From Greenhouse to Icehouse

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Nesbitt, Elizabeth R. QE692.8 . ... along the Chickasawhay River in Wayne Counry,. Mississippi, as ... means by which Charles Lyell (1830) subdivided. Europe's ...
From Greenhouse to Icehouse THE MARINE EOCENE-OLIGOCENE TRANSITION

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EDITED B Y DONALD R. PROTHERO , LINDA C. IVANY, AND ELIZABETH A. NESBITT

FROM GREENHOUSE TO ICEHOUSE The Marine Eocene-Oligocene Transition

EDITED BY DONALD R. PROTHERO, LINDA C. IVANY, AND ELIZABETH A. NESBITT

COLUMBIA UNIVERSITY PRESS NEW YORK

Columbia University Press Publishers Since 1893 New York

Chichester, West Sussex

Copyright © 2003 C olum bia University Press Ali rights reserved Library of Congress Cataloging-in-Publication data From greenhouse

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icehouse : th e marine Eocene-Oligocene transition / edired by Donald R. Prothero,

Lind a C. lvany, and Elizabeth A. Nesbitt. p. cm.

Includes bibliographie references and index. ISBN 0-231-12716-2 (acid-Iree paper) 1. Eocene-O ligocene boundary. 2. Marine fauna-Gulf Coast Region (U .5.) 3. Marine faunaAtlanti c Coast Region . 4 . Marine faun a-Pacific Co ast Region. I. Prothero, Don ald R. II. Ivany, Linda C. III . N esbitt, Elizabeth R. Q E6 92. 8 .F76 200 3 560' .457-dc21

Co lumbia Uni versity Press books are printed on perm anent and durable acid-free paper Printed in the Un ited States of Am erica c 10 9 8 7 6 5 4 3 2 1

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CHAPTER 18

Molluscan Faunas Across the Eocene/ Oligocene Boundary in the North American Gulf Coastal Plain, with Comparisons to Those of the Eocene and Oligocene of France D avid T. Dockery III and Pierre Lozouet ABSTRACT Distribution data is given for 947 mollu scan taxa of late Eocene (M oodys Branch Formati on ) to early Ol igocene (Byram Formation) age in th e No rt h Ame rican G ulf Coas tal Plain . Only 26 of th ese taxa range across th e Eocene/O ligoce ne boundary; th e appare nt extinc tion rate in th e latesr Eoce ne Yazoo Formation is 88 .6%. The succession fauna of the lower O ligocene Vicksburg Gro up conrain s Tet hyan elements havin g related species in the Sta m pian of th e Aqui taine Basin in southwesrern France; several related species are nored, Eoce ne/ O ligoce ne boundary extinctio ns are att ributed to falling sea level and climatie coo ling. New appearances of related early Oli gocene species on bath sides of the Atla nt ic O cean are att ribured to the transport of plan torr ophic larvae by ocean cur rents . INTRODUCTION A nearly continuous record of late Eoce ne and early Oligocene marine deposition is present in th e North Ameri can G ulf Co astal Plain . This section contains diverse mollu scan faunas above and below th e boundary as weil as excellent planktoni c nannofossil and foraminiferal assem blages and radiom etri cally dated bentoni tes near th e boundary interval. D ockery (in M acN eil and Dockery, 1984) proposed th e disconform able contact of the late Eocene Shub ura C lay Member of th e Yazoo Format ion with the overlying early O ligocene Red Bluff Forma tion as exposed along the C hickasawhay River in Way ne Counry, M ississip pi, as a stratotype for th e Eoce ne/Oligocene boundar y, a site whe re m olluscan-rich early O ligocene sedime nts overlie pelagie clays of the latest

Eocene. A strato type for thi s boundary was eventually selected in th e M arche-Umbria Basin of Iraly in a pelag ie section with a good microfossil record , but without a signi ficant ben th ic molluscan record. T he radi ometr ie age of th e boundary stratotype was inte rpolated by M ontan ar i et al. (198 8) as 33 .7 ± 0 .5 M a. T his age match es th ar of sanidi ne ages from bentonites near the to p of the Yazoo Formation in corehol es at Society Rid ge (33.70 ± 0.1 9 M a, Obradovich and D ockery, 1996 ) and Mossy Grove (33.7 Ma, Flu egeman , 1996), both in northwes rern H inds County, Mi ssissipp i. The mollu scan record of weste rn Europe is un even across th e Eoce ne/O ligocene boundary int erval. T he late m iddl e Eoce ne Bartonian Stage of th e Paris Basin contai ns sorne 1,300 to 1,400 species of mollusks with 1,000 species of gastropod s alone (Lozouet, 1997). However, the molluscan faunas of the so ut hwes te rn European late Eocene typ e Priabonian section in Italy are not weil preserved ; the se faunas are best preserved in Germany wh ere Cavelier (1979 ) documented sorne 800 species of gastropods. Above the boundary, the early O ligocene Stampian sectio n of France's Aquitain e Basin conta ins (counring only th e gastropods and bivalves) 577 molluscan species (unpublished data and Lozou et, 1997, 199 9), while th e Sram pian of the Paris Basin contains 289 molluscan species (unpublished data and G itto n et al., 1986). In com pa riso n, th e lare Eocene (Priabo n ian) sectio n w ithi n th e M ississipp i Embayment of th e North Am erican G ulf Coas t co ntains 426 m ollu scan taxa in the Jackson Group, and th e early O ligoce ne section contai ns 54 7 spec ies in th e Vicksburg Gro up. T he appendix lists a to tal of

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THE ATLANTIC, GULF, AND CARIBBEAN

947 molluscan taxa, including spec ies, sub species , varieries, and unnamed species, recorded in the Jackson and Vicksburg groups of th e north-central Gulf Coas tal Plain , onl y 26 of which ran ge across th e Eocene/O ligoce ne boundary. Ir is inreresting to note th ar whil e mollusks are not an important component of the Eocene/ Oligocene boundary stratotype in Iraly, the y were th e mean s by wh ich C ha rles Lyell (18 30 ) subdivided Europe's Terti ary section into Eocene, Miocene, and Pliocen e epochs. Lyell chose th e name Eocene to represent the "dawn of the recent," an epoch followin g the extinction of many C reraceous molluscan taxa (as weil as the din osaurs and other creatures) and with taxa resembling rhose of recent fauna s, but with few living molluscan species. The Miocene was a name meaning "less recent [living molluscan species]," and the Pliocene was a name meaning "mo re recent [living mollu scan species]." Thus, Lyell construcred a Terti ary tim etable based on percentages of extanr molluscan spe cies. At th ar rime there were no planktonie microfossil P zon es and NP zones, an d benrhic mollusks pro ved their worth in region al correl ations of geologic rim e, Lyell traveled to Ame rica in 1841-1842 and in 1845-1 846, in part to see if his Tertiary epochs applied to the American Coastal Plain section as weil as to th ar of Eur ope. On M arch 19, 1846 , Lyell arrived at Jackson, Mi ssissippi , by rail and was taken to wha r wo uld becom e th e type Jackson Group localiry, an exposure of th e Moodys Branch Form ation at Town C reek (only a ten-rninute walk from the train station) . Lyell was irnrnediately able to idenrify th e exposure as Eocene in age based o n th e fossil mollusks he collected. H e also recogni zed the Jackson exposure as younger rhan thar of the type Claiborne G roup (Barto nian) section he had visited earlier in Alabama and as older than the type Vicksburg Group section he had visited th e day before . H aving only Eocene, Mio cene, and Pliocen e divisions, Lyell recognized th e Vicksburg mollusks to be interrnediare berween the Eocene and Miocene faunas and placed them as upper Eoce ne. Co nr ad followed this placement when he published th e Vicksburg mollusks in 1848. In 1854 , Beyrich named the Oligocene Epoch, meaning "little recent," and Conrad recogni zed the Vicksburg mollusks to be of O ligocene age in his faunal lists of 1865 and 1866. SEQ UE NCE ST RAT IG RAPH Y Distribution . data for 2,816 Paleocen e and Eocene molluscan taxa (includ ing species, subspecies, and

unnamed species) for the North American Gulf and Atlantic coastal plain s show thar 2,261, or 80 % , of the se occur in four adjoin ing states: Texas, Loui siana, Mi ssissippi, and Alabama (D ockery, 1986). These states straddle a plunging syncline and ancienr seaway known as the Mi ssissippi Em bayment. Distribution data for 547 early Ol igocene mollusks from the Vicksburg G roup sho w ail th ese taxa to occur within (but not necessarily restricred to) M ississippi between the C h ickasa whay River o n th e east and th e Mis sissippi River on the west. Thus, the important marine record for fossil mollusks for both the late Eocene and early O ligocen e is centered in the northern G ulf within th e M ississippi Ernbaymenr Palmer ( 197 9) recogni zed the importance of the molluscan record in understanding the history of sealevel or "rhythm of th e Paleocene-Eocene seas" in the central Gulf C oastal Plain. She recognized a correlation berween regional strat igraphic stages (groups), molluscan faun as, and glob al sea-Ievel cycles. Vail et al. (19 77 ) and Vail and Hardenbol (19 79 ) also depended heavily on the Gulf Coastal Plain record in developing their eusratic sea-level charts for th e Tertiary Period . In these cha rrs, the lare Eocene Priabonian Stage was placed in cycle TE3, and th e early Oligocene Rupelian Stage was placed in cycle TO 1. Baum and Vail (1988) later broke th e correlation berween stratigraphie stages and sea-level cycles wh en the y recognized th ree cycles in the Priabonian Stage of th e Gulf and Atlanti c coasral plains. The first, cycle T E3. 1 included the Gosport Sand, and thu s exrended across the C laiborn e/Jackson Group/ Stage boundary. The third, cycle TE3.3, included th e Red Bluff and Forest H ill form ations, and th us exrended across th e Jackson/Vicksburg Group boundary. T he placement of early Vicksburg sediments in cycle TE3 .3 was strongly influenced by the Eocene/Oligocene boundary section at St. Srephens Quarry in Washington Court ry, Alabama , a downdip section with deep-water clay and limestone facies. H ere Baum and Vail ( 1988) placed a co ndensed section at the Jackson-Vicksburg G ro up contact. Mancini and Tew (1991) restricted cycle T E3.l ta include onl y th e Gosport Sand and placed only lower Jackson Group sed ime nts of th e Moodys Bran ch Form ation and th e North Twisrwo od C reek Clay Member of the Yazoo Form ation in cycle TE3.2. H owever, th ey followed Baum and Vail (1988) in exrending cycle T E3.3 into the Vicksburg G roup, placin g within ir th e C ocoa Sand, Pachuca Mari, and Shubuta Cl ay members of th e Yazoo Formation along with the Red Bluff and Forest Hill formations.