Final answer:
Jazz fusion, or jazz-rock fusion, arose in the 1970s as a blend of jazz with rock, funk, R&B, and other styles, characterized by electronic instruments and rhythmic emphasis. The genre's emergence was influenced by the ideological and technological changes of the 1950s, as well as the burgeoning rock and roll movement's impact on social barriers.
Step-by-step explanation:
The different approaches that defined fusion jazz after 1970 included the combination of jazz harmony and improvisation with styles such as rock, funk, R&B, and Latin music. The use of electronic instruments and a strong emphasis on rhythmic groove are characteristics of fusion jazz. Artists like Miles Davis and bands like Weather Report and Return to Forever played significant roles in the development of the genre.
Jazz-rock fusion emerged because of several factors. The 1950s' societal landscape saw significant shifts, with youth seeking excitement and an identity separate from their parents. This led to the birth of rock and roll, which in turn blurred racial lines and made contributions towards ending certain types of segregation. Advancing technology and affluence facilitated the spread of rock 'n' roll and eventually its merging with jazz, as musicians sought to explore new sounds, push musical boundaries, and appeal to the new generation's desire for innovation and rebellion against cultural norms.