scholarly journals Microbes, organic matter and ore deposits

2004 ◽  
Vol 25 (1) ◽  
pp. 36 ◽  
Author(s):  
Craig P Marshall ◽  
Karen L Mackenzie ◽  
Junhong Chen ◽  
Dorothy Z Oehler ◽  
Graham A Logan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Northern Territory ◽  
Ore Deposits ◽  
Silver Deposits ◽  
The World ◽  
Lead Zinc

The 1640 Ma (million years old) Here?s Your Chance (HYC) deposit at McArthur River, Northern Territory, Australia is one of the largest and least metamorphosed lead-zinc-silver deposits in the world. The mineralised interval has been divided into several orebodies and is separated by relatively barren sediment.

Pétrographie et altération de la matière organiquedu gisement de plomb–zinc–cuivre de tourist–Bou Beker,Maroc nord oriental

1996 ◽  
Vol 33 (10) ◽  
pp. 1363-1374 ◽  
Author(s):  
M. Bouadellah ◽  
A. C. Brown ◽  
Y. Héroux
Keyword(s):  
Organic Matter ◽  
Ore Deposits ◽  
Mississippi Valley ◽  
Sulfide Mineralization ◽  
Mineralization Process ◽  
Associated Gas ◽  
Regional Flow ◽  
Lead Zinc ◽  
Reflectance Measurements ◽  
Ore Deposition

Reflectance measurements and organic petrography were used to study altered organic matter in the dolomitic Middle Jurassic Beddiane sequence hosting the Beddiane lead–zinc deposit. Organic matter occurs in the lower dolostone units of the formation where zinc sulfide mineralization prevails. The upper units, where lead sulfide mineralization is dominant, contain lesser amounts of organic matter. The organic matter in the Beddiane sequence consists of macerals, amorphous kerogen, and solid bitumen, inertinite and vitrinite are ubiquitous. The amount of exinite increases toward mineralized areas but the ratio exinite/kerogen remains constant. Two types of vitrinite are considered on the basis of their reflectance: Vt1 with low reflectance values (0.3–0.5%) and Vt2 with higher values (0.7–1.25%). The ratio Vt1/Vt2 increases and the reflectance values for Vt1 decrease toward the zinc-prevailing units, Organic matter associated with the mineralization exhibits features such as oxidation halos and desiccation cracks, together with a low-fluorescent exinite. The association of the kerogen content, the trend in reflectance values, and the alteration features of the Mississippi Valley-type Beddiane deposit support the hypothesis that the regional flow of hot brines associated with the mineralization process was the cause of anomalous heating, that the occurrence of exinite maceral and its associated gas played a role in the ore deposition, and that the new chemical equilibrium reached by the zinc-dominant host rock after ore deposition is responsible for the suppressed reflectance values within and near the ore deposits.

Symposium: Role of organisms and organic matter in ore deposition/Le rôle des organismes et de la matière organique dans la formation des gisements métallifères

1985 ◽  
Vol 22 (12) ◽  
pp. 1890-1892 ◽  
Author(s):  
R. W. Macqueen
Keyword(s):  
Organic Matter ◽  
Ore Deposits ◽  
Sulphate Reduction ◽  
Sulphide Mineral ◽  
Special Session ◽  
Geochemical Cycle ◽  
Lead Zinc ◽  
Pine Point ◽  
Earth’S System ◽  
Ore Deposition

The following seven papers were presented on May 16, 1984, at the Geological Association of Canada and Mineralogical Association of Canada joint annual meeting. The special session, organized by R. W. Macqueen and J. A. Coope, contained 10 papers and was sponsored by the Mineral Deposits Division of the Geological Association of Canada.Our objective in organizing the special session was to examine organically based processes and relationships that may be of major importance to the origin of ore deposits. As noted by Fyfe (1984), the concept of the geochemical cycle focuses attention on pathways of chemical elements and isotopes of the Earth's system during geologic history. It is clear from the chemistry of carbon-rich materials that a wide range of elements is concentrated directly or indirectly by biological processes operating as part of the geochemical cycle. Two of the papers of the special session examine some of these concentration processes, although definitive links to actual ore deposits cannot be made yet. Beveridge and Fyfe document the remarkable ability of the anionic cell walls of certain bacteria to concentrate metals and to provide sites for nucleation and growth of minerals. In a related paper, Mann and Fyfe show that several species of simple freshwater green algae readily concentrate large amounts of uranium under both experimental and natural conditions (Elliot Lake and Thames River, Ontario).Two papers deal with aspects of sulphate reduction. Birnbaum and Wireman describe controlled experiments that suggest that sulphate-reducing bacteria may be involved in the selective replacement of sulphate-evaporite minerals by silica and in the precipitation of silica in association with sulphide mineral phases in banded iron formations. Their work focuses directly on the effect that bacterial sulphate reduction has on silica solubility. Trudinger et al. examine the question of mechanisms of sulphate reduction at temperatures less than 200 °C and the bearing this has on origin of sulphide for low-temperature sulphide ore deposits. Although there is empirical evidence favouring abiological sulphate reduction at temperatures in the vicinity of 100 °C, Trudinger et al. have not been able to demonstrate abiological reduction of sulphate under controlled laboratory conditions and at temperatures under about 200 °C. Perhaps catalysts, as yet undiscovered, are involved in this process in nature.Impressive progress has been made in understanding the diagenetic evolution of organic matter in response to heat and pressure in geological environments: excellent reviews are found in Barnes et al. (1984) and Bustin et al. (1985). Simoneit's paper examines and reviews the genesis of petroleum in a most unusual setting, that of the active ocean ridge spreading centre of Guaymas Basin, Gulf of California. There, in the vicinity of black smokers and associated metallic sulphide deposits, petroleum originates instantaneously geologically as a result of hydrothermal activity. The question of genetic involvement of organic matter in the origin of the metallic sulphides (e.g., reduction of sulphate to H2S) cannot be answered yet for this setting with the available data.The final two special session papers included here are concerned with organic matter associated with mineralization in Canadian Shield Precambrian settings. Willingham et al. demonstrate that Elliot Lake – Blind River Early Proterozoic uranium deposits with minor amounts of associated gold also contain kerogen-like organic matter. Some of this organic matter has anomalously rich amounts of gold and uranium and appears to have originated as mats of cyanobacteria, possibly with the ability to concentrate these metals. For a number of settings in the Archean-aged Abitibi greenstone belt of Ontario and Quebec, Springer demonstrates that carbon, at least partly of organic origin, is closely associated with some gold deposits. Her interpretation is that carbon activated by shear-zone-associated hydrothermal fluids has provided sites for fixing some of the gold.Three of the papers given at the special session are not included here. H. T. Shacklette reviewed metal uptake by young conifer trees, demonstrating that nursery-grown seedlings of several species readily concentrated a variety of metals, including lead, zinc, tin, and gold, over a 7 year period. This work is of interest to those involved in geochemical prospecting and is now published elsewhere (King et al. 1984). R. W. Macqueen presented quantitative data on the genesis of sulphide by abiological bitumen–sulphate reactions at the Pine Point lead–zinc property, Northwest Territories, Canada (Macqueen and Powell 1983; Powell and Macqueen 1984). Although Trudinger et al. have not been able to demonstrate abiological reduction of sulphate at temperatures approximating those of Pine Point [Formula: see text], the data presented by Macqueen (Powell and Macqueen 1984) are consistent with the amounts, alteration, and composition of bitumens at Pine Point, as well as with the presence of native sulphur and the sulphur isotope compositions of the various Pine Point sulphur species. This work is continuing, and a more extensive account is in preparation. J. R. Watterson examined relationships between freezing climates and the local chemical behaviour of gold in the weathering cycle, concluding that ice-induced accumulation of organic acids, bacteria, and other organic matter at mineral surfaces may increase rates of chemical attack, leading to dissolution of normally insoluble metals such as gold (Watterson 1986).Interest in organic aspects of the geochemical cycle, including ore deposition, is growing dramatically (e.g., Fyfe 1984). Although the following papers address a limited range of topics within the field, they do indicate some of the diversity and variety of active processes and associations between metallic elements and organic components. Perhaps, in the not too distant future, we will be able to identify or even discover whole classes of ore deposits that owe their origin directly to organic influences operating within the geochemical cycle.

scholarly journals ORGANIC CARBON DYNAMICS IN GRASSLAND SOILS. 1. BACKGROUND INFORMATION AND COMPUTER SIMULATION

1981 ◽  
Vol 61 (2) ◽  
pp. 185-201 ◽  
Author(s):  
J. A. VAN VEEN ◽  
E. A. PAUL
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Experimental Studies ◽  
Decay Rates ◽  
Background Information ◽  
Plant Residues ◽  
Decomposition Rates ◽  
Straw Decomposition ◽  
Soil Biomass ◽  
The World

The decomposition rates of 14C-labelled plant residues in different parts of the world were characterized and mathematically simulated. The easily decomposable materials, cellulose and hemicellulose, were described as being decomposed directly by the soil biomass; the lignin fraction of aboveground residues and the resistant portion of the roots entered a decomposable native soil organic matter. Here it could be decomposed by the soil biomass or react with other soil constituents in the formation of more recalcitrant soil organic matter. The transformation rates were considered to be independent of biomass size (first–order). Data from 14C plant residue incorporation studies which yielded net decomposition rates of added materials and from carbon dating of the recalcitrant soil organic matter were transformed to gross decomposition rate constants for three soil depths. The model adequately described soil organic matter transformations under native grassland and the effect of cultivation on organic matter levels. Correction for microbial growth and moisture and temperature variations showed that the rate of wheat straw decomposition, based on a full year in the field in southern Saskatchewan, was 0.05 that under optimal laboratory conditions. The relative decay rates for plant residues during the summer months of the North American Great Plains was 0.1 times that of the laboratory. Comparison with data from other parts of the world showed an annual relative rate of 0.12 for straw decomposition in England, whereas gross decomposition rates in Nigeria were 0.5 those of laboratory rates. Both the decomposable and recalcitrant organic matter were found to be affected by the extent of physical protection within the soil. The extent of protection was simulated and compared to data from experimental studies on the persistence of 14C-labelled amino acids in soil. The extent of protection influenced the steady-state levels of soil carbon upon cultivation more than did the original decomposition rates of the plant residues.

Thinking honeyeater: nectar maps for the Northern Territory, Australia

2000 ◽  
Vol 6 (1) ◽  
pp. 61 ◽  
Author(s):  
John C. Z. Woinarski ◽  
Greg Connors ◽  
Don C. Franklin
Keyword(s):  
Northern Territory ◽  
Dry Season ◽  
Spatial And Temporal Variation ◽  
Wet Season ◽  
Nectar Production ◽  
The World ◽  
Eucalypt Forests ◽  
The Times ◽  
Species Specific ◽  
Nectar Availability

We create monthly maps of nectar availability for the 1.4 x 106 km2 jurisdiction of the Northern Territory, Australia. These are based on a combination of vegetation mapping and a series of indices of plant species specific nectar scoring. The maps reveal complex spatial and temporal variation in nectar availability, but most notably a greater nectar resource in the monsoon-influenced north than in the arid south, and a peak in nectar availability in the dry season. The latter is associated with the extensive tropical eucalypt forests (especially those co-dominated by Eucalyptus miniata and E. tetrodonta). In contrast, wet season nectar availability in these forests is limited, but riparian and swampland forests, typically dominated by Melaleuca species, provide rich but spatially restricted nectar resources. The extensive and rich nectar resources available in eucalypt forests in the dry season supplement the diets of many species which are not primarily nectarivorous. This resource helps shape the singularity of northern Australian eucalypt forests relative to other extensive forests elsewhere in the world. Nectarivores remain in the system through a combination of movements across a number of scales, habitat shifting, and diet shifting. The latter is aided by the peaking of invertebrate and fruit resources at the times of minimum nectar production; a shuffling in resource availability brought about by the extreme climatic seasonality.

Pruning residues incorporation and reduced tillage improve soil organic matter stabilization and structure of salt-affected soils in Citrus tree orchard under semi-arid climate conditions 

2021 ◽  
Author(s):  
Noelia Garcia-Franco ◽  
Martin Wiesmeier ◽  
Luis Carlos Colocho Hurtarte ◽  
Franziska Fella ◽  
María Martínez-Mena ◽  
...  
Keyword(s):  
Organic Matter ◽  
Drip Irrigation ◽  
Management Practices ◽  
Reduced Tillage ◽  
Citrus Tree ◽  
Climate Conditions ◽  
The World ◽  
Pruning Residues ◽  
Salt Affected Soils ◽  
Semi Arid

<p>Arid and semiarid regions represent about 47% of the total land area of the world and around 40% of the world’s food is produced there. In these areas, soil salinization is an emerging problem due to unsustainable land management practices and climate change. However, the use of sustainable land management practices in salt-affected soils can offset the negative effects of salinization and increase soil carbon stocks. In a Citrus tree orchard under semi-arid climate conditions, we evaluated the effect of (i) intensive tillage along with flood irrigation (IT); (ii) combination of no-tillage with pruning residues (branches and leaves) as mulch, and drip-irrigation (NT+PM); and (iii) combination of reduced tillage with the incorporation of pruning residues and drip-irrigation (RT+PI), on aggregate stability, amount and quality of organic matter fractions and soil organic carbon (OC) sequestration. Our results showed that the incorporation of pruning residues through reduced tillage decreased bulk density and salinity while soil porosity, soil OC and N stocks, and percentage of OC-rich macroaggregates increased compared to the IT system.  However, the positive effects of the NT+PM system on soil properties were limited to the topsoil. The IT management system showed the highest values of bulk density and salinity and lower amounts of macroaggregates and soil OC stocks. In conclusion, the combination of pruning residues through the reduced tillage and drip-irrigation was the most effective systems to improve soil structure and OC sequestration and reduced the salt content under Citrus tree orchard in semi-arid soils</p>

Introduction

1994 ◽  
Author(s):  
Václav Nēmec
Keyword(s):  
Ad Hoc ◽  
International Association ◽  
The United States ◽  
Ore Deposits ◽  
Western World ◽  
Mathematical Geology ◽  
25Th Anniversary ◽  
European Universities ◽  
The World

Friends and associates of Daniel F. Merriam have prepared this volume in Dan's honor to commemorate his 65th birthday and mark the 25th anniversary of the International Association for Mathematical Geology. This compendium is in the tradition of the Festschriften issued by European universities and scholarly organizations to honor an individual who has bequeathed an exceptional legacy to his students, associates, and his discipline. Certainly Dan has made such an impact on geology, and particularly mathematical geology. It is a great privilege for rne to write the introduction to this Festschrift. The editors are to be congratulated for their idea to collect and to publish so many representative scientific articles written by famous authors of several generations. Dan Merriam is the most famous mathematical geologist, in the world. This statement will probably provoke some criticism against an over-glorification of Dan. Some readers will have their own candidates (including themselves) for such a top position. I would like to bring a testimony that the statement is correct and far from an ad hoc judgment only for this solemn occasion. It may be of interest to describe how I became acquainted with Dan. In my opinion this will show how thin and delicate was the original tissue of invisible ties which helped to build up the first contacts among Western and Eastern colleagues in the completely new discipline of mathematical geology. The role of Dan Merriam in opening and increasing these contacts has been very active indeed. In the Fall 1964 I was on a family visit in the United States. This was— after the coup of Prague in 1948—my first travel to the free Western world. With some experience in computerized evaluation of ore deposits, I was curious to see the application of computers in geology and to meet colleagues who had experience with introducing statistical methods into regular estimation of ore reserves. I had very useful contacts in Colorado and in Arizona. In Tucson I visited the real birthplace of the APCOM symposia.

Socioeconomic Development in Balochistan

2020 ◽  
pp. 26-43
Author(s):  
Naveeda Erum ◽  
Naima Saeed ◽  
Tansif Ur Rehman
Keyword(s):  
Socioeconomic Development ◽  
Work Force ◽  
Factors Affecting ◽  
Agrarian Society ◽  
The World ◽  
Copper Gold ◽  
The Status ◽  
Lead Zinc ◽  
The Government ◽  
Juniper Forests

Balochistan has witnessed rapid social change since the 1970s. These changes were augmented by the national and international political situation. The traditional, tribal, and largely pastoral nomadic society of Balochistan gradually transformed into a modernizing agrarian society. On 1st July 1970, when ‘One Unit' was dissolved, Balochistan gained the status of a province and the bureaucratic expansion required educated work force. Thus, the Government of Pakistan expanded educational facilities in Balochistan, but this expansion continued at a very slow pace. Unfortunately, Balochistan is still the most backward province in terms of socioeconomic development in Pakistan. Though, it is the largest province in Pakistan, almost 44% of Pakistan's total area. It also possesses one of the largest blocks of juniper forests in the world. Along with it, Balochistan is rich in biodiversity and possess natural resources in abundance, like copper, gold, lead, zinc, iron, coal, and marble. This article focuses on the various factors affecting the socioeconomic development in Balochistan.

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