Geology Reference
In-Depth Information
The Canning basin is situated to the southwest of the region. According to Allsopp
et al. there are three main roughly east
west-trending lamproite
fields occurring in
-
this broad zone. One
field is referred to as Ellendale Field, which is located within
the King Leopold Mobile Belt on the northern
flank of the Leonard Shelf; the other
is called the Calwynyada
field situated south of the Leonard Self and the last one is
called the Noonkanbah
field (located in the central zone of the Fitzroy Trough).
There is another small cluster of lamproites occurring within the King Leopold
Mobile Belt about 100 km east of the Ellendale Field and to the north of Fitzroy
River. The lamproites occur as eroded craters, plugs, lava
flows, lava lakes, sills,
and dykes. Allsopp et al. (1985) summarized the radiometric ages of different
intrusives from the West Kimberley region (Table
4.4
).
Table 4.4 Isotropic ages of Lamproites from West Kimberley (Alsopp et al. 1985)
Locality
Average age
Method
22.2
±
0.0
a
Mt. North
K
-
Ar
Rb
-
Sr
22.0
±
1.6
Old Leopold Hill
20.7
±
0.6
a
K
Ar
-
Rb-Sr
21.8
±
0.8
17.8
±
0.0
a
Wolgidee Hills
K
-
Ar
K
Ar
17.5
±
0.2
-
Rb
Sr
-
22.1
Howes Hill (west)
K
-
Ar
19.0
Mt. Percy
K
Ar
22.0
±
0.3
-
Rb
Sr
-
20.8
Camarotoechia Bore
K
-
Ar
0.3
a
22.1
±
Hoper West
K
-
Ar
21.9
±
0.2
Winjana
K
Ar
21.9
±
0.2
-
81 Mile Vent
21.5
+
0.2
K
Ar
-
Water Reserve Sill
K
-
Ar
21.4
±
0.2
Noonkanbah Hill
K
Ar
20.1
±
0.2
-
“
P
”
Hill
K
Ar
19.5
±
0.7
a
-
Dadja Hill
K
-
Ar
19.6
±
0.2
Fishery Hill
K
-
Ar
19.6
±
0.2
Machells Pyramid
K
Ar
-
18.4
±
0.6
Mt. Gytha
K
-
Ar
17.0
±
0.9
Ellendale 9
Rb
-
Sr
24.0
±
1.0
Mt. Rose
Rb
Sr
23.2
±
5.0
-
Seltrust Pipe 2
Rb
Sr
-
23.9
±
0.8
a
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