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“Large Igneous Provinces (LIPs)”: Definition,
recommended terminology, and a hierarchical classification |
Hetu C. Sheth
Department of Earth Sciences, Indian Institute of Technology
(IIT) Bombay, Powai,
Mumbai 400 076 India, hcsheth@iitb.ac.in
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Correct and appropriate terminology is important
for the so-called Large Igneous Provinces (LIPs).
The term LIP is widely applied to large basaltic provinces
such as the Deccan, and the term Silicic Large Igneous
Province (SLIP) to volcanic provinces of dominantly
felsic composition, such as the Whitsunday. Neither
term has been applied to the large granitic batholiths
of the world (e.g., Andes) to which both are perfectly
applicable. LIP has also not been applied to broad
areas of contemporaneous magmatism (e.g., Mongolia)
and sizeable layered mafic intrusions (e.g., Bushveld)
which are also true “large igneous provinces”.
I suggest that the term “LIP” is used
only in its broad sense and that an “LIP”
should have an area of 50,000 km2 as a minimum size
limit. I will present a simple hierarchical classification
of LIPs that is independent of composition, tectonic
setting, or emplacement mechanism. I suggest that
provinces such as the Deccan and Whitsunday should
be called Large Volcanic Provinces (LVPs), and large
mafic intrusions, dyke swarms, and other intrusive
provinces should be called Large Plutonic Provinces
(LPPs). LVPs and LPPs together cover all large igneous
provinces (LIPs), having felsic to ultramafic compositions,
of sub-alkalic and alkalic lineages, emplaced in continental
and oceanic settings. LVPs are subdivided here into
four groups: (i) the dominantly/wholly mafic Large
Basaltic Provinces (LBPs) (e.g., Deccan, Ontong Java);
(ii) the dominantly felsic Large Rhyolitic Provinces
(LRPs) (e.g., Whitsunday, Sierra Madre Occidental);
(iii) the dominantly andesitic Large Andesitic Provinces
(LAPs) (e.g., Andes, Indonesia, Cascades), and (iv)
the bimodal Large Basaltic-Rhyolitic Provinces (LBRPs)
(e.g., Snake River-High Lava Plains). The intrusive
equivalent of LRPs are the Large Granitic Provinces
(LGPs) (e.g., the Andean batholiths), but a corresponding
term for intrusive equivalents of LBPs is not necessary
or warranted. The largest LBP, and LIP, is of course
the ocean floor. It is hoped that the proposed classification
and nomenclature of LIPs will result in more accurate
use of terminology and hence understanding of the
wide variety of large igneous provinces.
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