COMMONWEALTH OF AUSTRALIA

DEPARTMENT OF NATIONAL DEVELOPMENT

BUREAU OF MINERAL RESOURCESGEOLOGY AND GEOPHYSICS

RECORDS:

1965/134 5014_13

501413

A NEW OCCURRENCE OF PROTEBOZOIC"JELLYFISH"FROM THEKI/MERLEY REGION, WESTERN AUSTRALIA.

by

D. Dunnet

The information contained in this report has been obtained by theDepartment of National Development, as part of the policy of the Common-wealth Government, to assist in the exploration and development of mineralresources. It may not be published in any form or used in a companyprospectus without the permission in writing of the Director, Bureau ofMineral Resources, Geology and Geophysics.

0"

".

A N~'W OCCURRENCE OF PROTEROZOIC "JELLYFISH" FROM THE KIMBEaLh'Y REXlION WESTERN AUSTRALIA

by

D. Dunnet

Records 1965/134 .

CONTENTS

SlllMARY

Desoripti on of Oocurrence

REFERENCES

PLATES

FIGURES

0"

Plate 1 The main site of the MOunt Brooking II jellyfish" , showing the scarp of the flat-dipping Hanford Formation.

Plate 2 ; A single specimen of the larger " jellyfish" which .. ,ere found up to 10 em in diameter .

Plate 3 A profusion of the most abundant forms.

Plate 4 , Fossil "Jellyfish" from the Cambrian Elder Formation .

Figure 1 Geological map of the "Jellyfish " locality~ Western Austr·alia .

MOWlt Brooking Kimberley Reg10n

Page No ..

1

5

The infonnation contained in this report has been obtained by the Department of National Development, as part of the policy of the Common­wealth Government, to assist in the exploration and development of mineral resources. It m~ not be published. in any form or used in a company prospeotus ldthout the permiss i on in writing of the Direotor~ Bureau of Mineral Resources, Geology and Geophysics.

FIG. IVt

MT BROOKING JELLYFISH LOCALITYs iss`ti KIMBERLEY REGION WESTERN AUSTRALIA

QUATERNARY

LOWER CAMBRIANa.

UPPER

PROTEROZOIC occ

PROTEROZOIC

Qa

Po' ,

REFERENCEAlluvium

Antrim Plateau Volcanics

Ranford FormationJarrad Sandstone Member

Moonlight Valley Tillite

Undifferentiated Older Proterozoic

........

...

^Road ^X Dip of bedding

^

}‘.. Creek^ Dip of cleavage

Geological boundary^cz.- Spring

^

N Fault^ 6 Jellyfish locality

.............

SCALEPoj

2 MILES

124'00'

A V L

<74>^L

1^.1L "

Xf^ L/,^• •

> .4 L. > 7 </f

^>^n^ Or^LA4 71:4 .•.< Cl 12"4C."2Qa ^n,^Cla 4

4GREAT NORTHERNHIGHWAY

LISSADELL

P250,CO2 SHEET

E52/A2/5

A NE'tf OCCURRENCE OF' · PROTEROZOIC "JELLYl"IS H" J~lt()J<] 'l'llo!! lCHfBERLBY REG I ON TtlESTEnN AUSTRALIA

D ~ ·Dunne t

SUl-U!..IRY

Objects whi ch look like fossil jellYfish have been ·found in late

Upper Proterod·oiC rocks of the Kimberley Region of Western Austra,lip._ '1'he

II jellyfishli are abundant and particularly ~Jell preserved j on preliminary . . .

investigation the fauna appears to i nclude several new forms together with

forms similar to the Ediacara Fauna. of South Australia .

DUl~ine t he ·1 963

Australia .by .the Bureau of

r·e. g-ional OlaIJping of "the Kimberley :tee-ion of ·.re:::·~el·n ! . -

Mineral Resuurces and the Geological Survey' 01

to/estern Australia , abun:i3J1.t I well- preserv'ed objects , sim·ilar to fOSSil jelly-"

fish, of Upper Proterozoic ~ we r e found. by ' the author.

The fOSSil locality is .70 miles south east of Ttlyrdham, near the

·Uynd.h·am-Nichols:on 1'000 ; 3 . 2 miles south of t he Ord Damsite turno-ff

itude approximate ly 1280 58 1E, and. lati·tude approximat ely 16005 1S .

at long­

(Looality

map, fig . 1) . , The 11 jellyfis.l!-II ar.€: e;x:posed at numerous localities on the surface

of the Mount Brooking Plateau j but are most abundant on the eastern s carp above

the road . The cest 1003.li ty foum to date (Plate 1) is situated along the

northern margin of a promontory , jutting out to tbe east of tbe main plateau .

The stratigraphy of the are a has been detailed by Dow, Gemuts, Plumb

and. Dtinnet (1 964) ani Dow and Gemut.6 (in prep .). The " jellyfish" occur in

the Ranford Formation, the upper unit of the Ord Group . The Ord Group lies .

with strong angular unconformity on older Proterozoio ·rocks and is overlain

unconformab ly by Lower Cambrian ·Antrim Plate au Vol oanios_ To the south in the

"Albert Fliward .Range, the Group i s overlain by the Alber t Eiward Grou·p- of Upper

Proterozoic age . The Ord Group sequence at V~unt Brooking i s as f ollows :

'"

'.

- --_ ._----------------

Estima.ted. thickne$s in feet

200

350

-~-

Lithology

Laminated and thinly bedded siltstone and fine-grained micaceous quartz sandstone . Dist inctive red and wh:L te to buff coloured in upper part. Arg.,le DOl'ms Zebra-stone in lower part. "Jellyfish" appear to be restricted to upper part of the exposed Formati (:ln . '

Red- brorm.·ferruginous fine- grained qua.:t;tz· greY'o'l acke.

WM, te -to mauve clayat'one',I,:sll tstone ani sbal~ , I ::;ome micaceous siltstone ard fJ,ne.- , grained. kaolii1i tic s~stone:'

, " Massive red- brown ferruginous quartz greT~acke with high s ilt matrix content and mud pellets . ---.--------------------------------------

2-1 0 Laminated pink dolomite

Tillite

, \ ,

Formation

Ranford Fcrmation

.J obnny Cake Shale Member

Jarred Sanistone Member

Moonlight Valley

Tillite

The Ranford Format1on is over 1000 feet thick in the type area~

comp~ed with a maximum of '750 feet in the Mbunt Brooking area. A considerable ,

part ~f the Formation may have been removed by erosion. '

The Ranford Formation includes the well-known Argyle Downs

Zebra-stone or Ribbonatone as ' desoribed by Larcombe (1926), Blatohford (1927), ' and Hobson (1930) . . The Zebra-stone oonsists of a white silty rook oontaining

irregular "Ded. bands ani elliptical rods, which Hobson suggested. were the resUlt

of differential leaching. Red siltstones at the II j e llyfiehll ' locality contain

wh1 teo spots a.'ld spheres, up to 1 om in diameter. These rocks superfioially

resemble the Zebra-stone, ani the spo·ts are thought to be leached organic

material . A number of the "jellyfishll are white in a dark red or purple rock.

At V.oUl1't Brooking the "jellyfish" are most abundant in a Zione about 100 feet

above the main Zebra-stone bede. IIJellyflsh" have not been fourd at the mai...?}.

Zebra~stone looality near Argyle Downs homestead j where the Zebra-stone 1s

apparently the highest part of the exposed Ranford Formation .

The sequence at Mount Brooking dips shallowly east-wards in a

broad synoline , ani dips do not exceed 100•

-3--

The age of the sequence at Mount Brooking is late Upper Proterozoic.

It is overlain unconformably by probable Lower Cambrian Antrim Plateau

Volcanics, and Overlies with strong unconformity rocks of older Proterozoic

ages. Preliminary radiometric dating of illite from the Johnny, Cake Shale

Member. of the.Ranford Formation in the Moonlight Valley area, 70 miles to

the south, indicates a late Upper Proterozoic- age.

The fauna consists of circular Objects which, because of their

resemblance to the Ediacara forms described by Sprigg (1947) have been termed, .

'jellyfish'. The "jellyfish" are found over most of the Mount Brooking

plateau; an area of at least^square miles. They are not restricted to a

single stratum but occur throughout at least 20 feet of section; and possibly

much more.

The main locality is characterized by an abundance of specimens

of several different forms. At least five types were recognized in the field

and a greater diversitymay be expected on detailed exaMination. The various

types include Small (0.5 to 1.0 cm) at shaped and strongly serrated forms and

larger (1.0'to 10.0 cm) forms, with fine radial, and concentric structure, and

a wide, apparently structureless outer margin with a scalloped edge (Plate 2)9

The Most prolific form has, a subcircular shape, unscalloped margins, and a

fine radial structure which, in some specimens, is divided by raised and

depressed areas into six sectors (Plate 3). Several different species are

probably included.in this group; Dr. bpik of the Bureau of Mineral Resources

- suggested that 'Cyclomedusa' could be a more/committal term of reference for

these objects. Several relatively structureless objects were also noted.

Some of the star-shaped forms resemble gypsum rosettes and the

structureless forms could be the products of non-organic agents. However,

the Cyclomedusa.form is almost certainly of organic origin and because of the

close association of the. three forms, they are all thought to be organic.

As can be seen from Plates 2 and 3, the state of preservation is

excellent. There has been no metamorphism and apparently little compaction;

specimens have been preserved with slight flattening.

In the main locality specimens are so abundant that individual

specimens overlap each other. (Plate 3). In some instances as many as 30

-4-

specimens were estimated to be present in a squ.are foot of bediiing sUr.·faM91o

with specimens up to six deep.

No formal desoription haa yet been made, but the material 16

at present being studied ' by palaeontologiets of the Bureau of Mineral

Resources . The fauna inolude some forms apparently resembling those from

lliiaoara' in ~outh Australia (Sprigg g 1947 t 1949)") ~ several new forms '. .

appesx ' to be ,'present (Op1k, verbal camm. }':'" They-beat' ,nQ resemblance to the

Forms fow>! by Wade' (19'24) .;.,. described, biSprigg (1949) from rocks lower

: in the sB9,uence near Mount Jobn, 80 miles SSW of Mount Brookir.g.- The

possib le ~rganio origin of the Mount John forms is doubtful '(Harrington &

Moore, f956) . However n jellyfiahl1 stiperf10ialiy similar to tho,sa from Moun,t

Brooking have been found in rocks of probable Middle Cambrian age (Dow,

et a1.~ 1964). These specimens were oolleoted four miles north-north-weet

of tne ··Oro.-Elvir.e River junction, 75 miles to the south of Moimt Brooking.

Two types were found; one of whioh (Plate 4) is similar to the f1n~ radial

and ooncentric form at M~unt Brooking_ . The specimen illustrated in Plate 4

is smaller than average , and most of the individuals collected are between

two and. five centimetres across . These Ujellyfish" are not as abuniant as

the MO~t Brooking fauna _

•

"

-5-

111.ATCHFOj!O, T., 1927

DOW, D • .B~· , GEl.ruTS, I .. V_~ PLltMB 1 K.A.~

al'.d DUNNir;il;', '1964

DqW, D.ll:, and QlilMlJTS, I., in prep.

I!JJIRINGTCll!, 'i!.J;, and MOORE, R.C.,

1956

LARCOMBE, C.O.G., 1926

SPRICG, R.C., 1947

SPRICG, R.C., 1949

WADE, A., 1924

~ I) ·~·:,~:...:~gic-i •. o'0gez"'V"8;~ions bet1;f""lf.!::<"

-:h,:: ····-jL"TI,;, :Y.>s-t 5..."Xi Ki.".g· R:iYol"'~ 1

t "e'" ,- . <>+1 ~, 1' S t', ArD'<:'-" S~, .: .. ' 'r ,!~ ...:. "=' ~~) _",""'.... , """.1.0 . • -,],.J ~'} •• _o

~'l!ll~eQlo$t:.:.."Z.! W.o. k~;~, 93~

- The Geolng'{ of the Ord Rlver

Region~ Western Aus·tral~.a .•

Bg£ ... ~n .R.e~Q.1¥1",,"4¥i!~ "Se=~ 0

1964/104. (unpuOl.)

... The Geology of th.e East Kim­

bel'ley'l Western Australia.

Bu:t' .Min"Resow:- .Au.st .Bu 11 ~ . ... . .... = . .... n_

..... Medusae Incertae Sadie:' and U:c~

reoognisable forms. E'l: T:!"8at:ts6

on Invertebrate Palaeontology-.

Part F ~ Coelenterata. l!!}:!:v;!:'!~a

of ]Ca.!'.8~§. ~~~.9M~_g~ql' .. ~2Il" ~., 1956.

- Zebra Rock from the East Kimb­

erley. :l.:R_C?;v:" SQ.Q .• y ..... Au§."Ii. 16 0

- Some Rooka from 4 miles Eaet

of Argyle StatioD9 Ord River~

King Dietz'i at ~ Kimber leyo

#J.n •. Rep.l?~:e .Min~~!! ~f\us;t; w ~ 1926.

- Early Cambrian Jellyfish from

the Fli!Xl.ers Ra.nge~ S.A . Trane. ,---RoX •• Soc.S.Aust . 71 (2). /

- Early CambraL'1. 'Jellyfishes' of

Ediacara South Australia and Mt. John, Kimb~rley Distriot. W. A ..

T;.wBo.RoX:,~Qo .§.Aus't'j 73.

~ Petroleum ProspeGts. Kimberley

distriot of Western Australia

and Northern Territory_

C~mm"Aust.~Parl.Pa.E. 142 .

Plate 1^

The main site of the Mt. Brookinejellyfish;showing the scarp of the flat dipping RanfordFormation.

Plate 2 A single specimen of the largr * jellyfish; whichwere found up to 10 ems diameter. The fine radialand concentric structure and the scalloped structure—less margin are clearly shown. (2X natural size).(Photograph by R. Mineotas, B.M.R.).

•

t.^-.)••

••

44,-‘4111,k,:.

Plate 3 A profusion of the mostsegmented form is on theapparently struoturelessright. (2X natural sizeR. Mineotas 2 B.M.R.).

abundant forms. Thelower left, anform on the lower). (Photograph by

Plate 4 Fossil "jellyfish" from the Cambrian ElderFormation. (5X natural size).