| Jasper Seamount | |
|---|---|
| Summit depth | 700 m (2,297 ft) [1] |
| Height | 3,300 m (10,827 ft) [1] |
| Summit area | Total Volume: 690 km3 (166 cu mi) [1] |
| Location | |
| Location | west of Baja California, Mexico |
| Coordinates | 30°26.40′N122°44.40′W / 30.44000°N 122.74000°W Coordinates: 30°26.40′N122°44.40′W / 30.44000°N 122.74000°W [1] |
| Geology | |
| Volcanic arc/chain | Fieberling-Guadalupe seamount trail |
| Age of rock | 11.5–10 million years [1] |
| Last activity | 4.1–4.8 MYA [1] |
Jasper Seamount is a seamount (underwater volcano) located in the Fieberling-Guadalupe seamount track, west of Baja California, Mexico. Jasper is the site of detailed geophysical geological and geochemical studies which suggest that many seamounts, big and small, follow the same pattern of growth and death that was originally used to describe the Hawaiian - Emperor seamount chain.
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface, and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly and are usually found rising from the seafloor to 1,000–4,000 m (3,300–13,100 ft) in height. They are defined by oceanographers as independent features that rise to at least 1,000 m (3,281 ft) above the seafloor, characteristically of conical form. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea. During their evolution over geologic time, the largest seamounts may reach the sea surface where wave action erodes the summit to form a flat surface. After they have subsided and sunk below the sea surface such flat-top seamounts are called "guyots" or "tablemounts"
Submarine volcanoes are underwater vents or fissures in the Earth's surface from which magma can erupt. A large number of submarine volcanoes are located near areas of tectonic plate movement, known as mid-ocean ridges. The volcanoes at mid-ocean ridges alone are estimated to account for 75% of the magma output on Earth. Although most submarine volcanoes are located in the depths of seas and oceans, some also exist in shallow water, and these can discharge material into the atmosphere during an eruption. The total number of submarine volcanoes is estimated to be over 1 million, of which some 75,000 rise more than 1 km above the seabed.
Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northernmost and westernmost of the 32 Federal Entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of Baja California. It has an area of 70,113 km2 (27,071 sq mi), or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California Peninsula, north of the 28th parallel, plus oceanic Guadalupe Island. The mainland portion of the state is bordered on the west by the Pacific Ocean, on the east by Sonora, the U.S. state of Arizona, and the Gulf of California, and on the south by Baja California Sur. Its northern limit is the U.S. state of California.
Jasper Seamount is an elongated volcano, with a northwest-northeast summit and several volcanic cones on the summit. The base is 4000 meters below sea level and it rises to a peak of 700 meters below sea level. A total of 15 dredge hauls from the seamount have been collected, and ocean-bottom seismometers have been placed to observe earthquake activity. In-depth studies have given scientists a detailed view of the seamount's internal structure. [1]
Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption. Types of volcanic cones include stratocones, spatter cones, tuff cones, and cinder cones.
Dredging is the operation of removing material from one part of the water environment and relocating it to another. In all but a few situations the excavation is undertaken by a specialist floating plant, known as a dredger. Dredging is carried out in many different locations and for many different purposes, but the main objectives are usually to recover material that has some value or use, or to create a greater depth of water.
An ocean-bottom seismometer (OBS) is a seismometer that is designed to record the earth motion under oceans and lakes from man-made sources and natural sources.
The model developed by the Jasper Seamount studies closely resembles that of the Hawaiian islands, especially the eruption, in stages, of increasingly alkalic rocks. More than 90% of the volcano is tholeiitic to alkalic basalt [1] in a wide variety of forms, including pillow lava and vesicular lapilli, evidence of shallow submarine eruptions in the past, and a wide range of xenoliths. [2]
Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. Flood basalt describes the formation in a series of lava basalt flows.
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion. Pillow lavas in volcanic rock are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one metre in diameter. They form the upper part of Layer 2 of normal oceanic crust.
Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities at its surface and inside. This texture is common in aphanitic, or glassy, igneous rocks that have come to the surface of the earth, a process known as extrusion. As magma rises to the surface the pressure on it decreases. When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles.
Jasper Seamount formed 11.5–10 million years ago. Base volcanics are very similar to those found at Hawaii. The flanks formed about 8.7–7.5 million years ago, and its summit 4.8–4.1 million years ago. The maintenance of a near-constant silicon dioxide ratio in all of the rocks collected is a sign of increasingly lower degrees of mantle melting. Overall Jasper Seamount rock is very similar, even in trace elements, to Hawaiian volcanics, despite Jasper's much smaller size (690 km3 or 166 cu mi versus ~3,000 km3 or 720 cu mi). These results seem to show that the Hawaiian model could be applied to other seamounts as well, and that many seamounts go through the same processes regardless of their size. [1]
Silicon dioxide, also known as silica, silicic acid or silicic acid anhydride is an oxide of silicon with the chemical formula SiO2, most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as synthetic product. Notable examples include fused quartz, fumed silica, silica gel, and aerogels. It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries.
A mantle is a layer inside a planetary body bounded below by a core and above by a crust. Mantles are made of rock or ices, and are generally the largest and most massive layer of the planetary body. Mantles are characteristic of planetary bodies that have undergone differentiation by density. All terrestrial planets, a number of asteroids, and some planetary moons have mantles.
A trace element is a chemical element whose concentration is very low. The exact definition depends on the field of science:
