LOS ANGELES (AP) _ In the fourth high-level departure at Occidental Petroleum Corp. since 1979, vice chairman Zoltan Merszei has resigned effective later this month, according to a company announcement late Tuesday.

In a brief statement, Occidental said only that Merszei was resigning ''to pursue private interests and will not stand for re-election to the board.''

The company declined to elaborate or to comment on whether Merzsei's departure resulted from conflicts with Occidental's chairman and chief executive, Dr. Armand Hammer.

Industry analysts have said other executives have left Occidental because of frustration at Hammer's close control of the company, which is the nation's ninth largest oil company.

Between 1979 and 1984, Occidental went through four men - including Merszei - as president and chief operating officer.

Merszei, 63, who formerly was chairman and chief executive of Dow Chemical Co., joined Occidental in 1979 as vice chairman and also has held a number of other top positions. He was president and chief operating officer during his first year with Occidental.

Last year, according to Securities and Exchange Commission documents, Merszei signed a new employment contract with Hammer calling for annual compensation of not less than $490,000 a year.

The SEC documents said that under a revised contract signed this week, Merzsei will remain a consultant to Occidental until his retirement in 1988 and will receive annual compensation of $500,000, plus fringe benefits.

When Merszei became president and chief operating officer in 1979, he replaced Joseph Baird, who resigned after six years in the job.

Merszei lasted little more than a year in the job and was succeeded A. Robert Abboud, who quit in August 1984. Abboud's replacement, Ray Irani, remains in the job, and sources say he appears to get along better with Hammer than his predecessors.