The principal features, geotectonic settings and association with near-surface hydrothermal mineral systems of ancient and present subaerial hot springs, fumaroles and geysers are herein reviewed. ...Fumaroles and geysers usually occur in volcanic craters and are in most cases, part and parcel of hot spring environments. Subaerial hot springs are characterised by siliceous- and carbonate-rich chemical sediments, such as sinters and travertines, respectively. Sinters are commonly enriched in various metalliferous elements. Hot springs surface discharges are also characterised by pools, which exhibit bright colours due to the presence of microorganisms. Present-day examples discussed in this paper, include the fumaroles and hot springs of the White Island volcano (New Zealand), the world-renowned Yellowstone caldera (USA) and the Afar region of the East African Rift System. The Afar triangle, in the northern part of East African Rift System, provides a good example of hot springs associated with evaporative deposits. The Tuli-Sabi-Lebombo triple junction rifts were formed during the ~ 180 Ma Karoo igneous event in southern Africa, of which the Tuli arm is the failed rift (aulacogen), as is the Afar region. The Tuli rift is effectively an unusual, if not unique, tectono-thermal setting, because it comprises Karoo-age hot springs systems and associated vein stockworks and breccias, which includes the Messina Cu deposit as well as currently active hot springs with sinter deposits probably due to post-Karoo uplift. Fumarolic pipes in ignimbrites of the Erongo Volcano-Plutonic Complex in Namibia are discussed. This is followed by an example of banded chert rocks in the Killara Formation of the Palaeoproterozoic Capricorn Orogen (Western Australia), interpreted as hot spring chemical sediments, which also show evidence of “fossil” microbial filaments. The paper ends with a brief overview of possible analogues of hot springs on planet Mars.
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•Subaerial hot springs.•Fumaroles.•Associated hydrothermal mineral systems.•Hot springs in continental rifts; Yellowstone, Afar, Tuli-Sabi-Lebombo.•Water and hot springs on Mars.
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Hydrothermal processes on Earth have played an important role in the evolution of our planet. These processes link the lithosphere, hydrosphere and biosphere in continuously evolving dynamic systems. ...Terrestrial hydrothermal processes have been active since water condensed to form the hydrosphere, most probably from about 4.4 Ga. The circulation of hot aqueous solution (hydrothermal systems) at, and below, the Earths surface is ultimately driven by magmatic heat. This book presents an in-depth review of hydrothermal proceses and systems that form beneath the oceans and in intracontinental rifts, continental margins and magmatic arcs. The interaction of hydrothermal fluids with rockwalls, the hydrophere and the biophere, together with changes in their composition through time and space, contribute to the formation of a wide range of mineral deposit types and associated wallrock alteration. On Earth, sites of hydrothermal activity support varied ecosystems based on a range of chemotrophic microorganisms both at surface and in the subsurface. This book also provides an overview of hydrothermal systems associated with meteorite impacts and explores the possibility that hydrothermal processes operate on other terrestrial planets, such as Mars, or satellites of the outer planets such as Titan and Europa. Possible analogues of extraterrestrial putative hydrothermal processes pose the intriguing question of whether primitive life, as we know it, may exist or existed in these planetary bodies. Audience: This volume will be of interest to scientists and researchers in geosciences and life sciences departments, as well as to professionals and scientists involved in mining and mineral exploration.
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Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms ...that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite-haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.
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The giant East China Mesozoic metallogenic province hosts some of the World’s largest resources of tungsten, tin, molybdenum, antimony and bismuth. Ores of gold, silver, mercury, lead, zinc, copper, ...uranium and iron are also of major importance. The province and its constituent metallogenic belts or regions (South China; Middle–Lower Yangtze River Valley; East Qinling–Dabie; Interior of North China Craton; Yan-Liao and North-east China) are the products of several pulses of igneous activity and mineralisation between ~240 and ~80 Ma. Each successive stage has produced a distinctive suite of deposits that can be readily related to the geodynamic evolution of the region during the Mesozoic. This geodynamic evolution is linked to a complex series of tectonic events, involving far-field-subduction, plate collisions, crustal thickening, post-collision collapse and rifting.
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The Qinling Orogen in central China is a complex collage built through the closure of the northernmost Paleo-Tethys and the suturing of the Yangtze and the North China cratons. In this contribution, ...geochronological, geochemical and isotopic data of Late Mesozoic granitoids are compiled, which in turn allow for a broad overview on their petrogenesis with respect to tectonic regime of the Qinling Orogen. After a magmatic hiatus during 160–195 Ma, extensive Late Mesozoic granitoids were emplaced, with an age range of 108–160 Ma. They are dominated by I-type granites that indicate formation through remelting crustal rocks at mid to lower crustal levels, although the magma temperatures are generally lower than 800 °C. The Sr-Nd-Hf isotopic data have provincial characters, which could be a reflection of regional differences in the compositions of their source rocks, and hence of the deep crust.
Late Mesozoic granitoids occur in three pulses without any magmatic quiescence: i.e. 108–125 Ma, 125–140 Ma and 140–160 Ma. There is a marked variation between granitoids aged pre- and post-125 Ma in terms of spatial distribution, petrology, geochemistry and isotopic features. The older suite displays a northward younging trend if taking the Mian-Lue suture as the boundary line. Rocks in this suite are composed of quartz diorite-granodiorite-monzogranite-granite association, and occur widespread between 109°E and 112°E. The younger suite occurs only in the easternmost part of the orogen (between 111°E and 113°E), and is dominated by monzogranite, granite and syenogranite. Compared with the older suite, the younger suite is characterized by evolved composition (with higher silica but lower Al2O3, FeOT, MgO and CaO contents) and involved juvenile crust. The magma has a much shallower source as evidenced by low Sr/Y ratios and pronounced Sr, Ba and Eu negative anomalies.
The above features indicate that the Late Mesozoic tectonic regime of the Qinling Orogen was an integrated effect of post-collisional compression-extension transition, the back-arc extension related to paleo-Pacific subduction and/or a Cretaceous Pacific superplume event.
•Granitoids aged 108–160 Ma occurred in Qinling, with no volcanic equivalents.•Pre- and post-125 Ma granitoids show sharp geochemical and isotopic distinction.•Adakites are restricted to the northernmost part of Qinling during 125–140 Ma.•Highly fractionated I-type occur in the easternmost part during 108–125 Ma.•Paleo-Pacific subduction overprinted Paleo-Tethyan post-collision since 125 Ma.
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The Qinling Orogen was formed from the closure of the northernmost paleo-Tethys sea and the tectonic suturing of the Yangtze and North China Cratons. The timing of this collision and the tectonic ...framework are debated. The widely developed Triassic granitoids in the western Qinling Orogen offer a key to understand the tectonic evolution of this region. Here we compile the geological, geochemical and geochronological data of the Triassic granitoids from the Qingling Orogen and conclude that the granitoids north of the Mian-Lue Suture were emplaced in an active continental margin related to the northward subduction of the Mian-Lue oceanic plate during 248−200Ma. The granitoids can be classified into I- and S-types, with the former constituting the major variety. Northward from the Mian-Lue Fault, an S-type granite belt appears, followed by and locally overlapping with an I-type granite belt. The I-type granite belt can be subdivided into four sub-belts from south to north, with increasing contents of K2O, K2O+Na2O, SiO2, Th and U, and the ratios of K2O/Na2O, Rb/Sr and (87Sr/86Sr)i, but decreasing contents of Na2O, Al2O3, Mg#, and εHf(t), except for the northernmost belt which occurs in the Huaxiong Block of the North China Craton. This geochemical polarity of I-type granitoids and the zoned distribution of S- and I-types granitoids cannot be explained through continental collision orogeny (including syn- to post-collision), but can be well interpreted by considering the progressive subduction of the northernmost branch of the paleo-Tethys, as represented by the Mian-Lue Ocean. Thus, the termination of the northernmost paleo-Tethys and the onset of the continental collision between the Yangtze and the North China plates are considered to have occurred at about 200Ma, during the transition from Triassic to Jurassic. Our model is also supported by the available data from other studies and provides a revised framework for the timing and tectonics of assembly of the Yangtze and the North China Cratons.
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•Triassic granitoids in Qinling Orogen are dominated by I-type, minor of S-type.•The S-type granitoids also formed in an active continental margin.•The I-type granitoids northward subduction-related geochemical polarities.•The northernmost paleo-Tethys terminated at end Traissic in Qinling Orogen.
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Northeast (NE) China lies in the eastern sector of the Central Asian Orogenic Belt (CAOB) that connects with the Circum-Pacific Orogenic Belt in the east, and accommodates multistage magmatism, ...crustal growth and mineralization. In this region 69 Mo-only or Mo-dominated and 9 Cu-Mo deposits have been discovered, including 65 deposits ranking medium-size (>10Kt Mo metal) or larger in tonnage and containing a total resource of 10.5Mt Mo metal. Six giant and seventeen large deposits have total reserves of 6.7 and 3.1Mt Mo, respectively. These deposits occur in the areas surrounding the Songliao Basin, including the northern margin of the North China Craton, the Great Hingan Range and the Ji-Hei Fold Belt, and have been formed during Paleozoic and Mesozoic tectono-magmatic events. All the Mo-only or Mo-dominated deposits were formed in the Mesozoic, postdating the closure of the Paleo-Asia Ocean, and in a series of pulses around 250–200Ma, 200–160Ma, 160–130 and <130Ma (130–100Ma), suggesting that the Paleozoic crust, compared with the Mesozoic crust, was less sialic and unfavorable for Mo mineralization. This is supported by the variation of Re contents in molybdenites from the deposits, i.e., increasing with the Cu/Mo ratios and the ore-forming ages. Mineralization was generally associated with granitic rocks mainly of crust-sourced and high-K calc-alkaline to shoshonite series. The majority of the deposits are porphyry (including breccia pipes) type, followed by the skarn and quartz vein types. The porphyry Mo deposits can be further subdivided into three subtypes, i.e., collision- or Dabie-, rift- or Climax-, and subduction- or Endako-types. The Mo deposits aged 250–200-Ma and 200–160-Ma belong to the collision-type and have been formed in syn- to post-collisional tectonic setting. The 160–130-Ma Mo mineralization mainly occurs in the Great Hingan Range and northern margin of the North China Craton, and includes Endako- and Climax-types of porphyry Mo systems, which resulted from southward subduction of the Mongol-Okhotsk oceanic plate. The 130–100-Ma deposits belong to the Endako-type and are only located in the eastern Ji-Hei Fold Belt, which must be related to the westward subduction of the Paleo-Pacific oceanic plate. Therefore, as shown by the porphyry Mo deposits in NE China, these mineral systems are a powerful indicator of tectonic settings and associated evolutionary trends.
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•NE China contains 69 Mo and 9 Cu-Mo deposits with a total reserve of 10.5 Mt Mo•The Mo-only and Mo-dominated deposits in NE China began to form in the Triassic.•Porphyry Mo deposits aged >160 Ma are Dabie-type formed in collisional orogeny.•Mineral systems are a powerful indicator of tectonic setting and geologic evolution.•Mongol-Okhotsk plate subduction caused the Great Hingan Mesozoic Igneous Province.
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In this paper we present a review of mineral systems in northern Xinjiang, NW China, focussing on the Tianshan, West and East Junggar and Altay orogenic belts, all of which are part of the greater ...Central Asian Orogenic Belt （CAOB）. The CAOB is a complex collage of ancient microcontinents, island arcs, oceanic plateaux and oceanic plates, which were amalgamated and accreted in Early Palaeozoic to Early Permian times. The establishment of the CAOB collage was followed by strike-slip movements and affected by intraplate magmatism, linked to mantle plume activity, best exemplified by the 250 Ma Siberian Traps and the 280 Ma Tarim event. In northern Xinjiang, there ale numerous and economically important mineral systems. In this contribution we describe a selection of representative mineral deposits, including subduction-related porphyry and epithermal deposits, volcanogenic massive sulphides and skarn systems. Shear zone-hosted Au lodes may have first formed as intrusion-related and subsequently re-worked during strike-slip deformation. Intraplate magmatism led to the emplacement of concentrically zoned （Alaskan-style） mafic-ultramafic intrusions, many of which host orthomagmatic sulphide deposits. A huge belt of pegmatites in the Altay orogen, locally hosts world-class rare metal deposits. Roll-front,
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► The Shirengou iron deposit is an Algoma type BIF deposit hosted in meta-volcanic rocks. ► The iron deposit was formed in an arc-related basin in the Neoarchean. ► Zircons U–Pb age ...(2541–2553Ma) can constrain formation time of the Shirengou BIF deposit.
The Shirengou iron deposit, a typical BIF deposit located in eastern Hebei province in the North China Craton, is hosted in Neoarchean metamorphic rocks. The metamorphic rocks include hornblende plagiogneiss, plagioclase amphibolite and magnetite quartzite. We use contents and ratios of major elements for protolith reconstruction, showing that protoliths of the hornblende plagiogneiss and plagioclase amphibolite should be dacite and basaltic andesite, respectively. Based on geology and geochemistry of the hosting rocks, we infer that the Shirengou BIF is an Algoma type deposit formed in an arc-related basin in the Neoarchean. Constrains from SIMS U–Pb dating and oxygen isotopic analysis of zircon from wall-rocks and interlayer of the Shirengou iron bodies can be summarized as follow: (1) igneous zircons from two samples of amphibolite and gneiss yield U–Pb ages of 2541±21Ma and 2553±31Ma, respectively, providing the age of the Neoarchean protolith. Because the Shirengou BIF is an Algoma-type deposit, determined U–Pb age (2541–2553Ma) for zircons from hosting volcanic rocks can constrain the BIF-forming time. (2) Metamorphic overgrowth zircons from amphibolite and gneiss give two U–Pb ages of 2512±13Ma and 2510±21Ma, respectively, corresponding to the Neoarchean matemorphism. (3) The zircons with δ18O values of 5.9–7.6‰ also indicate magmatic origin. The zircons have δ18O values of 6.8–9.9‰, suggesting that exotic high δ18O fluids were involved during metamorphism. Based on the geology and geochemistry of BIF, and combing with zircon age and oxygen isotopic systematics, we suggest that the Shirengou iron deposit was formed in a submarine volcanic setting related to subduction of an oceanic slab.
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