فارسي | English
  About Us | About Iran | Contact Us | Staff Info[Geoportal Info] [Maps] [Mining Info] [Other Activities]  
 
  News | Events | Photo Gallery | Downloads | Links | Kids  Search    Region    Scale    Subject   :Access to information by   Home | Newest   
 

Hydrogenous Sediments
 
  
For viewing each title click it:

  Manganese Nodules
   


About the sources of ore material supply to the ocean, there were once three major presumptions:

(1) Main ore material supply to the ocean comes from terrigenous and volcanic, and also hydrothermal material.
(2) Volcanic material is the major source of the supply of ore matter to the ocean.
(3) Terrigenous is the major source of the supply of ore matter to the ocean.


Goldschmidt was the first to open the problem of balance for discussion. In 1954, he pointed out that absolute masses of some metals in the ocean exceed their supply from continental rock weathering over geological time. This problem has risen a great interest in geochemistry. It is sustained by the problem of manganese nodule origin and also by the problem of hydrothermal matter supply to the ocean. In 1966, Scientists computed the balance of some elements in the ocean. Their computations revealed an actual excess of manganese over its supply from continental sources.The computation result also revealed that elements such as chlorine, sulfur, bromine, iodine, molybdenum were "excessive." According to the calculating result of Elderfield (1976), dissolved manganese supply to the ocean from various sources is 2.2-4.0 million tons annually; 0.7-7.4 million tons of manganese sink to the ocean bottom annually; 0.5-10 million tons of hydrothermal manganese are supplied to the ocean annually. But according to different estimates, the supply of labile and dissolved manganese to the ocean is 0.2-0.4million tons yearly through river discharge; 0.05-0.3 million tons yearly by atmospheric material; 1-10 million tons by hydrothermal material; and 0.4-4 million tons yearly by diagenetic flow. So, the amplitude of minimum-maximum summary estimates is 1.2-14.7 million tons per year. These are the general profiles of the accumulation of manganese nodules. The accumulation rate of manganese should be studied in individual oceanic regions.

Classification of Manganese Nodules
Oceanic nodules may be formed from the ore material of polygenic origin, although some researchers would emphasize the predominant role of hydrothermal sources. Manganese nodules may grow due to a supply of material both from above (out of oceanic water) and below (out of host sediments). Depending on the major ore elements (manganese, iron and base metals) the nodules contain, three major types were distinguished:

(1) hydrogenous, i.e., formed due to slow deposition of metals out of sea water and characterized by a high concentration of base metals and varying Mn/Fe rations (from 0.5-5)
(2) hydrothermal, i.e., rich in iron and depleted of other metals, and turns out to be having an extremely wide range of Mn/Fe rations
(3) diagenetic, i.e., characterized by high Mn/Fe ratios and relatively low concentration of base metals.

 
Search with:   
  Comment 1 to 1 of 1
The list of the above branch explanation
  Evaporites Salt Deposits
   


Evaporite chemical sedimentary rocks form as water evaporates from a lake or ocean. During the process of evaporation, water molecules change from the liquid phase to the gas phase, but atoms such as calcium, sodium, and chlorine are left behind. As a result, the remaining water becomes enriched in these atoms which begin to precipitate from the water. Evaporite minerals and rocks tend to form in arid climates where the rate of evaporation greatly exceeds rainfall. Therefore, evaporites are common where lakes form and then evaporate in a desert (such lakes are referred to as playa lakes), or in shallow and warm arms of the ocean adjacent to desert areas. Evaporites are light in color, and so can be readily recognized, even from a great distance.
 
 
 
Publications  Library
Glossary  Papers
 
 
 
 
FAQ  Members
Job Offer  Training
 
 
 
 
• NanoBioEarth Database 
• Medical Geology Database 
• Geological Atlas of Roads 
• 4th National Development Plan 
• Marine Geology 
• Geography information 
• Mines and Deposits of Iran 
• Landslide Database of Iran 
• Exploration Area DB 
• Copper Database 
• Gold Database  
• Geoscience Laboratories 
• Mineral Information 
• Bibliographic Database 
• Geochemistry Database 
• Earthquake database 
• Abandoned mines DB of Iran 
• Mineral processing database 
• Minerals database 
 
 
 
 
Login Name:
Password:
Sign Up for membership ]
 
 
 
   Others Activities:• Geo Hazard Of South Caspian • Geoscience database of ALBA • Geoscience Database of ECO 
• GEOLOGICAL SURVEY OF IRAN • Tajikistan Geoscience Database • Geo Database of Venezuela • 4th National Development Plan 
• Export & Import Regulation Act     
 
 
Maps:• Map of Iran's Last Earthquake • Distribution Map of mineral Processing Plants 
• Mineral Distribution Map of Iran • Geosciences laboratories distribution map of Iran • Orohydrographic Map of Iran 
• Select state on iran map • Geological Map of Iran(1:1000, 000 Scale) • 2500 K Magnetic Lineament Map of Iran 
• Map of Iran's Earthquake    
 
Best viewed:1024*768
National Geoscience Database Of IRAN
URL:www.ngdir.ir
Contact Mail:Info@ngdir.ir
 
 
 Search with:           
Designed by Payvand Software Group  Privacy | Copyright | Disclaimer