New records of Jurassic Molluscs from the Cadda Formation at Enanty Hill, Irwin River District, Western Australia

9 Pages·2000·2.6 MB·English

by  G W Kendrick

THE WESTERN AUSTRALIAN
NATURALIST
Vol.22 30th May2000 No.4
NEW RECORDS OF JURASSIC MOLLUSCS FROM THE CADDA
FORMATION AT ENANTY HILL, IRWIN RIVER DISTRICT,
WESTERN AUSTRALIA
By GEORGE W. KENDRICK and KRISTINE M. BRIMMELL
Department of Earth and Planetary Sciences, Western Australian Museum
Francis Street, Perth WA 6000
ABSTRACT
Fourteen species of Mollusca (12 Bivalvia, two Cephalopoda) have
been collected from the Cadda Formation at Enanty Hill, Irwin River
district, northern Perth Basin, increasing from 11 to 18 the number
of species recorded from this source. New bivalve records are:
juvenile gryphaeid oyster: Ludnidae undetermined species; cf. Astarte
cliftoni Moore; two species of undetermined Heterodonta. New
cephalopods are the ammonite Rseudoto/ressp.and an unidentified
belemnite. The assemblage compares closely with that of the Middle
Jurassic (Bajocian) Newmarracarra Limestone of the Geraldton
hinterland
INTRODUCTION 147 and maps). Fossil evidence indicates
that the Cadda Formation is, in part at
The Cadda Formation is a sequence of
least, equivalent in age to the Middle
diverse lithologies - sandstone,
Jurassic (Bajocian) Newmarracarra
siltstone, shale and limestone - which
Limestone of the Geraldton hinterland,
forms limited, sporadic outcrops in the
of which it appears to be a southerly,
northern Perth Basin between the Hill
more restricted and shallow water facies
River area and south to about the
equivalent
latitude of Dandaragan. There, it lies in
conformable contact with the A small, isolated surface deposit
Cockleshell Gully Formation (below) correlated with the Cadda Formation is
and Yarragadee Formation (above) located on the southwestern slope of
according to Playford et al (1976:144- Enanty Hill, about 3 km NNE of the
211
town of Mingenew (lat. 2910’S, long. exclusively to the west. Evidently
115^27’E; Figure 1), from where fossils faulting has preserved the Cadda
were first recorded by Coleman and Formation remnant at Enanty Hill, all
Skwarko (1967). This exposure, located other surface evidence of coeval
in a disused road-gravel pit, lies ca 120 sedimentation in the district having
km N from the nearest known outcrops been removed by erosion.
of the Cadda Formation in the Hill The greater part of Enanty Hill is
River area and about 50 km ESE from formed of Permian rocks of the
the nearest occurrence of the Mingenew Formation. Mingenew Spring
Newmarracarra Limestone at Mt Hill. and other major springs in the district
Drilling at Enanty Hill shows the Cadda lie within the Urella Fault system,
Formation there to be at least 19.8 m. which allows groundwater to come to
thick, overlying Triassic Kockatea the surface
Shale.
At the Enanty Hill gravel pit, the
Enanty Hill lies within a zone of Cadda Formation occurs as discrete
complex faulting associated with the pebble to cobble-sized pieces of
major NNW-trending Urella Fault ferruginous reddish-brown to purple-
(Playford et al. 1976, p. 236). Down¬ brown fine to very coarse-grained,
throw is to the west with Permian lateritised sandstone, sometimes gritty
sedimentary rocks confined to the or conglomeratic. Fossils are sparse,
eastern side of the fault and Mesozoic occurring as internal or external moulds
(Triassic to Cretaceous) deposits of mollusc shells, principally single
212
valves of Bivalvia, with rare inflation agree well with Moore’s
cephalopods and small indeterminable criteria for the species (Moore, 1870:
gastropods. Small pieces of fossil wood 250, pi. 14, figs 1, 2).
are not uncommon. No bedded
Type localities for Cucullaea inflata
sequence is visible on the surface, where
Moore and C. semistriata Moore are
material appears to be a mantle of
“Greenough district”, Newmarracarra
accumulated weathering residue
Limestone. Both species have been well
overlying coherent strata (Coleman and
figured by Skwarko (1974: pis 21,22).
Skwarko, 1967).
Moore (1870), inter alia, recognised four
Fossils collected in May 1999 by species of Cucullaea in the
members of the Western Australian Newmarracarra Limestone but the most
Naturalists’Club include new records recent revision of these by Skwarko
for both locality and formation and (1974) acknowledged three, a
have been added to the research conclusion with which we concur.
collections of the Western Australian
Museum (WAM).
Family L1M1DAE.
All specimen numbers cited below are
Incomplete external moulds (99.367,
from the Museum's catalogues of fossil
99375) bearing sculpture identical with
invertebrates and plants.
that of Pseudolimea duplicata (]. de C.
Sowerby) supplement those reported by
Coleman and Skwarko (1967). Radial
NOTES ON THE FOSSIL
ribs are strong, with V-shaped
ASSEMBLAGE
interspaces, the base of each being
occupied by a thin radial riblet.
Bivalves
P. duplicata is a widespread Middle
Family CUCULLAE1DAE Jurassic species, which is not uncommon
Of the four specimens of Cucullaea sp. in the Newmarracarra Limestone.
from Ervanty Hill figured by Coleman Skwarko (1974, p. 88) noted that the
and Skwarko (1967), two (figs 16,19, Western Australian specimens, in their
20) have the elongate form, i.e., length smaller size and reduced rib-count, are
exceeding height, of the common, closer to Indian examples from Cutch,
rather variable C. semistriata Moore and compared with those from Europe
may represent that species. One
specimen (fig. 15), a juvenile, is Family GRYPHAE1DAE.
proportioned more like the relatively
Several internal moulds of juvenile
uncommon C. inflat'd Moore (height
oyster shells are present on the external
generally exceeding length) but has a
mould of a right valve of a small
reticulate umbonal sculpture, as is seen
Camptonectes greenoughi Skwarko
on well-preserved C. semistritata (e.g.
(99.368, see below and Figure 2A).
91.914).
Limestones of the Cadda Formation in
Two internal moulds (WAM 99.365) of the Hill River district “are usually
single valves are of mature size, closely coquinas of small oyster shells”
resembling others attributable to C. (Playford et ai, 1976: 144) and
inflata Moore and are identified concentrations of similar material also
accordingly. Neither is complete but occur in the Newmarracarra Limestone
length to height ratios and umbonal The identity of these small oysters
213
requires further study but provisionally Chlamys enantyiby Skwarko (1974, p.
they may be regarded as probable 83, 84, pi. 26, figs 1, 6, 12). This
juveniles of the common gryphaeid uncommon species is otherwise known
Amphidonte rho//fom?/s(Etheridge). The only from fragmentary specimens from
type locality for A. tholiformisEtheridge the Newmarracarra Limestone. The type
is “Tibradden Station, Greenough River locality is “Waggrakine via Geraldton.
district", Newmarracarra Limestone One mile south of road to Nanson on
W side of hills", i.e., Moresby Range.
Family OXYTOMIDAR A second small pectinid from Enanty
Hill was reported by Coleman and
Two representatives of this extinct
Skwarko (1967) as Camptonectes sp.
family of pectinoid clams are known
nov. aff. C. lens (Sowerby, 1821) and
from Enanty Hill. Coleman and
subsequently described as Cgreenoughi
Skwarko (1967) record the mould of a
Skwarko, 1974. An external mould,
small left valve consistent with Oxytoma
99.368 (Fig. 2A), represents this species
decemcostata Whitehouse and the species
in the present material As noted above,
is also reported from the Hill River area
it bears moulds of juvenile oyster shells,
by Playford et al (1976). The type
probably Amphidonte tholiformis
locality is the Bringo railway cutting,
(Etheridge).
Newmarracarra Limestone
C. greenoughi is only occasionally
Incomplete external moulds of
collected in the Newmarracarra
Meleagrinella sinuata (Teichert) in the
Limestone; the type locality is
present material (99.359, 99.365)
“Approximately one mile [1.6 km] NW
supplement those reported by Coleman
of Mt Fairfax, via Geraldton, \V face
and Skwarko (1967). These are readily
of hills", i.e., Moresby Range. It is
recognised by the narrow, spaced, radial
distinguished from other pectinids in
ribs of alternating strengths on the left
the assemblage by its thin shell and
valve. M. sinuaca is common in the
very fine divaricate sculpture. It is not
Newmarracarra Limestone and occurs in
significantly related to the large
the Cadda Formation, Hill River district
“Camptonectes" waggrakinensis
(Playford etal 1976); the type locality
Skwarko, which, lacking any kind of
is the Bringo railway cutting,
radial-divaricate sculpture, is better
Newmanacarra Limestone
located in the genus Mclearnia
O. decemcostata and M sin uata are both Crickmay, 1930.
strongly inequivalve species. Most
Fine, divaricate sculpture also
collection specimens are the larger, distinguishes C. greenoughi from
costate and strongly inflated left valves; “Pecten "greenoughiensis Moore, 1870, a
the smaller, flattened and faintly
rare species from “Greenough district”,
sculptured right valves are less often
unrevised since its original, limited
collected.
description.
Family PECTINIDAE. Family TR1GONIIDAE.
As Chlamysl sp. nov. aff. C. splendens Trigotiia moorei Lycett in Moore, the
(Dollfuss, 1863), a small pectinid was common and characteristic fossil of the
recorded from Enanty Hill by Coleman Newmarracarra Limestone (and
and Skwarko (1967 p. 206, pi. 25, figs associated formations of the Champion
9,13,17) and subsequently described as Bay Group), is well represented in all
214
Figure 2. Molluscs from the Cadda Formation, Enanty Hill. A WAM 99.368. Camptonectes
greenoughi Skwarko. Natural mould of right valve exterior with moulds of attached juvenile
oysters, x 2. B WAM 99.370. Lucinidae, genus unidentified. Latex cast of right valve exterior,
x 1.8. C WAM 99.374. Pseudotoites sp. Latex cast of venter, x 1.8. All whitened.
collections from Enanty Hill and from the original description (Moore,
elsewhere in the Cadda Formation 1870), is “Greenough River district,
(Coleman and Skwarko, 1967; Playford W.A.”, Newmarracarra Limestone,
et al. 1976). The type locality, omitted according to the label accompanying
215
the holotype (Skwarko, 1974 pi. 33 also represented in the present
caption). collection (99.375). Another specimen
(99.372), a fragmentary external mould,
The trigoniids were a dominant, diverse
retains sculpture quite similar to that of
and cosmopolitan family of shallow-
Astarte cliftoni Moore, a species now
burrowing bivalves throughout the
included provisionally in the Enanty
Mesozoic (Triassic to Cretaceous).
Hill assemblage. Both A. apicalis and
Their robust, strongly sculptured shells,
with elaborate, interlocking hinge teeth, A. cliftoni are common in the
Newmarracarra Limestone, the former
enabled them to flourish in energised,
coarse-grained substrates of inner shelf also present in the Kojarena Sandstone
and the latter in the Colalura Sandstone
environments (Stanley, 1977).
(Playford et ai, 1976). Type localities
All WAM specimens (99.361, 99.369)
(Moore, 1870:249-250) are "Greenough
of Trigonia moorei from Enanty Hill are
district" and "Greenough river”
disassociated single valves, that have
respectively, both Newmarracarra
been separated post-mortem. These
Limestone. Neither species has been
contrast markedly with the thin-shelled,
recorded elsewhere from the Cadda
fragile, near-edentulous Gresslya
Formation.
sanfordii (below), which occurs
frequently as conjoined, paired valves,
Family CERATOMYIDAE
in likely consequence of a deep¬
burrowing habit. The most common fossil at Enanty Hill
is the thin-shelled Gresslya sanfordii
(Moore), found as either external or
Family LUCINIDAE.
internal moulds of single or paired
A species of this family has been listed,
valves (Coleman and Skwarko, 1967).
as “Lucina sp.” by various authors (see
Even fragmentary impressions of
Playford, 1959; Playford et ai, 1976 and
external surfaces (93.362, 99.371) are
references) in the fauna of the
readily recognisable from the presence
Newmarracarra Limestone but has never
of very fine, close, radial micro-
been considered further and at present
striation, crossing the low, irregular
remains somewhat enigmatic. Some
growth ridges. More conjoined valves of
possible examples of this rare species
this species are found at Enanty Hill
have been collected recently from the
than of any other, probably a
Newmarracarra Limestone and now also
consequence of a deep-burrowing habit
from Enanty Hill (99.370, Figure 213).
in fine-grained substrate, which favours
The latter does not closely resemble any
the close association of both valves /wst-
of the genera of Jurassic Lucinidae in
mortem.
Chavan (1969) and identification is
The type locality of this species was not
deferred until the hinge and other
stated by Moore (1870. p. 253) but the
internal characters are known.
label accompanying his figured
specimen (pi. 13, fig. 9) reads "Shark
Family ASTARTIDAE.
Bay, W.A.”, according to Skwarko
One confirmed and one probable species (1974, caption to pi. 32). This
of this family are present in the Cadda erroneous locality evidently arose from
Formation at Enanty Hill. The small confusion accompanying specimens
Astarte a pica l is Moore was recorded by collected by M.W. Clifton and sent to
Coleman and Skwarko (1967) and is W.A. Sanford in England prior to 1862.
216
In providing Clifton’s material to from W.A. Sanford ex M.W. Clifton, as
Charles Moore, Sanford opined that it discussed above
had come either from "Shark’s Bay” or
This species is unknown from all
"Champion Bay”, more likely the former
subsequent collections and is clearly
(Moore, 1870, p. 228-229). The species
most rare In view of the prevalence of
is unknown from the Shark Bay district
fossil wood in the Cadda Formation at
but is common in the Newmarracarra
Enanty Hill, the possibility of its
Limestone. Both of Skwarko’s figured
discovery there should be kept in mind.
specimens are from problematical
Three small incomplete external moulds
sources and the type locality for the
(99.363, 99.364, 99.377) representing
species remains undesignated.
two species of bivalve, probably
Unidentified bivalves. Fossil wood Heterodonta, remain unidentified.
(99.378) showing on the freshly broken
cross-section two narrow, infilled,
Cephalopods
tubular borings, parallel to the sides of
the wood, may be attributable to a Ammonoidea
wood-boring marine bivalve, though at
present a non-marine origin for these Family SONNIN1IDAE
seems equally plausible. No shell
Three specimens of the ammonite
remains are visible and interpretation is
Newmarracarroceras clarkei (Crick) were
conjectural.
reported (as Fontannesia clarkei) from
Moore (1870, p. 255, pi. 12, fig. 11) Enanty Hill by Coleman and Skwarko
described a presumed wood-boring (1967). The species is one of the more
bivalve. Teredo australis Moore from common ammonites of the
"Western Australia”, without more Newmarracarra Limestone and Enanty
specific locality data. He evidently had Hill provides the only other known
two specimens, both of which were occurrence. This and related taxa have
figured by Skwarko (1974, p. 99, pi. 34, been revised recently by Hall (1989).
fig. 20, pi. 36, fig. 1) and reclassified as
Martesia (Particorna) australis (Moore), Family OTOITIDAE
family Pholadidae. The locality of the
A specimen (99.374) of a species of
former specimea designated by Skwarko
Pseudotoites (Fig. 2C) from Enanty Hill
as “holotype” is not given. That of the
provides the first record from there of
latter, a colony attached to a remnant
this genus, previously known from the
of fossil wood in a block of richly
Cadda Formation of the Hill River
fossiliferous shelly limestone, is “Shark
district and from the Newmarracarra
Bay, Western Australia" (Skwarko,
Limestone.
1974. caption to pi. 36, fig. 1). This
specimen may be regarded as the
Coleoidea
paralectotype. According to Moore
(1870, p. 230), it is associated with "as Belemnite, unidentified. The mould of
many as thirty species” of typical part of a belemnite guard (99.373),
Newmarracarra Limestone fauna, showing the posterior part of the
unknown from the Shark Bay area. phragmocone, provides the first record of
Evidently Moore’s specimens of this group from Enanty Hill. It remains
"Teredo” australis were among those generically and specifically unidentified.
with spurious locality data obtained Fossil wood. Small pieces of fossil wood,
217
Table 1. Molluscan fossils recorded from the Cadda Formation of Enanty Hill. Sources: I
Coleman & Skwarko, 1967; II WAM collection, 1999.
Species I 11
1. Cucullaea inflata Moore ? +
2. Cucullaea sp. cf. C. semistriata Moore +
3. Pseudolimea sp. cf. P. duplicata (J. Sowerby) + +
4. Ostreoidean, juvenile cf. Amphidonte +
tholiformis (Erheridge)
5. Oxytoma decemcostatii Whitehouse +
6. Meleagrinella sinuata (Teichert) + +
7. Camptonectes grecnoughi Skwarko + +
8. “Chlamys’ enantyiSkwarko +
9. Trigonia moorei Lycett in Moore + +
10. Lucinid, genus undetermined +
11. Astarte apical is Moore + +
12. cf. Astarte cliftoni Moore +
13. Gresslya sanfordii (Moore) + +
14. Bivalve, genus undetermined, species A +
15. Bivalve, genus undetermined, species B +
16. Newmarracarroceras clarkei (Crick) +
17. Pseudotoites sp. +
18. Belemnite, genus and species undetermined +
variously preserved are not uncommon faunistically deficient gulf environment,
at Enanty Hill, at times associated essentially enclosed by land on three
directly with marine fossils and a sides and with a marine connection to
possible leaf (99.369, P.99.57). From the north, allowing only restricted
this, it would appear that the site was in oceanic exchange/circulation and more
proximity to a river that discharged significant fluviatile discharge,
terrestrial flood debris into the adjacent compared with the more fully marine
inshore sandy shallows depositional environment of the
Newmarracarra Limestone
Because the Champion Bay Group
CONCLUSION
(which includes the Newmarracarra
As presently known, the fauna of the Limestone) and Cadda Formation are
Cadda Formation is a subset of that of the only known marine Middle Jurassic
the Newmarracarra Limestone, the deposits in surface outcrop in Australia,
former entirely, the latter substantially their Mollusca have been studied
molluscan in character, in which extensively since 1870, as reviewed by
Bivalvia predominate. The lesser faunal Skwarko (1974). The more common
diversity of the Cadda Formation species of Bivalvia are now known
reflects its relative paucity of outcrop, reasonably well but there remain many
rarity of fossils and the limited attention uncommon to rare species of which
which they have received. It appears little or nothing is known. The small
that the Cadda Formation represents a gastropod and scaphopod fauna remains
218
essentially unknown. The Western Geologist - with descriptions of the
Australian Museum is currently species. Geological Magazine, new series,
enlarging its research collection of Dec. 4, v. 1, p. 385-393, 433-441.
Jurassic molluscs in order to better
HALL, R.L. 1989. Lower Bajocian
understand the composition of the
ammonites (Middle Jurassic-,
fauna and its biogeographical
Soninniidae (sic)) from the
significance.
Newmarracarra Limestone, Western
Australia. Alcheringa 13:1-20.
ACKNOWLEDG EMENTS
MOORE, C. 1870. Australian Mesozoic
We have to thank Mr and Mrs C. Geology and Palaeontology. Geological
Gillam of.“Irwin Park” Irwin for access Society of London Quarterly Journal 26:
to Enanty Hill and consent for the 226-261.
removal of fossil material. We are
PLAYFORD, P.E. 1959. Jurassic
greatly obliged to members of the W.A.
stratigraphy of the Geraldton district,
Naturalists' Club for their generous
Western Australia. Journal of the Royal
contributions to collection. Mrs A.
Society of Western Australia 42: 101-124.
Nevin typed the manuscript.
PLAYFORD. P.E., COCKBA1N, A.E.
and LOW, G.H. 1976. Geology of the
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Mollusca 6, Bivalvia. Geological Society Bivalvia of the Newmarracarra
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COLEMAN, P.J. and SKWARKO, S.K.
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219