© ICDP, the International Continental Scientific Drilling Program, 1996-2021

www.icdp-online.org

Blue Hole Drilling Project

Central America, Belize, Gulf of Mexico

new preliminary-proposal: ICDP-2008/06
for the funding-period starting 2008-01-15
by Eberhard Gischler, Eugene A. Shinn, Flavio Anselmetti
Abstract
Sediment from the bottom of the Blue Hole, a 125 m deep Pleistocene sinkhole located in the lagoon of Lighthouse Reef Atoll, Belize, consists of undisturbed, annually layered biogenic carbonate muds and silts with intercalated coarser grained storm beds. Sedimentation-rate of layered sections is 2.5 mm/yr on average, and up to 6 m long cores collected during a pilot study span the past 1500 yrs. Oxygen isotopes of laminated sediment in these cores provide a late Holocene climate proxy: a high-resolution d18O time series traces the final Migration Period Pessimum, the Medieval Warm Period, the Little Ice Age, and the subsequent temperature rise. Carbon isotopes (d13C) decrease upcore and potentially show the impacts of the decline of the Maya culture and the Suess Effect. Time series analyses of d18O and d13C reveal 88, 60, 52, and 32 year cyclicities, and suggest solar forcing. Storm event beds are most common during AD 650-850, around AD 1000, during AD 1200-1300, and AD 1450-1550. Major storm beds are rare during the past 500 years BP. The total Holocene marine sediment sequence in the Blue Hole alone can be expected to cover about 8 kyrs and more than 20 m of annually layered sediment, given the average sedimentation rate of 2.5 mm/yr and the early Holocene marine inundation of the Lighthouse Reef lagoon. Because the Blue Hole probably formed not only during the previous but during several Pleistocene sea-level lowstands, we expect similar, laminated marine sediments of previous Pleistocene sea-level highstands below the Holocene sediment package. We attempt to investigate this late Quaternary record in a core study within the framework of the International Continental Scientific Drilling Program (ICDP).
Scientific Objectives
  • First Priority:
  • (1) Reconstruction of a high-resolution Holocene climate record. The undisturbed, annually-layered sedimentary record of the Blue Hole offers an ideal opportunity to study climate variation of the past 8.000 years at very high resolution. Potential climate parameters include sea surface temperature, salinity, and nutrients, as well as major storm frequency. The record could not only serve for regional but also for larger-scale climate reconstructions because the study area is connected with the Gulf Stream and the northern Atlantic Ocean via the Caribbean Current.
  • (2) Investigation of Holocene climate record in the context of human cultural evolution in the hinterland, i.e., rise and fall of the Maya Culture. Because of the study area location, the climate record may be compared with the evolution of the Maya Culture since ca.
  • 2.000 BC. The collapse of the Classic Maya Culture around 1000 AD may be further investigated regarding its relation to climate variation. In turn, the influence of the Maya Culture on the environment may also be estimated (e.g., run-off caused by forest clearing, agriculture). Second Priority:
  • (3) Possible reconstruction of Pleistocene high-resolution climate records from late Pleistocene interglacial periods. The sinkhole did not form during the last glacial sea-level highstand alone. Presumably, it took several subaerial exposure phases in order to dissolve the more than 10 million cubic meters of limestone, the current volume of the Blue Hole. Therefore, similarly undisturbed and layered deposits of late Pleistocene interglacials should underlie the Holocene sediment package. These late Pleistocene sediments will allow to obtain high-resolution climate archives from previous interglacial periods.
Keywords
Belize, BLUE HOLE, Central america, Climate archive, Climate change, ICDP-2008/06, Quaternary, Sea drilling, Sediment
Location
Central America, Belize, Gulf of Mexico: 17.31556, -87.53444

© ICDP, the International Continental Scientific Drilling Program, 1996-2021

www.icdp-online.org