Mid atlantic ridge plate boundary12/31/2022 ![]() ![]() ![]() Arrows indicate the direction of plate motion on either side of the fault (USGS, Public domain, via Wikimedia Commons). Figure 4.5.2 Closeup of the mid-Atlantic ridge system, showing transform faults perpendicular to the ridge axis. The mid-ocean ridge system can be seen as the light blue chain of mountains running throughout the oceans (). As we will see in section 4.7, movements along transform faults between two adjacent ridge segments are responsible for many earthquakes.įigure 4.5.1 Ocean floor topography. These transform faults make the mid-ocean ridge system look like a giant zipper on the seafloor (Figure 4.5.2). #Mid atlantic ridge plate boundary seriesAlthough oceanic spreading ridges appear to be curved features on Earth’s surface, in fact the ridges are composed of a series of straight-line segments, offset at intervals by faults perpendicular to the ridge, called transform faults. Running down the middle of the mid-ocean ridge is a rift valley 25-50 km wide and 1 km deep. Because the new crust formed at the plate boundary is warmer than the surrounding crust, it has a lower density so it sits higher on the mantle, creating the mountain chain. The mid-ocean ridge system is a giant undersea mountain range, and is the largest geological feature on Earth at 65,000 km long and about 1000 km wide, it covers 23% of Earth’s surface (Figure 4.5.1). Most divergent boundaries are located along mid-ocean oceanic ridges (although some are on land). This process is known as “ sea floor spreading” and results in a symmetrical alignment of the rocks of the ocean floor which get older with distance from the ridge crest.Modified from "Physical Geology" by Steven Earle*ĭivergent boundaries are spreading boundaries, where new oceanic crust is created to fill in the space as the plates move apart. In this way, as the plates move further apart new ocean lithosphere is formed at the ridge and the ocean basin gets wider. This produces basaltic volcanoes when an eruption occurs above the surface ( Eyjafjallajökull in Iceland) and characteristic basalt “ pillow lava” in underwater eruptions. As the mantle rises towards the surface below the ridge the pressure is lowered (decompression) and the hot rock starts to partially melt. ![]() The Mid Atlantic Ridge, like other ocean ridge systems, has developed as a consequence of the divergent motion between the Eurasian and North American, and African and South American Plates. The ocean ridge rises to between 2 to 3 km above the ocean floor, and has a rift valley at its crest marking the location at which the two plates are moving apart. The Ridge extends into the South Atlantic Ocean between the South American and African Plates. The North American and Eurasian Plates are moving away from each other along the line of the Mid Atlantic Ridge. ![]()
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