Mudstone

Menaichizawa, Sasahata), is composed mostly of brecciated andesite lavas and andesitic hyaloclastics. This formation is conformably overlain by the formation (Hotakizawa, Sunakobuchi) composed of thick sequence of basaltic lavas and tuff breccias with minor intercalations of mudstone and felsic tuff. 

The formation which is mostly composed of dacite lavas, tuff breccia and mudstone (Hanaoka, Yukisawa, Uwamuki formations) conformably overlies the Hotakizawa and Sasahata formations. The thickness of these formations is 300-400 m. Kuroko ore deposits occur at the upper part of this formation. White rhyolite lava domes characterized by intense sericite alteration have a close spatial relationship with Kuroko deposits. 

The younger formations (Ittori, and Tobe formations) of late Miocene to Pliocene overlie the Shishigamori, Shigenai and Harukizawa formations and are comprised mostly of mudstones, interbedded felsic tuffs, and tuffaceous sandstones. The total thickness of these formations is ca. 500 m. The formations of Pleistocene unconformably overlie the... 

The age of Kuroko mineralization can be estimated from (1) K-Ar ages of igneous rocks associated with Kuroko deposits and (2) foraminiferal assemblages in mudstone directly overlying Kuroko deposits. 

Figure 1.13. Distribution of three different sub-types of the Kuroko deposits in the Hanaoka district. The top of M mudstone is also shown to visualize the structure of country rocks (Horikoshi and Shikazono, 1978).

As already noted, most epithermal Au-Ag vein-type deposits are hosted by young (late Miocene-Pliocene) volcanic rocks and by sedimentary rocks, but dominant host and country rocks for base-metal vein-type deposits are submarine sedimentary and volcanic rocks. Submarine felsic tuff, tuff breccia, dacite lava, intrusive rocks and mudstone are dominant host and country rocks of Kuroko deposits. 

Tertiary rocks are distributed widely. They are composed of alternations of sandstone, mudstone, andesitic and dacitic tuff, tuff breccia and lava. These rocks are intensively and extensively altered and are called as Green tuff. Tertiary volcanic rocks are variable in composition. Andesite, dacite and basalt are found. Quaternary volcanic rocks are dominantly andesite lava and are abundantly distributed in the northern part of the province (Fig. 1.148). 

The Nishikurosawa Formation is composed of siltstone, mudstone, conglomerate and sandstone. Siltstone and mudstone contain foraminiferal fossil such as Globorotalia birnageae, and G. denseconnexa, indicating Zone N. 9 by Blow (1969). The upper part is characterized by glauconite-bearing sedimentary rock. The total thickness is about 150 m. 

The area consists of Quaternary late Pliocene pyroclastics and sedimentary rocks. Marine mudstone and sandstone of Mesozoic-lower Tertiary Shimanto Supergroup are overlain by these rocks. Thick (more than 1,000 m) dacitic tuffs interbedded with marine sedimentary rocks of late Pliocene-early Pleistocene age occur. These rocks overlie altered andesite lava and dacitic pyroclastics of Miocene-late Pliocene (Yoshimura et al., 1988). 

Central and Eastern England is almost entirely underlain by sedimentary rocks that young from west to east. Four major geological sub-divisions are presented in Figure 1. Permian and Triassic mudstone and sandstone dominate the East Midlands and parts of Yorkshire Jurassic clays crop out within the centre of the study area and Cretaceous chalk underlies most of Central East Anglia. 

The Otway Project is using a multilevel completion with three U-tubes to sample above and below the gas-water contact of a depleted gas reservoir, while C02 is injected in a well located 300 meters downdip. The uppermost U-tube was installed just below the mudstone cap rock and is sampling predominantly supercritical CH4, while the lower two U-tubes initially produced water, but transitioned to predominantly C02 and CH4 as the gas-water contact was pushed down by the increasing volumes of C02. 

Sediments ranging from clay-rich to carbonate-rich from ODP Sites 1039 and 1040, outboard of Costa Rica, had variable isotopic compositions, unrelated to their bulk chemistry (5 Li = +9.5 to +23.3 Chan and Kastner 2000). Turbidites and underlying ash-rich mudstones at ODP Site 808, southwest of Japan, defined a similarly large range in isotopic compositions (5 Li = -1 to +8 You et al. 1995). James et al. (1999) reported 8 Li for variably altered sandy to silty turbidites to hemipelagic muds from ODP Site 1038, off the coast of northern California (-0.5 to +5.6). 

Macquaker JHS, Curtis CD, Coleman ML (1997) The role of iron in mudstone diagenesis Comparison of Kimmeridge Clay Formation mudstones from onshore and offshore (UKCS) localities. J Sed Res 67 871-878... 

Roser, B.P. Korsch, R.J. 1988. Provenance signatures of sandstone-mudstone suites determined using discriminant function analysis of major-element data. Chemical Geology, 67, 119-139. 

The analysed sandstones with accompanying mudstones, claystones and subordinate conglomerates are of fluvial origin and interlayered with marine and deltaic deposits (Waksmundzka 2008). 

The lower assemblage consists predominantly of red mudstone, with narrow sections (5-20 cm) of reduction spots and entire sections (0.5 to 2 m) of grey reduced and pyritic mudstone becoming more common towards the base. Narrow (0.5 to 5 m) intermediate extrusive volcanic flows become more common towards the base of this assemblage, and display basal textures indicating that moisture and mudstone rip-clasts were acquired into the flow and that heat was supplied to the underlying mudstones, which produced narrow (< 5 cm) contact metamorphism bands of re crystallized mudstone. 

Figs. 3-6. Gold and trace element geochemical concentrations with depth In DDH-WB-08-04. Values are not corrected for mass loss or gains. Higher values of Cu, Zn and As exist In the mudstones underlying the rhyolites In hole WB-08-04. 

The Tyrone Volcanic Group sequence comprises basaltic pillow lavas, tuffs of basic to intermediate composition, rhyolites, cherts, siltstones and dark grey mudstones representing up to three volcanic cycles. From base to top of each cycle and through the sequence as a whole, the Tyrone Volcanic Group becomes progressively more acidic in composition. 

Fig. 12.25 Di ssolution features of hematites Upper Undissolved (a) and partly dissolved (b c) synthetic Al-hematite (AI/(Fe+AI) = 0.094 mol moT j in dithionite/citrate/bicarbonate at25 (Araki Sch A/ertmann unpubl.), Lo A/er Undissolved and partly dissolved hematite from a redoxomorphic subsoil of a typical Hapludalf on Permian mudstone, Ohio (Bigham et al., 1991, A/ith permission).

Earth material (typically spoil, m eibiinlcii containing large quantities of mudstone), which can be conditioned tby mixing with compost) such that it evolves over a period of a Tew years to form a semi-natural soil, which is a key step in developing revegeiated mine sites... 

Equations such as equation (1) above imply that the oxidative dissolution of pyrite is congruent, directly liberating Fe2+, SO4, and H+ to solution. However, in the common circumstance that water is insufficiently abundant to immediately transport the oxidation products away from the mineral surfaces, pyrite oxidation more commonly results initially in the accumulation of various hydroxysulphate evaporite minerals. These minerals form efflorescent crusts, typically white and yellow in colour, on the surfaces of pyrite-rich coals and mudstones (Fig. 1), and they effectively store the oxidation products in a readily soluble form until some hydro-logical event delivers sufficient water to dissolve and transport them away. Because pyrite often occurs in mudstones, where Al-bearing clay minerals are in contact with acidic pyrite oxidation waters, A1 is frequently released from the clays and is also stored in these hydroxysulphate phases. When these minerals finally dissolve, they result in abrupt and extreme increases in dissolved acidity. For this reason, they have been termed acid generating salts (AGS) (Bayless... 

Fig. 2. Carbonate minerals, which play important roles in the hydrogeochemistry of coal mines and coal mine wastes (a) A typical siderite concretion (from the mudstone overlying the Halifax Hard Seam at Bullhouse, West Yorkshire, UK) long axis of concretion is 11 cm (b) Patchy films of creamy-white ankerite on a cleat surface of coal (from the Main Seam, Ravensworth Grange Opencast Coal Mine, Durham, UK) maximum width of hand specimen is 10.5 cm.

The mudstones and sandstones associated with coals contain many aluminosilicate minerals of... 

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