Abstract
| Original language | English |
|---|---|
| Pages (from-to) | 1127-1130 |
| Journal | Geology |
| Volume | 41 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 2013 |
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Globally synchronous marinoan deglaciation indicated by U-Pb geochronology of the cottons Breccia, Tasmania, Australia. / Calver, C.R.; Crowley, J.L.; Wingate, Michael; Evans, D.A.D.; Raub, T.D.; Schmitz, M.D.
In: Geology, Vol. 41, No. 10, 2013, p. 1127-1130.Research output: Contribution to journal › Article
TY - JOUR
T1 - Globally synchronous marinoan deglaciation indicated by U-Pb geochronology of the cottons Breccia, Tasmania, Australia
AU - Calver, C.R.
AU - Crowley, J.L.
AU - Wingate, Michael
AU - Evans, D.A.D.
AU - Raub, T.D.
AU - Schmitz, M.D.
PY - 2013
Y1 - 2013
N2 - U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacialpostglacial transition on King Island, Tasmania, provide the first direct age constraint on the Cryogenian-Ediacaran boundary in Australia. Zircons in four samples from the topmost meter of the Cottons Breccia, dated by sensitive high-resolution ion microprobe, exhibit two modes ca. 660 Ma and ca. 635 Ma. The younger component predominates in the uppermost sample, a possibly volcanolithic dolomitic sandstone, apparently lacking glacially transported debris, in the transition to cap carbonate. Chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of euhedral zircons from that sample yields a weighted-mean age of 636.41 ± 0.45 Ma. Equivalence to published TIMS ash bed dates from Cryogenian-Ediacaran transitional strata in Namibia (635.51 ± 0.82 Ma, within glacial deposit) and China (635.23 ± 0.84 Ma, 2 m above glacial deposit) supports correlation of those strata to the Australian type sections and globally synchronous deglaciation at the end of the Cryogenian Period. © 2013 Geological Society of America.
AB - U-Pb zircon data from the uppermost Cottons Breccia, representing the Marinoan glacialpostglacial transition on King Island, Tasmania, provide the first direct age constraint on the Cryogenian-Ediacaran boundary in Australia. Zircons in four samples from the topmost meter of the Cottons Breccia, dated by sensitive high-resolution ion microprobe, exhibit two modes ca. 660 Ma and ca. 635 Ma. The younger component predominates in the uppermost sample, a possibly volcanolithic dolomitic sandstone, apparently lacking glacially transported debris, in the transition to cap carbonate. Chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) U-Pb dating of euhedral zircons from that sample yields a weighted-mean age of 636.41 ± 0.45 Ma. Equivalence to published TIMS ash bed dates from Cryogenian-Ediacaran transitional strata in Namibia (635.51 ± 0.82 Ma, within glacial deposit) and China (635.23 ± 0.84 Ma, 2 m above glacial deposit) supports correlation of those strata to the Australian type sections and globally synchronous deglaciation at the end of the Cryogenian Period. © 2013 Geological Society of America.
U2 - 10.1130/G34665.1
DO - 10.1130/G34665.1
M3 - Article
VL - 41
SP - 1127
EP - 1130
JO - Geology
JF - Geology
SN - 0091-7613
IS - 10
ER -