Could you please explain the relationship between a rift basin, a rift valley, and the intrusion of seawater in the geological process?
Dear Jaeguk
being just a botanist I'll try to help you with simple words, waiting a more experienced scientist to answer.
A rift is a part of Earth where the crust becomes thinner. In a rift blocks of continental crust "sink" (go downward) while the rims usually go upward (rise).
A rift is generally elongated (linear), hence the name of "valley". It is also a "basin" as far as it is lowland, where sediments are trapped.
If the bottom goes below 0 m a.s.l. and if it connects to ocean, a rift can be invaded by seawater.
Does it help ?
Greetings. One part of the difference is scale with a valley being a relatively smaller scale than a basin. The basin may contain multiple valleys and be flanked by regional-scale uplifted fault blocks. The valleys often are asymmetric with greater uplift on one side. Along the length of the basin, the uplifted sides of the basin may shift from valley to valley. Where these shifts occur, there are transverse zones of faulting that cut across the axis of the basin. The Miocene-to-Recent Rio Grande Rift basin of New Mexico and Texas is a well-researched example with these characteristics plus related volcanics. Just south of the Rio Grande Rift, the older Chihuahua Trough of northern Mexico is a example with Jurassic evaporites that were deposited by invading marine water.
Rift refers to the wholesale rupture of the lithosphere under extensional strain. It can be a narrow valley such as most East African rifts and Rhein graben in Europe, but it can also be a very wide and long extensional area such as the Aegean System and Basin & Range province of North America without a single narrow depression but multiple basins and ranges in an extending area. Rifts are genetically developed by extensional tectonics, whereas rift valley refers to the morphological expression of a type rift that has linear topographic depression developed during rifting. According to some, width width-length ratio of rift valleys is 1/3. Originally, the "Rift Valley" was used for Kenya Rift for the first time by John Walter Gregory (1896) before the advent of Plate Tectonics. This is a common problem; pre-plate tectonic definitions continued to be used after its advent which has been causing confusion.
Rift basin, however, refers to an area (often a depression) where there is net deposition, whereas rift valley can be a site of deposition or not since it refers to a topographic linear depression which can be basins or no basins at all. So, rift basin and rift valley are not interchangeable.