Final answer:
The reaction between seawater and basalt at spreading ridges results in hydrothermal alteration of the basalt and contributes chemicals like metals and sulfur to the ocean.
Step-by-step explanation:
When seawater and basalt from the rising magma at spreading ridges interact, a process known as hydrothermal alteration occurs. This reaction between the hot basalt and cold ocean water results in the alteration of the basalt's mineral composition and the formation of new minerals like chlorite and serpentine.
Simultaneously, the seawater, upon contact with the hot basalt, transfers heat spontaneously and can lead to the creation of steam as indicated by the spontaneous transfer of heat from a hot substance to a cold one (Figure 13.4.7). The interaction also leads to the contribution of various chemicals to the ocean, including metals and sulfur, which can be evidenced by events such as the green-hued bacterial eruptions that occur when hydrogen sulfide is produced and released into the water.