There is an overall fining upwards trend, from coarse gravel to sandstones, pebbly sandstone
A complete cycle starts with pebbly sandstone
accomplished by thin layer of basal conglomerate and terminates with claystone.
The main lithology of the target reservoir is composed of thin sandstone, thick sandstone, and pebbly sandstone
mainly; the primary content of rock fragment is quartz; the second content is feldspar and other minerals.
Lithofacies Code Lithology Sedimentary Structures Gm conglomerate massive, imbrication Gh conglomerate stratified, inclined <10[degrees] Gp conglomerate planar-tabular crossbeds Smc sandstone massive Sh sandstone stratified Sp sandstone planar-tabular crossbeds St sandstone trough crossbeds Sr sandstone tipple laminated Se sandstone with massive mud intraclasts Ss pebbly sandstone
scours Fm siltstone massive Lithofacies Code Environmental Interpretation Gm bar-head or bar-core Gh bar-tail Gp bar-margin foresets Smc bar-top deposit Sh bar-top deposit Sp 2-D dune deposit St 3-D dune deposit Sr ripples Se scour fills Ss scour fills Fm mudstone drapes Modified from Miall 1977, 1978; Rust 1978.
On Catons Island, similar fine-grained, maroon and grey green, micaceous sandstone and siltstone, maroon pebbly sandstone
and conglomerate are in faulted contact with Cambrian rocks of the Saint John Group.
Lithofacies include clast-supported massive boulder conglomerate (Gcm(a)), clast-supported massive cobble conglomerate (Gcm(b)), clast-supported pebble to cobble conglomerate (Gcm(c)), clast-supported pebble conglomerate (Gcm(d)), Matrix-supported pebble conglomerate (Gmm), trough cross-stratified pebbly sandstone
(St), horizontally stratified sandstone (Sh), trough cross-stratified sandstone (St), ripple cross laminated sandstone (Sr), massive sandstone (Sm), siltstone (F), massive mudstone (Fm), massive variegated mudstone (Fmv).
Less distinct ning upward successions, sheet-like geometry of sandstone and pebbly sandstone
imply a shallower uvial system.
The group is divisible into two lithostratigraphic units; 1) the Late Cretaceous Ispikan group in lower part; comprising mudstone, shale, siltstone and sandstone; and 2) Palaeocene Ispikan Conglomerate in upper part; comprising very coarse pebbly sandstone
and conglomerate beds are also present in upper part of the formation.
These Tethys sediments pass up conformably into the siliciclastic-dominated units of Mughal Kot and Pab formations, comprising of fine to coarse and pebbly sandstones
, with subordinate marls and mudstones.