late eocene to oligocene events: molino de cobo, betic cordillera

REVISTA EspAÑOLA DE MICROPALEONTOLOOIA
Vol. XX, mlm. 3, 1988, pp. -491.51-4
EUSTaQUIO MaLINA
Departamento de Paleontología
Universidad de Zaragoza
50009 Zaragoza, España
GERTA KELLER
MARINA MADILE
Departmellt 01 Geological and Geophysical Sciences
Princeton University
Princeton, NJ 08544, U.S.A.
Dipartimento Sciem.:e del/a Tena
Universitá di Firenze
50121 Firenze, Italia
LATE EOCENE TO OLIGOCENE EVENTS:
MOLINO DE COBO, BETIC CORDILLERA, SPAIN
Quantitative analysis of upper Eocene to Oligocene planktonic foraminifers and
calcareous nannofossils in the Molino de Cobo section, Betic Cordillera, Spain indicate three major extinction evenLS: 1) in the upper Eocene at the extinction of
Globigerapsis index, 2) at the Eocene-Oligocene boundary and 3) al tbe lower/upper
Oligocene boundary. The Globigerapsis index extinction event in Ibis area coincides
with the dramatic abundance decline of the discshaped discoasters (D. saipanensis,
D. barbadiensis). This faunal and floral assemblage change coincides with a carbonate dissolution interval.
The Eocene-Oligocene boundary extinction event involves five planktonic foraminiferal species, which contrary to common belief did not go extinct simulta~
neously, but stretched out over a 3m intervalo This extinction event is probably related to the isotopic enrichment that signals the development of the psychrosphere,
or two layer ocean with cold bottom and warm surface water. The lower/upper
O1igocene faunal tumover event involves the extinction of surviving Eocene species
and the evolulion of late Oligocene to Miocene species. A short hiatos may be present at this intervalo This faunal turnover is most likely related to global cooling
and a major sea level drop.
El análisis cuantitativo de los foraminíferos planctónicos y nannofosiles calcáreos del Eoceno superior y Oligoceno del corte. de Molino de Cobo (Cordillera Bética,
España). pone de manifiesto tres importantes eventos de extinción; en el Eoceno
superior, en el límite Eocene/Oligoceno y en el límite Oligoceno inferior/superior,
respectivamente. El evento del Eoce.no superior implica la súbita desaparición del
genero Globigerapsis. el cual constituia el 20 por 100 del tolal de la población. Los
discoaster en roseta (D. saipanensis y D. barbadiensis) también declinan dramáticamente en este momento. Estos cambios en las asociaciones de foraminíferos y nannofosiles, coinciden estratigráficamente con un intervalo de disolución.
El evento de. extinción del límite Eoceno/Oligoceno involucra a cinco especies de
foraminíferos planctónicos, las cuales contrariamente a la creencia más generalizada
no se extinguen simultáneamente, sino que se producen en un intervalo de 3 metros.
Este evento de extinción está probablemente ligado al desarrollo definitivo de la
psicrosfera.
El último evento coincide con el límile Oligoceno inferior/superior y supone un
importante relevo; la extinción de especies supervivientes del Eoceno y la evolución
de especies del Oligoceno superior y Mioceno. Este relevo está seguramente ligado
a un enfriamiento global y a una importante caída del nivel del mar, habiéndose
detectado además, un breve hiato dentro de este intervalo.
491
MOLINA, KELLER, MADILE
INTRODUCTlON
The late middlc Eocene 10 Oligocene represcnts a time of majar paleoenvironmental and
paleoclimatic changes as observed by a series
of stepwise extinctions (Keller. 1983. 1986)
accompanied by a longlerm c1imatic cooling
trend and a permanent dTay in bollom water
temperatures ncal' the Eocene·Oligocene houndary (Shackleton and Kennclt, 1976; Keigwin,
1980; Keigwin and Keller. 1984; Millcr and
Thomas. 1985; Kcigwin and Corliss, 1986;
Oberhansli and Toumark.ine, 1985; Williams
el aL, 1985). 'Lowering of sea level and widespread hiatuses are frenquently associated with
these faunal and climalic cvenls (MilJer el aL,
I98S; Keller el aL, 1986, 1987; Haq el al., 1987).
Faunal changes gene rally parallcl climalic
trends. Late middle Eoeenc tO Oligoeene wano
water asscmblages are sueeessively replaeed
by planktonic foraminifera (Ke!lcr, 1983, 1985,
1986), ealcareous nannoplanklon (Haq and Lohman, 1976; Haq el al., 1977; Pereh-Nielsen et
al., 1986), ostraeod faunas (Steincck et al., 1984)
and mollusks (Hut el al., 1987). The climatie
eooling trend is gene rally eonsidered lO be related lo Ihe developmenl of the drcum-Anlarelie eurrenl and subsequent eooling of Antareliea initialed by lhe northward movement of
Tasmania and Auslralia by mi~dle Eoeene time (Wcissel and Hayes, 1972; MeGowran, 1973;
Kennctt, 1977).
The recent diseovcry of t.hree micrOlektite
and relatcd mierospherule layers in low latilude upper Eocene marine sediments (Keller
et al., 1983, 1987; Glass et al., 1985), however,
has suggested that some faunal turnovers
and climalic coolings may have becn triggcred
01- acc!cl-alcd by cxtraterrest,·ial impacl events.
Invcsligation of microplanklon in marine sectians containing one 01' more of these microtcklite or micl"Ospherule layers re"caled lhal
no planktonie foraminiferal specics extinetions
coincide prccisely wilh these cvents, but five
radiolarian spccies cxlinction al·e associalcd
with one lnycr (Maurasse and Glass, 1976; San-
492
filippo et al., 1985). One olher microspherule
layer is associated with a catastrophic decline
in the planklOnic foraminiFer Cenus Glabigerapsis fe. semiínvolutus, e. luterbacheri, e. howei) and t.he extinction of lhis group occurs
shortly aboye lhis layer (Keller, 1986; Keller
et al., 1987).
These investigations indieate that species exlinetions aione may be a pOOl' measure of the
effect on a population after a sudden environmental jolt such as ao impacI by an eXlraterres·
lria! body. Species popuJatioos are geoeraUy
rare at time oC evolution and extinetion and
reaeh Iheir apex sometime in between. ·Sudden adverse environmental eonditions may decimate a species population lO the point where only Cew individuals survive, bUI do not reeover as a stable population, and eventually
become extinel. Quantitative population sludies
based on relative abundances of individuals in
a species may thcrefore provide a more accurate measure oC the covironmental effects
(Keller, 1986). It is therefore important to
search for good physical (microtektites) and
biological (fossil) evidenee in late Eocene seclions, to document whether species eXlinetions
as well as major fauna! tumovers and climatic
changes are triggered by largc body Eanh impacts.
The upper Eocene sedirncnts of the Molino
de Coba scction of the Betic CordilJera of Spain
(Figure 1) offer a unique opportunity to iovestigale biotic cvents during late Eocene to early
Oügoeene time. We have studicd the planktonie foraminifers and ealcareous nannofossils
of this scction quamitatively lO determine the
slratigraphy and population changcs in lerms
oC relative abundanees of dominant species. We
have been able lO document three majar faunal
evcnts which apparcnlly correlate with a late
Eocene evcnt, Ihe Eocene-Oligocene boundary
evenl and the carly/late Oligocenc sea-Ievel
drop. Faunal evenls al thcse lime have also
becn obscrved in lo\V lalilude seetions (Kcller,
1983, 1985, 1986) and are lhus believcd to represenl global events.
MOUNA, KELLER, MADILE
LOCATION AND LITHOLOGY
GeographicaJly, thc Molino de Cobo section
is located in (he Cañada de Jaen Ravine, in
the lownship cf El Gobernador (Granada Province), 2 km northeast from the village and
200 ro west froro the Molino de Cobo farmhouse. The section is exposed a]ong the Granada-Madrid railway tracks accessible by a
path fTom the Gobernador viUage lo the Pedro
Martinez train stalion.
Geologically, the Molino de Cobo section is
located in the Subetic Zone of the Betic Cordillera. The section is part of lhe Cañada FormalioÍl {Eocene-Aquitanian} of the Cardela
Graup. Sediments of the Cañada Formation
are over SOO ro thick and consist of detritic
Iimestone of turbidite origin, interbedded with
tbid hemipelagic mar!s.
Upper Eocene to Oligoeene sedimeots of the
Molino de Cobo section eonsist of 194 m of interbedded bioclaslic calcarenites and macis
that dip 30 degrees north forming the southern
f1ank of a wide syncline. The eontinuation lowards the oucleus was named Cañada de J aen
(El Gobernador) seetion and biostratigraphically studied by meaos ef planktonic forami·
nifers (Malina, 1979). The sediments are lithologically similar lo tbe nearby coeval Fuente
Caldera section (Comas et al., 1984-85; Molina,
1986), excepl lhat tbe turbidite facies are.less
extensive and 00 olithostromes are present in
the Molino de Cobo section. The bioclastie
calcareoites are 30-90 cm lhick and range from
packestones to pseudograinslones with frequent marly inclusions. The bioclasts consist
mainly of smaller and larger bentbonic foraminifera and calcareous algae primari1y of pe·
necontemporaoeous platform origin, although
sorne middle Eocene species have been found.
The autochthonous hemipelagic Olarly interbeds mnge between 1-5 ro thiek and do not
eontain displaced larger benthonic foraroini·
fers. Reworked rniddle Eocene planktonic foraminifers and calcareaus nannafossils are few
to cornman in sorne mar! beds.
METHOD5
.
out<
...
,
Figure I
Location map oC the Molino de Cobo section
i!'l Andalucia. southcrn Spain.
Sediment samples were disaggregated by soaking in water ayer night with the addition af
a small amOUnl or 10 OJo hydrogen peroxide. Iri·
durated samples wece also heated to aid the
djsaggregalion process. Samples were then
washed over 63 and 150 rnieron screens with
tap water. Quantitative eounls for faunal anaIysis wece obtained from aliquots (using a Olodified Otto microsplitter) of approximately
300-500 specimens of the size fraetion greater
(han 150 microns. AH spccimens were then
picked from the aliquot and mountcd on a microslide for identification and 'pennanent re493
MOLINA, KELLER, MADlLE
cardo The sample was a150 scanned for rare
species and the smaU size fraclion was exa.
mined far smaller species.
Thin sections were marle cf the calcarenitie
limes tone beds lo study the larger foraminifera
and examine the lithology. Calcareous Dannofossils were studied from the marly beds. A
small quantity af a c1ean rack chip was crus·
herl with a pestle in a mortar contain.ing diso
ti1led water (ph 6/7). A drop cf the suspension
was then smeared on a cover slide, dried and
emhedded on a slide with Pyccolite. A semi·
quantitative analyses cf the abunrlance cf dominante species was estimated using the Back.
mano and Shackleton (1983) method. Abun.
dance is expressed in number of specimens
per mmJ al a magnification cf x 1250.
BIOSTRATlGRAPHY
PLANKTONIC FORAMINIFERA
A planktonic foraminiferal biostratigraphic
analysis of the Molino de Cobo section was
earlier published by Martinez-Gallego (1974).
We have resampled the section at closer intervals and studied tbe planktonie foraminifera
and caleareous nannofossils based on both
standard biostratigraphic techniques (first and
last appearances of index species) and quantitative faunal analysis. These combined methods
pennit a higher resolution time control and
in addition provide paleoecologic and paleoclimatic 'information. Quantitative faunal ana·
Iysis can also minimize problems of reworked
older faunas and contamination by isolating
these species. II also permits a more accurate
assessment of the magnitude of an cxtinction
event by providing information 00 the relative
portion of individuals of the population
affected.
Our faunal counts are shown in Table 1.
Figure 2 shows the stratigraphie ranges of
species indieating where they are abundant,
common or few. Figure 3 i1ustrates relative pereeot abuodances of dominant species. We have
uscd the standard low Iatitudc zonations of
494
BoIli (1966) and Blow (1979) as well as a revised middle latitude zonatioo for this region
by Molina (1979, 1986). BolJi's 10w latit~de
zonation is applicable, except tbat the boundary between Cassigerinella cllipolensis-Pseudo-hastigerilla micra and Globigerina ampliapertura Zones could not be recognized due
to absence or rarity of P. micra. Blow's zonation was a1so sometimes diffieuh to apply because of absenee or rarity of species and difficulty in identification of sorne index species.
In sorne cases (Zones PIS-PI6) the species ranges also appear diaehronous. We therefore prefer Bolli's (1966) zonation to correlate to low
lalilude sections and Molina's (1979, 1986) ronatioo for middle latitudes.
Although the aim of this paper is nol lo
discuss the taxonomic problems of tbe planktonie foraminifers, sorne enteria of identificalion should be clarified. The species eoncept
that has been followed in this work is lhe
sarne as proposed by the European Working
Group on Planktonie Forarnioifera (Robasynski et al., 1984). Thus, no subspecies have been
coosidered. The species are general1y defined
by typological eriteria. and are often morpbotypes with rather arbitrary boundaries due lo
their interspecific variations. For stratigrapbic
purposes morphotypes with bioslratigraphical
signifieance are choscn. Tbus, sorne of thesc
species may not be tme biological species.
Other speeies rnay inelude a wide variety of
morphotypes of uncertain affinities such as
Catapsydrax unicavus 5_ 1. which ¡neludes
C. pera and eertain .Clobigerinasa with small
abortive final chambers.
Taxonomic problems in this paper a1so eoneero the genus Pseudohastigeril1a.. Pseudohastigerina. micra is a laterally eompresscd forro
which spans the Eocene/Oligocene boundary
and is an important stratigraphic marker. In
1979 Blow proposed the name P. danvillensis
for this form which we eonsider a junior synonym. Two similar but much smaller morphotypes of the species P. naguewichiensis and
P. barbadoensis are also present, but can be
distinguished only with the scanning electron
MOLINA, KELLER, MADILE
microscope: We have IUlhped these two smaJl
species as P. naguewichiensis. Also because of
their small size and difficulties in identification with the stereomicroscope, biserial Chiloguembelinas have been lumped as Ch. cubensis s. 1.
Upper Eocene
The Jowennost 20 m (up to sample 2'4, Figure 2) oF the Molino de Cobo section correspond
to the Gfobigerapsis semiinvolurus Zone. The
top of this zone is defined by the extinction
of G. semiinvolwus. Blow's (1979) PIs/PI6
Zone boundary based in the first appearance
of Cribrohantkemna inlfara occurs at 13m
from the base of the section where also Globigerina gartanii which defines Blow's Zone P17
was found. Both these species first appearances seem diachronous between middle and low
latítudes (Boersma and Premoli-Silva, 1986).
Species charactenstic oF the Gfobigerapsis
semiinvolutus Zone are G. semiinvolutus, G.
howei, G. index, G. luterbacheri, Glaboratalia
cerrOl1l.ufensis, GI. pomeroli, Globigerina rransdanubicá, and abundant G. linaperta (Figures 2, 3, Plates 1,2).
The uppennost pari of the Eocene sediments
(20 m· 68 m) correspond to me Globororalia
cerroazulensis Zone. The top of this zone coincides wilh the extínction of the GI. cerroazulensis group. Molina (1979, 1986) subdivided
tbis interval into Cribrohantkenina inflata and
C. lazzarii Zones based on the last occurrences
of these species respectively. These species
have only been rarely observed in low latitude
sections (KeUer, 1983, 1985). Because the last
appearance of Gl. cerroazufensis and C. lazzarii
do not occur at the same time, there is a sligbt
difference in age of the Eocene/Oligocene
boundary between MoJina's (1979, 1980) and
BolH's (1966) zonal systems. Characteristic
species of me uppermost Eocene are Glaboro-
talia cocoaensis, Gl. cuniaJensis, GI. increbescens, Gl. nana, Cribrohantkenina lazzarii, Hant~
kenina alabamensis, H. brevispina, Pseudohastigerina micra larger than 150 microns, Globi-
gerina ampliapertura and G. gnlavisi (Figures 2, 3, Plates 1, 2).
The maio biostratigraphic event io the upper
Eocene occurs at the top of the Globigerapsis
semiinvalutus Zone (sample 2, 4) where this
species goes extinct. In the middle latitude
Molino de Cobo section G. semiinvolutus is not
as abundant as in low latitude sections (Keller,
1986), therefore, the population change associated wilh tbe extinction of this species is
less pronounced. Tbe Globigerapsis group goes
extinct 23 m aboye the last appearance of G.
semiinvolutus in the Molino de Cobo section
and is associated with carbonate dissolution.
This is considerably' higher than observed. in
low latitude sections where G. index, the last
surviving Globigerapsis species, Frequently disappears sbortly above G. semiinvolutus (Keller,
1986). Oiachroneity of last appearances of these
species must be assumed between middle and
low latitudes.
In sorne low latitude sections (DSDP Sites
216 and 292) a microspberule layer of impact
origin is found near the extinction of G. semiinvolwus and tbe Globigerapsis group disappears shortly thereafter (Keller, 1986; Keller
et al., 1987). In OUT original sample analysis
glassy microspberuJes were also found in tbe
Molino de Cobo section in sample 4 near the
extinction of the Globigerapsis group (Kel1er
et al., 1987). However, in samples coIlected
subsequently at the same locality we failed to
find microspheruJes. It is possible that we
missed coUection the ¡ayer, or lhat the microspherules carne from surface contamination of
a yet unknowo source.
Above the decline in tbe Globigerapsis group
and the dissolution interval in ¡he Molino de
Coba section there is a major decrease, relative to other species, in tbe abundance of Globigerina linaperta and an increase in G. galavisi, G. ampliapertura, G. officinalis, G. ouachitaensis, Gfoborotalia nana and Gl. increbescens
(Figure 3). This suggests a major paleoecologic
shift possibly toward cooler climatic conditions
which has also been observed in low latitude
section (Keller, 1986). A general cooling trend
495
MüLINA, KELLER, MADILE
during the late Encene is indicated in the oxygen isotope record (Corliss el aL, 1984; Ober-
hansli and Toumarkine, 1985; Williams el aL,
1985; Keigwin and Corliss, 1986).
Eocenc-Oligocene Bounda!")'
The Eocene-Oligocene Boundary is defined
by the simultaneous extinction of the GlaboroTafia cerroaz.ulensis eroup (GI. cerraoazulensis,
GI. cocoaensis, Gl. crmialensis) and the genus
Hantkenilla and Cribrohanlkenina. To determine the nature of these extinctions in the
Molino de Cobo section a 3 m interval across
the boundary was sampled al approximately
25 cm intervals. This expanded bounclary section revealed that these species extinctions did
nol occur simultaneously (Martinez·Gallego
and Molina, 1975; Molina, 1979, 1986). The G/oborotalia cerroaztllensis group disappeared before the genus Hantkenina (H. alabamensis,
H. brevispilTa) 'which disappeared before the
genus Cribrohanlkenj¡1Q
fazzariO (Table 1,
Figure 2). Thus, Ihe Eocene-Oligocene boundary
extinctions appear to have occurred more gradually than prcviously assumed.
re.
Although five species extinctions occurred
across the Eocene-Oligocene boundary, the
overall effect on the faunal assemblage appears
not to have been very dramatic. This is best
illustraled by the relative abundances of the
dominanl species in Figur~ 3. The' spedes going
extinct were general1y less than 10 % of the
total fauna at the time of their demise; the
same' has been observed in low latitude sections (Kel1cr, 1983, 1985, 1986). No new species
evolved at lhis time (Figure 2). No majar spedes abundance ehanges are observed (Figure 3), although lhere is a general increase in
the deeper water spedes Calapsydrax and Gioboquadrina venezuelana. This inerease in the
deeper water dwellers has also been observed
in low lalitudes (Keller, 19B3, 1985, 1986).
There is, however, a cucious morphologic
ehange in the size of Psel/dohastigerina micra
at the Eocene-Oligoccne houndary which has
also been ohserved in the nearby Fuente Caldera seclion (Molina, 1986) and in low latitude
sections (Kel1er, 1983, 1985). Psetldohastigerina
micra is common to abundant in upper Eocene
sedimenls in the size fraction greatcr than 150
mierons, hui disappcars from lhis size fraction aboye the Eocene-Oligocene boundary
(Figure 3). In low latitudes this species is still
common lO abundant in the smaller than 150
micron size fraction along with P. barbadoensis (Keller, 1983, 1985), but in Ihe Molino de
Cobo section P. micra is very rare whereas
P. nagtlewichiensis s. L (which ineludes P. barbadoel1sis) is common (Table 1, Figure 2). The
common presence or absence of P. micra in
Ihe larger than ISO micron size fraclion is a
seconclary indicator lo differentiate upper Eocene and lower Oligocene sediments.
Oligocene
According lo Bolli's (1966) zonation the
Oligocene is divided inlo the Cassigerhwlla
cllipolel1sis-Pselldohasfigeril7a micra Zone defined by the extinction of P. micra, and the
Globerigeril1a amplil1.perll1Ya Zone defined by
the first appearance of Globorotalia opima opima. As noted earlier P. micra is very rare in
the Oligocene of the Molino de Cobo section
and is therefore not useful as index species.
The altemative middle lalitude zonation of Mo·
lina (1979, 1986) provides better control here.
The lowermost Oligocene Globigeril1a gorta¡¡¡iIG. faptlriemis Zone boundary is defined
by the firsl appearance of G. taptlriel1sis and
correlates to the P17/P18 Zone boundary of
Figure 2
Range chart of planktonic foraminifers from the Molino de Cabo section.
Relative thickness of range lines indica tes abundant, common or few specimens.
496
MQLINA KELLER MADILE
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6.
EU"PERTURA
VEtlHUELANA
OFFIClNAlIS
"NGUl!OFFICINAl IS
ANGUl! SUTURAlI S
ANGUSTl~ILICATA
OUAOUTAENSIS
CIPEflOEIlSlS
PP.AEBUUOlDES
OCCLUSA
ti.
UROYI
6. SOlERI
C. UNlCAVU$ S.L.
C.
C.
G.
DISSIlUllS
CIPEROENSlS
GLOIUUR lS
G. CF. GLOBOSA
(tI. CtrBENSIS S.L.
C.
CHlPOLE~SIS
497
MOLINA, KELLER, MADILE
Blow (1979). The first appearance of Globige·
rina aflgulisuturalis defines lhe C. selli/G. ano
gulisuturalis Zone boundary and corresponds
lo Lbe base of Zone P21 (Figures 2. 3). All thes~
species are rare or absent in low latitudes secliaos (KeUer, 1983, 1985).
The lower Oligocene is marked by a relatively low diversity bUl stable faunal assemblage
consisting primarily of Late Eocene survivors.
There are no majar species extinclions or abundance changes apparent. Faunal assemblages
are charaeterized by the coa! water species
GlobigeriJ1a linaperta, G. galavisi, Globorota.lia
nana and the surface dwellers Globigerina amo
pliapertura and Gl. increbescens.. Except for
GI. nana, these species ahruptly disappear between samples 11 and 11'3 marking the lower/
upper Oligocene boundary (Figures 2, 3). The
evolving species Globigerina angulisuturalis,
G. binaiensis, Gl. siakensis, Gl. pseudocontinuosa, and common typical Globigerina cipe·
roensis appear aboye lrus interval (Figure 2).
A shon hiatus of about 1 m.y. (31.5-32.5 Ma)
may be presenl at this faunal change as suggested by sediment accumulation rates. The
majar faunal turnover and short hiatus coincide with a major drop in sea level postulated
by Vail and Hardenbol (1979) and Haq et al.
(1987). Widespread erosion or nondeposition
occurred at lhis time globally as observed by
the widespread distribution of Lhis hiatus
(Keller el al., 1986).
CALCAREOUS NANNOFOSSILS
Calcareoux nannofossils from Lhe marly intervals are generally abundant and well diver·
sified. Preservation varies from poor lo mode·
raleo Reworked Cretaceous and Eocene nannofossils have been identified lhroughout this
seetion (Figure ~).
As a resul t of reworked nannofossils tbe positian of the zonal boundaries based on last
occurrences are often uncertain. To circumvent this problem a semiquantilative analysis
(Figure 4) lo estimate the relative abundances
of the domioant species has heen roade· (Fi498
gure 5). Nevertheless, lhe zonal'boundaries are
frequenlly not in tbe standard relative position
to lhe planktonic foraminiferal zones as repor·
ted by Beruren et al. (1986). Despite these
problems a complete sequence of Late Eocene
Subzone CP15a to Late Oligocene Subzone
CP19a has becn identified using the biozonation of Bukry (1973, 1975) and Okada and
Bukry (1980).
Late Eocene
The late Eocene assemblages are characte·
rized by abundant Cyclicargolithus Iloridanus,
Coccolilhus pelagicus, Dictyococciles bisectus,
Ericsonia formosa, Discoaster btirbadiensis
and D. saipanensis (Figures 4, 5). The genus
Spllenolilhus ranges from the late Eocene to
the early Oligoccne and is represented by
S. moriformis and S. predistenlus. Sphenolitifus pseudoradians used by Martini (1971) to
define the base of Zone NP20 was nol found.
Tbe genus Chiasmolilhus is very rare and it
is lherefore not possible to cakulate the Discoaster/Chiasmolitlzus ratio used by Bukry
(1973) as indicator of water temperature. Zygrhablithus bijugatus, Lallternithus minutus
and a few solution resistanl Pedinocyclus larvalis were also found; all these species are
considered as indicative of ncar shore environments.
The first appearance of lsrhmolithus recurvus which defines the base of Subzone CP15b
occurs near the base of the Molino de Cabo
section (sample 1,4 m). The extinction of Cribroce'ltrum reticulatum occurs just below the
extinction of the disc shaped Discoasters as
also reported by Nocchi et al. (1986) and
Perch-Nielsen et al. (1986).
A major biostratigraphic event is lhe decline
in abundance and extinction oC Discoaster barbadiensis and D. saipanensis. Relative species
abundance analyses indicates that Discoaster
barbadiensis is always more abundant than
D. saipanel1sis and both appear to decline simultaneous·ly. The top of Zone CP15b has
been placed at sample 4 where a strong de-
MülINA, KEllER, MADIlE
PLANKTONIC
DOMINANT
SPECIES
FORAMINIFERA
ABUNDANCES
•"
1~1-
l'\§-Jt5 ... ,.
"
...
>U
•
,• "•
•
§
~
•
"
, i
• " "u
•,
•
u
~
u
•
••
ª~
,
u
i
•
u
"
,
i
!
•
•
Figure 3
Relative percent abundances of dominant Illanktonic foraminifcra! species in
the Molino de Cobo section. Note short hiatus al the LowerjUpper üligocene
boundary.
499
MOLINA, KELLER, MADlLE
crease of D. barbadiensis and D. saipanensis
is observed. The number of specimens/mml of
D. barbadiensis decreases from 43 in sample
3 lo 13 in sample 4 and lO 2 in sample 4, 5.
Likewise D. saipanensis decreases from 16 spe·
cimens in sample 3. 5 to 3 in sample 4 and
lo 1 in sample 4, S. A similar decrease in these
species abundances was a150 observed in lhe
nearby Fuente Caldera section by Monechi
(1986) and Perch-Nielsen el al. (1986). The few
specimens of Diseoasters above sample 4 are
considered reworked (Figure 4, 5).
Imerestingly. the strong decrease and probable extinction of D. barbadiensis and D. sajo
panensis in t..he Molino de Cobo seclion coin·
cides Wilh the decline and extinction of the
planklOnic foraminifer genus Globigerapsis
and [he dissolution interval. No quantitative
analysis of nannofossils are available fram low
latitudes at this time. Therefore, it is not
known whether the decline in lhe nannofossil
species con-eiates preciscly with the micraspherule layer.
The uppermost Eocene layers between the
extinction of D. barbadiensis and D. saipanensis, and the Eocene/Oligocene boundary (based
on planktonic foraminirers) are characterized
by the rollowing variations in nannofossils.
boundary. This event has also b....---en observed
in rtaly (Nocchi et al.. 1986) and in Hungary
(Baldi el al., 1984).
Early Ollgocene
rt was not possible to subdivide the early
Oligocene Zone CPI6 inla subzones CPlóa/
CPI6b (Ericsonia subdisficha/E. formosa) because the acme of E. subdisficha which defines
this subzonal boundary (Okada and Bukry,
1980) cannot be recognized. Ncither could the
acme of E. obrufa be recorded which was used
by Madile and Monechi in the Contessa Highway section to identify the same boundary
(Premoli Silva et aL, in press). The. extinclion
of EricSO'lia formosa which defines the top of
Subzone CP16b is placed in sample 8 (89 m),
although variable abundance is presenl throughout lhe earIy Oligocene.
In subzone CPlóc an increase in abundance
of L. mimltus is observed. A similar increase
in abundance of L. minufus and Z. bijugatus
was observed in CP16b/c Subzones of the Conlessa Highway of Italy by Premoli Silva et al.
(in press) and in Hungary by Baldi el al. (1984)
who interpreled this abundance change as a
decrease in surface water temperature.
Ericsonia far/nasa ..
The extinction of Reficulofenestra umbilica
defines the top of Subzone CPI6c (R. hillae).
As wilh all nannofossil last occurrences in the
Molino de Cabo section, reworking of older
sediments makes it difricuh lo determine the
true extinction of index fossils. It is assumed
that lhe extinctions of, R. wnbilica and L. mi·
nutus occur in sample 9'4 (112 m) near the
extinction of l. recurvus, altbough rare specimeos intcrpreted as reworked occur above trus
interval. In sorne sections where R. umbilica
is rare (e.g. Contessa Quarry in Italy, Lowrie
el al., 1982), the extinclion of l. recurvus has
becn used to mark the top of Subzone CPI6c.
This suggests that the top of Subzone CPI6c
is inded c10se to sample 9'4 of the Molino de
Cobo section.
3. An increase in abundance or L. miltUfus
and Z. bijugatus ncar the Eoccne/Oligocene
The first occurrence or S. dislenlus in sample 10'6 (137 ro) marks the base of Zone CPI8,
A slight increase in lhe abundance of
ISll1molilhus recurvus, indicative of relative1y
caoler walcrs. This increase has also been observed in lhc nearby Fuente Caldera section
by Monechi (1986) and Pcrch Nielsen et al.
(1986), in lhe Umbro-Marchean Apennines (Ita·
Iy) by Monechi (l986). Nocchi et al. (1986, in
press), Premoli Silva et al. (in press). as well
as in DSDP Site 522·522A (Soulh Atlantic) by
Backmann (1986), in Sitc 362-363 (Angola Basin) by Proto Decima (pers. comm.) and in
several si tes of the Pacific Oeean by Perch
Niclsco (1986).
1.
2.
500
A slight decrease in lhe abundance of
MülINA, KEllER, MADlLE
MOLLNO DE COSO
Cale, nannofosslls
1Il
W
1Il
...J
o
<:
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··
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.
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++
I
-'---"-'-'~~-L:-'-':~L-'-':~,-,-,:~'-'-'''-'~. : "-"-~-'--':~:-'UiI. lLlJ~·
• .¡.
-0+
....
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·on
O'U
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n
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c.
m
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l:' ....
.
.
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+
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O
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,
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O' o· O
·0
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l
--,,-"--,--,''-''--'-
~
Figure 4
Range chart óf calcareous nannofossils fmm the Molino de Cobo section.
The assemblages were called abundant (A) ir the relative abundanceS exceeded
60 % af all componcnts, common (C) it there were more lhan 40 % coccoliths,
few (F) tor more lhan 10 % coccolilhs and rore (R) tor a relaLive abundance
af identifjable coccolith af less than 10 %.
Relative ahundancc af calcareous nannofossils is based on the rrequency af
lhe species per ficld of view in the Light microscope al a magnificaLion of 1500.
The species was considered:
A • I species x neld of view
e • 0,5-1 species x field of view
+ Reworkcd species
F ~ 1-4 species x 10 field of view
0,2-0.9 species x 10 field of view
R
o
501
MOLINA, KELLER, MADILE
::md the top of lhis Zone is marked by the
first appearance uf Sphcl10lirhus ciperoensis
in sample 18 (191 m).
Thc Globigerapsis exlinction 'event in the
Molino de Cobo section is associated with a
dissolution intcrval and involvcs thc cxtinction
or a1l species of the Genus Glubigerapsis as
well as Globigerillll Iral1sdtlllllbica and Globorowlia pUl'l1eroli and coincides with a major
decline in disc shaped discoasters. A catastrophjc decline in thc dise shaped diseoaslers at
Ihis leve! has al so been observed in the nearby
Fuente Caldera seelion (Perch-Nielsen et al.,
1986) and in Umbrian sequcnees or haly (Nocchi et al., 1986). These species extinctions and
faunal abundance changes imply a majar paleoeeanagraphic event al Ihis time.
DJSCUSSION
The correlation between planktonic faraminifers and calcareous nannofossils is il1ustrated in Figure 6 along wilh the con-csponding
EW'opean stages. Over 40 first appearances and
extinctions uf stratigraphically significant species (see Plates 1-3) have becn irlenlified as usefui dalum events. Mast uf tbese datum events
cluster around three time periods: the late
Eocene, al ¡he Eocene-Oligocene boundary, and
al the early lo late Olígoccnc boundary. Severa}
species extinctions and first appearances a1so
occur scattered in the early Oligocene, bu!
these species are general1y very rare (Table 1).
,•
N.\1lNOrOSS1LS
"
<
.U~aY
...
,,~
"
u
z
u
u
,•
SAIIPHS
0_,
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1111
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o
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"n- "
O
, '. ,,
o.'
f-" "" "•, o.'
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,
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i
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'70
~
..
,..
1h/b
~9
O
••• ¡.•
---- ---- ",'
•
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"
19/20
" .
""" "
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o.;
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,
¿'
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b'
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l~~
i~
;I~
15'
r~
r~
-=:::::
~It
Figure 5
Relative abundances of domimml ea1careous nannofossils in the Molino de
Cobo seclion. Abundance cxpresscd in numbcr of spccimcns pcr mm 2 at a
magnif.ication of x 1250.
502
o ,
-.
8,2
6,
"
I
"
11,7
m
U
'j ,
¡,•
,
10.6
H
Z
•
13.~
o
U
,,
•••
•o
••
o
•
MAl\TIMl
"
,•
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zmlES
~
Oxygen isolape dala summarized by Keigwin and Carliss (1986) show that a global
cooling Irend aecurred during middle to late
Eocenc lime. This coo!ing trend resu1ted in
gradual replaecmcnt of warm waler species.
i
,
'7J
MüLINA, KELLER, MADILE
The abundance decline <lnd subsequent extinclion of Ihe Globigerapsis group could Iherefore
have becn a consequence of this global cooling
trend_ However, Lhis inlerpretation does not
cxplain lhe near inslanlaneous decline in the
Globigerapsis group from a high of more Ihan
60 % lo I % in low latitudes al Lhe time of
deposition of a microspherulc layer. or from
20 % to zem in ¡he Molino de Coba section.
The de mise of Ihe Globigerapsis group in low
latitudes \Vas probably has tened by an extra-
lerreslrial impact evenl. TI is nol yet clear
whclher lhc extinction of Ihis gmup in Ihe
Molino de Coba scction con-elates lO this evenl
01' is diachronoLls, espedal1y since we failed lo
reconfirm our earlier microspherule discovery
(Keller et aL, 1987).
The Eocene-Oligocene boundary exlinction
event is not associated \Vilh any calcareous
nannofossil specics cxlinctions (Nocchi et al.,
1986) and no majar spccics abundance changes
,.
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lIo'''''lfl...
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•
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• • •
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. •., ••,
, •
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•
¡
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·....... .
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, ••
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•,,"•
,
,
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Table 1
Percent abundance data of specics in Lhe Molino de Coba scclion bascd on
population counts of 300-500 individuals. X = lcss than 2 %.
503
MaLINA, KELLER, MADlLE
are evidcnt among planktonic foraminifers
(Keller, 1983. 1985, 1986). However, large
(> 150 microns) Pseudohasrigerina micra
disappears shortly after the boundary. ln addj·
tion. lhe five foraminifer species extinctions
occur more gradually Ihan previously thougbt.
These faunal changes may be related to pro·
gressively adverse environmental condilions
which may be related lO the maximum developmeDt of lhe psychrosphere, or two layer ocean
with cold bollom water and warm surface
water al this time (Keonett and Shackleton.
1976; Keigwin, 1980).
The earIy to late Oligocene extinction even t
is somewhat obscured due to a possible 1 m.y.
hiatus. Nevertheless. a majar faunal turnover
occurs during Ihis interval with four species
extinclions and seven firsl appearanees including the nannofossil Dictyococcites abisectus
and Spheno/ithus distentus and the larger benthic foraminifer genus Lepidocyclina which
appears at the 10p of lhe early Oligocene (Figure 6). The four planktonic foraminiferal spedes Globorotalia increbescel1s, Globigerina ampliapertura, G. linapena and G. angiporoides
going extinct are Eocene survivors which constitute between 30-40 % of the foraminiferal
assemblage. Their clemisc occurs globally al
this time ·(KeIler, 1983, 1985). This major faunal tumover may be related to the global
cooling recognized by Keigwin and Keller
(l984) at this time and to the drastic sea level
drop noted by Vail and Hardenbol (1979) and
Haq el al. (1987).
CONCLUSIONS
Three major faunal event are observed in
lhe upper Eoccne to Oligocene strata of the
Molino de Cobo section:
Extinction of Globigerapsis group and
disc shaped discoasters. This Faunal event involves the demisc of the Globigerapsis group
(e. il1dex survives in lo the lalest Eocene in
high lalilude sections). Species of the elobige·
rapsL~ group constitute 20 % of the lotal foraminifcral populalion at the time of eXlinction.
The dise shaped discoasters D. saipanensis and
D. barbadiensis also decline dramatically at
this time. This faunal turnover is associated
with a dissolution event and a microspherule
layer in low latitude deep-sea sections.
2. The Eocene-Oligocene Boundary extinction cvent involves S planktonic foraminiferal
species, which did not go extinct simultaneousIy, but stretched oul over a 3 m interval. The
Globorotalia ccrroazulensis group (el. cocoaen<;is, GI. CL/nialensis) disappears before the ex·
tinction of the Genus Hantkenina (H. alaba·
mensis, 1/. brevispinaJ, which in tum preceeds
the extinction of Cribrohant kel1ina (e. lau.arii)
and Pseudohastigerina micra > 150 microns.
This gradual extinction event appears to be
related to adverse environmental conditions
associated with the maximum development of
I he psychrosphere.
3. The early/latc Oligocene faunal turnover
event involves thc extinclion of Eocene survivors (Globorotalia increbescens, Globigerina
ampliapertura, G. /inaperra, and G. angiporoides) and the evolution of late Oligocene to Miocene spedes (Globif!,eri/la binaiensis, G. angtlIisuturalis, and el. siakensisJ as wel1 as two
nannofossi¡ spccies (Dictyococcites abisectus
and Spllenolitllus distentus). This faunal turnover appears to be rclatcd lO paleoceanogra·
phic changes associatcd with a global cooling
and majar sea leve! drop.
ACKNOWLEDGEMENT
We would Iike to thank I. Premoli Silva and
S. Monechi for their comments. This research
was supporled by the U.S. - Spain Joint Committcc for scientifie and Technological Coope·
ration and by M.P.1. 60 % (S. MoneehO.
1.
504
REFERENCES
BACKMAN J., SIlACKU:rON N. .l.
1983
Quulllilalive
bioc/¡ronology 01 PUocenc. mld
Early PleiSlOcc.J1I: calcareOI/S nUIlIJOlossils Iro/11
AtltJnlic, Jndian alld Pacific Dcealls. Mar. Mi·
cropalcont., vol. 8. pp. 141-170.
MaLINA, KELLER, MAOlLE
B
•
DATUM
MAlN
EVENTS
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"'
....
Illro
!~
•
Figure 6
Surnmary chart of planktonic foraminife.ral and calcareous nannoplanklon
zonalions and datum cvents (rirSI and lasl appcarances) in the Molino de
Cobo seclion.
505
MOLINA, KELLER, MADILE
flAWI T. el al.
1984 Tlle Eocene Oligocene hall/ldar", in HWlgary:
Tlle Kiscellian Stuge. Acta Ceo!. Hung., vol. n.
pp. 41-65.
IIERGGREN W. A., KEt-..,- D.
1985
v.,
FLYN J. J.
1975 Coceofi", and 5;lico{lagellare stratigrap1Jy.
Northll'cSlerl1 Paci{ic OceuII DSDP Leg 32. In
Larson R. L el al. ¡nitial RcpoTls oC the DSDP,
vol. 32 pp. ón.701.
CO.\lAS M.
Po/cagene geocJ¡rollofogy olla c/lrOIlOslraligrtl'
1984--85
p1zy. Geol. Soc. Amer. Bull., vol. 96. No. JI.
pp. 1419·1427.
BLOW W.
li.
1979 The CailJuzuic Globigerinida. Leiden, Brill, ] vol.
c.,
.\IARTlNEZ-GAU.ECO J., .\IDUNA E.
Lito{acie.{)' sucesiÓn cslraliráfica de/ Eoce110 y Oligoceno al Norll! del cerro Menca/
(10110 Stlbbit;cu Proll. de Grallada). Cuad.
Cco!., vol. 12 pp. 145·155.
CORI.ISS O. 11., ¡\UBREY M. P., BIlRCGREN W. A.,
Jr.,
BOERSM" A. o PRUIOL.l-SILVA l.
FENNER J. M., KEIGWIN L. D.
1986
1984 Tlle Eocene Dligocem:: boundary Eve", in the
Deep Sea. Sciencc, vol. 226, pp. 806-810.
Terminal Eocene Evctl/s: plollktollic (orami.
,¡¡{era ami isotopic evidenCI!. Developments in
Pale. and Slnuig., \'01. 9, pp. 213-224.
KELt.ER G.
O'IIONDT S. L.. KELLER G., STAl.L\RD R.
BOLL.¡ H • .\\.
1987 Ma;or element composiliollal variarioll \Villlin
1966 Zorra/ion of CreraceOl4s lo Pliorenc marine se·
diments based 011 pfallktollic lorumillifera. Bol.
1nfor. AsSQC. Venez. Ceo!. Mine. y Petrol., \'0lume 9, pp. ]·31.
alld betll't!en diflerell/ late Eocellt!' ",icrolektite streIV {ields. Mclcorilics, vol. 22, No. 1,
pp. 61-79.
GL\SS O. P., IlURNS C. A., CROSIlll! J. R., lIUUOIS D. L.
DUKRY
n.
1973a Coccolilll olld Silicofragellale slroligrapllY Tas.
mml sea alld sOlltll\vcstem l'ucific Ocean D$DP
leg 2/. In R. E. Burns et al., ¡nitial rcports of
DSDP, vol. 21, pp. 885-893.
1985 Late Eocene Norl/r American microteklile.\· alld
cli'IOpY"oxe¡¡c-bcar¡',g sp/rerulcs. Proee. 16th
Lunar and Planct Sei. ConC. Jour. Gcophys.
Res., vol. 90. pp. 175·196.
1973b Luw lat;flldcs coccofitll bioslratigrapJty ~olla­
tiOll. In Edgar N. T. et al., Inilia1s Reports oC
the DSDP vol. 21. pp. 685-703.
1976 Early Cellol.u;c IIalllloplollklon b;ogeograpl,y
u{ file Allanlic Dccan. Mar. Micropalcont., vol. 1,
pp. 119-194.
HAQ B. U., t.OH,\IAN G. P.
PLATE 1
Scale bar = 100 ¡.lm
1.
2_
3, 4.
5.
6.
Hatllke"ina aloballlf!lIsis (Cushman). sample 1.5. lop of Gfobigerapsis
semiinvolutus Zonc.
Globigerop!is semiinvolulUS (Kcijcr), samplc 2. G. semiinvolutus Zone.
Gfobigerapsis index (Finlay), sample 2, G. semiirlvo/utus Zone.
G/obigerapsis interbacJlCri (Bolli), samplc 2, C. sf!miinvolutl/s Zone.
Globigeropsis 1Io\Vci (Blow and Banncr), samplc O, G. semiirlvolr41us
Zonc.
7. '8.
9, 10.
11. 12.
13, 14.
14, 15.
506
Gfoborotofia pol1leroli (Toumarkinc and Bolli). samplc 1,5, C. semiillvoluiHS Zonc.
Globororolia cerrOGl,ulellsis (Cole). sample 2. G. sellliillvolutlls Zonc.
Cloborotalia cocoaellsis (Cushman). samplc S, GI. cerroazulellsis or
C. inllala Zone.
CribruluUllkenilla i/Jflala (Howc), sólmplc 2, C. sell'liiHvo/u/tls Zonc.
Cribrollalllk·enina lazzadi (Pcrieo1i), samplc 6.4, Globoro/lllia cerroal.ulellsis or C. laZl,a,.ii Zone.
MüLINA, KELLER, MADILE
PLATE 1
REVISTA ESPAÑOLA DE MICRO PALEONTOLOGÍA,
Vol. XX, núm. 3, 1988
507
MaLINA, KELLER, MADILE
REVISTA ESPAÑOLA DE MICRQPALEONTOLOGÍA,
508
PLATE 2
Vol. XX, núm. 3, 1988
MOLlNA, KELLER, MADILE
HAO B. H., PREMOLl-SH.VA l., LOHMAN C. P.
ltI!.lGW1N LO., CORUSS 8. H.
19TI CalcareollS pfankto" biogeograpllic l!vidence for
1986 Slabfe isOIOpes in Lale Eocelle to Ofigocel1e
Foromini/era. Geol. Soc. Amer. Bull., vol. 97,
pp. 335·345.
/IIajor e/imafic flllCtllatiOIlS in lile earl)! Ce1loHAO B. 1-1., llARDENBOL J., VAIL P. R.
1987
C/tremology of fluclllaling sea levels since lile
Triassic. Science, vol. 235, pp. 1156-1167.
KELLER G.
1983 Bioc1lrollology olld Palcoclimalic implicolions
of middle Eocene lO Oligocelle planklOllic /oro.
mini/eral faunas. Marine Micropal., vol. 7, pa·
ges 464-486.
HUT P., ALVAREZ W., EUIER W. P., l-IAN5EN T.,
lCAUFFMAN E. G., KELLER G., SH OEUAKER E. M.,
WEISSMAN P. R.
1987 Comel showers as a passlble cauSe uf mass
extillcli01ls. Naturc, vol. 329, pp. 118-126.
K.E..lGWIN L O.
1985 Eocelle and Oligocelle slraligraplry olla erosiollal uncullformities in lhe GIIJ/ of Mexico
ond GIIJf Cuasi. Jour. Paleo., vol. 59, No. 4,
pp. 882·903.
J r.
1980 Paleoc:eal1ographic cllange in lIle Pacific al lile
Eocen¡;·Oligocene Boundary. Nature, vol. 287,
pp. 722-725.
1986 Stepwise Mass Extillction ond ¡/IIpaCI Evenls:
Lale Eocene lO Early Oligocene. Mar. Micropal.,
vol. 10, pp. 267·293.
KEIGWIN LO., KElJ..ER G.
KEU.ER
1984 Middle Oligoccne e/imolie ellonge frotll equotoriol Pacific DSDP Sile 77B. Geology, vol. 12,
No. 1, pp. 16--20.
e., U'HONUT S., VIILLlER T. L
1983 MII/liple microlektite 110riZOllS ill upper Eocelle
Marine Sedimenls: No evidence lor Mass ExIinctions. Seicnc!:, vol. 221, pp. 150-152_
PLATE 2
Scale bar = 100 um
1. 2.
3. 4.
5.
6.
7.
8.
9.
10.
11,12_
Globigerina cocaella (Gumbel), samplc 6,49, Cribrohantkeniru1 lauarU
or Globormalia cerruazulensis Zonc.
PseudolrllStigerina micra (Cole), sample 2,4, Gtobiguapsis semiinvolu/us Zone.
Pseudollastigerina barbadoensis (Blo",,), sample 9, Globigerina /apu·
riensis Zone.
Clliloguembelina cllbensis S. L. (Palmer). sample 9, Globigeril1a lapuriellsis Zone.
'
Globigerina galavisi (Bermudez), sample 6,48, C. lazzarii or Gl. cerroazulensis Zonc.
Globigerina tapuriensis (Blo"" and Banncr), sample 9,7, Globigerina
seW or G. ampliaperlura lonc.
Globigerina selli (BorsclIi), sample 12, GtobigerirTa angulisuturalis or
Globoro(alia opin¡a Zone.
Globigerina bil1aiensis (Koch) , sample 11.3, G. angulisuturalis or Gl.
opima Zonc.
Globorotalia nana (Bolli), samplc 5,6, C. lazzar;i or Gl. cerroazulensis
Zo~nc.
13.
14.
15.
16.
Globigerina gorlmlii (Borsctli), sample 13,5, G. al1gulisuturalis or GI.
opillla Zone.
Globorolalia siakensis (Le Roy). sample 12, C. al1gulisLHuralis or Gl.
opima Zonc.
Globiger;na angulislltllralis (BolJi), samplc 12, G. angulisulllralis or
Gl. opima Zone.
G/oborolalia opima (Bolli), sample 11,7, G. allgulisuturalis or Gl. opima Zone.
509
MOLlNA, KELLER, MADll.E
KEU.ER G., HER8F.RT T., DORSEY R., JDHNSSON M.,
CHI W. R.
MARTINEZ-cAllECO J.
1986 Global distributi011 o( lAte Paleogene Hiatuse.s.
Gcology, vol. 15, No. J. pp. 199-203.
c., D'HONDT S. L. ORTH C. J., GIL\'ORE J. s.,
o, SIiOEMAKER E. M., MOUNA E.
1987 lAte Eocene ImpaCI Microspherules: Slratígraphy, Age and Geochemistry. Meteo;'ilics, vol. 22,
No. 1, pp. 25-60.
1977
de un sectOr comprendido entre Mort!da Pina,
Pedro Martinet. (Zo"a SlIbbilica). Tesis Doct.
Univ. Granada, No. 175, 264 pp.
KEU.ER
OUVER P.
KENNETT J. P.
1977
Ceno~ojc EWJlution o( Anlarclic g/adalion, Ihe
circum hllarctic Ocean and their impac/ on
global Paleoceanography. Jaur. Geophys. Re!.,
vol. 82, No. 27, pp. 3843·3860.
Estudio micropaleontof6gico del Nummulitico
MARTlNEZ-GAll.F:CO J .• ),lOUNA E-
ro-
1975 ESl/(dio del lrdnsito Eouno-oUgoceno con
raminiferos plallct6nicos al Sur de Torre Car·
dela (Prov. de Granada. Zona Subbilica). Cuad.
Geol.• vol. 6. pp. 1TI-195.
MARTlNI E.
1971 Standard Tt!rfiary and Quaternary calcareous
nannoplankton lOna/io". Proc. Second Plank.
Canf. Roma, 1971, vol. 2, pp. 739--785.
LOWRIE W. el al.
1982
Paleogellf~
magnelic s/ratigraplly in
Umbrian
pelagic carbonate rocks in tJu: Conlessa seco
rions, Gubbio. Ceol. Soc. Amer. Bull., vol. 93,
pp. 321-325.
MAURASSE F.• CIASS, B. P,
1976 Radiolarian stra/igraphy and Norlh American
micro/ektiles itl Caribbean Core RC9-58:¡;;jplication cotlcernin, La/e Eocene radiolarian
PLATE 3
The abbrevialions XN and QL de,note cross-poIarized and trasmited light.
1. Discoaster de/landrei Bramlelte and Riedel, sample 3,5 (OL) x 2200.
2. Discoasler lani nodifer Bramlette and Riedcl, sampIe 3,5 (Ol) x 2200.
3, 4. Cruciplacolill1us crux (Deflandre and Fert) ROlh, samplc 3,5. (3) OL,
(4) XN. x 2200.
5, 6. HelicospJtaera euphratis Haq, sample O. (5) Ol, (6) XN. ¡( 2200.
7, 8. HelicosplJaera bramlettei Mullcr.
9, 10. Pontospllaera plana (Bramlelte and Sullivan) Haq, sample O. (9) Ol,
,(lO) XN. x 2200.
11, 12. Pontosphaera multipora (Kamptner) Roth, sample 9. (11) OL, (12) XN.
x 2200.
13, 14. Transversopon/is obliquipons (Deflandre) Hay, Mohlcr and Wade,
sample 3,5. (13) OL, (14) XN. x 2200.
15. 16. Ericsonia fOTmosa (Kamplner) Romein, sample 6,37. (15) OL, (16) XN.
x 2200.
17, 18_ Diclyococciles abiseclus (Muller) Bu"-ry and Pcrcival, sample 10,6.
(17) Ol, (18) XN. x 2200.
19. 20.
~1.
'22.
23.
24_
25, 26.
27.
510
ZygThablilhus bijugalus (Deflandre) Deflandre. sample 18. (19) Ol,
(20) XN. x 2200.
Coronocyclus nilescens (Kamptner) Bramlette and Wilcoxon, sampIe 2,6. (21) OL. (22) XN. x 2200.
Corannulus germanicus Slradner, sample 6,5, Ol. x 2200.
Discoaster sublodoensis BramIette and Sullivan, sample 5, OL. x 2200.
Chiasmolilhus oamaruePfsis (Deflandre) Hay, MohJer and Wade, sampie 5,6. (25) OL. (26) XN. x 2200.
Discoasler baTbadiensis Tan Sin Hok, sample 3.5. OL. x 2800.
MüUNA. KELLER, MADlLE
PLATE 3
..
-
,.
,
~
I
.
...
.••• .. .
.¡ •
~
.'
,
.'
•
• ,•
••
REVISTA ESPAÑOl~ DE M1CROPAlEOmOlOO1A. Vol.
XX. mlm.
3, 1988
511
MOLlNA, KELLER, MADlLE
REVISTA EspAÑOLA DE MlCao'AL[ONTUlOGlA, Vol. XX, nOmo J, 1988
512
PLATE 4
MüLINA, KELLER, MADILE
chronology and tlle ape 01 l/le Eoeene-Oligo.
eene bOlmdary. 7th Caribean Gcol. Conf. Proc.
1974, Guadeloupc, pp. 205-212.
MCGQWRAN B.
1973
Rifling and drifl af Australia and Ihe migralían 01 mamma/s. Sciencc, vol. 180, pp. 759.
MIu..ER K. G., THOMAS E.
1985 Lale Eoeene lO O/igocene bcnlhíc /uramíni/eral
isotope record, Sile 574, equaloria/ Paci/ic. Inilials Rcports oC Ihe DSDP, vol. 85; pp. 771-7&0.
s., TUCHOLKE B. E.
1985 Oligoeene glacioellsla.sy and erosion on Ihe
margín of Ihe Norrh AI/maie. Geology, vol. 13,
pp. 1-13.
MIl.l.ER K. G., MOUNTAlN G.
s.
1986 Calcareous nannofossils of lhe Fuente Caldera
seclion. Develop. in Paleont. and Stratig., vol. 9,
pp. 65-70.
MONECHI
In press Cu/careollS nannofossil cvellls around Ihe
Eocene Oligocl;lle bOlmdar)! in lhe Umbrian secliolls (Ita/y). Submitted to Palco. Palco. Paleo.
NOCCHI M., PARISI
1986 T/lI.' Eocene Oligocene boundar)! in the Umbriall pelagic seqtlenccs, Ila/y. Devclop. in Paleont. and Stratigr. vol. 9, pp. 25-40.
NOCCHI M., PARlSt G., MONACO P., MONECHI S.,
MADILE M.
1979 O/igoceno-Mioeeno inferior por medio de foramini/eros plunclónicos en el seclor cenlral de
las Cordilleras Belieas (Espalia). Tesis Doct.
Public. Univ. Granada y Zaragoza, 342 pp.
In
el al.
1986 Biostraligrap/¡ic corre/alioli belll'eell LIle cellIru/ Sllbbelic (Spaill) mld Umbro-Marc!leUfl
(1Ialy) pelagic seqw:l1t:es al l!le E/O bOllndary
IlSillg farwlli/lilera. Develop. in Paleont. and
Stratig., No. 9, pp. 75-86.
MOLlNA E.
MONACO P., MONECHI S.,
PREMDLI-SILVA l., lIlCE D. M.
MOUNA E.
1986 Descriplion alld bioslratigraphy 01 lhe maill
reference seclioll o/ l/le Eocene Oligocene botlndary hl Spai,l.· Flleme Caldera seClioll. Develop.
in Paleont. and Slralig., No. 9, pp. 49-52.
e.,
Mo\tHLE M., NAPOLEONE G., RIPEPE M., ORLANDO M.,
press Middle Eocene lO Ear/)! O/lgocenc faraminiferal and calcareous namlOlossils biostratigrapJlY and paleoenvironmental c/lallges in Ihe
Soul/¡ Eas/crll seqlleflces, Ilaly. Submitted to
Palco. Paleo. Paleo.
OBERHANSLI 1-1., TOUMARKINE M.
1985 T}¡e Puleogene oxygen and carbon is%pe hislury of Sites 522, 523 and 524 Irom /he cefl/ral
SOllt!J Atlalllic. In: Hsu K. J., Weissert H. J.
eds. South Atlantic Paleoceanography. Cambrigc Universily Prcss, pp. 125-148.
o KADA H., BUKRY D.
1980 SlIpp/emc'l/ary modificalion al/d inlrodllction
(J/ code IIl1mbers ro l!Je lolV lariLUdes cOCCOlitll
PlATE 4
Reticlllofel1estra lIlIlbilica (Levin) Martini and Ritzkowsky, samplc 3,5.
(1) Ol, (2) XN. x 2800.
3, 4. EricsOIlia sp., sample 6,4. (3) Ol, (4) XN. x 2800.
S, 7. Spllel101illlUS disretl!us (Martini) Bramlette and X ilcoxon, sample 16.
(5) Ol, (6) XN, (7) XN 45". x 2800.
8, 9. Eriesollia ObTUra Perch Nielsen, sample 5,4. (8) Ol, (9) XN. x 2200.
lO, 11. SpllcllolitJltIs predislcnlllS Bramlcllc and Wilcoxon, sample 5,6. (ID) al
(11) XN. x 2200.
12. Hulodiscolillws solidlls (Deflandre) Roth, sample 3,5, aL. x 2200.
13. Diseoas/er saipallensis Bramlette and Riedcl, and Braarudospllaera
bigelowii (Gran and 8raarud) Deflandrc, sample 3,5, OL. x 2800.
14, 15. CyclococcolitJJilla killgi (Roth) Roth, sample 1,5. (14) al, (15) XN.
x 2200.
16. Isllil/loli/llUS recllrvus Deflandre, sample 5,6, Ol. x 2200.
I7, 18. Cribrocen/rwll reliculalwl1 (Gartner and Smith) Perch Niclsen, sampIe 1,5. (17) Ol, (18) XN. x 1200.
19. Pedillocyclus larvalis (Bukry and Bram1cttc) Loeblich and Tappan,
sample 5,6, aL. x 2800.
1, 2.
513
MOLlNA, KELLER, MAOILE
bioslrotigro.ph¡c
W"lJ.lioll,
Mar. Micropalcont.,
SHACKl..lrrON N. J., KENNETT J. P •
1976
vol. 3, pp. 32J-325.
PERe 1I NIElSEN K.
1986 CalcareollS NOlltlofossil elle'1ll al Ihe Eocelle/
Ofigocerre bOll1ldafY. Develop. in Palcont. and
StraLig.. vol. 9, pp. 215-282.
¡'RUIOU SILVA l., MOS:ECIlI
s.,
MAUlLE: M., SA.POLEONE
u.,
ORLANDO M., RIPEI'E M.
Paleotemperalllre I-listory 01 lile Cenoz.oic and
tlle ;"itiaríon of Antarctic g/aciation: oxigen
alld carbOIl istope allalysis in DSDP Sites 277,
n9 al/d 181.. IniEia! Rcports of the D5DP, vol. 29,
pp. 743-755.
STE.lNECK P. L., BREF_" M•• NEVlNS N., O'I-IAR-' r.
1984
Middle Eocenc mld Dligocelle dl!ep sea ostra·
coda Iro", lile oceallic formation Barbados.
J. Palconlology, vol. 58, No. 6, pp. 1463.. 1496.
In press CalcareollS plallkto" bioslratigrap/,)' alld
magllt!lDslraligraplly lIf fhe Eoccnc 01igoccIle
Irtll/siliOI! fmm ti/e G/lbbio area Early Paleocene fJ¡rougJi Earl)' Oligocen/!o Submiltcd lO
Palco. Palco. Pako.
VAII.. P. R, II,\ROENBOL J.
Il.OI:IASZ\'NSKI 1'., CARUN M., GONZALEZ-DONOSO J. M.,
WEISSEL J. K., Il",VES D. 1:"
WONDEllS .\. H.
1972
1984 Atlas 01 /(lIe Creluceolls globolnmCtlllids. Revue de Micropalcontologic, vol. 26, pp. 145-305.
1979
Sea level ellallges dllring tlJe Terliary. Occanus,
vol. 22, No. 3, pp. 7J.80.
Magl1elic ulIol11111ies ¡" flre sOIlI}¡ea..s1 Indian
Dccan. In Hayes O. E. ed. Antarctic Oceanology JI. Anlarclic Res. Ser., vol. 19, p. 165.
SANFIUPPO A., RIEOEl. W. R., GUSS B. P., KYTI': F. T.
WILLIAMS O. F., TIIUNELL R. e .• 1I01)EI.l. 11. A.,
1985 LA/e Eoccue microtekliles 0",1 radia/ariall ex·
tillClioll U/I Barbados. Nalure. vol. 314, pa·
ges 613-615.
VERGN... UlI-GItAZZINI
SAUSOERS J. R.• IIERNOULLl O. ,MUU,.EK-MERZ E.,
OIlERHA/'IlSU 1-1., PERII NII,ISEN K., RIEDH.. W. R.,
Jr.
1984 StrOligroplly 01 tl,e lAte Middle Eocene lO
Eorly O/igocene in tllC Batll Cliff Section, Bar·
bodas. Ulest IlIdies. Micropaleontology, vol. lO,
pp. 390-425.
SANFII.IPI'O A., TORRINI R.
514
c.
1985 SYlltcsis of IAle CretaceollS, Tertiary alld Quaternary sluble isolope records of Ole SOIlIfI
Atlamic basea 011 Leg 7Z DSDP core Material.
m Hsu K. J., Weissen H. J. cds. Soulh Allantic Palcoccanogrnphy. Cambridge UniveTSilY
Press, pp. 205-242.
MallflScrito recibido el S-VI-1987