Lower Cretaceous Ostracoda From Wells In 

 Central and Northeastern North Carolina 



An occurrence of previously unknown marine 

 rocks of Early Cretaceous age was reported by 

 Brown (1958) in several water wells in Lenoir 

 and Pitt Counties, North Carolina. Recently, addi- 

 tional wells have penetrated these rocks that con- 

 tain an abundant ostracode fauna, probably of 

 Albian age. 



The Ostracoda of these pre-Tuscaloosa deposits 

 are of interest because they indicate nearshore 

 deposition in a lagoonal environment, character- 

 ized in part by brackish water, and differ, there- 

 fore, from Cretaceous ostracode faunas previously 

 described from the Atlantic and Gulf coastal 

 areas. A somewhat similar fauna, believed to be 



much older, was described by Swain (1952) from 

 the Lower Cretaceous section in a well at Cape 

 Hatteras, North Carolina. 



The Lower Cretaceous rocks consist of inter- 

 layered sandstone, mudstone, and shale that over- 

 lie crystalline rock and in turn are overlain by the 

 Tuscaloosa Formation of Late-Cretaceous age. 

 The stratigraphic relationships of the Lower Cre- 

 taceous rocks with younger rock units in the area 

 are shown in Table 1. 



Three recognizable but intratransitional facies 

 occur in the Lower Cretaceous section from top to 

 bottom as follows: 



Well 

 Number 



Elevation 



of 



Well 



(feet) 



Total 

 Depth 



(feet) 



Beds of 



Post- 

 Miocene 

 Age 



(feet) 



Beds of 



Miocene 



Age 



(feet) 



Navarro 



Taylor Austin 



Tuscaloosa 



Beds of 



Early 



Cretaceous 



Age 



(feet) 



Basement 

 Depth 



(feet) 



Basis of 

 Correlation 



(feet) 



Equivalents 



(feet) (feet) 



(feet) 





Rock Typt 





LE-T6-55 



+ 53 



823 



0-29 





29-143 



143-282 282-566 



566-713 



824 + 





Electric log 

 Microfauna 

 Lithologic 



P-Tl-56 



+ 59 



754 



0-19 



19-38 



38-104 



104-162 162-440 



440-600 



600-754 + 





Electric log 

 Microfauna 

 Lithologic 



NH-T1-61 



+ 68 



480 



0-48 









48-136 



136-280 



280 



Gamma log 





Granite 



Microfauna 

 Lithologic 



NH-T3-61 



+ 70 



294 



0-51 









51-131 



131-282 



282 

 Granite 



Gamma log 

 Microfauna 

 Lithologic 



H-fl-62 



+ 111 



345 



0-40 



40-82 







82-242 



242-340 



340 

 Unakite 



Electric log 

 Microfauna 

 Lithologic 



H-T2-62 +98 342 0-28 28-70 



70-254 



254- 



338 Electric log 

 Unakite Microfauna 

 Lithologic 



H-T3-62 +96 356 0-37 37- 



346 Electric log 

 Gneiss Microfauna 

 Lithologic 



H-T2-61 



+ 58 



251 



0-16 — 



— 16-100 



100-247 



247 Electric log 





Granite Microfauna 

 Lithologic 



H-T4-61 



+ 59 



246 



0-14 — 



14-82 



82-240 



240 Electric log 

 Granite Microfauna 

 Lithologic 



Table 1. — Correlation of Strata in North Carolina Wells. 



1. Fossiliferous, variegated, grayish-green to 

 reddish-brown shale and interlayered gray to 

 greenish pink and white sandstone. Accessory 

 minerals include siderite (rare), glauconite 

 (rare), hematite aggregates (common), and mica 

 (abundant). Lignite occurs as scattered particles 

 in the shales. Contains ostracodes and rarely are- 

 naceous Foraminifera. 



2. Fossiliferous, black to light gray waxy shale 

 interlayered with tan to gray-colored sandstone. 

 Chalky, coarse, broken and abraded shell frag- 

 ments (chiefly oysters) may comprise as much as 

 30 percent of individual samples. Accessory min- 

 erals include siderite (common), pyrite (rare), 

 glauconite (common to rare), and mica (abun- 

 dant). Lignite is common to abundant. Contains 



