The Late Miocene Biogenic Bloom : A globally distributed but not an
ubiquitous event
Abstract
The Late Miocene Biogenic Bloom (LMBB) is a late Miocene to early
Pliocene oceanographic event characterized by high accumulation rates of
opal from diatoms and calcite from calcareous nannofossils and planktic
foraminifera. This multi-million year event has been recognized in
sediment cores from the Pacific, Atlantic and Indian Oceans. The
numerous studies discussing the LMBB lead us to believe that this event
is omnipresent in all oceans, although this hypothesis need to be
tested. Moreover, the origin of this event is still widely discussed. In
this study we aim to provide a comprehensive overview of the
geographical and temporal aspects of the LMBB by compiling published
ocean drilling (DSDP, ODP and IODP) records of sedimentation rates,
CaCO\textsubscript{3} and opal and terrigenous
accumulation rates that cover the late Miocene and early Pliocene
interval. Our data compilation shows that traces of the LMBB are present
in many different locations but in a very heterogeneous way,
highlighting that the LMBB is not a pervasive event. The compilation in
addition shows that the sites where the LMBB is recorded are mainly
located in areas with a high productivity regime (i.e. upwelling
systems). We suggest that the most likely hypothesis to explain the LMBB
is a global increase in upwelling intensity due to an increase in wind
strength or an increase in deep water formation, ramping up global
thermohaline circulation.