TY - JOUR
T1 - Geology and geochronology of the Paleoproterozoic Hart Dolerite, Western Australia
AU - Ramsay, R.R.
AU - Eves, A. E.
AU - Denyszyn, S. W.
AU - Wingate, M.T.D.
AU - Fiorentini, M.
AU - Gwalani, L. G.
AU - Rogers, K. A.
PY - 2019/12/1
Y1 - 2019/12/1
N2 - The Hart Dolerite is the intrusive component of the Hart–Carson Large Igneous Province, which extends over an area of >160,000 km2 in the Speewah and Kimberley Basins in the western part of the North Australian Craton. In the core of the Speewah Dome, a ca. 500 m thick composite sill of Hart Dolerite intruded metasedimentary rocks of the Speewah Group, which have a maximum depositional age of 1814 ± 10 Ma. Referred to here as the Speewah sill, it comprises four discrete gabbroic units and two later-stage dyke and sill units of potassic granophyre. The gabbros locally contain sulfide-poor, Stella-type platinum-group element enrichment and vanadiferous titanomagnetite mineralisation. New ID-TIMS U-Pb geochronology of baddeleyite from gabbro units in the Speewah sill yield upper-intercept ages (all 2σ) of 1792.7 ± 1.3 Ma and 1791.7 ± 4.1 Ma. These results are complemented by a SHRIMP age of 1792.1 ± 5.9 Ma (2σ) for baddeleyite in a late-stage pigeonite vein in Hart Dolerite 120 km south of the Speewah Dome. These new data are consistent with previous regional geochronology of late-stage quartz–feldspar granophyres, and with a model of rapid emplacement of the Hart Dolerite at 1792.6 ± 1.2 Ma in an intracratonic extensional setting. Globally, the period around ca. 1793 Ma includes several large igneous provinces, suggesting that this interval was characterised by high mantle heat flow, continental extension, and voluminous mafic magmatism over large areas.
AB - The Hart Dolerite is the intrusive component of the Hart–Carson Large Igneous Province, which extends over an area of >160,000 km2 in the Speewah and Kimberley Basins in the western part of the North Australian Craton. In the core of the Speewah Dome, a ca. 500 m thick composite sill of Hart Dolerite intruded metasedimentary rocks of the Speewah Group, which have a maximum depositional age of 1814 ± 10 Ma. Referred to here as the Speewah sill, it comprises four discrete gabbroic units and two later-stage dyke and sill units of potassic granophyre. The gabbros locally contain sulfide-poor, Stella-type platinum-group element enrichment and vanadiferous titanomagnetite mineralisation. New ID-TIMS U-Pb geochronology of baddeleyite from gabbro units in the Speewah sill yield upper-intercept ages (all 2σ) of 1792.7 ± 1.3 Ma and 1791.7 ± 4.1 Ma. These results are complemented by a SHRIMP age of 1792.1 ± 5.9 Ma (2σ) for baddeleyite in a late-stage pigeonite vein in Hart Dolerite 120 km south of the Speewah Dome. These new data are consistent with previous regional geochronology of late-stage quartz–feldspar granophyres, and with a model of rapid emplacement of the Hart Dolerite at 1792.6 ± 1.2 Ma in an intracratonic extensional setting. Globally, the period around ca. 1793 Ma includes several large igneous provinces, suggesting that this interval was characterised by high mantle heat flow, continental extension, and voluminous mafic magmatism over large areas.
KW - Baddeleyite
KW - Large igneous province
KW - Mafic igneous rocks
KW - Petrography
KW - U-Pb geochronology
UR - http://www.scopus.com/inward/record.url?scp=85073724725&partnerID=8YFLogxK
U2 - 10.1016/j.precamres.2019.105482
DO - 10.1016/j.precamres.2019.105482
M3 - Article
AN - SCOPUS:85073724725
SN - 0301-9268
VL - 335
JO - Precambrian Research
JF - Precambrian Research
M1 - 105482
ER -