Paleozoic

Paleozoic Cambrian 600 Myr Climate warms, O2 levels approach current level most animal phyla present, including some that failed to survive algae and cyanobacteria diversify... 

The lowest rock units are basement rocks, composed of phyllites, cherts, and minor sandstone probably of Paleozoic age. The oldest Tertiary formation, which is called Ohya... 

Figure 1.62. Location of epithermal-type deposits in Japan (Shikazono and Shimizu, 1988a). 1 Green tuff and subaerial volcanic region of Tertiary/Quaternary ages, 2 Main Paleozoic/Mesozoic sedimentary terranes, 3 Main metamorphic terranes. TTL Tanakura tectonic line, ISTL Itoigawa-Shizuoka tectonic line, MTL Median tectonic line. Open circle epithermal Au-Ag vein-type deposits, solid circle epithermal base metal vein-type deposits, open triangle epithermal Au disseminated-type deposits.

Geology of the province is composed of Paleozoic basements. Tertiary altered submarine volcanic and sedimentary rocks (Green tuff) and Quaternary volcanic rocks. The basements are shale, tuff, limestone and chert of unknown ages. A simplified geologic map is shown in Fig. 1.148. 

It is inferred that in the northern part of the province submarine volcanic rocks are thick in the central zone, while at marginal zone it is thin and the Plio-Pleistocene subaerial volcanic rocks are exposed. The vein-type deposits occur widely in the province. The precious vein-type deposits occur in relatively young (Plio-Pleistocene) volcanic rocks, while large base metal vein-type deposits (e.g., Toyoha, Inakuraishi, Ohe) and Kuroko deposits (e.g., Kunitomi) occur in central zone where thick Miocene submarine volcanic rocks are distributed (Figs. 1.149 and 1.150). Small base metal vein-type deposits occur in Paleozoic rocks in the southern part. 

The Yamizo Mountains are mostly occupied by Paleozoic-Mesozoic sedimentary rocks, mainly of Jurassic age (e.g., Sashida et al., 1982) with a small amount of intrusive granitoids of unknown ages. The Paleozoic-Mesozoic sedimentary rocks have been called the Yamizo Formation (Kanomata, 1961). It is composed chiefly of shale, sandstone, alternating beds of shale and sandstone, and a small amount of limestone and chert. The succession of the geologic units and geologic structure of the Yamizo Formation have been left pending due to complex structure such as upturned beds (Kasai, 1978) and submarine land sliding (Aono et al., 1985). 

The Beppu hot springs are located at the eastern end of the Beppu-Shimabara Graben, Kyushu. The basement rocks are composed of Paleozoic crystalline schists and Cretaceous granitic rocks. Miocene to early Pleistocene andesitic rocks occur mainly in the southern part of the area, while lava domes of hornblende andesite which are younger than 100,000 years occur in the western part. 

Paleozoic-Mesozoic volcanogenic stratiform Cu deposits in Japan which are generally metamorphosed have been called Besshi-type deposits (Kato, 1937) or bedded cupriferous iron sulfide deposits (Kanehira and Tatsumi, 1970). 

Geological characteristics and inferred tectonic settings of Paleozoic to Mesozoic volcanogenic Cu sulfide Besshi-type deposits of Japan (Sato and Kase, 1996)... 

Shinozuka et al. (1999) analyzed the host volcanic and intrusive rocks in the Minamidani mine district in the Maizuru tectonic Belt and found that these rocks formed in an island arc back-arc system near Laurasia during late Paleozoic. Probably the Yanahara deposits, one of the representative Hitachi subtype deposits, were formed in an island arc back-arc system as same as the Minamidani. Sato and Kase (1996) thought that the Hitachi-subtype deposits formed in back-arc rift or continental rift (Table 2.21). 

The 8 S data on barites from the Yanahara and Hitachi (Yamamoto et al., 1984b Kase and Yamamoto, 1985) are -f-12%o to - -15%o which is similar to those of Late Paleozoic seawater sulfate, indicating that barite formed by the mixing of seawater and hydrothermal solution as same as Kuroko barite (Kusakabe and Chiba, 1983). 

Berner, R.A. (1987) Models for carbon and sulfur cycles and atmospheric oxygen application to paleozoic geologic history. Am. J. Sci., 287, 177-196. 

In Chapter 2, a geochemical, geological and mineralogical summary of active subaerial and submarine back-arc basin hydrothermal systems and mineralizations is given. The characteristic features of above-fossil and active subaerial and submarine hydrothermal systems are compared with fossil hydrothermal systems (epithermal vein-type and Kuroko deposits), and the causes for the differences in the characteristic features are considered. Characteristic features of Paleozoic-Mesozoic volcanogenic stratiform Cu deposits (Besshi-type deposits) are compared with those of midoceanic ridge deposits and Kuroko deposits. 

Formations from all geologic periods have been used for deep-well injection, but Paleozoic rocks are used for most injection zones (53%), followed by Tertiary-age formations (39%). Older Paleozoic rocks have been more frequently used for injection primarily because they tend to be more deeply buried. However, the more recent Tertiary-age Gulf Coast sediments are also very thick, and most injection in rocks of this age takes place there. 

Grove, D. B., Rubin, M., Hanshaw, B. B., Beetem, W. A., Carbon-14 dates of ground water from a Paleozoic carbonate aquifer, southcentral Nevada, U. S. Geol. Survey Prof. Paper 650-C, p. 215-218, 1969. 

Paleozoic limestone (Webb et al. 2004). These kimberlites all have similar groundmass mineralogies consisting mainly of carbonate, spinel, and serpentine with lesser monticellite, mica, apatite, and perovskite (Kong et al. 1999) and they are all of volcaniclastic facies near ground surface. Varying thicknesses of clay and fine marine sediments of the Tyrell Sea ( 4000 - 12000 years BP) and 1 to 4 m of peat overlie kimberlites (Fraser et al. 2005). Bioherms composed of coral and skeletal remains of other marine organisms sometimes outcrop. 

New Brunswick s bedrock geology is well mapped and largely well understood. Because of NB s mineral wealth, a great deal of mineral exploration work has been carried out since the 1950s. The bedrock in NB is also diverse in age. The oldest Precambrian rocks can be found in the Saint John area, whereas some of the younger ones, in the form or Triassic basalts, occupy more than half of the Island of Grand Manan. Most of NB s rocks are of Middle Paleozoic age. The triangle between Moncton, Fredericton, and Bathurst is occupied by a thick sequence of Carboniferous rocks that host... 

The Ulsan carbonates (Fig. 1) have long been interpreted as limestone of Paleozoic age or "age unknown" and as the host of a skarn-type iron (magnetite) deposit due to the intrusion of Cretaceous granitic rocks (Park Park 1980 Choi et al. 1999). However, a Paleozoic marine limestone hypothesis fails to explain the spatial association or the relationship between carbonate and ultramafic rocks in a concentric, ellipsoidal shape surrounded by Cretaceous sedimentary, volcanic, and granitic rocks. The sedimentary hypothesis also fails to explain the isolated exposure of a funnel-shaped Paleozoic marine limestone where no marine limestone has been previously observed within the Mesozoic Kyongsang Basin. 

At this point, nothing is known about Cu and Zn isotopic variability in seawater. Zn is very depleted in surface waters because it behaves as a nutrient. A substantial amormt of Zn isotope data is available for sediments. Marechal et al. (2000) found that the 5 Zn values of clay minerals from different environments (Paleozoic shales, including a black shale, Mediterranean sapropels. Pacific and Atlantic sediments, a eolian dust) fall within a narrow range (0.17-0.35%o) centered around the magmatic values and therefore reflect the Zn isotope composition... 

As seen in Figure 6, mean 8 Mo in these ancient sediments is significantly offset from that of modem seawater and from mean 8 Mo of recent euxinic sediments. The offset is in the direction of less fractionation of Mo isotopes in the oceans (closer to the likely 5 MOjj ), as would be expected if removal of Mo to euxinic sediments expanded at the expense of removal to oxic (and suboxic) sediments. The result is consistent with the hypothesis of expanded ocean anoxia, and consequent increase in the areal extent of euxinic depositional settings, during this time. A similar, albeit smaller, offset is seen in repeated measurements of a Devonian black shale sample (USGS SDO-1 Fig. 6). This shift could he interpreted as consistent with somewhat expanded euxinic deposition during this time—an interpretation consistent with other evidence of expanded Paleozoic ocean anoxia in inland hasins. While further work is needed, these initial results are promising. 

Over very long periods during the Paleozoic era, the continental shelves were covered by only a few centimeters of water. This was too shallow for currents or tidal exchange to circulate the water. Evaporation increased salinities enough to cause halite and gypsum to precipitate, forming evaporites that extend over thousands of square kilometers and range in thickness from 5 to 10 km. These are referred to as platform evaporites. 

Figure 11,21 Age spectra of hornblendes of a Paleozoic gabbro (367 Ma) intruded by a granitic body during the Cretaceous (114 Ma). Samples underwent permeation of " Ar from lower crustal portions and differential losses of radiogenic argon (32, 57, and 78% respectively), proportional to distance from contact (0.3, 1, and 2.5 km). Reprinted from T. M. Harrison and I. McDougall, Geochimica et Cosmochimica Acta, 44, 2005-2020, copyright 1980, with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK.

Munizaga, F., Maksaev, V., Fanning, C.M., Giglio, S., Yaxley, G., Tassinari, C.C.G. 2008. Late Paleozoic-Early Triassic magmatism on the western margin of Gondwana Coiiahuasi area. Northern Chile. Gondwana Research, 13, 407-427. 

The Kokchetav Massif of northern Kazakhstan is a very large, fault-bounded metamorphic complex of Late Proterozoic-Paleozoic protolith age, surrounded by the Caledonian rocks of the Ural-Mongolian fold belt. The Kokchetav UHP and HP belt runs NW-SE extending at least 150 km long and 17 km wide. This massif has attracted much interest since the discovery of metamorphic diamonds. It is the first locality where microdiamonds were found within metamorphic rocks derived from crustal material. 

The Silver Bell Mine area consists of dipping units that are composed of dacite porphyry, alaskite and monazite. The rock ages span the Paleozoic, Mesozoic and Cenozoic periods. The Paleozoic wall rocks consist of quartzite, siltstone and altered limestone. The carbonate rocks are exposed along the contact between the host rock and intrusions, and host the... 

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