Correlation of Palynomorph Darkness Index and vitrinite reflectance in a submature Carboniferous well section in northern Saudi Arabia

Palynomorph Darkness Index (PDI) determinations are presented from a sub-mature, cored, Carboniferous well section in northern Saudi Arabia and are correlated to Vitrinite Reflectance (Ro) and Vitrinite Reflectance (Calculated) results from the same section. PDI values from smooth, simple miospores range from 34-57%, whereas mean Ro and Vitrinite Reflectance (Calculated) both range from ca. 0.4-0.6%. The PDIs of the Recent spores Lycopodium clavatum and Cheilanthes viridis were also determined for comparative purposes. Considerable variation in PDI was recorded in all the samples investigated. A very tentative correlation of PDI to Ro is presented for samples with a range of thermal maturity from those unaffected by any heating, to those at the top of the oil window.