functions.php

<?php

function change_author_capabilities() { 

    $role = get_role( 'author' ) ;
    $role->remove_cap( 'edit_published_posts' );
    $role->remove_cap( 'publish_posts' );
    $role->remove_cap( 'delete_published_posts' );
    $role->remove_cap( 'edit_posts' );
    $role->remove_cap( 'delete_posts' );
    $role->add_cap( 'upload_files' );
    $role->add_cap( 'edit_pages' );
    $role->add_cap( 'edit_others_pages' );
    $role->add_cap( 'edit_published_pages' );

}

add_action( 'admin_init', 'change_author_capabilities' );