470 likes | 590 Vues
Explore the dynamics of convergent margins, transforms, and fault zones in tectonic settings worldwide, including notable examples such as the Kane FZ and the South Atlantic Spreading Rate. Learn about compression, extension, gravity anomalies, and the formation of multiple new fracture zones. Delve into the geological implications of transverse ridges, J-structures, flexural bulges, and flexure at trenches. Gain insights into focal depths of earthquakes and the collision of Ontong Java Plateau, leading to subduction reversal. Discover the significance of double Benioff zones and metamorphic reactions in subducted crust and mantle. Join us on this informative journey through tectonic transformations.
E N D
South Atlantic Spreading Rate
EPR 9° North Compression Cocos plate Pacific plate Extension
Bain FZ: Multiple new FZs under extension FZs re-combine under compression 34 21 34 21 21 34 21 34
Udintsev FZ, Pac-Ant Ridge Note: Transverse ridges
Also know as “J structures”
Pitman FZ, Pac-Ant Ridge Note: J structures and Transverse ridges
Hawaii: classic flexural bulge due to load of seamounts
Gravity anomalies due to flexure across fracture zones Menard FZ Udintsev FZ Eltanin FZ
Convergent Margins Focal Depths: green < 50 km, yellow = 50 to 250 km, red > 250 km
ocean - ocean M&T ocean - continent KK&V Fig 9.18
Focal Depths: green < 50 km, yellow = 50 to 250 km, red > 250 km
Focal Depths: Green = 0 – 50 km Yellow = 50 – 250 km Red = > 250 km
Ontong Java Plateau Note: Collision of Ontong Java Plateau with trench around 15 Ma led to reversal of subduction “polarity” in SW Pacific
Double Benioff Zone KK&V Fig 9.12 Upper plane: metamorphic reactions in subducted crust Lower plane: metamorphic reactions in subducted mantle
Ontong Java Plateau Tonga Trench