Great Wall of Baffin Island
West-facing view of ~100 m-wide Franklin dike on Borden Peninsula in Mala River drainage halfway between Arctic Bay and Pond Inlet, Nunavut, Canada.
718 million years ago, a plugged-up mantle plume went sideways, travelling at depth within the Earth's crust. The underground molten rock moved eastwards along the Canadian Shield's Arctic coast from a long lost source in the western Arctic Ocean.
Obstructed mantle plume events form thick horizontal sills in layered sedimentary rocks near the mantle plume. The mafic-ultramafic melt also forms vertical dike swarms that often travel in parallel. Such underground dikes traverse plastic continental crust at depth. They advance at the speed of galloping horses when slicing through granite and metamorphosed migmatite terrains.
The giant mafic-ultramafic dike shown here has travelled 2000 km to reach western Baffin Island. GSC geology maps show substantial dikes continuing for another 1000 km to Baffin Island's east end.
Great Wall of Baffin Island
West-facing view of ~100 m-wide Franklin dike on Borden Peninsula in Mala River drainage halfway between Arctic Bay and Pond Inlet, Nunavut, Canada.
718 million years ago, a plugged-up mantle plume went sideways, travelling at depth within the Earth's crust. The underground molten rock moved eastwards along the Canadian Shield's Arctic coast from a long lost source in the western Arctic Ocean.
Obstructed mantle plume events form thick horizontal sills in layered sedimentary rocks near the mantle plume. The mafic-ultramafic melt also forms vertical dike swarms that often travel in parallel. Such underground dikes traverse plastic continental crust at depth. They advance at the speed of galloping horses when slicing through granite and metamorphosed migmatite terrains.
The giant mafic-ultramafic dike shown here has travelled 2000 km to reach western Baffin Island. GSC geology maps show substantial dikes continuing for another 1000 km to Baffin Island's east end.