Sacajawea Patera is a large, elongate

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

located in Western

Ishtar Terra Ishtar Terra is one of the three continental regions on the planet Venus, the others being Aphrodite Terra and Lada Terra. It is a highland region named after the Akkadian goddess Ishtar, and is found in the north of the planet. In size, i ...

on the smooth plateau of

Lakshmi Planum Lakshmi Planum is a plateau feature approximately 2 million sq km ringed by rugged mountains, the surface of Venus on the Western Ishtar Terra. It is named after Lakshmi, the Hindu Hindus (; ) are people who religiously adhere to Hind ...

, on the planet

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...

. The image is centred at 64.5 degrees North latitude and 337 degrees East longitude. It is approximately wide at the base. Sacajawea is a depression approximately deep and in diameter; it is elongate in a southwest–northeast direction. The depression is bounded by a zone of circumferential curvilinear structures interpreted to be graben and fault scarps. These structures are spaced apart, are in width and up to in length. Extending up to approximately in length from the southeast of the patera is a system of linear structures thought to represent a flanking rift zone along which the lateral injection and eruption of magma may have occurred. A shield edifice in diameter with a prominent central pit lies along the trend of one of these features. The impact crater Zlata, approximately in diameter is located within the zone of graben to the northwest of the patera. Few flow features are observed in association with Sacajawea, possibly due to age and state of degradation of the flows. Mottled bright deposits in width are located near the periphery and in the center of the patera floor within local topographic lows. Diffuse patches of dark material approximately in width are observed southwest of the patera, superposed on portions of the surrounding graben. The formation of Sacajawea is thought to be related to the drainage and collapse of a large

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it up ...

. Gravitational relaxation may have caused the resultant caldera to sag, producing the numerous faults and graben that circumscribe the patera. Regions of complex, highly deformed

tessera A tessera (plural: tesserae, diminutive ''tessella'') is an individual tile, usually formed in the shape of a square, used in creating a mosaic. It is also known as an abaciscus or abaculus. Historical tesserae The oldest known tesserae ...

-like terrain are located north and east of the patera and are seen in the upper portion of the image.

References

* Volcanoes of Venus {{Venus-stub