Download Mature vs. Immature Sandstone

Brittani Felder
Ch. 5, Question 5
Mature vs. Immature Sandstone
The maturity of sandstone sediments can be identified by the textures found in the
sediment grains as well as the types of sandstone present. The compositions of the
grains distinguish the source area and rock type. It also correlates with the amount of
transport and erosion the sediments encounter.
Mature sandstones can be found far from the source area. The amount of transport and
weathering has formed rounded, well-sorted grain sediments. The minerals found in the
sediment are mostly the same though out and contain very few minerals. The energy of
mature sandstone is constant and is a reflection of stable depositional regions and
shallow waters. The composition of mature sandstone is dominated with quartz. There
is little to no feldspar, clastic matrix, or mica grains found within the sediment. It is
typically bonded together with calcite or silica cement.
Immature sandstone is equipped with diverse, unstable minerals. Its grains are poorlysorted and angular. The sandstone has not been transported far and is close to the
source area. Near the source area, the sandstone has varying energy. The composition
of immature sandstone mostly quartz, however have an abundance of other minerals,
such as feldspar, mica, chert, and rock fragments. Arkose sandstone is one type of
immature sandstone. It can form as basal sandstone from granitic coastal areas or can
be found in faults and low areas adjacent to granite mountains (ch.5, pg.99). It contains
quartz and a great amount of feldspars, which are angular-course grains. Greywacke is
immature sandstone that can be found deposited in unstable tectonic settings, like rising
mountainous regions. They consist of quartz, feldspar, chert, mica, and fine-grained
volcanic rock particles in the matrix.