Southern Flinders Ranges

Ç 0 FIG. 4

4.2.2 Southern Flinders Ranges

The "southern Fllnders canyon series"

(Fig.4.1) _trends in

an east-

southeasterly direction from

the

Waukarie Creek Canyon ^Complex and

the

Yarra

88

FIGTJR,E 4.2

Extract

from

the

COPLEY 1:250 000 geological sheer ^(Coates, 1973), showing

the locality of the

maps presented

tn Fig.4.3

(Salt Creek Canyon),

Fig. 4.4

(Puttapa Canyon),

Fig.

4,6 (Nankabunyana Canyon) and Fig.

4,6

^(slump induced intraformational

truncation

surfaces and ^possible canyon

tributary

southwest

of

Beltana Township),

withln the

Beltana and

Mt,

Scott Range areas.

Fig.4.5

Fig.4.3

ì

Bwa

BELTANA _DIAPIR

Wonoka

Formation

o

K ILOM E TR ES

10

Vale Canyon Complex (new name) near

the

western edge

of the

Fllnders Ranges,

through

the

Pamatta Pass Canyon (new name)

to the

Yunta Canyon Complex ^(new name), near

the

eastern edge

of the

ranBes;

a total of

l7O km.

The Waukarie Creek Canyon Complex, described

briefly by

Jenkins ^(1981),

is a structurally

repeated

feature

incised

tip to

⁸⁰⁰ m ^(Jenkins

&

Gostin,

1983) through

the

Bunyeroo Formation and

into the

ABC Range Quartzite,

l3

^km

south

of Quorn,

^{The canyon}

fiil

sequence bears

a

close resemblance

to

that developed

in the northern

canyons, consisting

of

basal calcareous sandstones

and coarse debris

flow

material, which ^grades

up into a

carbonate dominated sequence. Palaeocurrent data from

turbidites is variable,

suggesting

in-

canyon meandering,

but

^generally suBgest

an

easterly

flow

direction.

The Yarra Vale Canyon Complex comprises

a

series

of three

incisions through

the

Bunyeroo Formation and

into the

^{ABC Range} Quartzite about 20 ^km

north of Quorn.

The structures are ^repeated on

both flanks of a

north-south orientated syncline,

two

incisions on

the

west and one broader incision to

the east.

^Some

of

these were noted

by

Plummer (1978), who mapped

part

of one

of the

structures near Buekaringa

Gorge.

Outcrop

is very

poor and

deeply weathered, leading Plummer (1978)

to

conclude

that the

incisions were

infilled with

Bunyeroo Formation, and

he

suggested

that a

major pre-Bunyeroo erosive

event

had occurred

in this

region

of the geosyncline.

Recent

investigations

indicate that the fill is

^{Wonoka Formation}

^(V.4.

^{Gostin &}

R.J.F. Jenkins, pers. com. 1984) and

that the

struetures

are of

^similar

dimension

to the

Waukarie Creek Canyon ^Complex, 30 km

to the south.

^No

palaeocurrent data er¿ availâble

but the repetition of

incisions indicates an

east-west axial trend,

and

the

suggestion

of bifurcation of the

system to

the

west argues

in ^{favour of}

^an

^{easterly flow}

^direction.

The

identification of the

following canyon

fills ls

based

largely

on

discordances mapped

on l:260

000 scale sheets, and

thus their

identification remains

tentative at this stage,

Because

of their structural setting

these

89

do

not

dlsplay

the typical

canyon morpliology,

but

are ^pÌeserved

only

as

isolated ^patches

of

unconformable outcrop

wlthin

synclines,

interpreted

^as representing

only the

deepest

parts of

incislons.

The Pamatta Pass Canyon, 13 km northeast

of

Carrieton, uras

first briefly

described

by

Binks (1971), who noted Wonoka Formation resting unconformably on Bunyeroo Formation, ABC Range Quartzite and ^Brachina Formation equivalents

in the keel of the

^White Valley

Syncline.

Binks (1971) described breccia beds and considered

the structure to

be

of

slump origin.

The Yunta Canyon Complex

is a

series

of four

separate masses

of

Wonoka

Formation

resting

unconformably on Brachina Formation equivalents,

that

have been mapped on

the

eastern side

of the

^ORROROO 1:250 000 geological sheet (Binks, ₁₉₆₈₎ and western side

of the

OLARY

l:250

000 preliminary geological

sheet. All of

these structures

lie within the

^{Ulupa Syncline.}

The contact between

the

Wonoka Formation and underlying sediments in

the

eastern

half of the

^Waroonee Syncline 30 km

north of the

Yunta Canyon Complex appears

to

^be unconformable as mapped on

the

OLARY 1:250 000

preliminary geological sheet, and may represent

a further

outcrop

of

canyon

fill

sediments.

4.3

SALT CREEK CANYON

The

Salt

Creek Canyon (new name)(Fie. 4.3), largest and deepest

of

the newly discovered

structures

described

in this

^chapter,

is situated

^about

17.5 km

north

northeast

of the old

Beltana township and 12,5 km southeast of

the

Leigh Creek South township ^(30o 40'S, 138o

29'E)'

^Access

is

readily afforded

by

several unseaied roads which cross

the structure.

^{Outcrop is}

generally poor and

of

low

relief,

and much

of the

lower canyon

fill

^is

overlain by

Quaternary

alluvium

^{and scree, and remnants}

of a

^gravel terrace probabty

of Tertiary age.

The exposed outcrop

of the

^canyon

is ⁶

^{km ln}

width, but

as

the

northwestern side

of the structure

^does

not

crop

out

at

90

Geologlcal map

of the Salt

Creek

Canyon. All units

are

referred

to in the text.

Coarse material

refers

to

conglomerates and diamictites (largely debris

flows)

with c.lasts

of

cobble size and

larger.

Palaeocurrents from flutes, separately

plotted for

canyon

units A

and

B,

are presented at

bottom.

Note

that the

map

is

oriented

with

respect

to

the e¿rnyon and

north is

^towards

the

lower

right

eorner.

...=,:.

Rormtey

0u

iÌe...

Bo

^Sondstone

2km

Urit F...

udr E...

Unit 0...

Unit C...

Unit 8...

Unit 4...

Unit 3...

Unit 1,2...

ra

¡

Atluviun ond scree....

Terroce ^grovel Yonoko

Fo¡notion

Bunyeroo

Fa

ion...

ABC Ronge Ouortzite . ... ..

Brochino Fornotion ^. ... ...

Roqd,

trock. a:

=====

Oip of beddirP Foutt..

unconfocnity

Coorse ^{debris ..} ...1r' ,|

'.'

Polqeocurrents

f¡on ftufes

Unit A Unit ^B

all, the true wldth is

^possibly

significantly greater.

The canyon

fill

^is

structurally

uncomplicated, aìthough

a

bedding

parallel thrust fault

repeats

part of the

post-canyon lVonoka Formation above

a portion of the

structure.

Bedding dips

vertically

near

the

base

of the incision

and steeply

to

the south higher

in the

sequence.

Aerial

photographs and

field

observations

indicate that the wall

and

base

of the

eanyon represent

an

angular unconformity

of local extent,

and

are

unrelated

to faulting,

^The southeastern

wall

has

a

maximum slope of about ^3Oo near

the

base

of the incision. This is ^a

^minimum

value for

the

true

^slope, which

will vary

depending on

the orientation of the

cross- section

with

respect

to the orientation of the

canyon

axis.

To the southeast

of the

^canyon

the entire

sequence appears

to

be conformable,

However, poor outcrop and cover ^preclude recognition

of the point of

maximum

lateral extent of the

^canyon unconformity

or its

^exact stratigraphic

position.

The lower

portion of the

Wonoka Formation

(units _1, 2

and at

least part of 3) is

truncated, and hence

the

canyon

is an

intraformational

feature with

respect

to ^the time of infilling.

^{The maximum depth of}

incision is

estimated

at

^{800 m from}

aerial

photographs and

dip

measurements.