A process-oriented approach to mantle geochemistry

Stracke, Andreas

doi:10.1016/j.chemgeo.2021.120350

Cited by 32 publications

(40 citation statements)

References 349 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, with plate migration a seemingly unlikely driver, we must now examine the mechanisms by which a recycled component can be increasingly incorporated into the source of the Kaavi-Kuopio kimberlites. In fact, the progressive enrichment in εHf ( i ) compositions recorded in these kimberlites ( R 2 = 0.72, p = 0.02; Figure 6 ) is contrary to the expectation that progressive melt extraction from a particular source region would be accompanied by its progressive depletion in geochemically enriched fusible components as observed in the Lac de Gras kimberlite field ( Tovey et al, 2021 ) and hypothesized for basalts globally ( e.g., Stracke, 2021;Stracke & Bourdon, 2009 ).…”

Section: Mantle Plume-driven Geochemical Enrichment Of the Kaavi-kuop...contrasting

confidence: 67%

“…If kimberlite melts are generated by partial melting at or just below the LAB, spatial heterogeneities in lithospheric thickness could have influenced the extent of partial melting ( e.g., Gudfinnsson & Presnall, 2005;Massuyeau et al, 2021 ) and hence the composition of kimberlite magmas including Hf isotope variability in the Kaavi-Kuopio region. In this scenario we envisage that changes in the LAB depth, possibly due to thermal erosion or extensional tectonics during the ∼30 Myr of kimberlite activity, would have influenced the degree of melting ( lower for deeper LAB ), with lower degree melts preferentially sampling more enriched, more fusible portions of the same sub-lithospheric source ( e.g., Ito & Mahoney, 2005a;Ito & Mahoney, 2005b;Stracke, 2021 ) thus generating kimberlites with lower εHf ( i ) .…”

Section: Geothermobarometric Effectsmentioning

confidence: 99%

See 1 more Smart Citation

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Dalton

Giuliani

Hergt

et al. 2022

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Despite the scientific and economic significance of kimberlites and related magmas, their origin is unclear. Here, we address this issue using whole‐rock and perovskite‐derived Sr‐Nd‐Hf isotopes for the three occurrences of kimberlite, lamproites and ultramafic lamprophyres (UMLs) in Finland. Mesoproterozoic olivine lamproites at Lentiira‐Kuhmo and UMLs at Kuusamo have different isotopic signatures yet were emplaced contemporaneously at 1,200 Ma in response to an extensional regime linked to the Baltica‐Laurentia breakup. The low εNd(i) and εHf(i) values of the olivine lamproites are consistent with an enriched subcontinental lithospheric mantle (SCLM) source while UML compositions are intermediate between those of typical kimberlites and lamproites and are interpreted to reflect mixing of asthenospheric melts and ∼10%–15% of melts sourced from metasomatized SCLM. The ∼750 Ma Kuusamo kimberlites, are probably linked to the mantle plume activity that initiated Rodinia's break‐up, exhibiting homogenous isotopic compositions which mirror the prominent Geodynamic and Source Constraints for ∼1,200 Ma Olivine Lamproite and Ultramafic Lamprophyre Magmatism in Eastern Finland (PREMA)‐like signature of kimberlites globally. By contrast, ∼620–585 Ma Kaavi‐Kuopio kimberlites show limited range in εNd(i) and 87Sr/86Sr(i) but have remarkably heterogeneous εHf(i) (+6.5 to −6.3) with a temporal trend toward lower εHf(i) values. While the Kuusamo kimberlites erupted during the early stage of continental break‐up, the Kaavi‐Kuopio kimberlites were emplaced when Rodinia break‐up was completed, coeval with formation of the Central Iapetus large igneous province. Magmas forming the Kaavi‐Kupio kimberlites may have formed from an upwelling mantle source similar to PREMA modified by increasing incorporation (up to 10%) of recycled crustal material through time accounting for the trend toward lower εHf(i) in these kimberlites.

show abstract

Section: Mantle Plume-driven Geochemical Enrichment Of the Kaavi-kuop...contrasting

confidence: 67%

Section: Geothermobarometric Effectsmentioning

confidence: 99%

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Dalton

Giuliani

Hergt

et al. 2022

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…Alternatively, the dominant pattern of heterogeneity may be simple enough to approximate using a combination of lherzolite, harzburgite, and pyroxenite, in which case inversion methods may constrain their proportions (e.g., Ito & Mahoney 2005;Shorttle et al 2014). But refractory lithologies, by definition, contribute little to melt production and are therefore difficult to detect (Stracke 2021). Moreover, melt extraction can both create (Spiegelman & Kelemen 2003) and destroy (Bo et al 2018) geochemical variability, making it difficult to disentangle the effects of source and transport.…”

Section: The Contributionmentioning

confidence: 99%

Physics of Melt Extraction from the Mantle: Speed and Style

Katz

Jones

Rudge

et al. 2022

Annu. Rev. Earth Planet. Sci.

View full text Add to dashboard Cite

Melt extraction from the partially molten mantle is among the fundamental processes shaping the solid Earth today and over geological time. A diversity of properties and mechanisms contribute to the physics of melt extraction. We review progress of the past ∼25 years of research in this area, with a focus on understanding the speed and style of buoyancy-driven melt extraction. Observations of U-series disequilibria in young lavas and the surge of deglacial volcanism in Iceland suggest this speed is rapid compared to that predicted by the null hypothesis of diffuse porous flow. The discrepancy indicates that the style of extraction is channelized. We discuss how channelization is sensitive to mechanical and thermochemical properties and feedbacks, and to asthenospheric heterogeneity. We review the grain-scale physics that underpins these properties and hence determines the physical behavior at much larger scales. We then discuss how the speed of melt extraction is crucial to predicting the magmatic response to glacial and sea-level variations. Finally, we assess the frontier of current research and identify areas where significant advances are expected over the next 25 years. In particular, we highlight the coupling of melt extraction with more realistic models of mantle thermochemistry and rheological properties. This coupling will be crucial in understanding complex settings such as subduction zones. ▪ Mantle melt extraction shapes Earth today and over geological time. ▪ Observations, lab experiments, and theory indicate that melt ascends through the mantle at speeds ∼30 m/year by reactively channelized porous flow. ▪ Variations in sea level and glacial ice loading can cause significant changes in melt supply to submarine and subaerial volcanoes. ▪ Fluid-driven fracture is important in the lithosphere and, perhaps, in the mantle wedge of subduction zones, but remains a challenge to model. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

show abstract

“…However, the low-order structures of the global MORB-OIB isotopic database, the data trends or clusters formed by the local data sets, contain the principal information about the isotopic composition of the underlying mantle source. That is, they represent melts whose isotopic composition is variably dispersed around a weighted average of the isotopically different mantle source ingredients (e.g., Stracke, 2021b and references therein). When using dimensionality reduction algorithms such as PCA Figure 1.…”

mentioning

confidence: 99%

Chemical Geodynamics Insights From a Machine Learning Approach

Stracke

Willig

Genske

et al. 2022

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Thousands of oceanic basalts have been analyzed in the last six decades, building up a large database of Sr, Nd, Hf, and Pb isotope ratios. A characteristic feature of these data is that they are not randomly distributed. In 2D and 3D isotope ratio diagrams, the isotopic variation of oceanic basalts on a local scale, that is, for basalts from one ocean island or ridge segment, is often in form of approximately linear data trends. Combining the local data into a large global data set does not have a randomizing effect. Rather, despite considerable overlap, higher-order structures, that is, reproducible trends or clusters composed of groups of local data, appear in 2-3D isotopic space. These higher-order trends or clusters of the global data set have often been described as linear combinations

show abstract

A process-oriented approach to mantle geochemistry

Cited by 32 publications

References 349 publications

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Geodynamic and Isotopic Constraints on the Genesis of Kimberlites, Lamproites and Related Magmas From the Finnish Segment of the Karelian Craton

Physics of Melt Extraction from the Mantle: Speed and Style

Chemical Geodynamics Insights From a Machine Learning Approach

Contact Info

Product

Resources

About