Convergent active margins will have a steep continental slope, whereas passive margins will have a more gradual slope. Where would you expect to find graded bedding? … Each light-colored layer is sandstone that marks the coarser bottom of a graded bedding sequence. How did these turbidite deposits form?
shelf break, submerged offshore edge of a shallow continental shelf, where the seafloor transitions to continental slope. A shelf break is characterized by markedly increased slope gradients toward the deep ocean bottom.
Along divergent boundaries like the mid-Atlantic ridge and the East Pacific Rise, earthquakes are common, but restricted to a narrow zone close to the ridge, and consistently at less than 30 km depth. Shallow earthquakes are also common along transform faults, such as the San Andreas Fault.
“Submarine canyons” are deep valleys at passive continental boundaries. They are likely carved out by “turbidity currents,” which occur when sediment-laden water rapidly moves down slope.
Graded bedding simply identifies strata that grade upward from coarse-textured clastic sediment at their base to finer-textured materials at the top (Figure 3). The stratification may be sharply marked so that one layer is set off visibly from those above and beneath it.
Volcanic eruptions, dust storms, annual and climatic rhythms, rejuvenation of relief at the source or filling in of the sedimentary basin, churnin sediment by storm waves, are among the more obvious potential causes of graded deposits.
An active continental margin is found on the leading edge of the continent where it is crashing into an oceanic plate. An excellent example is the west coast of South America. Active margins are commonly the sites of tectonic activity: earthquakes, volcanoes, mountain building, and the formation of new igneous rock.
Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
Although earthquakes occur along all plate boundaries, they are much more common along collision zones that include an oceanic trench than they are at midocean ridges.
The distribution of the volcanoes, earthquake epicenters, and major mountain belts are distributed in close proximity of the borders of the tectonic plates. Most of the active volcanoes nowadays are found at the so called ”Ring of Fire” which is practically the border of the Pacific Tectonic Plate.
They start on continental shelf and cut into (erode) shelf and upper slope, commonly near the mouth of a bay or river. They are carved by undersea erosion processes associated with turbidity currents. Turbidity currents transport sediment into deep ocean basins via submarine canyons.
graded bedding can help determine whether some beds are older or younger than the beds next to them. there has been some uplift and erosion but no folding between deposition of rocks above and below the disconformity. a series of sedimentary rocks sits upon eroded igneous rocks.
Cross-bedding can also be produced when wind blows over a sand surface and creates sand dunes. The picture on the left shows ancient sanddunes with cross-bedding. GRADED BEDDING means that the grain size within a bed decreases upwards. This type of bedding is commonly associated with so called turbidity currents.
Lamination, current bedding, and ripple bedding in graded beds are at- tributed to tractional transport along the bottom. The features of graded series can be used to gain important information on paleogeographic problems. … Graded bedding has been repeatedly used as an indication of top and bottom.
Most graded beds form in a submarine-fan environment (see Figure 6.17), where sediment-rich flows descend periodically from a shallow marine shelf down a slope and onto the deeper sea floor.
Graded bedding refers to a sequence of increasingly coarse- or fine-grained sediment layers. Graded bedding often develops when sediment deposition occurs in an environment of decreasing energy. A Bouma sequence is graded bedding observed in a clastic rock called turbidite .
In the Atlantic Ocean, continental margins have a shelf that is broad and flat and reaches a depth of 100 m. The slope is the steep transitional area between the shelf and rise, and it lies between depths of 100 and 2,500 m.
About 35 miles off the coast of North Carolina, the continental shelf dramatically slopes off from a depth of approximately 200 meters (656 feet) to more than 2,000 meters (6,561 feet) toward the continental rise and eventually the deep and flat abyssal plain.
The continental margins consist of three portions: (1) the continental shelf which has shallow water depths rarely deeper than 650 ft) and extends seaward from the shoreline to distances ranging from 12.3 miles to 249 miles, (2) the continental slope where the bottom drops off to depths of up to 3.1 miles, and (3) the …
Within oceanic crust lie abyssal hills, which were formed from the development of normal faults and volcanism at the original ridge crest where the crust was created.
Tectonic plates are formed and move apart at mid-ocean ridges. Some portion of this plate-separation process can occur by stretching of the crust, resulting in a complex pattern of extensional faults. Abyssal hills, the most ubiquitous topographic features on Earth1, are thought to be a product of this faulting2,3.
Would you expect to see a folded mountain range at a mid-ocean ridge? … No, you are more likely to see volcanic mountains where magma is rising along the mid-ocean ridge spreading center.
match the feature to the correct province
what are turbidity currents?
trenches are typically associated with
which list of features was detected by the echo sounder in this recording?
in this recording, at what depth is the shelf break located?
which of the following features would you not see at an active continental margin
which of the following is an example of an active continental margin?
what common item is used in this video to demonstrate a turbidity current?