The Cret
aceous O
khots
k-
Chukot
ka volc
anic belt (OCVB) is
a prominent subduction-rel
ated m
agm
atic province, h
aving the rem
ar
kably high proportion of silicic roc
ks (c
a. 53%of the present-d
ay crop
are
a,
and presum
ably over 70%of the tot
al volc
anic volume). Its estim
ated tot
al extrusive volume r
anges between 5.5 脳 10
5 km
3 (the most conserv
ative estim
ate)
and over 10
6 km
3. This
article presents
a brief outline of the geology of OCVB, yet poorly described in intern
ation
al scientific liter
ature,
and results of
a geochronologic
al study on the northern p
art of the volc
anic belt. On the b
ase of new
and published U-Pb
and
40Ar/
39Ar
age determin
ations,
a new chronologic
al model is proposed. Our study indic
ates th
at the
activity of the volc
anic belt w
as highly discontinuous
and comprised
at le
ast five m
ain episodes
at 106-98 M
a, 94-91 M
a, 89-87 M
a, 85.5-84 M
a,
and 82-79 M
a. The new d
at
a allow
a semi-qu
antit
ative estim
ate of the volc
anic output r
ate for the observed p
art of the OCVB (
are
a and volume
approxim
ately 10
5 km
2 and 2.5 脳 10
5 km
3, respectively). The
aver
age extrusion r
ate for the entire lifetime of the volc
anic belt r
anges between 1.6
and 3.6 脳 10
鈭?#xA0;5 km
3yr
鈭?#xA0;1 km
鈭?#xA0;1, depending on the
assumed
aver
age thic
kness of the volc
anic pile; the optim
al v
alue is 2.6 脳 10
鈭?#xA0;5 km
3yr
鈭?#xA0;1 km
鈭?#xA0;1. Despite imprecise, such estim
ates infer the time-
aver
aged volc
anic productivity of the OCVB is simil
ar to th
at of silicic LIPs
and most
active recent subduction-rel
ated volc
anic
are
as of the E
arth. However, the most extensive volc
anic fl
are-ups
at 89-87
and 85.5-84 M
a h
ad higher r
ates of over 9.0 脳 10
鈭?#xA0;5 km
3yr
鈭?#xA0;1 km
鈭?#xA0;1.
The main volumetric, temporal and compositional parameters of the OCVB are similar to those of silicic LIPs. This gives ground for discussion about the geodynamic setting of the latters, because the widely accepted definition of a LIP implies a strictly intraplate environment. Considering the genesis of the OCVB and other large provinces of silicic volcanism, we propose that residual thermal energy preserved in the continental crust after a previous major magmatic event may have been one of major reasons for high proportion of felsic rocks in a volcanic pile. In this scenario, underplating of mantle-derived basalts causes fast and extensive melting of still hot continental crust and generation of voluminous silicic magmas.