[Eoas-seminar] EOAS Colloquium at 3:00 PM on Friday, April 24, 2025 at EOA 1044

[eoas-seminar at lists.fsu.edu]

Hi all,



I am happy to announce that we will have the last EOAS colloquium of 2025-2026 academic year on Friday, April 24, 2026. The following is the information about the colloquium:



Speaker: Dr. Vincent Salter, EOAS, Florida State University



Title: Anciently melt-depleted mantle resurfaces again at mid-ocean ridges



Abstract:


The convecting Earth mantle transports peridotite toward the surface, where it melts under mid-ocean ridges (MOR) and forms oceanic crust. This accounts for ca. 75% of today's volcanic activity. The return mass transport is at subduction zones where melt-depleted mantle, oceanic crust and sediment sinks into the mantle. Abyssal peridotites recovered from MOR are residual from the oceanic crust extraction, but their Hf isotopic compositions are vastly different from the basalts and require ancient melt depletion at MOR followed by the long-term (up to 3-4Ga) residence in the mantle.

Ultra-depleted peridotites have been documented at multiple localities, indicating their ubiquity in the sub-ridge mantle. Hence, melts from such ultra depleted peridotite influences mid-ocean ridge basalt compositions and variably melt- depleted sub-ridge peridotites should be considered when evaluating ridge depth variations. The large spectrum of Hf isotope ratios in abyssal peridotites, ranging to εHf > 450, confirms that the predicted variation of melt-depleted peridotites characterizes peridotites in the sub-ridge mantle.

The covariation between variable peridotite composition and density establishes a critical link between basalt chemistry and the thermochemical buoyancy forces that control mantle upwelling and basalt production rates under mid-ocean ridges or ocean islands. The Marion Rise at the southwest Indian Ridge is an example where ultra depleted peridotites are the likely cause for the shallow ridge depth.


Time: 3:00 PM, Friday, April 24, 2026



Location: EOA 1044



Contact: Prof. Zhaohua Wu (zwu at fsu.edu)



A flyer of the colloquium is also attached.



Cheers,



Zhaohua


***************************************************************

Zhaohua Wu, Professor

Earth, Ocean, and Atmospheric Science Building, Room 6041, and

Center for Ocean-Atmospheric Prediction Studies, Room 295

Florida State University

Tallahassee, Florida

zwu at fsu.edu<mailto:zwu at fsu.edu>

****************************************************************


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.fsu.edu/pipermail/eoas-seminar/attachments/20260420/fdc51b37/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 042426_Vincent_Salter.pdf
Type: application/pdf
Size: 100738 bytes
Desc: 042426_Vincent_Salter.pdf
URL: <http://lists.fsu.edu/pipermail/eoas-seminar/attachments/20260420/fdc51b37/attachment-0001.pdf>