BH250-250
Title
BH250-250
Subject
Basalt
Description
Mid-oceanic ridge basalt (MORB) from East Pacific Rise, showing glassy, basalt and a chilled margin.
Petrologic and Mantle Significance:
This mid-ocean ridge basalt (MORB) from the East Pacific Rise represents the dominant volcanic rock type forming the oceanic crust at divergent plate boundaries. It originated from partial melting of the upper mantle at depths of ~60–80 km. The presence of glass and a chilled margin reflects rapid quenching during submarine eruption, preserving the melt composition with minimal alteration.
Geochemically, MORB is typically depleted in incompatible elements and exhibits relatively uniform isotopic ratios (e.g., low ⁸⁷Sr/⁸⁶Sr and high ¹⁴³Nd/¹⁴⁴Nd), indicating a well-mixed, depleted mantle source that has experienced prior melt extraction. Once analyzed for its chemistry and thin sections are made, this sample will serve as a valuable geochemical reference for understanding mantle composition, magma generation processes, and global mantle heterogeneity.
Petrologic and Mantle Significance:
This mid-ocean ridge basalt (MORB) from the East Pacific Rise represents the dominant volcanic rock type forming the oceanic crust at divergent plate boundaries. It originated from partial melting of the upper mantle at depths of ~60–80 km. The presence of glass and a chilled margin reflects rapid quenching during submarine eruption, preserving the melt composition with minimal alteration.
Geochemically, MORB is typically depleted in incompatible elements and exhibits relatively uniform isotopic ratios (e.g., low ⁸⁷Sr/⁸⁶Sr and high ¹⁴³Nd/¹⁴⁴Nd), indicating a well-mixed, depleted mantle source that has experienced prior melt extraction. Once analyzed for its chemistry and thin sections are made, this sample will serve as a valuable geochemical reference for understanding mantle composition, magma generation processes, and global mantle heterogeneity.
Coverage
East Pacific Rise, recovered by HOV Alvin at 2500 m depth
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample 250. Housed at Carleton College in Minnesota.
Publisher
Bereket Haileab
Contributor
Bereket Haileab, Carleton College Geology Department
Adam Soule '97
Adam Soule '97
Type
Hand sample
Relation
Collection
Citation
Bereket Haileab, “BH250-250,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/368.