The default Genesis post info can be tweaked for a bit of extra SEO goodness. This will change your posts publish date to use the last-updated date instead. It also allows you to select a custom author page rather than using the standard post archive. This part is optional and doesn't affect the post date at all.

genesis-seo-post-info.php

<?php
/**
* Some tweaks to the Genesis post info for SEO purposes.
*
* This set of functions are designed to change the output of the Genesis post info
* to reflect the date a post was updated rather than the date it was published. A
* function to set a custom author page is also included and is entirely optional.
*
* @author FAT Media, LLC
* @link   http://auditwp.com/genesis-post-info-seo/
*/

add_filter( 'genesis_attr_entry-time', 'prefix_attributes_entry_time' );
/**
 * Filter attributes to show the modified timestamp for the entry.
 *
 * @param array $attributes Existing attributes.
 * @return array Amended attributes.
 */
function prefix_attributes_entry_time( $attributes ) {

	$attributes['itemprop'] = 'dateModified';
	$attributes['datetime'] = get_the_modified_time( 'c' );

	return $attributes;

}

add_filter( 'genesis_post_date_shortcode', 'prefix_post_date_filter' );
/**
 * Filter the output of the post date to show the modified date.
 *
 * @param  array $output Existing output.
 * @return string $output Modifed output.
 */
function prefix_post_date_filter( $output ) {

	$display = get_the_modified_date();

	$output = sprintf( '<time %s>', genesis_attr( 'entry-time' ) ) . $atts['before'] . $atts['label'] . $display . $atts['after'] . '</time>';

	return $output;

}

add_filter( 'genesis_post_author_link_shortcode', 'prefix_custom_author_link' );
/**
 * Filter the output of the post link to resolve to a custom URL.
 *
 * @param  array $output Existing output.
 * @return string $output Modifed output.
 */
function prefix_custom_author_link( $output ) {
	// If we're not showing a post by you, do nothing.
	if ( get_the_author() != 'Your Name' ) {
		return $output;
	}

	// Set the URL to your "About" page.
	$url = get_permalink( 15 );

	$author = get_the_author();

	$output  = sprintf( '<span %s>', genesis_attr( 'entry-author' ) );
	$output .= $atts['before'];
	$output .= sprintf( '<a href="%s" %s>', $url, genesis_attr( 'entry-author-link' ) );
	$output .= sprintf( '<span %s>', genesis_attr( 'entry-author-name' ) );
	$output .= esc_html( $author );
	$output .= '</span></a>' . $atts['after'] . '</span>';

	return $output;

}

add_filter( 'genesis_post_info', 'prefix_post_info_filter' );
/**
 * Filter the output of the post info to remove links to post comments in archives.
 *
 * @param  array $post_info Existing post info.
 * @return string $post_info Modifed post info.
 */
function prefix_post_info_filter( $post_info ) {
	if (  is_page() ) {
		return;
	}

	$post_info = 'Last Updated on [post_date] // Written by [post_author_link] [post_edit]';

	if ( is_singular( 'post' ) ) {
		$post_info = 'Last Updated on [post_date] // Written by [post_author_link] [post_comments] [post_edit]';
	}

	return $post_info;
}