| 31685 |
Creator |
1b8a71ef5b52b9dd4b573c12680d2e74 |
| 31685 |
Creator |
1c5c32b11b5ad1bd9c846a77784abc38 |
| 31685 |
Creator |
b35b6181f0ce6bbdf5a9817cbd3db971 |
| 31685 |
Creator |
8ee2610823a9f97019d289b7d54d7511 |
| 31685 |
Date |
2011-08 |
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Is Part Of |
repository |
| 31685 |
Is Part Of |
p03019268 |
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abstract |
The kimberlites and lamproites of southern India are thought to have formed in the
most prolific known period of Precambrian ultramafic/ultrapotassic magmatism at around
1100 Ma. This study reports new age data for southern Indian ultrapotassic rocks (kimberlites
and lamproites), a controversial topic due to the wide range of published age data
and disagreements over the reliability of previously published ages. In this study
we obtained new high-precision Ar–Ar data that better constrain the ages of southern
Indian ultrapotassic rocks. Dates from three samples are presented, including two
kimberlites from Wajrakarur kimberlite field and one lamproite from the Krishna lamproite
field. These age data are then combined with bulk-rock geochemical and Nd isotopic
data to provide further constraints on the source region and primary magma composition
of southern Indian kimberlites and lamproites. Previously, the Chelima lamproite (ca.
1400 Ma) was considered to be one of the oldest lamproites in the world. However,
our age data suggest that at least one lamproite (Pochampalle) was generated in the
same region 100 Ma before the Chelima event. The Pochampalle lamproite was emplaced
around ~1500 Ma as shown by the Ar–Ar data in this study, roughly 250 Ma before the
other Krishna lamproites. It would seem that the Pochampalle lamproite was also derived
from an isotopically distinct source region with a lower <sup>143</sup>Nd/<sup>144</sup>Nd
ratio than other lamproites in the Krishna field. These findings not only have implications
for regional ultramafic/ultrapotassic magmatism, but also demonstrate that the mantle
processes for producing lamproitic melts existed earlier than previously thought. |
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authorList |
authors |
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issue |
1-2 |
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status |
peerReviewed |
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uri |
http://data.open.ac.uk/oro/document/364501 |
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uri |
http://data.open.ac.uk/oro/document/364507 |
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uri |
http://data.open.ac.uk/oro/document/364508 |
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uri |
http://data.open.ac.uk/oro/document/364509 |
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uri |
http://data.open.ac.uk/oro/document/364510 |
| 31685 |
uri |
http://data.open.ac.uk/oro/document/364709 |
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uri |
http://data.open.ac.uk/oro/document/651298 |
| 31685 |
volume |
189 |
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type |
AcademicArticle |
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type |
Article |
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label |
Osborne, Ian ; Sherlock, Sarah ; Anand, Mahesh and Argles, Tom (2011). New Ar-Ar
ages of southern Indian kimberlites and a lamproite and their geochemical evolution.
Precambrian Research, 189(1-2) pp. 91–103. |
| 31685 |
label |
Osborne, Ian ; Sherlock, Sarah ; Anand, Mahesh and Argles, Tom (2011). New Ar-Ar
ages of southern Indian kimberlites and a lamproite and their geochemical evolution.
Precambrian Research, 189(1-2) pp. 91–103. |
| 31685 |
Title |
New Ar-Ar ages of southern Indian kimberlites and a lamproite and their geochemical
evolution |
| 31685 |
in dataset |
oro |