Publikationsdatum:
2023-07-19
Beschreibung:
Large Igneous Provinces (LIPs) are unusual volcanic events in which massive amounts of melt (∼106 km3) erupt in relatively short time periods (〈106 years). Most LIP magmas have undergone extensive fractional crystallization and crustal contamination, but the crustal magmatic plumbing systems and the processes triggering eruptions are poorly understood. We present new major and trace element and radiogenic isotope data for 43 individual lava flows from a continuous 1,200 m thick stratigraphic profile through the upper, most voluminous part of the Deccan LIP (Bushe to Mahabaleshwar Formations). Eruption rates for this section are constrained by published paleomagnetic directions and absolute U‐Pb ages for zircons from weathered flow tops exposed in the profile. We find four magmatic sequences each lasting ∼104–∼105 years during which major and trace element compositions change systematically, followed by an abrupt change in geochemistry at the start of a new sequence. Within each sequence, the MgO content and proportion of crustal contamination decrease progressively, indicating a continuous replenishment of the associated magma reservoirs with less contaminated but more evolved melts. These geochemical signatures are best explained by repeated episodes of melt recharge, mixing, and eruption of variably evolved magmas originating from relatively small magma reservoir located in different crustal levels.
Beschreibung:
Plain Language Summary:
Volcanism occurs predominantly at plate boundaries, either at mid‐ocean ridges or subduction zones, where most mantle melts are produced. However, the Earth's history is punctuated by volcanic events which are not related to plate boundary processes and during which large amounts of melt erupt (∼106 km3) in relatively short periods of time (〈106 years). These Large Igneous Provinces (LIPs) are associated with the activity of mantle plumes and eruption rates during their main stages are significantly higher than those of today's largest magmatic systems. However, since no LIP is currently active, the architecture of the associated plumbing systems is relatively unknown. In order to understand the magmatic processes during the emplacement of a LIP, we generated geochemical data from a continuous stratigraphic profile covering the most voluminous stage of the ∼66 Ma Deccan LIP. By combining these new data with published paleomagnetic directions and absolute U‐Pb ages for zircons, we found four eruption sequences each lasting ∼104–∼105 years. During these sequences, geochemical compositions change systematically, which is best explained by repeated episodes of melt recharge, mixing, and eruption of variably evolved magmas originating from relatively small magma reservoirs located at different crustal levels.
Beschreibung:
Key Points:
Four recharge‐crystallization‐eruption sequences fed the most voluminous Deccan lava.
Magmatic plumbing system with interconnected small‐ to medium‐sized magma reservoirs.
Complex emplacement history including multiple stages of ascent, mixing, and storage.
Beschreibung:
Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659
Beschreibung:
https://doi.org/10.26022/IEDA/112672
Schlagwort(e):
ddc:551.9
;
intraplate processes
;
magma chamber processes
;
magma genesis and partial melting
;
major and trace element geochemistry
;
radiogenic isotope geochemistry
Sprache:
Englisch
Materialart:
doc-type:article
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