Mantle Provinces
Mantle Provinces refer to distinct, long-lived regions within Earth’s mantle that possess unique compositional, thermal, or isotopic signatures. These provinces are fundamental to understanding Plate Tectonics, Mantle Convection, and the heterogeneity of Earth’s interior. They are not uniform; instead, they represent segregated reservoirs of primordial or recycled material that influence volcanic output, hotspot tracks, and large-scale tectonic evolution.
Key Characteristics
- Compositional Heterogeneity: Distinct from the well-mixed upper mantle, provinces may contain depleted or enriched components (e.g., DMM, EM1, EM2, HIMU reservoirs).
- Thermal Anomalies: Some provinces are defined by thermal plumes originating from deep-seated anomalies, such as Large Low Shear Velocity Provinces (LLSVPs) in the lower mantle.
- Temporal Stability: Many provinces persist over billions of years, acting as stable reservoirs despite ongoing convection and subduction.
Geological Implications
- Hotspot Volcanism: Mantle plumes rising from specific provinces create linear chains of volcanoes (e.g., Hawaii, Iceland) that serve as tracers for deep mantle flow.
- Crustal Formation: The composition of oceanic crust and continental lithosphere is influenced by the source province from which magma is derived.
- Seismic Tomography: Variations in seismic wave speeds help map these provinces, revealing low-velocity zones that correlate with thermal or compositional differences.
Recent Discoveries and Context
New geological insights highlight the complexity of Earth’s subsurface structures, including hidden oceanic features and submerged continents that interact with mantle dynamics.
- Zealandia: A submerged continental remnant in the Southwest Pacific, Zealandia represents a significant lithospheric feature influenced by underlying mantle processes. Its rifting history provides constraints on mantle upwelling and plume-lithosphere interactions. Zealandia
- Hidden Oceans: Recent studies suggest the existence of massive hydrous reservoirs within the mantle transition zone, potentially holding more water than surface oceans. This affects mantle viscosity and melt generation. Mantle Transition Zone
- Integration of Data: Comprehensive reviews of geological discoveries emphasize that Earth’s interior is more heterogeneous than previously modeled, with mantle provinces playing a central role in segregating volatile and incompatible elements. See Unveiling Earth’s Geology: Hidden Oceans, Zealandia, and Mantle Provinces for detailed summaries of these findings.
Related Concepts
- Large Low Shear Velocity Provinces
- Mantle Plume
- Subduction Zone
- Isotopic Reservoirs
- Geochemistry