Beschreibung
An additional year of funding on the current SPP project is requested to develop a complete paleorecord of the late Pliocene transition from the warm ‘greenhouse world’ to the initiation of the Northern Hemisphere glaciations (iNHG) in NW North America. In our ongoing project we just confirmed that the Pliocene sediment sequence recovered at the ICDP Project HOTSPOT Site #3 in Western Snake River Plain (Idaho, USA) has a great potential for regional paleoclimate studies. We discovered that (a) the lower 260 m of the drill core consist of rather uniform fine deepwater calcareous lake sediments with rhythmic structure, and (b) this fine sediment sequence does contain a Matuyama/Gauss geomagnetic reversal, and therefore our record covers both the warmer Pliocene world and the iNHG at ca. 2.7 Ma. Here we propose to make this paleorecord as complete as possible because our HOTSPOT Site #3 was single-cored and inevitably has some gaps. To achieve this, we propose to study a 210-m interval from a legacy archive drill core of 1991, which we were fortunate to find and obtain. This 1991 drill core is virtually intact and was not studied except for 110 paleomagnetic and 79 pollen samples. Our preliminary study indicates that this core overlaps with the middle portion of our main record and does cover the gaps and poorly recovered intervals. With this additional year of funding we will produce a single spliced continuous high-resolution late Pliocene master record from paleo-Lake Idaho, first record of this kind for North America. Our results so far have already encouraged a new ICDP initiative of a US Great Basin multi-site drilling proposal with a goal of tracking past hydroclimate of a warmer Pliocene world.
