TY - JOUR
T1 - Widespread silicic and alkaline magmatism synchronous with the Deccan Traps flood basalts, India
AU - Basu, Asish R.
AU - Chakrabarty, Puloma
AU - Szymanowski, Dawid
AU - Ibañez-Mejia, Mauricio
AU - Schoene, Blair
AU - Ghosh, Nilotpal
AU - Bastian Georg, R.
N1 - Funding Information:
The samples analyzed in this study were collected in January 1994 with help and guidance from the staff and scientists of the Directorate of Geology and Mining, Gujarat State, India. The trachytes from Mumbai were collected with field guidance by S.F. Sethna. This research is partially supported by grants from the US NSF and the University of Texas (STAR grant) to A.B. This research also benefited from start-up funds to M.I.M. provided by University of Rochester . We are grateful for critical evaluations from Editor Rajdeep Dasgupta and reviewers Courtney Sprain and Richard Carlson, which helped to improve the clarity of this manuscript.
Funding Information:
The samples analyzed in this study were collected in January 1994 with help and guidance from the staff and scientists of the Directorate of Geology and Mining, Gujarat State, India. The trachytes from Mumbai were collected with field guidance by S.F. Sethna. This research is partially supported by grants from the US NSF and the University of Texas (STAR grant) to A.B. This research also benefited from start-up funds to M.I.M. provided by University of Rochester. We are grateful for critical evaluations from Editor Rajdeep Dasgupta and reviewers Courtney Sprain and Richard Carlson, which helped to improve the clarity of this manuscript.
Publisher Copyright:
© 2020
PY - 2020/12/15
Y1 - 2020/12/15
N2 - Deccan Traps (DT) volcanism and the Chicxulub bolide impact have been suggested as potential triggers of the Cretaceous–Paleogene boundary (KPB) mass extinction. Recently published geochronology has established a timeline for the main basaltic sequence of the DT, showing that the majority of eruptions occurred within 700–800 kyr spanning the KPB. Silicic to alkaline magmatism linked to the DT, spatially associated with the Narmada lineament in central India, has been long known but not as well studied. Previous geochronology of some of the felsic magmatic centers has yielded dates that span many millions of years, making their temporal relationship with DT volcanism uncertain. We present zircon U-Pb ages from the Alech, Barda, Girnar, Rajula and Phenai Mata silicic–alkaline complexes, in addition to a series of trachytes on the coastal plain near Mumbai. While the trachytes are ∼64 Ma and mark the continental breakup of India ∼1.5 Myr after the main phase of DT eruptions, the silicic-alkaline complexes were all emplaced coevally with the main phase of DT volcanism ca. 66.2-65.7 Ma. Initial εHf in zircons (+10 to -20), whole-rock 87Sr/86Sr (0.702439-0.760932) and εNd (+1.11 to -35.7) for all five intrusive complexes suggest a hybrid origin involving juvenile sources as well as significant assimilation of older continental crust. Recognition that the silicic-alkaline complexes are coeval with basaltic magmatism and associated with a significant thermal imprint on the crust in and near the Narmada rift sedimentary strata supports the hypothesis that outgassing of organic-rich sediments may have contributed to the end-Maastrichtian warming and biologic crisis.
AB - Deccan Traps (DT) volcanism and the Chicxulub bolide impact have been suggested as potential triggers of the Cretaceous–Paleogene boundary (KPB) mass extinction. Recently published geochronology has established a timeline for the main basaltic sequence of the DT, showing that the majority of eruptions occurred within 700–800 kyr spanning the KPB. Silicic to alkaline magmatism linked to the DT, spatially associated with the Narmada lineament in central India, has been long known but not as well studied. Previous geochronology of some of the felsic magmatic centers has yielded dates that span many millions of years, making their temporal relationship with DT volcanism uncertain. We present zircon U-Pb ages from the Alech, Barda, Girnar, Rajula and Phenai Mata silicic–alkaline complexes, in addition to a series of trachytes on the coastal plain near Mumbai. While the trachytes are ∼64 Ma and mark the continental breakup of India ∼1.5 Myr after the main phase of DT eruptions, the silicic-alkaline complexes were all emplaced coevally with the main phase of DT volcanism ca. 66.2-65.7 Ma. Initial εHf in zircons (+10 to -20), whole-rock 87Sr/86Sr (0.702439-0.760932) and εNd (+1.11 to -35.7) for all five intrusive complexes suggest a hybrid origin involving juvenile sources as well as significant assimilation of older continental crust. Recognition that the silicic-alkaline complexes are coeval with basaltic magmatism and associated with a significant thermal imprint on the crust in and near the Narmada rift sedimentary strata supports the hypothesis that outgassing of organic-rich sediments may have contributed to the end-Maastrichtian warming and biologic crisis.
KW - Deccan Large Igneous Province
KW - Narmada–Tapti lineament
KW - Saurashtra Peninsula
KW - zircon geochronology
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U2 - 10.1016/j.epsl.2020.116616
DO - 10.1016/j.epsl.2020.116616
M3 - Article
AN - SCOPUS:85090243675
SN - 0012-821X
VL - 552
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
M1 - 116616
ER -