From discogs:
Argentinan jazz bassist, cellist, pianist and arranger. Born: April 01, 1935 in Buenos Aires, Argentina. Died: December 11, 2018 in Buenos Aires, Argentina.
Unfortunately our stalwart source wiki is not much help:
Jorge López Ruiz ( La Plata , April 1, 1935- Buenos Aires , December 11, 2018) 1 was an Argentine musician , composer and double bass performer, interpreter and arranger of various genres of popular music, especially jazz . In his work, El grito (1967) and Bronca Buenos Aires (1970), prohibited by the military dictatorship, stand out . In popular music he has been an arranger and composer of songs for Sandro , Leonardo Favio and Piero , among others.
He was a regular participant in a series of informal folkloric experimentation and improvisation meetings at the home of Eduardo Lagos , humorously baptized by Hugo DÃaz as folkloréishons , which, in the manner of jazz jam sessions , used to bring together Lagos, Astor Piazzolla and DÃaz, with other musicians such as López Ruiz himself, Oscar Cardozo Ocampo , Domingo Cura and Oscar López Ruiz , among others. With his quartet he was awarded by the Konex Foundation as one of the 5 best jazz ensembles of the decade in Argentina.
For our purposes however he surely reached a peak with the albums Viejas Raices (1975) and Un Hombre (1978), when it comes to progressive composition and fusion, with the 1980 live in New York being well worth hearing as well. To me the earlier works are distinctly inferior, esp. El Grito which features quite 'by the book/chart' big band jazz arrangements for orchestra, while the follow up Bronca has relatively well composed modern music sometimes quite abstract, but under the ever-distracting (cf. Jean Vasca) spoken poetry.
From Viejas Raices, the Ellos Dos track begins with a nice obbligato on the guitar, but develops in such a gorgeously unique and creative way, I'm sure you'll all be entranced:
Surprisingly he made some more great music in 1988 with Contrabajismo and 1990's Espacios, which I'll include in a big package down below. Thus, from the former album, the quasi-atonal composition called De Un Oberheim Porteño is quite shockingly progressive, especially for the late year: