Related Experiment Video
Updated: May 3, 2026
07:40
A Noninvasive Hair Sampling Technique to Obtain High Quality DNA from Elusive Small Mammals
Published on: March 13, 2011
24.9K
A young source for the Hawaiian plume.
Alexander V Sobolev1, Albrecht W Hofmann, Klaus Peter Jochum
1ISTerre, University Joseph Fourier, Grenoble 1 and CNRS, BP 53, 38041 Grenoble, France. alexander.sobolev@ujf-grenoble.fr
Nature
|August 12, 2011
Summary
Ocean island volcanism involves recycling of oceanic crust. New strontium isotope data from Hawaiian lavas reveal seawater contamination, suggesting mantle circulation rates are faster than previously estimated.
Area of Science:
- Geochemistry
- Isotope Geochemistry
- Mantle Petrology
Background:
- Ocean island volcanism is explained by oceanic crust recycling via subduction and mantle plumes.
- Dating this recycling is crucial for understanding mantle circulation rates.
- Previous dating methods using lead and Re-Os isotopes have limitations due to mixing and rhenium mobility.
Purpose of the Study:
- To investigate the timescale of oceanic crust recycling in mantle plumes.
- To determine the age of subducted oceanic crust contributing to Hawaiian volcanism.
- To refine estimates of mantle circulation rates.
Main Methods:
- Analysis of strontium-87/strontium-86 ((87)Sr/(86)Sr) ratios in 138 melt inclusions from Mauna Loa olivine phenocrysts.
- Comparison of isotopic compositions with seawater and ancient crustal signatures.
- Modeling of isotopic data to infer source contamination and age.
Main Results:
- Enormous mantle source heterogeneity was identified in Mauna Loa lavas.
- Highly radiogenic strontium in depleted melt inclusions matches 200-650-million-year-old seawater.
- This indicates seawater contamination of the Mauna Loa source rock prior to subduction.
Conclusions:
- Seawater contamination provides a 'time stamp' for subducted oceanic crust.
- The presence of 200-650-million-year-old oceanic crust implies faster mantle circulation.
- Average mantle circulation rates are estimated at approximately 2 (±1) cm/yr, faster than previously thought.
Related Concept Videos
01:39Epistasis
37.3K
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence phenotypes in a phenomenon called epistasis. For example, rabbit fur can be black or brown depending on whether the animal is homozygous dominant or heterozygous at a TYRP1 locus. However, if the rabbit is also homozygous recessive at a locus on the tyrosinase gene (TYR), it will have an unshaded coat that appears white, regardless of its TYRP1...
37.3K
02:57piRNA - Piwi-interacting RNAs
6.1K
PIWI-interacting RNAs, or piRNAs, are the most abundant short non-coding RNAs. More than 20,000 genes have been found in humans that code for piRNAs while only 2000 genes have been found for miRNAs. piRNAs can act at the transcriptional and post-transcriptional levels and have a vital role in silencing transposable elements present in germ cells. They are also involved in epigenetic silencing and activation. Previously, they were thought to function only in germ cells but new evidence suggests...
6.1K
01:11Papillary Dermis
5.8K
Dermis
The dermis might be considered the "core" of the integumentary system, as distinct from the epidermis and hypodermis. It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that comprise an interconnected mesh of elastin and collagenous fibers, produced by fibroblasts.
Papillary Layer
The papillary layer is made of loose, areolar connective tissue, which means the collagen...
The dermis might be considered the "core" of the integumentary system, as distinct from the epidermis and hypodermis. It contains blood and lymph vessels, nerves, and other structures, such as hair follicles and sweat glands. The dermis is made of two layers of connective tissue that comprise an interconnected mesh of elastin and collagenous fibers, produced by fibroblasts.
Papillary Layer
The papillary layer is made of loose, areolar connective tissue, which means the collagen...
5.8K
01:19Pigmentation
3.8K
The color of the skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred to the keratinocytes via melanosomes.
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
3.8K
01:20Accessory Structures of the Skin: Hair Growth and Types
2.8K
Hair growth begins with the production of keratinocytes by the basal cells of the hair bulb. As new cells are deposited at the hair bulb, the hair shaft is pushed through the follicle toward the surface. Keratinization is completed as the cells are pushed to the skin surface to form the shaft of hair that is externally visible. The external hair is completely dead and composed entirely of keratin. Hair can be cut or shaven without damaging the hair structure because the cut is superficial. Most...
2.8K
01:15Reticular Dermis
4.6K
The papillary and reticular dermis are the two layers of the dermis. They are made of connective tissue with fibers of collagen extending from one to the other, making the border between the two somewhat indistinct. The dermal papillae extending into the epidermis belong to the papillary layer, whereas the dense collagen fiber bundles below belong to the reticular layer.
Reticular Layer
Underlying the papillary layer is the much thicker reticular layer, composed of dense, irregular connective...
Reticular Layer
Underlying the papillary layer is the much thicker reticular layer, composed of dense, irregular connective...
4.6K