Carbonate-rich conglomerate and sandstone deltaic rocks

Unit symbol: Kcc
Age range Cretaceous (145 to 66 Ma)
Lithology: Sedimentary
Group name: Nonmarine to shelf sedimentary rocks
Tan to light-gray siltstone, sandstone, and pebbly sandstone, and light-gray-weathering conglomerate mostly composed of marble, metalimestone, and dolostone clasts. Carbonate-rich sandstone and siltstone typically occur as rubble-covered hills but are best exposed in river-cliff outcrops (Till and others, 2011). Abundant plant debris and thin seams of bituminous coal (Patton and others, 2009) are typical. Clast-supported cobble to boulder conglomerate, composed almost entirely of carbonate rocks, grades eastward into trough cross-bedded, medium- to coarse-grained sandstone and pebble conglomerate fan-delta deposits. These fan-delta desposits, in turn, grade eastward into cross-bedded, fine- to coarse-grained, inner and outer shelf sandstone and shale. Chert, volcanic rock, quartz, and schist detritus are present in subordinate amounts. Unit contains sparse palynomorphs of Cretaceous(?) age in the Norton Bay quadrangle (Patton and others, 2009). Unit is found on the Seward Peninsula and other parts of northwest Alaska, and is probably of mid-Cretaceous age. Unit derived in large part from Paleozoic carbonate rocks of the Seward Peninsula (Till and others, 1986, Patton and others, 2009)

Source map information


Correlated geologic units

Label Kcc
Description Nonmarine and marine carbonate-rich conglomerate and sandstone deltaic deposits
Geologic age Cretaceous
Geologic setting Sedimentary, deltaic-and-nearshore
Lithology Form Importance
Conglomerate < Clastic < Sedimentary Bed Major
Graywacke < Sandstone < Clastic < Sedimentary Bed Major
Shale < Mudstone < Clastic < Sedimentary Bed Indeterminate, major
Bituminous < Coal < Sedimentary Bed Incidental