Crustal thickening and endogenic oxidation of magmatic sulfur

Porphyry ore deposits, Earth’s most important resources of copper, molybdenum, and rhenium, are strongly associated with felsic magmas showing signs of high-pressure differentiation and are usually found in places with thickened crust (>45 kilometers). This pattern is well-known, but unexplained, and remains an outstanding problem in our understanding of porphyry ore deposit formation. We approach this problem by investigating the oxidation state of magmatic sulfur, which controls the behavior of ore-forming metals during magma differentiation and magmatic-hydrothermal transition. We use sulfur in apatite to reconstruct the sulfur oxidation state in the Gangdese batholith, southern Tibet. We find that magma sulfate content increased abruptly after India-Eurasia collision. Apatite sulfur content and the calculated magma S6+/ΣS ratio correlate with whole-rock dysprosium/ytterbium ratio, suggesting that residual garnet, favored in thickened crust, exerts a first-order control on sulfur oxidation in magmatic orogens. Our findings link sulfur oxidation to internal petrogenic processes and imply an intrinsic relationship of magma oxidation with synmagmatic crustal thickening.

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Conditions of ore formation of the Aunikskoye F-Be deposit (Western Transbaikal)

Геология рудных месторождений ◽

10.31857/s0016-777061118-38 ◽

2019 ◽

Vol 61 (1) ◽

pp. 18-38

Author(s):

L. B. Damdinova ◽

B. B. Damdinov ◽

M. O. Rampilov ◽

S. V. Kanakin

Keyword(s):

Pressure Range ◽

Deposition Process ◽

Isotopic Signature ◽

Ore Deposits ◽

Ore Formation ◽

Ore Deposit ◽

Temperature Range ◽

Main Factors ◽

Low Solubility

This study examines the compositions of the ore and the ore formation solutions, conditions of formation, and sources of Be mineralization using the Aunikskoye F-Be deposit, which is an integral part of the Western Transbaikal beryllium-bearing provinces, as a representative example. Further, the main factors responsible for the formation of beryllium mineralization were evaluated. The ore deposits are presented by the feldsparic–fluorspar–phenacite–bertrandite metasomatites formed in the carboniferous limestones during their metasomatic alternation with hydrothermal solutions by introducing F, Be, and other associated elements. The formation of early phenacite–fluorspar association occurred in high-fluorite СО2-containing solutions of elevated alkalinity with a salinity of ~10.5%–12% wt eq. NaCl in a temperature range of ~ 370–260 °С at pressures ranging from 1873 to 1248 bar. More recent fluorite and bertrandite deposits were formed by solutions with a salinity of 6.4%–7.7% wt eq. NaCl in a temperature range of ~156 °C–110 °C and a pressure range of 639–427 bar. The examination of the isotopic signature of the ore association minerals confirmed the apocarbonate nature of the main ore deposit and allowed the determination of the magmatogene nature of the ore-forming paleothermal springs, which are the source of subalkaline leucogranites. The primary factors that influenced the formation of the F-Be ore included the reduction of the F activity in solutions because of the binding of Ca and F in fluorite as well as because of the decrease in temperature during the ore deposition process. The elevated alkalinity of the ore-formation solutions resulted in the low solubility of the Be complexes, which caused a relatively low Be content in the ore and a relatively small amount of mineralization in the deposit.

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Architecture of the crust and lithosphere beneath the Semail Ophiolite from ambient noise tomography and receiver functions: insights on the tectonic evolution of eastern Arabia

10.5194/egusphere-egu21-9890 ◽

2021 ◽

Author(s):

Christian Weidle ◽

Lars Wiesenberg ◽

Andreas Scharf ◽

Philippe Agard ◽

Amr El-Sharkawy ◽

...

Keyword(s):

Late Cretaceous ◽

Ambient Noise ◽

Function Analysis ◽

Oceanic Lithosphere ◽

Receiver Functions ◽

Crustal Thickening ◽

Ambient Noise Tomography ◽

First Order ◽

Pan African ◽

Semail Ophiolite

The Semail Ophiolite is the world&#8216;s largest and best exposed oceanic lithosphere on land and a primary reference site for studies of creation of oceanic lithosphere, initiation of subduction, geodynamic models of obduction, subduction and exhumation of continental rocks during obduction. Five decades of geological mapping, structural, petrological and geochronological research provide a robust understanding of the geodynamic evolution of the shallow continental crust in northern Oman and how the late Cretaceous obduction process largely shaped the present-day landscape. Yet, prior to obduction, other first-order tectonic processes have left their imprint in the lithosphere, in particular the Neoproterozoic accretion of Arabia and Permian breakup of Pangea. Due to the scarcity of deep structure imaging below the ophiolite, the presence and significance of inherited structures for the obduction process remain unclear.We discuss a new 3-D anisotropic shear wave velocity model of the crust below northern Oman derived from ambient noise tomography and Receiver Function analysis which allows to resolve some key unknowns in geodynamics of eastern Arabia: (1) Several NE-trending structural boundaries in the middle and lower crust are attributed to the Pan-African orogeny and align with first-order lateral changes in surface geology and topography. (2) The well-known Semail Gap Fault Zone is an upper crustal feature whereas two other deep crustal faults are newly identified. (3) Permian rifting occurred on both eastern and northern margins but large-scale mafic intrusions and/or underplating occurred only in the east. (4) While obduction is inherently lithospheric by nature, its effects are mostly observed at shallow crustal depths, and lateral variations in its geometry and dynamics can be explained by effects on pre-existing Pan-African and Permian structures. (5) Continental subduction and exhumation during late Cretaceous obduction may be the cause for crustal thickening below today&#8216;s topography. (6) Thinning of the continental lithosphere below northern Oman in late Eocene times &#8211; possibly related to thermal effects of the incipient Afar mantle plume - provides a plausible mechanism for the broad emergence of the Oman Mountains and in particular the Jabal Akhdar Dome. Uplift might thus be unrelated to compressional tectonics during Arabia-Eurasia convergence as previously believed.

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Coherence analysis of a family of weighted star-composed networks

International Journal of Modern Physics B ◽

10.1142/s0217979219502643 ◽

2019 ◽

Vol 33 (23) ◽

pp. 1950264

Author(s):

Meifeng Dai ◽

Tingting Ju ◽

Yongbo Hou ◽

Jianwei Chang ◽

Yu Sun ◽

...

Keyword(s):

Kronecker Product ◽

Future Research ◽

Weight Factor ◽

Node Number ◽

Laplacian Eigenvalues ◽

First Order ◽

Successive Generations ◽

Network Consistency ◽

Relationship Of ◽

The Relationship

Recently, the study of many kinds of weighted networks has received the attention of researchers in the scientific community. In this paper, first, a class of weighted star-composed networks with a weight factor is introduced. We focus on the network consistency in linear dynamical system for a class of weighted star-composed networks. The network consistency can be characterized as network coherence by using the sum of reciprocals of all nonzero Laplacian eigenvalues, which can be obtained by using the relationship of Laplacian eigenvalues at two successive generations. Remarkably, the Laplacian matrix of the class of weighted star-composed networks can be represented by the Kronecker product, then the properties of the Kronecker product can be used to obtain conveniently the corresponding characteristic roots. In the process of finding the sum of reciprocals of all nonzero Laplacian eigenvalues, the key step is to obtain the relationship of Laplacian eigenvalues at two successive generations. Finally, we obtain the main results of the first- and second-order network coherences. The obtained results show that if the weight factor is 1 then the obtained results in this paper coincide with the previous results on binary networks, otherwise the scalings of the first-order network coherence are related to the node number of attaching copy graph, the weight factor and generation number. Surprisingly, the scalings of the first-order network coherence are independent of the node number of initial graph. Consequently, it will open up new perspectives for future research.

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Role of rheological heterogeneities in vein-ore localization

Canadian Journal of Earth Sciences ◽

10.1139/e93-011 ◽

1993 ◽

Vol 30 (1) ◽

pp. 113-123 ◽

Cited By ~ 2

Author(s):

C. Castaing ◽

D. Cassard ◽

Y. Gros ◽

M. Moisy ◽

J. C. Chabod

Keyword(s):

Lower Order ◽

Shear Zones ◽

Ore Deposits ◽

Second Order ◽

Massif Central ◽

First Order ◽

Ore Localization ◽

Ore Minerals ◽

Partial Destruction

Structural studies of the Saint-Salvy zinc deposit and other Hercynian, veinhosted ore deposits in the French Massif Central and Pyrénées reveal a fourstage evolution of mineralized structures under rheological control: (i) localization of potential mineralized areas, guided by the presence of first-order lithological or structural heterogeneities that caused stress and strain perturbations; (ii) creation of second-order heterogeneities, corresponding to indurated shear zones that acted as rheological discontinuities; (iii) tectonic activation of these second-order heterogeneities, opening voids that allowed circulation of hydrothermal fluids and periodic trapping of ore minerals; (iv) reworking and partial destruction of the mineralized structures, caused by the reactivation of anisotropic surfaces acting as zones of weakness. The interaction between preexisting, first-order heterogeneities and regional shear strain caused instability, which in turn produced second-order and then lower-order heterogeneities. Such progressively smaller heterogeneities induced an increasingly focused, centripetal localization of structural disturbances that enabled hydrothermal fluid channelling. This is the reason that lower-order and late structures preferentially bear economic mineralization.

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Performance of low-fold scalar migration for downhole seismic imaging of massive sulfide ore deposits at Norman West, Sudbury, Canada

Geophysics ◽

10.1190/geo2011-0482.1 ◽

2012 ◽

Vol 77 (5) ◽

pp. WC3-WC13 ◽

Cited By ~ 2

Author(s):

Christof Mueller ◽

Gilles Bellefleur ◽

Erick Adam ◽

Gervais Perron ◽

Marko Mah ◽

...

Keyword(s):

Seismic Data ◽

Seismic Imaging ◽

Signal To Noise Ratio ◽

Massive Sulfide ◽

Ore Deposits ◽

Ore Deposit ◽

Seismic Scattering ◽

Vertical Seismic Profiling ◽

Sudbury Igneous Complex ◽

Sulfide Ore

The Downhole Seismic Imaging consortium conducted two consecutive vertical seismic profiling surveys in the Norman West mining camp (Sudbury, Canada) in 1998 and 1999. These were aimed toward imaging a massive sulfide ore deposit situated within the footwall of the Sudbury Igneous Complex (SIC). Three-component seismic data were acquired in four boreholes with variable signal-to-noise ratio and poor polarization quality. Consequently, the images suffered from strong azimuthal ambiguity. A strike filter, passing only reflections originating from within the SIC, was applied during migration to enhance interpretability of the images obtained. Migrated images showed structures correlating with the known position of an ore deposit located 1800 m away from one borehole (N40). Diffraction coherency migration enhanced the image of the deposit, and suggested strong seismic scattering from within the footwall of the SIC.

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THE EVALUATION OF AN ORE DEPOSIT DEVELOPMENT PROSPECT THROUGH APPLICATION OF THE "GAMES AGAINST NATURE" APPROACH

Asia Pacific Journal of Operational Research ◽

10.1142/s0217595913500292 ◽

2013 ◽

Vol 30 (06) ◽

pp. 1350029 ◽

Cited By ~ 3

Author(s):

MARIUSZ KRZAK

Keyword(s):

Decision Making ◽

Mineral Deposit ◽

Ore Deposits ◽

Supplementary Information ◽

Decision Making Process ◽

Final Decision ◽

Investment Risk ◽

Economic Market ◽

Ore Deposit ◽

Mining Projects

Geological-mining projects are usually associated with relatively high risk and uncertainty in many aspects, including geological, mining, ecologic, economic, market, legal and social conditions. A mineral deposit is an underground natural resource and hence it is difficult to unequivocally predict the actual results of its discovery. Depending on the extent of the resource, the operation of the mine can extend to a few decades. It is necessary to conduct investment actions in successive stages and to evaluate the results of the work stage by stage. This reduces the investment risk and facilitates the decision-making process. In this paper, the use of a specific kind of game, the so-called "game against Nature," is suggested before a final decision on deposit development is made. This methodology was tested on the example of one of the zinc-lead ore deposits in the Silesia-Cracow region. Apart from supporting the decision-making process, this methodology offers the means to evaluate further research and costs which may be incurred for obtaining supplementary information related to the ore deposit parameters, specifically its reserves.

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Kinetics of aquation of the fluoropentaamminecobalt(III) ion

Canadian Journal of Chemistry ◽

10.1139/v70-175 ◽

1970 ◽

Vol 48 (7) ◽

pp. 1054-1058 ◽

Cited By ~ 13

Author(s):

T. W. Swaddle ◽

W. E. Jones

Keyword(s):

Ionic Strength ◽

Rate Coefficient ◽

Hydrogen Ion ◽

Fluoride Ion ◽

Kcal Mole ◽

First Order ◽

Order Rate ◽

Relationship Of ◽

The Relationship ◽

Kinetics Of

The kinetics of the hydrogen-ion-independent pathway for the replacement of fluoride in aqueous (NH3)5CoF2+ by H2O have been reinvestigated using a specific fluoride-ion electrode, with due regard for the concomitant autocatalytic loss of the ammine ligands. In perchlorate media of ionic strength 0.1 M, the first-order rate coefficient is 1.22 × 10−6 s−1 at 45°, and the kinetics are represented by ΔH* = 24.4 kcal mole−1 and ΔS* = −9 cal deg−1 mole−1 over the range 35–75° at least. The relationship of these data to those for the aquation of other species of the type ML5Xn+ is discussed.

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A system of logic for partial functions under existence-dependent kleene equality

Journal of Symbolic Logic ◽

10.2307/2274574 ◽

1988 ◽

Vol 53 (3) ◽

pp. 834-839 ◽

Cited By ~ 3

Author(s):

H. Andréka ◽

W. Craig ◽

I. Németi

Keyword(s):

Practical Interest ◽

Order Logic ◽

First Order Logic ◽

Basic Relation ◽

Equational Logic ◽

Partial Functions ◽

First Order ◽

Complete Set ◽

The Subject ◽

Relationship Of

Ordinary equational logic is a connective-free fragment of first-order logic which is concerned with total functions under the relation of ordinary equality. In [AN] (see also [AN1]) and in [Cr] it has been extended in two equivalent ways into a near-equational system of logic for partial functions. The extension given in [Cr] deals with partial functions under two relationships: a relationship of existence-dependent existence and one of existence-dependent Kleene equality. For the language that involves both relationships a set of rules was given that is complete. Those rules in the set that involve only existence-dependent existence turned out to be complete for the sublanguage that involves this relationship only. In the present paper we give a set of rules that is complete for the other sublanguage, namely the language of partial functions under existence-dependent Kleene equality.This language lacks a certain, often needed, power of expressing existence and fails, in particular, to be an extension of the language that underlies ordinary equational logic. That it possesses a fairly simple complete set of rules is therefore perhaps more of theoretical than of practical interest. The present paper is thus intended to serve as a supplement to [Cr] and, less directly, to [AN]. The subject is further rounded out, and some contrast is provided, by [Rob]. The systems of logic treated there are based on the weaker language in which partial functions are considered under the more basic relation of Kleene equality.

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Geochemical Anomaly Characteristics of the Soil Secondary Halo of Pangjiagou Gold Polymetallic Deposit in Chengde, Hebei Province

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.807-809.2129 ◽

2013 ◽

Vol 807-809 ◽

pp. 2129-2132

Author(s):

Jiao Jiao Chen ◽

Ying Shu Li ◽

Da Qing He ◽

Dong Ming Yang ◽

Yi Ke Zhang

Keyword(s):

Surface Oxidation ◽

Wall Rock ◽

Hydrothermal Activity ◽

Ore Deposits ◽

Hebei Province ◽

Geochemical Characteristics ◽

Geochemical Anomaly ◽

Ore Deposit ◽

Polymetallic Deposit ◽

North East

Pangjiagou gold polymetallic deposit is located in bending parts of the north east direction of the Yanshan arc structural belt in Hebei province, which has a good regional metallogenic background. According to the collection of samples and tests of eight elements for the samples of the mining area, we studied the geochemical anomaly characteristics of the soil secondary halos of the ore deposit. By means of researching on geochemical characteristics of the ore deposit, it worked out that the ore deposit possesses the characteristics of multiphase ore-forming hydrothermal activity, which is divided into the Sb-Zn mineralization period and Cu-Au mineralization period. The important prospecting of the ore deposits in the area consist of the surface oxidation, the wall rock alteration and the geochemical characteristics.

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The Timing of Metamorphism, Magmatism, and Cooling in the Zanskar, Garhwal, and Nepal Himalaya

Journal of Nepal Geological Society ◽

10.3126/jngs.v11i0.32786 ◽

1995 ◽

Vol 11 ◽

Author(s):

M. P. Searle

Keyword(s):

Hanging Wall ◽

Crustal Thickening ◽

Indian Plate ◽

Eastern Himalaya ◽

Normal Faults ◽

The Tibetan Plateau ◽

Main Central Thrust ◽

Southern Tibet ◽

Peak Metamorphism ◽

Exhumation Rates

Following India-Asia collision, which is estimated at ca. 54-50 Ma in the Ladakh-southern Tibet area, crustal thickening and timing of peak metamorphism may have been diachronous both along the Himalaya (pre-40 Ma north Pakistan; pre-31 Ma Zanskar; pre-20 Ma east Kashmir, west Garhwal; 11-4 Ma Nanga Parbat) and cross the strike of the High Himalaya, propagating S (in Zanskar SW) with time. Thrusting along the base of the High Himalayan slab (Main Central Thrust active 21-19 Ma) was synchronous with N-S (in Zanskar NE-SW) extension along the top of the slab (South Tibet Detachment Zone). Kyanite and sillimanite gneisses in the footwall formed at pressure of 8-10 kbars and depths of burial of 28-35 km, 30- 21 Ma ago, whereas anchimetamorphic sediments along the hanging wall have never been buried below ca. 5-6 km. Peak temperatures may have reached 750 on the prograde part of the P-T path. Thermobarometers can be used to constrain depths of burial assuming a continental geothermal gradient of 28-30 °C/km and a lithostatic gradient of around 3.5-3.7 km/kbar (or 0.285 kbars/km). Timing of peak metamorphism cannot yet be constrained accurately. However, we can infer cooling histories derived from thermochronometers using radiogenic isotopic systems, and thereby exhumation rates. This paper reviews all the reliable geochronological data and infers cooling histories for the Himalayan zone in Zanskar, Garhwal, and Nepal. Exhumation rates have been far greater in the High Himalayan Zone (1.4-2.1 mm/year) and southern Karakoram (1.2-1.6 mm/year) than along the zone of collision (Indus suture) or along the north Indian plate margin. The High Himalayan leucogranites span 26-14 Ma in the central Himalaya, and anatexis occurred at 21-19 Ma in Zanskar, approximately 30 Ma after the collision. The cooling histories show that significant crustal thickening, widespread metamorphism, erosion and exhumation (and therefore, possibly significant topographic elevation) occurred during the early Miocene along the central and eastern Himalaya, before the strengthening of the Indian monsoon at ca. 8 Ma, before the major change in climate and vegetation, and before the onset of E-W extension on the Tibetan plateau. Exhumation, therefore, was primarily controlled by active thrusts and normal faults, not by external factors such as climate change.

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