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4了了
勿G Mapper, R Feist, R T Becker and M R House
'W'%vefinition of the Frasnian/Famennian Stage
boundary
盆The boundaryfor the FrasnianlFamennian Stage Global
Stratotype Section and Point (GSSP) has been ratified勿
ICS and IUGS and is drawn in a section exposed near
the Upper Coumiac Quarry in the southeastern Mon-
tagne Noire, France. The position of the boundary was
selected勿 the Subcommission on Devonian Stratigra-
phy in 1991 to coincide with the lower boundary of the
Lower Palmatolepis triangularis Zone in the conodont
biostratigraphy. The revised definition of the lower
boundary of the zone, proposed herein, excludes the
extremely rare occurrences of Palmatolepis triangularis
afew centimetres lower, within the uppermost conodont
zone. The GSSP also coincides with the boundary
between the Crickites holzapfeli Zone and the Phoenix-
ites frechi Zone in the goniatite scale. The position of the
GSSP is immediately above a major horizon of extinction
within the Devonian and is stratigraphically somewhat
lower thanformerly used boundary levelsfor the base of
the Famennian.
Introduction
Historically, several different levels have been used to define the
base of the Famennian. In the type area for the naming of the stages
in southern Belgium, precise documentation in recent years has been
given to a new reference section replacing the now-infilled classic
section in the Senzeilles railway cutting (Bultynck and others, 1988).
Largely resulting from work in the first quarter of this century in Ger-
many, another boundary was used that was based on the entry of the
goniatite Cheiloceras in the pelagic realm. In the latter half of this
century the considerable growth of conodont studies has led to much
refinement of the biostratigraphy. However, the level taken as the
base of the Famennian has varied between a level at the base of the
crepida Zone down to the base of the Lower triangularis Zone. The
need for an international definition has become urgent. The Subcom-
010 KM ,Bedarieux A-?00 /
因 ..二,二,
区鼓习
DEVON!AN /了
阅花二 / 夕
尹 洲
,气 Les
与UIIIII: m'0OUA RR Y.沙uranqe5
}"Q飞,’’
一/’“’7妙
牙'to cessenon
。Q户 wl}-
O
二又弓一扮代v
Coum iac 0 100 m
L一一 」
Nazaire de
Ladarez
六
Aurignac Bedarieux
子
Toulouse
N,亡ausses et
Veyran 。。瞿
PRO V/刀 C E
+叼ontpellier
AMagalas L卜14 阿 EDI TERRA NE AN
卜
+Cessenon 、_, .、
s 尸 A I N 0 一 100 KM
. 一」 -
Figure] Maps showing theposition of the Montague Noire in southeastern France and of the Upper户umiac_
Quar7y near Cessenon, the site of the Global Stratotype Section and Point (GSSP)for the definition of the base of the
Famennian Stage (inset map A). Modifiedfrom Becker and others (1989).
Episodes, Vol. 16, no. 4
434
mission on Devonian Stratigraphy (SDS) has given careful consider-
ation to which level is most appropriate for international correlation
and it decided, at a meeting in Washington in 1989, that a GSSP
should be sought in relation to the base of the Lower triangularis
conodont Zone. Final ballots and ratification by ICS and IUGS (in
January 1993) led to a level in a section at Courniac, southern France
being designated as the Global Stratotype Section and Point (GSSP).
A brief review of the documentation leading to this decision is given
here. The conodont and goniatite biostratigraphic divisions are
shown in figures 5 and 6.
It has been recognised by the Subcommission that, in general,
Devonian sections in pelagic realm facies are more likely to be com-
plete than those in the neritic fa,cies. The pelagic facies forms a better
basis for the biostratigraphical precision needed for international cor-
relation. In particular the conodont and goniatite records are better in
those facies. That is not to imply that there are not facies rich in other
groups, for example spores and brachiopods, which are very impor-
tant for correlation, but it is normally easier to correlate into such sec-
tions secondarily from primary sections in the pelagic facies. In the
last resort the Subcommission concentrated on two such sections, one
at Steinbruch Schmidt in the Rhenish Slate Mountains,
(Sandberg and others, 1990; Schindler, I Germany
other at
Courniac in the Montague Noire (Feist, 1990
selected because of the better documentation The latter was finally
ssil
groups.
Recommended stratotype
The recommended boundary GSSP between the Frasnian and
Famennian Stages (Devonian) is above the Upper Courniac Quarry,
near Cessenon, Montague Noire, France (figure 1). The section is sit-
uated in the southeastern Montagne Noire, D6partment 1-16rault, Dis-
trict of Cessenon (topographic sheet 1:25 000, No. 2544 E, Murviel-
1}s-136ziers
Figure 2
map of the
;Lambert's
Detailed
之加per
coordinates: x=130 375, y=658 55). It is
adjacent to the southeastern border of the disused upper marble quarry
(UQ) of Courniac, 175 in WSW of the Les Granges farmhouse, about
1.5 km NIE of Cessenon village and 2 100 m SW of Causses et Veyran.
It can be reached easily by a path up the hill from near the track to Les
Granges farmhouse from the road D136 between Cessenon and St
Nazaire-de-Ladarez. The ground is owned by the commune of
Cessenon and is already protected as part of a water supply area. Con-
servation and protection of the section has been assured by communal
and department officials. Free access for scientists is confirmed.
The sequence is one of pelagic calcilutites, mostly red tinted
and well bedded, with bedding probably controlled by Milan-
kovitch-Band climatic oscillations during sedimentation. The
sequence has been described in published accounts (House and oth-
ers, 1985; Mapper, 1989; Becker and others, 1989; Schindler 1990;
Becker 1993a) and is depicted in figure 2. The boundary is drawn
between Beds 31g and 32a as shown in figures 2 and 3. Distinctive is
Bed 3 1 g which is correlated with the Upper Kellwasser Limestone ot
Germany and which is a hypoxic dark grey calcilutite to calcarenite
above which is the most marked faunal boundary. Both Beds 31g
and 32a are characterized by pelagic faunas.
The sequence chosen shows a complete succession through the
early Frasnian to late Famennian. It is unfaulted and has no tectonic
problems. The beds are approximately vertical. Equivalent sections
can be found elsewhere in the area. The rocks are of low-grade meta-
morphism and thermal maturity (CAI 2-3) and comprise an homoge-
neous pelagic calcilutite sequence without marly or shaly interbeds.
There is a complete zonal succession with a rich fossil content, espe-
cially of the biostratigraphically significant groups of conodonts,
ammonoids, trilobites, tentaculites and ostracods. Detailed docu-
mentation has been provided of this (Feist, 1990). Geochemical
work across the boundary at Courniac has also been published
(Goodfellow and others, 1989; Grandjean and others, 1989; Grand-
jean-L6cuyer and others, 1993; Joachimski and Buggisch, 1993;
Girard and others, 1993) and currently other investigations are being
Quarry at Courniac,
near Cessenon,
showing the bed
numbering and the
position of the GSSP
defining the base of
the Famennian 1341二
between Beds 31
and 32. Modified 331
I I I-4r
!1 -1 }邢1 40
. , J736 :
Plan
户om House and
others (1985). 12
SCA LE O F M E TRES
(16)
F仓ure 3 The
detailed succession
of beds around the
GSSP level between
beds Mg and 32a
abovethe Upper
Coumiac Quany
near Cessenon.
FRASNIAN}FAMENNIAN 0.5 1.0 METRE
臼习
酬川 队{ 卿 {
17W刊?
9161519 15 16
d, e31
ele 护 ie7 9,18 33d 14 141 35- r-f79-. +61'6
6 16
C t d 1二 f
30 32 33
期go
CM
BED
December 1993
435
undertaken. Magnetostratigraphic work indicates that the area was
remagnetized during the Permian. is a key sequence for the thirteen-fold Montagne Noire Frasman
Correlation of the proposed boundary
level
zonation (Mapper 1989), substantial parts of which have been repli-cated at various sections in North America, Western Australia, and
European Russia (Mapper and Foster 1993, figure 2). The sequenceat Upper Courniac extends from Frasman Zone 5 to the top of Zone
The boundary level proposed represents perhaps the best correlated
horizon in the Devonian. A review of more than 30 international see-
13(=top of the Frasnian), but only the higher part of the Frasman
seauence is of concern here.
Bed 24a, the Lower Kellwasser Limestone, nas me iowest
occurrence of Ancyrognathus asymmetricus, which is the defining
tions has been presented by Sandberg and others (1988) including
localities in North America and Europe. Further correlation is estab-
lished in North Africa (Becker and others 1988), China (Ji, 1989)
and Australia (Becker and others, 1991). The boundary corresponds
to the extinction of all species of the conodonts Ancyrodella and
Ozarkodina and the loss of all but a few species of Palmatolepis,
Polygnathus, and Ancyrognathus, according to Sandberg and others
(1988, pp. 293-294). There is a well-known extinction among gom-
atites of the Gephuroceratidae and Beloceratidae and the record for
both conodonts and goniatites at Courniac demonstrates this well.
The last of the brachiopod Atrypidae occurs just below the boundary
level (Becker and others, 1991). Among trilobites the Dalmanitidae,
Odontopleuridae, Harpetidae and Aulacopleurinae all disappear atthe base of the end-Frasnian Upper Kellwasser Limestone level of
Bed 31g. Others have documented the global extinction of coral
(Sorauf and Pedder, 1986; Scrutton, 1988), stromatoporoid (Stearn,
1987) and acritarch (Vanguestaine and others, 1983) groups
there has been much recent local documentation in many areas.
changeover of benthonic ostracod faunas across
the boundary
Coumiac has been published (Lethiers and Feist, 1991).
Conodont record
The conodont sequence at the Upper Coumiac Quarry extends from
within the middle part of the Frasnian across the Frasnian/Famenn-
ian boundary and into the lower Famennian (as high as the Upper
crepida Zone in the current sampling up to Bed 44). Upper Counuac
species for the lower boundary of the Upper gigas Zone in the zona-
tion of Ziegler (1962, p.23; 197 1). The conodont fauna of Bed 24a is
interpreted as the highest sampled level of Montague Noire Zone 12
(Mapper, 1989, p. 456, figure 4). However, due to the facies of the
Lower Kellwasser at Courniac, which apparently resulted in the
extreme rarity of Palmatolepis in Bed 24a, a higher zonal identifica-
tion cannot be excluded. Nonetheless, the lower boundary of Zone
13 is necessarily taken at the lowest occurrence of PaIniatolepis bog-
artensis in Bed 24e (figure 5), as well as at the coincident lowest
occurrence of Pa. hassi s.s. The lowest occurrence of Pa. rhenana
sensu Mapper and Foster (1993, p. 24, figure 2) is high within Zone
13 in Bed 30b, coincident with the lowest Pa. boogaardi (figure 5).
It is noteworthy that species characteristic of the higher part of
the Frasnian at Upper Coumiac, Palmatolepis bogartensis, Pa.
winchelli, Pa. rhenana, Pa. boogaardi, Ancyrognathus asymmetri-
cus, and Ancyrodella curvata all terminate in either Beds 31f or 31g.
The conodont fauna of Bed 31g, the Upper Kellwasser Limestone,
has all but two of the foregoing species (figure 5) and is dominated
in terms of its Palmatolepis component, by Pa. bogartensis and Pa.
winchelli. On evidence of the lowest (and only) occurrence of Ancy-
rognathus ubiquitus in Bed 31g, the fauna is apparently correlative
with the upper part of the lingu扣rmis Zone (Ziegler and Sandberg,
1990, p. 21), despite the absence of Pa. lingu扣rmis. In the Mon-
tagne Noire Frasnian zonation, Bed 3 1 g represents the highest part
of Zone 13. Ancyrognathus uInquitus also occurs in faunas of the
Upper Kellwasser Limestone at three other nearby Montagne Noire
localities: Causses et Veyran North and South, and Lower Coumiac
(Feist, 1990, pp. 19, 24, 30). All these faunas are correlative with the
linguiformis Zone, but lack the nominal species (Becker and others,
1989,pp.262,265).
Figure 4
Photograph of the
succession above
the Upper Coumiac
Quarry. The GSSP
lies between Bed
31g and 32a. For
scale compare with
the profile of the
beds given in
figure 3.
黔--
煞71,翼 噢盗
纂墓
雌夔瓣毅井 价鬓粱省岁彩孚擎七万黔 像一巍砂色_坛
32a
瓣嚎脚
了I‘ 了I C 了峪
了弃a
Episodes, Vol. I反no. 4
尸... .月,,.网 ..尸一~一 一一一~-, 一. — — — 不 花 一
4了6
Figure 5 Range
chart of conodont
species across the
FrasnianlFamennin
boundary at Upper
Coumiac Quarry.
The GSSPfor the
base of the
Famennian is at the
base of Bed 32a.
Position of the
upperpart of
Frasnian Zone 12,
Frasnian Zone 13
(Mapper, 1989), the
Lower, Middle and
Upper triangularis
Zones, and the
Lower and Middle
crepida Zones is
indicated.
Recognition of the
Lower, Middle and
功少er crepida
Zones is cited in the
MIDDLE COUMIAC FORMATION LIDW G RIOTTE FM
FRAS N认 N
2日 1271 2习
,lb 1, Idle 1,lbIc Idlela JbIc ja Jbic id .lb Ic Id le I& lb Ic ld la 11, R31
a lb Ic Id le If 19 c ld le 361.37 1381 39lb . Ib
ZONE 12 ZONE 13 ID 八
L . M.
SP indet
如月二eUQ己
p0 u吧b七谈
尘犯 比d U二d妞ern口健口舀
I. sy} b它1巧
....
Rl hQS舀t
」七.d酬刀m s创曰 皿」丁
An.几笼白SQ
.. 口I七. ef.尸匕.breuLs
... Pa. LVW 沦 迸 f二Pa. .曲 注匕位
R L cE P. rh-
...
Pa rh己n口尸习1
Mehl臼U
召lm} }
p匕
text, but species
ranges are not 气 夕
I勺 。
shown above Bed
J6. 篡 p,B,mrnehk sp.
Pa.护 'delicatuta &katuta '
盆几飞 I dehwtla detfcatla
于 二一 一一 一贡 minufa rrdmta
目日口 二二孟二...
... - - d
〔二J inferred range
Pa. = I勺如ate,娜 t}
Pb.二内 山ana度h“污
AO. = Ancy-gnaU-
An- =
Ia. tenuipundata
P. a叫 } a
份 ..Ag sinelarnm}
是气. ef. Pa.P, ap, 。* Pa. crep曰a ? (me }
RANGES OF CONODONT TAXA AT THE UPPER COUMIAC QUARRY
Upper Coutruac Bed 3 Ig is also noteworthy. in haying叩e confi-
dently identified_ specimen otalniato‘ep‘s trangut仔ns冬and o些
questionable specimen of the same species,呼Igrmer usteu in月臀L,
1990, p. 36) among the many exampes ot Pa.ogarrens‘s. aDa ra.
winchelli. Although one cannot complete坚exc,uge tne possi甲liy。‘
stratigraphical leak from the overlying坤甲弓nn‘an, extre吧iy rare
occurrences of Palmatolepis triangularts in tne uppermost rrasm哩
are probably not unique to the UpperFourmac吻恻 ・’毛tie report ot
27 unfigured specimens i呼ent壑ed as塑. praetnangutans from thr
samples within Bed功 ot te_Upper Kewasser Limes‘one a Se‘n-
bruch Schmidt (Sandberg and oters,‘丫匕匕,乡ab‘e止!may repre
another Frasman occurrence o1尸a. trangulars. inis interence is
based on Mapper's study in 1990 of the holotype and two paratypes of
Pa. praetriangularis Ziegler and Sandberg (in Sandberg and others,
1988, p. 304, pl. 1, figures 1, 3, 4), all from the highest bed of the lin-
gu扣rinis Zone at Hamar Laghdad, southern Morocco. These three
types (Pa elements) have an arched outer-postenor platform, which
gently rises from the lobe to just before the tip, then arches downward.
This is exactly the same as in many specimens of Pa. triangularis in
the Lower and Middle triangularis Zones; however, in the holotype
(Sannemann, 1955, pl. 24, figure 3) the outer posterior platform rises
more steeply from the lobe to just before the tip, tnen_ arcnes uown-
ward. Consequently, the view is favoured here that Falmato吧S tr-
angularis and Pa. praettiangulails are synonyms. A slightly different
view perhaps could be supported in which the latter is treated as an
intraspecific morphotype, which is apparently a common form of
Pa. triangularis in the Lower triangularis Zone. Forms like the
holotype of Sannemann seem to be relatively rare in this zone at
least in the Montagne Noire. Clearly the praetriangularis morpho-
type crosses the Frasnian/Famennian boundary at Schmidt Quarry,
as was well documented by Sandberg and others (1988, Table 1).
[The 27 specimens listed as Pa. praetriangulans in Bed 16 at
Schmidt Quarry occur with 3380 listed as Pa. subrecta (a junior
synonym of Pa. winchelli, see Mapper and Foster, 1993, but speci-
mens of Pa. bogartensis may have been included in this count)].
Thus, extremely rare Pa. triangularis as this species is delimited
here may occur slightly below the level of the lower boundary of the
Lower triangularis Zone at both Coumiac and Schmidt quarries (up
to 12 and 10 cm below the boundary, respectively). In both
instances, this is within the context of the dominant upper Frasnian
fauna of the Upper Kellwasser Limestone. Palmatolepts tnangu-
laris does not occur in the beds equivalent to Bed 3 1 g at the other
Montague Noire localities cited previously.
It follows, from the foregoing discussion, that there should be
modification of the definition of the lower boundary of the Lower
triangularis Zone (Ziegler, 1962, P. 25; Ziegler and Sandberg,
1990, p. 22) for which the sole criterion is the first occurrence of the
nominal taxon. Instead it is proposed here to use for definition the
D ecember 1993
437
abundant or flood occurrence of Palmatolepis triangularts, to the
virtual exclusion of other species of the genus, stratigraphically
above the fauna dominated by the characteristic upper Frasnian
species. These include Palmatolepis winchelli, Pa. bogartensis, Pa.
rhenana, Pa. boogaardi, Ancyrognathus asymnietricus, Ancy-
rodella curvata (late form), and in some areas, Pa. linguifonnis and
Pa. i . untianensis. Thus, in the three sampling intervals within Bed
32a at Upper Coumiac (Feist, 1990, p. 36) and Bed 32b, Pa. trian-
gularis is the only Palmatolepis species with the exception of tran-
sitional specimens here termed Pa. aff. 'delicatula delicalula'.
None of the species in Beds 31 and lower at Upper Counijac (figure
5) ranges above the GSSP positioned at the lower boundary of Bed
32a, except Icriodus altematus, which is well known to cross the
Frasnian/Famennian boundary elsewhere [the designation Mehlina
spp. represents several species whose demarcation is unclear]. The
new species of Ancyrognathus in Bed 32b is part of the Famennian
lineage including Ag. sinelaminus and Ag. cryptus and is morpho-
logically distinct from the main Frasnian Ancyrognathus lineages
that include Ag. asymmetricus and Ag. ubiquitus. Characteristic
upper Frasman species of Polygnathus, such as Po. webbi and Po.
decorosus, do not range above the GSSP and are replaced by Po.
brevilaminus and Po. n. sp. above the boundary at Coumiac.
The lower boundary of the Middle triangularis Zone, defined by
the lowest occurrence of Palmatolepis clarki and Pa. delicatula deli-
catula (Ziegler, 1962, p. 26; 1971, chart 5), is at the base of Upper
Coumiac Bed 32c. The former species is perfectly useable for defin-
ing the base of the zone and that part of the original definition is fol-
lowed here. But use of the latter taxon is clouded by a taxonomic
problem. That is, Pa. delicatula delicatula in the sense of most
authors since 1962, and Pa. delicatula platys of Ziegler and Sandberg
(1990), are characterized by platform outlines of the Pa element dis-
Recognition of the Upper triangularis Zone (Beds 34a, 35a,
36), the Lower crepida Zone (Bed 37, on the unquestioned occur-
rence of the nominal species), and Middle crepida Zone (Beds
41-44) is straightforward, but not especially pertinent to the descrip-
tion of the GSSP.
Goniatite record
Courniac is one of the few known places with。continuous goniatite
succession from the Middle Frasnian to the Middle Famennian.
Ammonoids occur both in the latest Frasnian (Bed 3 Ig) and basalmost
Famennian (Bed 32a). Preservation, however, is in many cases rela-
tively poor, extraction tedious, and species-level determination is
often difficult. The faunal record (figure 6) has gradually been built up
over the past several years and certainly can be further extended. Bed-
by-bed investigations were first conducted by House and others (1985)
and updates of faunal lists were supplied in consecutive years to SIDS
and later summarised (in Feist, 1990). A detailed description of the
Famennian part is provided in Becker (1993a).
The boundary itself is clearly marked by the disappearance of
the gephuroceratids and beloceratids with the immediate subsequent
bloom of the tornoceratid Phoenixites frechi in the haematite-
enriched base of Bed 32a, but the species is known to occur in late
Frasnian beds elsewhere (Becker, 1993a). Thefrechi (partial range)
Zone or Phoenixites Genozone (do H-A) is followed in Bed 35c by
the entry of first Falcitornoceras and questionable cross-sections of
Cheiloceras. Both genera are defining forms of the do 11-B.
Undoubted Cheiloceras specimens have not been collected below
Bed 39 and earliest falcitornoceratids (especially those found in Bed
36) are still somewhat intermediate to Phoenixites.
tinctly different from
that of the lectotype
of Pa. delicatula
Branson and Mehl
(1934, pl. 18, figure 4;
a new photograph in a
non-oblique view is
available from GK on
request). As the solu-
tion of this problem
cannot be treated
fully in this paper, the
name of specimens
corresponding to Pa.
delicatula delicatula
(sensu auct.) in Upper
Courniac Beds 32c,
33c, and 34a is writ-
ten in quotation
marks.
Figure‘ Range
chart of succession
of goniatites so far
recordedfrom Bed
23 to Bed 39 in the
section around the
GSSP above the
Upper Coumiac
Quarty, with the
assignment of
ammono记 zones.
For correlation with
the conodont
zonation, seefigure
反
│ MIDDLE COLIMIAC FORMATION │LPPER COLIMIAC FORMATION │LOW. GRIOTTE FM. │
│F R A S N I A N │F A M E N N I A N │
│。},}:}'l}。│. lb I小 . │。25lb 1} │a}。}:Id │27│。}。}:k I-│。卜I小 │.30. It,│。!b !} ld 1. !1!,│. lb I} Id卜},19│a}。!:1, 1- 1, │。134b 1} │。}。!:!d}. │36│.37. lb │38│ 3}│
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │. lb│
│巴详嘿 } 一一一一一一一一 │ RANGES OF GONIATI花TAXA囚刀f │
│ 解ent. Cf.自Uc附 │ LPPER OUARRY AT COLIM IAC │
│ Aulat. cf. aurts │ Lobobactrltes甲 ・ │
│已王loceras terxiistrfatu们 │ Phoenfxftes frechl │
├───────────────────────────────────────────────────────────┤- 一一一 一 一 - .......‘二二二二名二口二二二二二..- │
│ Archoceras .. 一 │ Tornoc-s ct typum │
│ Tornoceras vel L} }uofnoceras sp. W .-一 .— 一一 一一 │ Mactrites anellus │
│ Aulatornoceras sp. — 一一 一一 一 一 │ 二盟一oceras T. │
│ C尝竿 }.2.. 一 一一 一一 │ 一Phoenfxltes cf. sulcatuS │
│ Mant. cordatum │ W alc1tornoceras falclCulum │
│ M朋 t. adC 飞们5心 │ Lobobac. termlerorus │
│ 尝550之OI’me era“争 一 │ Lobobac. guerichl │
│ 竺 t1coceras lamd 9p. │ │
│ Ceratabeloceras schulzi │ │
│ Lfrquat竺)oceras clausum │ │
│ Archoceras罗ulatum │ │
│ CrIckites halzapfelf │ │
│ Arch. cf. varlco} m │ │
│邃 ,二。rd │ │
│巨亚理 taxonomic imprecission │ │
│【二] infwed range │ │
│0一i】 │I一K │ │I一L │11一A │“- B │
│(NEOM) │ARCHOCER人3 │?│ CRICVJTES │PHOENIYJTES │FALCITOR./CK (RAYMOND】 │
Enisodes. VoL 16 no. 4
438
The Courniac goniatite sequence generally matches faunal suc-
cessions described from classical sections of the Rhenish Slate
Mountains and Thuringia. Correlation with the new international
zonation based on the appearance and spread of genera (House and
Kirchgasser, 1993; Becker and others, 1993; Becker, 1993b) is
straightforward, although there are regional features mirroring
local facies developments. For example, international marker gen-
era such as Thmanticoceras, Carinoceras, Neonianticoceras and
Playfordites are still lacking in the Montagne Noire area. Late
Middle Frasnian beds at Coumiac, below the equivalent of the
Lower Kellwasser Limestone (Bed 24a), contain Beloceras, vari-
ous manticoceratids and somewhat ambiguous Costamanticoceras
(House and others, 1985; pl. 2, figure 11-12). The latter is a marker
for the Playfordites and Neomanticoceras Genozones (do I-I and I-
J), or for the cordatum Zone (do 113/y) of the classical goniatite
zonation. Index species for Divisions I-K so far have only been
found above the Lower Kellwasser level in Bed 25b (Archoceras
sp.) and Bed 26b (Manticoceras ado价 nse). The first evidence for
the latest Frasnian Crickites Genozone (do I-L) comes from Bed
26c. At Counnac and neighbouring sections ot the Mont Peyroux
Nappe a succession of Crickites species can possibly be estab-
lished. All early, often somewhat doubtful members of the lineage
have whorl forms similar to Manticoceras cordatum and may be
related to the Canadian Crick. cordiforme (Miller). Crick.
holzapfeli, the index species of the classical holzapfelt Zone, enters
in great profusion in the lower part of Bed Me and continues to
Bed 3 1 g and to the end of the Frasnian. The apparent patchiness of
the Upper Frasnian goniatite record is only to a limited extent a
consequence of sampling bias. Clearly two different goniatite
assemblages alternate with each other. The first is characterized by
great abundance of Beloceras tenuistriatum (e.g. in Beds 26d and
31a) and rarity of gephuroceratids and tornoceratids. Other beds
have rich Manticoceras or Crickites faunas accompanied by more
abundant tornoceratids, and Buchiola. Due to the lack of lithologi-
cal differences between beds containing the two faunal types it is
inferred that changing assemblages mirror fluctuations in the
trophic structure. Especially the Upper Kellwasser Limestone
equivalents with their rich Crickites and pelecypod faunas associ-
ated with unusually large ostracods but without Beloceras may
have been deposited under eutrophic ecological conditions. This
suggests that beloceratids thrived during oligotrophic periods.
The chosen stratotype has one of the best known goniatite
records around the Frasman/Famenman boundary and is the best
known anywhere for index species occurring in beds exactly at the
boundary. However, it is far from being an ideal ammonoid locality
due to aspects of preservation and difficult recovery of large faunas.
This misfortune can partly be balanced by the wide range of other
goniatite-bearing and easily coffelatable localities nearby in the
Montagne Noire, which supply additional information on strati-
graphical ranges and occurrences in slightly different facies settings
These will be documented elsewhere (Becker and House, 1994 in
press).
Trilobites
Among bottom-living biotas, trilobites are most frequent and
diversified in the Late Frasnian strata at Courniac. Of eight families
│MIDDIZ COUMIAC FORMATION } UPPER COUMIAC FORMATION │
│FRASNIAN │FAMENNIAN │
│a lb Ic Id le │a lb Ic Id}’│a lb Ic │a lb Ic Id│27│a lb Ic Id}‘│a lb Ic Id│alb │a户卜Idle}‘1 9│a}”}“I d}’}‘}‘│a lb Ic}d}’I f │a lb}c │alb}“}d}‘│
││日.. record │ │
││= Inferred range │ │
Figure7 Range chart showing the trilobite recordfrom Bed 23 to Bed 39 around the GSSP in the section at
the Upper Quany at Counziac. Modifiedfrom data of R Feist (in Feist, 1990).
[)Prpmhpr 1993
439
known giobally to he present at the Upper Kellwasser extinction
c\cnt (Feist.]990: 1991).Six Occur in the stratotype section
(Pioctidae, AUlacopleuridae. OdontoplCUridae. Harpetidac, Dal-
manitidae and Phacopidae) and of a total of 13 species known
,dobaliy, nine are represented at COLIfluac (see fi-ure 7). All but
three families and川 species disappear w ithin Zone 13. or at the
base of the Upper Kellwasser Limestone eqUIValent (Bed 3}9).The
latter does not yield any trilobites, nor do the Succeeding beds ofthe
Lower triangtdari.s Zone (Bed 32a-b), a fact which has been observed
in all known Frasman/ Farneriman boundary sections world wide.
Recovery does not take place earlier than from the Middle triangulari,}
Zone onwards when solely phacopids ofthe genus A劝Aratiops occur
(Beds 32c-e). Thus the del’ined basal Famenman at the base of the
Lower triam}iilaris Zone. cannot be precisely recogrused LIS111"
trilobites. By contrast. the base of the topmost Frasnian Kellwassei
Liirc,,tone level can be located with considerable precision by the
major extinction affectin., trilobites at that level (Feist and
Schindler, 1994).
Fine-scale intrazonal subdivision and biostratigraphical cori-c-
lation ofthe latest Frasnian at CoLuniac is provided by evolutionary
species of、 the proetid Palpeb,一(dia which are characterized by a trend
in reduction of the palpebral lobe and in the straightening of the
facial suiures. The ancestral form, Pal. latepalpebralis being alreadyI
present below the Lower Kelbvasscr[finestone cqL]i\alent (Bed
24a), has been recovered as hi,,h as in the middle of Zone]3 (Bed
29d). It gave rise to Pal. palpebralis which is abundantI 川Beds 3 1。
to 3 1 e and is also known froin latest Frasinan sections in the Rhen-
ish Schicfcr1(,cbfi-gc and Harz (Feist and Schindler, 1994) and may
Occur in the Cannim, Basin of Western Australia (K McNamara. oral
communication) The last represcritative of the lineage is Pal. bre(-
(ioe v\ hich ciners the stratollype section in Bed 3 1 c and f, thus mark-
ing precisely the last oxygenated lcvel-bottoin environment prior to
the hypoxic overturn of the Upper Kellwasser Limestone. This
species is at least of moderate value for long distance correlation as
it has been recovered in the Rhenish Schiefergebirge (at Stembruch
Schmidt) ai记 in the Harz (Ackc Valley) in an equivalent position
and associated there with Pali) iatolepis linguUi)rinis (Schindler.
1990). Consequently Pal. brecciae appears to be limited to the lower
part of the linguiMi-mis Zone. This supports the results obtained by
graphic correlation, which indicated the presence of lingit咖rMIA
Zone equivalents at Courniac in Beds 3 If and g (Mapper in Becker
and others, 1989, p. 262).
Concomitantly with the Palpebralia line, another evolutionary
trend is seen in Succeeding populations of CrYphops acuticeps and
this trend is of biostratigraphical significance. This group, which is
rather common in Beds 3 1 a to 3 1 f, exhibits a spectacular reduction
in the inean number of its eye lenses which drop from ten lenses in
Bed 3 1 a to only three lenses in Bed 3 1 f before its final extinction
(Feist, 1991).This CVOILItion may represent:、further potential foi
tine-scale hiost rati graphical subdivisions and correlation during a
period of'world-wide biotic crisis.
Frasman. arnom, the benthonic forms. the Frasnian[Faniennian
boundary is characterized b} a major extinction since 05 per cent of
all recorded taxa山sappear there (Lethiers and Feist. 1991).Thus.
the Courniac stratotype bears evidence()【an extraordinary breadth
offaunal representation enabling correlation into re-in-les with better
spore and acritarch records. The SDS views this documentation as
the best ofany ofthe levels it has recommended lot- b0Lmdary strato-
types in the Devoinan.
Other fossil groups
Palynomorphs have been obtained from the Upper Kellwasser level
(Bed 3 1-) but are too badly preserved for precise identification: fur-
ther work is required here. The stratigraphically important entorno〕-
zoaccans are a rather minor faunal element} detailed work is cur-
rently being carried out by F Lethiers. Solitary rugose corals, gas-
tropods, orthoconic and breviconic nautiloids, crinoids and rare fish
scales represent further accessory fossil groups Still to be investi-
"ated in detail. Brachiopoda and bivalve records of C Babin and P R
Racheboeut have been presented (in Feist. 1990). Rich hornoctenid
faunas have been determined by M Truvols-Massorn (in Feist.
1990)} the Hoinocienus ultimus Zone is first recognized in Bed 26c
and therefore seems to correlate with the Crickites Genozone. 0stra-
cod data of' F Lethiers have been listed (in Feist, 1990), and more
than 30 different species are recognised in the topmost beds of the
Chemostratigraphy
Asyet geochernical method,, do not provide an unairibi2t-IOUS guide
to correlation internationally. although there is great potential espe-
cially with strontium isotope chernostratigraphy applied within the
frarnework of conodont biostratigraphy (e.g. Ruppel and others.
1993). Geoclicinical methods do. however, provide an important
clue to environmental interpretation. The stratotype section at
C011111jac has been investigated for 6 "CI"C values by Joachimski
and Buggisch(1993) where:、positive Shift of (3-1 T was noted at the
boundarv. Rarc-carth elements iRLI---) have been investigated by
Grandjean-L&Llyer and others(1993) using individual Devonian
conodonts, but no anornaly at the boundary was noted although the
REF patterns did not conform with those of modern sea water.The
pursuit Of it-idillm anomalies has not been Successful at Counnac
(Girard and others, 1993), nor at Steinbruch Schmidt (McGhee and
others, 1984). Those claimed at the boundjry in the Canning Basin
have proved to he from a much InLher stratigraphic level (Becker
and others, 1991: Nicoll and Playford. 1993) although there is a
weak iridium anonialv apparently at the correct level at Xiangtian
(Wallg and others, 199 1)and other element anomalies, but the cause
is uncertain. There has been no link of ruicrotektites with the bound-
ary stratotype and records elsewhere are higher in the Famennian
(high within the Lower triangidaris Zone at Senzcillcs in Belgium:
Claeys and others, 1992. figure I;Lower crej)ido Zone in South
China: Wang, 1992).
Relationship to the Upper Kellwasser Event
The main sedimentary marker ofthe GSSP is the top of the distinc-
tivc level known in Germany as the Upper Kellwasser Limestone
(Walliser and others(1989). This dark hypoxic limestone appears to
reDrcsent ail acme in the sm-cad of a distinctive九cies which in
many sections ,Iot)ally is precisely constraineo ny conocioni mos-
tratigraphy. In parallel with the work of the SDS in recent years has
been the recognition of an important extinction event near the
Frasnian/Farnennian boundary. Some of一 these extinctions were
listed in the previous sections. The recommendation of the Sub-
commission for a GSSP falls at a level immediately above the acme
of extinctions. that is at the base of the Lower trionguloris Zone.
The most precise documentation for this (Becker and others, 1989)
has been followed by data assembled for the Subcommission and
illustrated here (figures 5-7). Following especially the work ofI
Sandberg and others(1988) this level has been widely traced inter-
nationally.
There has been much debate on the Cause of the sedimentary
perturbation represented by the Upper Kellwasser Limestone. The
matter cannot be said to be resolved. Indeed, some members of the
Subcommission earlier took the view that a more appropriate bound-
ary might be chosen away from the sudden faunal and sedimentary
changcjust below the base ofthe Lower triangularis Zone but in the
end, the ease ofinternational con elation based on the faunal changes
led to this boundary being reco in me tided.
Four main groups of hypotheses have been invoked to explain
the faunal and sedimentary changes around the base of the Lower tri-
angularis Zone. Firstly, causes related to a bolide impact or inapacts
(Sandber- and others 1989, McLaren and Goodfellow 1990). Sec-
ondly, a spread of' anoxic conditions on continental shelves a}soci-
ated with possible tectonic events and ocean overturn (Wilde and
EpisMes,、初/.I6,,,(,.4
440
Berry, 1984} Buggisch, 19911 )with a transgression followed by
quick regression at the Lipper boundary (Sandberg and others, 1988).Z,
Thirdly. these second events but associated with a peak of cold cli-
inatic conditions, resulting in a rise of' the pycnochne (Copper,
1986). Fourthly. the sanie, but with the Upper Kellwasser Limestone
representing a peak of hot climatic conditions, resulting also in a rise
of the pycnoclinc and probable disruption ofthe trophic tiering, par-
ticularly that of the plankton (Becker and House. 1994); this latter
theory was first invoked for Devonian anoxic events by Becket
(1992). Related hypotheses involving climatic warming have been
suggested by Thompson and Newton(1989) and Ormiston and
Klapper(1992). It is -enerally recognised that the collapse of stro-
matoporoid reel'systerns ricar the end of the Frasnian led to extinc-
tions(){’associated faunas. House(1985) has drawn attention to the
many similar events at other levels in the Devonian su,,gcstiilg thatI
an interpretation enablinc, a common hypothesis is to be preferred.I
Whatever the cause(s) ofthis sedimentary perturbation may be,
the SDS took the、iew that the hypoxic perturbations bclo\N the base
of the I-o\x,cr trimigularis Zone resulted in a considcrjbie faunal
chant,eover and an horizon which may be correlated internationally
with perhaps more precision than any other in the Devonian. It is in
the li,,ht ofthis view that Courniac was recommended for the GSSP
to deline the base of the Fainennian Sta-c.
Feist, R, ed,1990, The Frasnian/Famennian boundary and adjaccnt strata ol
the eastern Montague Noire, France: RjGS Subcommission on
Devonian Stratigraphy, Guide Book, 69即.
1-cist, R, 199 1,The late Dcvonian trilobite Crisis: Historical Biology, v. 5,
pp.197--214
Feist, R, and Schindler, E-, 1994, Trilobites dt-11-ifli!, the Frasnian KcIlwasser
crisis in European Late Devonian cephalopod linicsiones: Courier
Forschungsinstitut Senckenhcrg, v. 169, 195-223.
Girard. C, Rocchia, R, Feist, R, Froget,[一,and Robin, F.. 1993, No cvidence
of impact at the Frasnian/Famennian bOUndarv in the siratotvpc area.
Southern France- Interdisciplinary Conference on Global BO、L1ndai\1
Fvcins, Kielce, 27-29 Scptc[iibcr 1993. Abstract.
Goodfellow, W 「),Geldsetzei, IF IF J, McLaren, D J, Orchard, M J, and
Kk甲per, G, 1989, ']'he Frasnian/Famennian extinction- current 1-C.SUItS
and possible causes. in McMillan, N J, Embry, A F and Glass. 1) J, c(Is.,
Devonian‘)}the World: Canadian Societ}()!Petroleum (wologists,
Mcnioir 14, }. 3, pp. 9--2 1.
Grandican, 1'. Albarede, F. and Feist, R, 1989, REE N arialions acioss the
1了r是1、111之111/1了之汇lllclllll之川 bol-Inclarv. Ferra八hstract、一\. I } pp. 184
Grandjean-1.6cuyei, P, Feist, R, and Alhai&lc, F, 1993, Rate cat(h clements
in old biogenic apalitcs: Geochemica ct (’ o,moclicinica八c t } l. v. } 7. 1) p.
2507--2514.
House, M R} 1985, Correlation ofmid-Palacozoic arnmonoid c\ olui ionarv
events with global sedimentarvI perturbations: Nature, Londor,、3 1 ',
pp. 17 -22.
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Dr Gilbert Mapper (top right) is Professor of Geology at the Uni-
versily of Iowa, Iowa City, Iowa 52242, USA. His research concen-
trates on Silurian and Devonian conodont taxonomy and biostratig-
raphy, with special emphasis on the Frasnian. He is currently
involved with methods of morphometric analysis of conodonts and
their use in graphic correlation. He is a Titular Member of the Sub-
commission on Devonian Stratigrap勺 and was its Vice-Chairman
from 1976 to 1984.
Dr Raimund Feist (bottom right) is Director of Research with the
French National Scientific Research Centre (CNRS) at the Univer-
sity of Montpellier (USTL, 34095 Montpellier, France). His
research concentrates on north-Gondwanan trilobite geograp勿,
systematics and biostratigraphy. He is currently analysing the
impact of global events on late Devonian outer shelf trilobite bio-
jacies, evolution and diversity. He is Vice-Chairman of the Sub-
commission on Devonian Stratigraphy.
Dr R Thomas Becker (bottom left) works at the Palaeontological
Institute of the Free University Berlin (Malteserstraj3e 74-100,
Building D, 12249 Berlin). He received his doctorate in 1991, from
the Ruhr-University of Bochum, Germany. From 1988 to 1990 he
worked at the University of Southampton on Devonian extinction
events. His research concentrates on Middle Palaeozoic
ammonoids, high-resolution stratigraphy, sea-level fluctuations and
the links between global environmental change and evolution in the
Devonian. He is a Corresponding Member of the Subcommission on
Devonian Stratigrap柳.
Professor Michael R House (top left) is Professor of Geology at the
University of Southampton (Southampton S09 5NH, UK) and for-
merly of the University of Hull, He is a former President of the
Palaeontological Association, the Systematics Association and
Palaeontographical Society. His researches have mainly concen-
trated on mid-Palaeozoic international correlation and regional
and event synthesis, mainly using aninionouls. He is currently
Chairman of the Subcommission on Devonian Stratigraphy.
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Episodes, Vol. 16, no. 4