Ferromanganese Nodules—2021 North Atlantic Stepping Stones Exped. (AD)

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Detailed Description

During a recent dive on the New England Seamount chain off the North Atlantic coast, researchers aboard the NOAA Ocean Exploration Expedition, North Atlantic Stepping Stones, discovered a marine geological feature known as a ferromanganese (Fe-Mn) nodule field in the saddle between two peaks of Gosnold Seamount. These seamount-hosted nodules were an exciting find, since Fe-Mn crusts are more common in seamount settings.

Marine Fe-Mn minerals are unique among marine rocks in that they grow slowly over millions of years, building layers and accumulating metals as they precipitate from seawater and/or sediment pore waters. The study of Fe-Mn deposits can yield clues about past climatic conditions and geologic history, shedding light on how the world’s oceans have changed over time.

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Details

Date Taken:

Length: 00:01:48

Location Taken: US

Transcript

Voice of Rhian Waller: We're in the New England Seamount Chain, and today we're exploring a seamount called Gosnold. 

When we landed on this dive, we actually landed on a manganese nodule field. 

Text reads: On a recent dive, NOAA Ocean Exploration’s 2021 North Atlantic Stepping Stones Expedition encountered a marine geological feature known a ferromanganese nodule field. 

Voice of Kira Mizell: We're going over this incredible debris field coated in ferromanganese, and instead of growing in one stratigraphic direction like crusts on rock surfaces and rock outcrops, manganese nodules actually form around a nucleus and grow outward radially and form concentric layers, kind of like tree rings. 

Text reads: USGS scientists Jason Caytor and Kira are the expedition’s marine geology leads. We spoke with Kira about the ferromanganese substrate. 

For this expedition, because we're looking at seamounts, I'll be looking at the ferromanganese crusts. 

We'll get to see what kind of seawater chemistry they've recorded over their growth histories. 

So ferromanganese crusts grow layer by layer, about a millimeter per million years. When you go back in time through the rock, you can see the seawater chemistry being recorded in those ferromanganese crusts. You can also look at the metal enrichments to see if there's anything that might be of interest in terms of resource potential. 

So there's just several different aspects of ferromanganese crusts that are really interesting. 

Voice of Kira: I think the key ingredient here is the available of material on top of sediments that is allowing nodules to grow in this region, which is definitely an unexpected setting that 

we've landed here today. 

Credits read: Footage from the 2021 North Atlantic Stepping Stones Expedition courtesy of NOAA Ocean Exploration 
 
Video by Peter Pearsall/USGS