Geochemical cycle As all closed systems, it follows the law of conservation of mass which states that matter cannot be created nor destroyed, thus, the matter, although transformed and migrated, remains the same as when the Earth was formed. The Earth system contains seven different reservoirs that are separated into surface reservoirs, which include atmosphere, hydrosphere, biosphere, pedosphere, and lithosphere and the isolated reservoirs that include deep Earth and outer space. Geochemical cycles are concerned with the interactions between deep earth which consists of Earth´s mantle and core, and the lithosphere which consists of the Earth´s crust. Flux in geochemical cycles is
Lithosphere-Asthenosphere boundary extent of partial melt; these are factors that affect the rheological differences in the lithosphere and asthenosphere. The lithosphere-asthenosphere boundary represents a rheological boundary. Colder temperatures at Earth's shallower depths affect the viscosity and strength of the lithosphere. Colder material in the lithosphere resists flow while the "warmer" material in the asthenosphere contributes to its lower viscosity. The increase in temperature with increasing depth is known as the geothermal gradient and is gradual within the rheological boundary layer. The lithosphere is the portion of the thermal boundary layer commonly defined by its purely conductive heat transport. Throughout the rheological boundary,