A new compilation of 3He and xs230Th(o)
data from 12 new deep-sea sediment cores
and previously published data, provide a
global estimate of the Holocene xs230Th(o)
normalized flux IDP 3He at ~0.8 ± 0.2x 10-12
cm3STP·cm-2ka-1. The implied flux of
helium-retentive IDPs of ~250 tons/yr is
consistent with stratospheric collection values
We have extended our estimates to the past
few hundred thousand years and provide
evidence that the IDP flux has remained
relatively constant to within ~30% of the
modern value with no observable cyclic
patterns.

Normalizing concentrations of extraterrestrial
3He in marine sediments to 10Be at 3
locations in the Pacific Ocean, suggests that
the accretion of IDPs has remained constant,
to within a factor of two, throughout the past 7
Ma. At ODP Sites 885/886, the measured
3He flux for the periods between 7.5 and 5.3
Ma, as well as during the past 3.6 Ma is 1.0 ±
0.3 x10^-12cm3STP·cm-2·ka-1. By normalizing
other sedimentary constituents concentrations
to that 3He flux, we calculate a period of
maximum opal accumulation between ~4 and
5 Ma. Furthermore, the 3He-normalized of
eolian mineral aerosol flux indicates a gradual
four-fold rise in dust flux beginning as early as
6 to 7 Ma, rather than a rapid
order-of-magnitude increase beginning at 3.6
Ma, as previously inferred.

Sediment accumulation rates on the Ontong
Java Plateau (OJP) derived using d18O
stratigraphies reveal ~100 ka cycles with
maximum accumulation occurring during
interglacial periods. Normalizing to
xs230Th(o) eliminates the apparent 100 ka
cycle in 3He accumulation in OJP sediments.
We have also found in a study of 230Th
accumulation rates in Holocene equatorial
sediment from the OJP is in excess of that
expected from production by uranium decay in
the overlying water column.

The observed 10Be fluxes in the NE Atlantic
are not providing information on iceberg melt
and ice volume as originally hypothesized.
10Be appears to be a sensitive indicator of
changing particle rain rates but the other sinks
for 10Be, like the amount of boundary
scavenging or lateral transport during glacial
periods, would need to be inventoried as well
in order to achieve a realistic mass balance.