Trough (geology) in the context of Basin (geology)

A structural basin is a large-scale structural formation of rock strata formed by tectonic warping (folding) of previously flat-lying strata into a syncline fold. They are geological depressions, the inverse of domes. Elongated structural basins are a type of geological trough. Some structural basins are sedimentary basins, aggregations of sediment that filled up a depression or accumulated in an area; others were formed by tectonic events long after the sedimentary layers were deposited.

Basins may appear on a geologic map as roughly circular or elliptical, with concentric layers. Because the strata dip toward the center, the exposed strata in a basin are progressively younger from the outside in, with the youngest rocks in the center. Basins are often large in areal extent, often hundreds of kilometers across.

The Suruga Trough (駿河トラフ, Suruga Torafu) is a trough that lies off the coast of Suruga Bay in Japan, forming part of the Nankai Trough, the latter being responsible as the source of many large earthquakes in Japan's history. Both mark the boundary of the Philippine Sea Plate subducting under the Amurian Plate.

The Nankai Trough (南海トラフ, Nankai Torafu; Southern Sea Trough) is a submarine trough located south of the Nankaidō region of Japan's island of Honshu, extending approximately 900 km (559 mi) offshore. The underlying fault, the Nankai megathrust, is the source of the devastating Nankai megathrust earthquakes, while the trough itself is potentially a major source of hydrocarbon fuel, in the form of methane clathrate.

In plate tectonics, the Nankai Trough marks a subduction zone that is caused by subduction of the Philippine Sea plate beneath Japan, part of the Eurasian plate (Kanda et al., 2004). This plate boundary would be an oceanic trench except for a high flux of sediments that fills the trench. Within the Nankai Trough there is a large amount of deformed trench sediments (Ike, 2004), making one of Earth's best examples of accretionary prism. Furthermore, seismic reflection studies have revealed the presence of basement highs that are interpreted as seamounts that are covered in sediments (Ike, 2004). The northern part of the trough is known as the Suruga Trough, while to the east is the Sagami Trough. The Nankai Trough runs roughly parallel to the Japan Median Tectonic Line.

The Annapolis Valley is a valley and region in the province of Nova Scotia, Canada. It is located in the western part of the Nova Scotia peninsula, formed by a trough between two parallel mountain ranges along the shore of the Bay of Fundy. Statistics Canada defines the Annapolis Valley as an economic region, composed of Annapolis County, Kings County, and Hants County.