Page Abstract-____-___- _._-_-._____-____.-.____,-__._______-^___-----^-_ Gl Introduction._______-_______-__-_-_---______-_-_ ____---__--__--__ 1 Cambrian System.________________________________________________ 5 Vintage, Kinzers, and Ledger Formations__-^___^_-___-_--____-___ 5 Zooks Corner Formation______________________________________ 6 Conococheague Group.___-____-_-__-___- -______--___-_--_-___ 7 Buffalo Springs Formation_____-_-_---_---_-----_---_----- 9 Snitz Creek Formation.____________________________________ 9 Millbach Formation____-_-________^.__.___________________ 9 Richland Formation._______________________________________ 10 Ordovician System.-_______________________________________________ 10 Conestoga Limestone___---__-____-____-_-_-_-__--_-__---__-__ 10 Beekmantown Group.______-_--___---__.--_____-_-_____________ 11 Stonehenge Formation.____________________________________ 11 Epler Formation._________________________________________ 11 Ontelaunee Formation___-_-_-______-_.___^-__---__---__--__ 12 Annville Limestone.______________--___.-___--___--___----_---_ 13 Myerstown Limestone._______________________________________ 13 References cited.__________________________________________________ 13 ILLUSTRATIONS Page FIGURE 1. Map showing the location of the Lancaster quadrangle and general physiography of southeastern Pennsylvania. _______ G2 2. Generalized geologic map of the Lancaster quadrangle.______ 4 3. Map showing the location of the type section of the Zooks Corner Formation.____________________________________ 6 TABLES Page TABLE 1. Stratigraphic section of the carbonate rocks of the Lancaster quadrangle used by Jonas and Stose (1930) and in this report____________________________________________ G2 2. Generalized section of the carbonate rocks of Cambrian and Ordovician age in the Lancaster quadrangle, Pennsylvania. _ _ 3 3. Correlation of the Conococheague Group in the Lancaster quadrangle and Lebanon and Berks Counties, Pa.-_____ 8 CONTRIBUTIONS TO STRATIGRAPHY CARBONATE ROCKS OF CAMBRIAN AND ORDOVICIAN AGE IN THE LANCASTER QUADRANGLE, PENNSYLVANIA By HAROLD MEISLER and ALBERT E. BECHER ABSTRACT Detailed mapping has shown that the carbonate rocks of Cambrian and Ordovician age in the Lancaster quadrangle, Pennsylvania, can be divided into 14 rock-stratigraphic units. These units are defined primarily by their relative proportions of limestone and dolomite. The oldest units, the Vintage, Kinzers, and Ledger Formations of Cambrian age, and the Conestoga Limestone of Ordovician age are retained in this report. The Zooks Corner Formation, of Cambrian age, a dolomite unit overlying the Ledger Dolomite, is named here for exposures along Conestoga Creek near the village of Zooks Corner. The Conococheague (Cambrian) and Beekmantown (Ordovician) Limestones, as mapped by earlier workers, have been elevated to group rank and subdivided into formations that are correlated with and named for geologic units in Lebanon and Berks Counties, Pa. These formations, from oldest to youngest, are the Buffalo Springs, Snitz Creek, Millbach, and Richland Formations of the Conococheague Group, and the Stonehenge, Bpler, and Ontelaunee Formations of the Beekmantown Group. The Annville and Myerstown Limestones, which are named for lithologically similar units in Dauphin and Lebanon Counties, Pa., overlie the Beekmantown Group in one small area in the quadrangle. INTRODUCTION Carbonate rocks of Cambrian and Ordovician age underlie a low land that occupies most of the Conestoga Valley in southeastern Penn sylvania. Detailed mapping by the authors of the Lancaster quad rangle in the Conestoga Valley (fig. 1) now allow carbonate rocks formerly assigned to the Conococheague and Beekmantown Limestones (Jonas and Stose, 1930) to be more closely subdivided into units de fined primarily by their proportions of limestone and dolomite. Most of these units are herein correlated with units in the Great Valley in Lebanon, Berks, and Dauphin Counties, Pa. (Geyer and others, 1958, 1963; Hobson, 1957, 1963; Prouty, 1959). In addition, a newly defined dolomite unit is herein named the Zooks Corner Formation. Gl G2 CONTRIBUTIONS TO STRATIGRAPHY 78 77° 76° 20 0 20 40 60 MILES I I I i I I FIGUEB 1. Location of the Lancaster quadrangle and general physiography of southeastern Pennsylvania. TABLE 1. Stratigraphic section of the carbonate rocks of the Lancaster quad rangle used by Jonas and Stose (19SO) and in this report Jonas and Stose (1930) This report Cocalico Shale Conestoga Shg|e ^ Limestone ^^ Myerstown Limestone ^^ Cocalico Annville Limestone O ^^Dasal limestone o c Ontelaunee Formation ^ ^^ Q 5 ce o 5? 5 c c Beekmantown Limestone || Epler Formation ?So)£"° O 1 yl w 03 ________ - - ~~ CO Stonehenge Formation ^'o 03 Richland Formation 00 ro Q) Q. SI D Millbach Formation 0 0 Conococheague Limestone o C3 o Snitz Creek Formation 2 o o Buffalo Springs Formation cc CO ^____^^-''^EIbrook Limestone Zooks Corner Formation 0 Ledger Dolomite Ledger Dolomite Kinzers Formation Kinzers Formation Vintage Dolomite Vintage Dolomite CARBONATE ROCKS, LANCASTER QUADRANGLE, PA. G3 TABLE 2. Generalized section of the carbonate rocks of Cambrian and Ordovician age in the Lancaster quadrangle, Pennsylvania System Formation Thickness Character (feet) Limestone, dark-gray, coarsely crystalline, Myerstown Limestone 200± thinly bedded; abundant pelmatozoan stem plates. Limestone, gray, finely crystalline, partly Annville Limestone 200± laminated. Ontelaunee Forma 0- 00± Dolomite, gray, very finely to finely crystalline; Ordovician tion finely laminated in part. Beekmantowii Groui) Limestone and dolomite, interbedded, gray; abundant white beds in lower part, cal- Epler Formation 2, 000-2, 500 carenite beds, pelmatozoan stem plates, coiled gastropods. Stonehenge Forma Limestone, gray; shaly laminae, calcarenite tion 500-1, 000 beds, pelmatozoan stem plates. Limestone and dolomite, interbedded, gray; Richland Formation 0-500± beds of fine conglomerate and calcarenite, rare cryptozoon. Limestone, white to pinkish-gray and gray; CouochcagueGroup Millbach Formation 1, 200-2, 000 scattered beds and laminae of gray dolomite. Snitz Creek Forma tion 300-400 Dolomite, gray, argillaceous, silty, sandy. Limestone and dolomite, interbedded, white to pinkish-gray and gray. Dolomite is com Buffalo Springs 1, 500-3, 800 monly argillaceous, silty, sandy; scattered Formation sandstone beds, cross laminae, ripple marks, Cambrian rare cryptozoon. Dolomite, gray, commonly silty and sandy; Zooks Corner Formation 1, 600± little gray limestone, cross laminae^ripple marks. Dolomite, light gray, mostly coarsely crystal Ledger Dolomite 1, 000± line, sparkling, partly mottled. Shale, gray, rusty weathering; white to gray limestone commonly containing reticulated Kinzers Formation 300-600 argillaceous and silty laminae; some dark- gray earthy dolomite. Dolomite, gray, very finely to coarsely crystal Vintage Dolomite 350-550 line; locally contains interbedded limestone. In southern part of quadrangle Limestone, gray, finely to coarsely crystalline, Ordovician Conestoga Limestone Unknown schistose in part; limestone conglomerate near base. The stratigraphic nomenclature used by Jonas and Stose (1930) and that used in this report are both given in table 1. A summary of the character and thickness of each formation is given in table 2. A generalized preliminary geologic map of the Lancaster quad rangle (fig. 2) shows a separation of the area underlain by carbonate rocks into three east-west trending belts. The Lititz belt is separated from the Mount Joy belt by a ridge of shale of the Cocalico. The Mount Joy belt is separated from the Lancaster belt by discontinuous G4 CONTRIBUTIONS TO STRATIGRAPHY 76°15' 40° 00' 5 MILES FIGURE 2. Generalized geologic ridges of Lower Cambrian quartzites and phyllites. Stratigraphic dif ferences between these belts are discussed in subsequent sections of this paper. This report is a product of the hydrogeologic investigation of car bonate rocks in the Lancaster quadrangle by the U.S. Geological Sur vey in cooperation with the Pennsylvania Geological Survey. CARBONATE ROCKS, LANCASTER QUADRANGLE, PA. G5 EXPLANATION Cocalico Shale Annville and Myerstown Limestones Ontelaunee Formation Epler Formation Conestoga Limestone Stonehenge Formation . Richland Formation Millbach Formation Buffalo Springs and Snitz -Creek Formations Zooks Corner Formation Vintage, Kinzers, and Ledger Formations Chickies, Harpers, and Antietam Formations Contact Fault Dashed where approximately located map of the Lancaster quadrangle. CAMBRIAN SYSTEM VINTAGE, KINZEKS, AND LEDGER FORMATIONS The definition and use of the names "Vintage," "Kinzers," and "Ledger" in this report follow that of Jonas and Stose (1930). These formations crop out only in the Mount Joy and Lancaster belts shown in figure 2. 285-190 68 2 G6 CONTRIBUTIONS TO STRATIGRAPHY ZOOKS CORNER FORMATION The Zooks Corner Formation