The Good, The Bad and the Ugly
Dr Gerry Dickens: Co Chief Scientist JR Exp371, gives a fresh new light on:
The Good, the Bad and the Ugly
Known for its musical score, groundbreaking cinematography, and fascinating characters, the now classic spaghetti western gives us a true epic, both in length and story. After nearly three hours, all comes to a three-way shootout over buried treasure — the three gunslingers, as almost any movie buff knows, each reflecting a facet of the title. Often forgotten, though, is that the film begins and ends backwards, telling, in order, the ugly, the bad, and the good.
We finally completed Site U1507. The emphasis on “finally” reflects the ugliness of spending ten days of drilling, much of this being the very slow wandering of rotary core after rotary core through pale green limestone with turbidites to reach seismic targets originally estimated at 700 m below the seafloor (mbsf) and originally ascribed to an early Paleogene age. The preferred method of coring, certainly for paleoceanographic work, is through APC or XCB. But, with the lithology that exists at Site U1507, which was not fully anticipated, such coring systems did not work effectively below about 300 mbsf.
The shipboard science team can tell the age of the recovered sediment fairly quickly by examining very small calcareous “microfossils”, and looking for age diagnostic marker species of nannofossils and foraminifera. At approximately 850 mbsf, and after drilling through ~100 m of upper to middle Eocene sediment ascribed to a nannofossil biozone horizon called NP 17, we finally passed into zone NP16. This time horizon, which is much more tellingly referred to as the Middle Eocene Climatic Optimum (MECO), has become a focal point for the geoscience community, because it was a ~500,000 year interval of anomalous warmth, when average global temperatures rose by nominally 4-5°C. The bad: Core 51R – the main phase of the MECO – returned to the ship empty except the bottom 30 cm of the core catcher.
As in the movie, though, the drilling saga, now subtitled Site U1407, comes with a good ending and a buried treasure. The 860 m thick sedimentary section, barring a few core recovery misfires, is nearly continuous in depth and time. For nominally 40 million years, sediment has accumulated at the fairly high rate of 20-25 m/million years. An amazingly complete Oligocene section exists in this part of the world. And, there is Core 50R, a previously unknown grave containing a great record for the latter part of the MECO.