WEST KIMBERLEY PLACE REPORT - Department of Sustainability ...

CRITERION (a) – The place has outstanding heritage value because of the place's
importance in the course, or pattern of Australia's natural or cultural history.
ASSEMBLING A CONTINENT
The King Leopold orogen represents the remnants of the three major orogenic or
'mountain building' events (orogenies) that affected the Kimberley from 1870 to 560
Ma (million years ago), exposed on Yampi Peninsula, and in the Fitzroy uplands
province which includes the King Leopold Ranges (as defined by Maher and Copp
2009). A product of plate tectonic activity, orogenies are time constrained and
associated with distinctive structures and lithology, including mountain ranges.
'Orogenic belts' or orogens are their legacy in the landscape. These orogenic belts can
be mountain ranges like the Andes or the Appalchians, but they can also be eroded
away, recognisable only by their structural and lithological footprint. Old orogenic
activity may be represented by the exhumed core of ancient mountains – intruded
granites or metamorphic rocks often uplifted from several kilometres below the
surface (Maher and Copp 2009; Stanley 1999). There is little consensus among
geologists on plate tectonic activity in the early Earth. Therefore rocks from the
period from 2,700 Ma to about 700 Ma, such as those encompassed by the King
Leopold orogen, are very important in understanding the timing and nature of modern
plate tectonics (Witze 2006; Stanley 1999).
Collisional orogenies like those represented in the King Leopold orogen occur when
the movement of tectonic plates causes continental plates to collide. The events of
these three Proterozoic orogenies are preserved and particularly well displayed in the
spectacularly folded Proterozoic quartzites and sandstones of Yampi Peninsula and
the granite domes, gneiss hills and schist ridges of the Fitzroy uplands province. The
rocks of the King Leopold orogen provide strong evidence of Palaeoproterozoic plate
tectonic activity, at a period prior to the formation of the Neoproterozoic
supercontinent Rodinia (which preceded the Greater Gondwana and Pangean
supercontinents of the late Palaeozoic and early Mesozoic eras). This early collision
event is known as the Hooper orogeny. The King Leopold orogen also preserves rocks
from the Yampi and King Leopold orogenies that occurred later in the Proterozoic
eon and record events associated with the current Kimberley topography (Maher and
Copp 2009; Maher and Copp 2010).
Other Proterozoic collisional orogens are preserved elsewhere in the North Australian
and West Australian cratons. Of those associated with the West Australian craton the
Albany–Fraser orogen is more restricted in its timing than the King Leopold orogen,
and along with the Pinjarra and Paterson orogens is poorly exposed in outcrop. As a
result, these orogens are also little studied. The Capricorn orogen represents four
orogenic events from 2,200–1,620 Ma, associated with ocean closure and so tells a
different story to that of the King Leopold orogen which is closely associated with the
Meso to Neoproterozoic formation of Rodinia. Of the Proterozoic collisional orogens
associated with the North Australian craton, the most significant are the Halls Creek
and Pine Creek orogens. The Pine Creek orogen contains rocks from events dated
from 1,863–1,780 Ma, making it more restricted in time than the King Leopold
orogen. The Halls Creek orogen spans the period from 1,870–300 Ma, including the
orogenies recorded in the King Leopold orogen as well as two more, the 1,850–1,840
Ma Halls Creek orogeny and the 300 Ma Alice Springs orogeny. However, the Halls
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