Laminated sandstone

The situation on the other side of the same crush zone is rather different. The basal fill is preserved at higher elevations, whereas laminated sandstone appears at lower elevations. In areas where laminated sandstone has not been found, there are some larger caverns, which are accessible to humans. Close to the caverns are larger, unroofed, caves containing basal fill (Gersl et al., 1999). No conglomerate has yet been found in this area. 

Plate 8. Large calcite-cemented concretion formed by merging of several concretions, plus a flattened spheroidal concretion in the lower left-hand corner. Perfectly preserved hummocky lamination is seen within the concretions, which were eroded from the otherwise unconsolidated shallow marine hummocky-laminated sandstone of the Upper Jurassic BenclilF Grit at Osmington Mills in Dorset, southern England. Feet for scale. 

B. Parallel laminated sandstone that was deposited by fast-flowing current after the coarser particles had settled out to form layer A... 

Garagon, M. Can, T. 2010. Predicting the strength anisotropy in uniaxial compression of some laminated sandstones using multivariate regression analysis. Materials and Structures, 43(4) 509-517. 

Fig. 25 Schematic cross-section of Lombre deposit (Allier). 1, Sandstone and conglomerate (fluviatile channel) 2, siltstone and finely laminated sandstone, lutite, sandstone tongues (lateral and paludal organic matter-rich sediments) 3, uranium ores. After Brulhet et al. ...

In some composites, filler and matrix are in direct contact with each other. An example from nature is a sedimentary rock, in which pebbles and small rocks (the filler) are embedded in a sandstone matrix. In many composites, however, there is an intermediary zone—an interphase—between filler and matrix. An example of an interphase is the adhesive that holds filler and matrix together in a laminated (layered) composite. 

The faults through the channel sandstones appear as curved and planar fault zones, internally characterized as fault-parallel (weakly) laminated sand-... 

By examining grain size and mineralogical composition of the fault zones it is clear that the material herein was derived from the channel sandstones (Sverdrup and Prestholm, 1990). Variations in grain size and matrix content define the fault-parallel lamination. The undeformed sandstones and the fault zones both have porosities in the range between 0 and 5%. Additional field observations and textural char-... 

Belly River Formation complexly interbedded pale-grey, bentonitic sandstone, laminated siltstone, and medium- to dark-grey carbonaceous claystone, thin-bedded dark-brown weathering sideritic ironstone and coal coastal plain or deltaic, notable gas producer (Locker, 1973)... 

CH Channel + levee Trough cross-bedded sand (St) planar laminated sand (Sp) low angle cross-bedded sand (SI) horizontally laminated sand (Sh) ripple cross-laminated sand (Sr) massive sand (Sm) massive, crudely bedded silts and muds (Fm) finely laminated to rippled silts and muds (FI) laminated silt, sand, and clay (Fsc) Tabular to lenticular 0.2-3 m thick 10 m to >2 km in lateral extent Fine to coarse, moderately sorted sand/sandstone Type 1 and type 3 (phreatic) tabular units... 

EC Cross-stratified aeolian dune bodies Trough cross-bedded sand (Ste) planar laminated sand (Spe) low angle cross-bedded sand (Sle) horizontally laminated sand (She) ripple cross-laminated sand (Sre) massive sand (Sme) Tabular, lenticular and wedge-shaped 1-3 m thick > 1 km lateral extent Fine to lower coarse, moderately to well sorted sand/sandstone Scattered ovoid to elongate concretions and small type 1 and type 3 phreatic tabular units... 

Sandstone- and mudstone-siltstone facies are slightly bioturbated, mostly as single vertical to horizontal burrows some finely laminated mudstone units are non-bioturbated. Desiccation cracks, filled with very fine sand, are common. Desiccation has also given rise to disturbed primary lamination. Massively carbonate-cemented beds and concretions of 2-3 cm occur in both the sandy and the muddy sediments. Root structures are rare. The overall high resistivity and low N/G ratio of the middle member reflects the extensive carbonate cementation in sandstones. 

Scott (1990). The low-angle beds consist mainly of laminated or cross-bedded and hummocky cross-bedded sandstone with a ripple-laminated upper part that has wavy clay bedding. The ripple and wavy bedded upper part can be caused by deposition under waning flow conditions, but can also be the result of wave reworking. In the intermediate area, where the delta complex is storm and wave dominated, lenses are abundant (Berners, 1985). 

The Namorado Sandstone is composed primarily of massive fine- to very fine-grained arenites. Sedimentary structures are rare, but occasional normal grading is observed. The fluidization process is identified by unusual dish and pillar structures. Rarely, individual beds present ripple cross-laminated divisions at the top. Individual beds have an average thickness of Im. Several individual beds may be amalgamated, resulting in sandy intervals up to 10 m thick. Individual beds or cycles are capped by thin beds of shales and calcilutites. 

Plate 3. Scattered calcite-cemented concretions in low angle-laminated beach to upper shoreface sandstones of the Middle Jurassic Valtos Formation at Valtos on Skye, Scotland. Scale is 1 m long. 

C. Ripple cross-laminated fine-grained sandstone that formed at lower current velocities than layers A and B... 

The sandstone beds have large-scale trough ctoss-beds and are ripple-laminated as are the siltstone layers. The flow direction on the western side of the synclinal axis is to the east, whereas on the eastern side it is to the south. In general, the transport direction is to the soniheast. Barrett et al. (1986) conclnded that the sediment of the Bnckley Formation originated partly from the East Antarctic craton located west the basin and partly from sources to the north where the Ross Ice Shelf is presently located. 

The sandstones are light gray in color, fine grained, well sorted, faintly laminated, and trough cross-bedded. The sandstone beds fine upward and grade into overlying mudstone layers which are several meters thick and grade up-section into fissile carbonaceous... 

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