ROV Deep Discoverer collects a spiral, fossilized shell of some sort. At the conclusion of this field season, this sample- along with all of the others will go out - will head to archival. Once there, scientists can request to analyse a specific sample, like this fossil, which will hopefully help to further characterize this region. We might even be lucky enough to figure out what this is a fossil of!

ROV Deep Discoverer collects a spiral, fossilized shell of some sort. At the conclusion of this field season, this sample – along with all of the others will head to archival. Once there, scientists can request to analyse a specific sample, like this fossil, which will hopefully help to further characterize this region. We might even be lucky enough to figure out what this is a fossil of! Image courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Marianas. Download larger version (jpg, 1.1 MB).

Dive 16: Subducting Guyot 1
20°27'11.16"N, 147°4'6.06"E, 4,997 meters
July 3, 2016
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Fossil Discovery

While exploring a guyot that is presumably a Cretaceous seamount in the process of being subducted within the Trench Unit of the Marianas Trench Marine National Monument, scientists saw very little in the way of living organisms, but there were fossils! Video courtesy of the NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Marianas. Download (mp4, 91.2 MB)

Dive 16 explored a guyot that is presumably a Cretaceous seamount in the process of being subducted within the Trench Unit of the Marianas Trench Marine National Monument (MTMNM). One of the goals of this dive was to investigate millions of years of Cretaceous reef growth that would otherwise be impossible to see. Although there was very little in the way of living organisms (one fish, a few shrimp, a couple anemones, and a carnivorous sponge), there were fossils! The dive began at a depth of approximately 5,000 m on a slope covered with talus consisting of sparse cobble- to boulder-sized rock fragments among soft sediment. As ROV Deep Discoverer (D2) neared the bottom of the steeper part of the wall, the sea floor became a smooth white surface with fewer loose rocks. The wall itself revealed a fascinating sequence of layered accumulations of varying texture and fossil types. Bivalve fossils dominated the darker layers. These layers were generally thinner than the more massive white layers between them. Some layers were a pale yellow and had a more granular appearance. These granular, yellow sequences were first seen at an outcrop as patches, then intermittently until they became visible as discrete layers higher up on the wall. As D2 moved upwards, the outcrops showed high-angle fractures. At the shallower elevations of the wall, distinct vertical ridges with chutes between them gave the wall a spectacular texture, easily viewed when the ROV was oriented in parallel to the strike of the wall.

After the benthic exploration, the dive continued with midwater transects at 4000 m, 3000 m, 2000 m, 1200 m, 1000 m, 800 m, and through an observed scattering layer at 482 m. To our knowledge, this is the first deep water column exploration in the Mariana Trench. There was very little in the midwater at 4000 m, but as expected, the number and diversity of plankton and organic particles increased as we moved up the water column. Larvaceans (pelagic tunicates) were present throughout all depths. During the shallow transects, fauna encountered included jellyfish, siphonophores, salps, fish, and shrimp.