Boundary of the Pennsylvanian and Permian(?) in the Subsurface Scurry Reef, Scurry County, Texas

Sep 29, 2026

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Subsurface sedimentary rocks forming the Scurry reef and the overlying terrigenous clastic unit in Scurry County, Texas, were previously treated as Canyon and Cisco Pennsylvanian in age. Core samples from the Wilshire Oil Company’s No. 8 Lunsford well at 6,804–6,828 feet show Triticites pinguis? and Schwagerina species, indicating early Wolfcamp Permian(?) age. The overlying black shales are at least as young as Wolfcamp. Fusulinids below 6,875 feet suggest Canyon (Missouri) age, while Cisco beds could not be recognized by fauna.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages26

Reading Time1 h 6 min

AccessFree to download

Contents

Abstract

Introduction

The age of the Scurry reef and the overlying black shales

Lithology and paleontology of the reef rock and overlying black shales

Depositional history

Conclusions

References

Illustrations

Figures

Plate

BUREAU OF ECONOMIC GEOLOGYThe University of TexasAustin 12,Texas JOHN T.LONSDALE,Director Report of Investigations—No.13 Boundary of the Pennsylvanian andPermian(?)in the Subsurface ScurryReef,Scurry County,Texas By W.A.Heck,K.A.Yenne,and L.G.Henbest Prepared in co-operation with the United StatesGeological Survey December 1952 Boundary of the Pennsylvanian andPermian(?)in the Subsurface ScurryReef,Scurry County,Texas By W.A.Heck,K.A.Yenne,and L.G.Henbest Prepared in co-operation with the United StatesGeological Survey December 1952 557.64T355 CONTENTS PAGEAbstract ………… …5Introduction………… The age of the Scurry reef and the overlying black shales……………… ……… ……7Lithology and paleontology of the reef rock and overlying black shales … ………10Depositional history …14Conclusions …………… ----14References …_… 14 ILLUSTRATIONS FICURES— 1.Map of major structural features of west-central Texas… … …… 6 2.Generalized subsurface contour map of the top of the Scurry reef 8 3.Profile of reef along A-A'of figure 2 … …… 9 4.Electric log and microlog of the Wilshire Oil Company's No.8 Lunsford well,Scurry County,Texas …11 5.Lithology of the reef limestones and overlying shales in the Wilshire OilCompany's No.8 Lunsford well 13 PLATE— I.Fusulinidae from the Wilshire Oil Company's No.8 Lunsford well,Scurry County,Texas.16 身 BOUNDARY OF THE PENNSYLVANIAN AND PERMIAN(?)IN THESUBSURFACE SCURRY REEF,SCURRY COUNTY,TEXAS* W.A.Heck,1 K.A.Yenne,l and L.G.Henbest² rocks of Canyon age.These conclusionswere announced in the Bulletin of theAmerican Association of Petroleum Ge-ologists(Heck et al.,1952).The pur-pose of this preliminary paper is to de-scribe the evidence that led to these con-clusions and to describe the later evidencethat has made some revisions necessary. # ABSTRACT The subsurface sedimentary complexthat comprises the Scurry reef and theoverlying terrigenous clastic unit in ScurryCounty,Texas,were formerly regarded asof Canyon and Cisco Pennsylvanian age.Core samples from depths of 6,804 to 6,828feet in the Wilshire Oi Company's No.8Lunsford well reveal the presence of Tri-ticites pinguis?Dunbar and Skinner,Schwagerina longissimoidea(Beede),and“Schwagerina”compacta(White),whichindicate early Wolfcamp Permian(?)age.Triticites pinguis?continues downward inlimestone to a depth of approximately The Scurry reef(fig.1)is located inthe western part of Scurry County and isthe southeastern segment of an arcuatechain of subsurface reefs that Adams andothers(1951)have called the "Horseshoeatoll."This group of reefs extends fromKent County on the north clockwisethrough Scurry and Borden counties on thesouth,northwest to Terry County,and thennorth to Hockley County.The ends of the“horseshoe”lie south of the southernflanks of the Matador arch,an east-westsubsurface ridge lying just south of theTexas Panhandle.The eastern part of theatoll,including the Scurry reef,fringesthe western edge of the Eastern Platform,as the limits of that feature are consideredby some geologists.Adams and others(1951),however,show that the boundarybetween the Eastern Platform and the Mid-land basin lay to the east during Pennsyl-vanian time in Fisher and Nolan countiesand that the atoll therefore lay entirelywithin the Midland basin. 6,875 feet,and since this form,so far asknown,is also restricted to rocks of earlyWolfcamp age,the stratigraphic unit isclassed as Wolfcamp.The overlying blackshales are therefore at least as young asWolfcamp. The fusulinids in the limestone immedi-ately below the 6,875-foot level indicateCanyon(Missouri)age.If beds of Ciscoage are present in this well,they could notbe recognized by their fauna. # INTRODUCTION The limestone complex that comprisesthe subsurface Scurry reef of ScurryCounty in west-central Texas was formerlyregarded as of Canyon Pennsylvanian age.Recently,paleontologists of

FAQs

What geological boundary does the report focus on?

It focuses on the Pennsylvanian and Permian(?) boundary in the subsurface Scurry reef of Scurry County, Texas.

What evidence was used to revise the age of the Scurry reef?

Core samples from depths of 6,804 to 6,828 feet in the Wilshire Oil Company’s No. 8 Lunsford well revealed fusulinid assemblages indicating early Wolfcamp Permian(?) age.

How old are the overlying black shales according to the report?

The overlying black shales are at least as young as Wolfcamp.

Sep 29, 2026

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