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Diffuse vents
Diffuse venting on the seafloor occurs where high-temperature fluids rising from depth become mixed with cold seawater before they exit the seafloor. The key difference between diffuse and focused vents is how much mixing with seawater occurs before they are released. In other words, the plumbing system of focused vents is well-sealed and transports hot fluid from depth to the seafloor with little or no mixing and the vent fluid comes out of one small pipe. On the other hand, the plumbing of diffuse vents is leaky and allows seawater to mix with the vent fluid and this mixture exits the seafloor over a larger area.
Because of this mixing, diffuse vents are typically low in temperature, with fluids cooler than 200°C (by definition) and usually cooler than about 50°C. Like the high temperature vents, the warm sulfide-rich water provides the foundation for a diverse ecosystem of chemosynthetic organisms which colonize these vent sites. After the 1998 eruption of Axial volcano, diffuse vents were widespread on the new lava flow. White microbial residue along the margins of cracks in the lava surface, in the recesses in lobate flows, and outlining every skylight are evidence for diffuse venting and abundant subsurface microbial growth throughout the lava flow area. Snowblower vents are a unique kind of diffuse vent where white flocculent material is blown out of the seafloor, evidence of a subsurface microbial bloom.
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Related video clips:
Marker 33 area over time | Marker 33 after the eruption
Snowblower vent at Pit | Magnesia vent | Cloud vent

Related Virtual Sites:
The Pit | Marker 33

Other NeMO-related concepts:
Mid-ocean ridges | seafloor spreading | seamounts & hot spots | calderas | Axial volcano
Hydrothermal vents | fluid paths | focused vents | diffuse vents | sulfide | anhydrite
Animal Gallery | chemosynthesis | biological colonization of new lava

Lava morphology | sheets | pillows | lava contacts | skylights | pillars | the 1998 flow
NeMO at Axial | the 1998 eruption | the rumbleometer story | lava flow animation

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