China
Africa
Explore chapters and articles related to this topic
The Late Cretaceous high-sulfidation Au-Cu Chelopech deposit, Bulgaria: geological setting, paragenesis, fluid inclusion microthermometry of enargite, and isotope study (Pb, Sr, S)
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
R. Moritz, I. Chambefort, M. Chiaradia, D. Fontignie, R. Petrunov, S. Simova, A. Arisanov, P. Doychev
The Chelopech deposit includes about 20 ore-bodies, with most of them hosted by breccias. Textural relationships indicate repeated breccia events. The breccias are probably of different origins, including phreatomagmatic and magmatic hydrothermal injection breccias. The orebodies typically dip at a high angle to the south and are roughly lens- or pipe-shaped (150-300m × 30-120m with a down plunge extension of up to 350m for the lenses, and a diameter of 20-60m and a 100-250m down plunge extension for the pipes). The morphology of the orebodies is variable, with disseminated, massive, banded, and vein-type ore. The vertical development of economic ore is known to a depth of about 600m and is open downward. A quartz-sulphide vein-type mineralisation has been crosscut by a drill-hole at a depth of 2000m (Andrew, 1997; Popov et al., 2000).
Sedimentary Rocks
Published in F.G.H. Blyth, M. H. de Freitas, A Geology for Engineers, 2017
F.G.H. Blyth, M. H. de Freitas
Breccias may also be formed by the crushing of rocks, as along a fault zone (p. 151), the fragments there being cemented by mineral matter deposited from percolating solutions after movement along the fault has ceased. These are distinguished as fault-breccias. The explosive action of volcanoes also results in the shattering of rocks at a volcanic vent, and the accumulation of their angular fragments as they fall to the ground to form volcanic breccias.
Recognising the different types of building stone
Published in John A. Hudson†, John W. Cosgrove, Understanding Building Stones and Stone Buildings, 2019
John A. Hudson†, John W. Cosgrove
A breccia (from the Italian for rubble) is a coarse-grained rock composed of angular fragments in a fine-grained matrix. A conglomerate (from the Latin for ‘lumped together’) is a coarse-grained rock composed of rounded fragments in a fine-grained matrix. This clear-cut distinction enables rapid identification of the two types of building stones.
Scientific ocean drilling in the Australasian region: a review
Published in Australian Journal of Earth Sciences, 2022
An intact record of a nascent (ca 47 Ma) arc is preserved in Unit IV comprising mudstones and overlying interlayered tuffaceous sandstones and silts plus sparse basaltic andesite lavas (Waldman et al., 2020). A local volcanic edifice preceding the development of the Kyushu–Palau Ridge is inferred. This is overlain by Unit III, consisting of 1046 m of Eocene–Oligocene tuffaceous mudstone, tuffaceous sandstone, sandstone with gravel, and breccia-conglomerate with pebble/cobble-sized volcanic and sedimentary rock clasts. Above that is 139 m of Oligocene tuffaceous mudstone, siltstone, and fine sandstone with localised slumping. The sequence is completed with 160 m of uppermost Oligocene to Recent mud and ooze of terrigenous and biogenic origin, with interspersed, predominantly Ryukyu Arc-derived tephra layers.
Influence of methane diffusion on geochemical characteristics of natural gas: a case study of the Shiqiantan area in Junggar Basin, China
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Zhaoyang Luo, Jungang Lu, Hongliang Zou, Yanping Li, Zhengzhou Hu
The Carboniferous is the key stratum in this study. The Dishuiquan Formation (C1d) of the Carboniferous is a set of normal continental clastic rock deposits. The lithology is grayish-green, gray tuffaceous breccia, tuffaceous conglomerate, sandstone, and siltstone, interbedded with tuff. The Songkaersu Formation (C1s) is divided into two subgroups. The lithology of the lower subgroup consists of andesite, rhyolite, andesite porphyrite and felsic porphyry, and volcanic rock assemblage of basaltic porphyrite, andesite porphyrite, rhyolite porphyry, and pyroclastic rock, with clastic sedimentary intercalation. The upper subgroup consists of yellow and yellow-green tuffaceous conglomerate, coarse sandstone, sandstone, and conglomerate. The lower subgroup of the Batamayineishan Formation (C2b) is a set of continental volcanic rock series. The lithology is neutral, basic and acid volcanic rock, pyroclastic rock with mudstone, carbonaceous shale, sandstone, conglomerate, and thin coal seam. The upper subgroup is mainly a set of normal clastic sedimentary rocks. For the Shiqiantan Formation (C2-3sh), the lithology is brown, dark brown mudstone, tuffaceous mudstone, and grayish brown, variegated, light yellowish-brown, dark gray, gray tuff, tuffaceous fine sandstone, tuffaceous glutenite with unequal thickness. Vertically, the lithology is dominated by sedimentary rocks with pyroclastic rocks.
Geology of New Zealand’s Sub-Antarctic Islands
Published in New Zealand Journal of Geology and Geophysics, 2019
James M. Scott, Ian M. Turnbull
This unit is only known from Camp Cove and Masked Cove in central Carnley Harbour (Speight and Finlayson 1909; Ritchie and Turnbull 1985). It comprises highly weathered, matrix-supported, poorly sorted bouldery pebble conglomerate and cobbly breccia (Figure 12C). The matrix varies from mud to sand. Dikes and sills are pervasive, and there may be intercalated flows (Ritchie and Turnbull 1985). Although some reports implied the Camp Cove Conglomerate clasts are largely plutonic to metamorphic in origin (Speight and Finlayson 1909; Fleming 1978; Cook 1981), they are mostly locally derived rounded to subangular volcanic rock (Gamble and Adams 1985). K-Ar dates from some volcanic clasts range from 21.7 ± 0.4–25.4 ± 0.5 Ma (Adams 1983), although the older ages do not overlap with the age range of volcanism on the island and Ar-Ar dating would be needed to better establish the age range. The smaller crystalline component includes coarse equigranular muscovite granite, adamellite, and rare biotite granite that although distinct from the nearby Musgrave Granite has a similar K-Ar age of 95.6 ± 1.4 Ma (Adams 1983). Rare pebbles of low-grade metasediment, comprising detrital quartz, albite, with rare sericite and chlorite, are present and one epidote-chlorite schist pebble has been recorded (Ritchie and Turnbull 1985). The Camp Cove Conglomerate may be a debris flow deposit, probably sub-aerial, incorporating reworked alluvial deposits and local outcrops of both basement and volcanic rocks, on the flanks of the growing Carnley Volcano (Ritchie and Turnbull 1985).