Subglacial Hydrothermal Alteration Minerals in Jökulhlaup Deposits of Southern Iceland, with Implications for Detecting Past or Present Habitable Environments on Mars

Astrobiology ◽  
2010 ◽  
Vol 10 (5) ◽  
pp. 523-547 ◽  
Author(s):  
Nicholas H. Warner ◽  
Jack D. Farmer
Keyword(s):  
Hydrothermal Alteration ◽  
Alteration Minerals

Lithium-Bearing Hydrothermal Alteration Phyllosilicates Related to Portalet Fluorite Ore (Pyrenees, Huesca, Spain)

Clay Minerals ◽  
1993 ◽  
Vol 28 (2) ◽  
pp. 275-283 ◽  
Author(s):  
J. M. Gonzlez Lopez ◽  
I. Subias Pirez ◽  
C. Fernandez-Nieto ◽  
I. Fanlo Gonzalez
Keyword(s):  
Hydrothermal Alteration ◽  
Half Cell ◽  
Ore Bodies ◽  
Alteration Minerals ◽  
Structural Formulae

AbstractPhyllosilicate associations in hydrothermally altered fluorite ore bodies are: Li-chlorite ± pyrophyllite ± interstratified minerals ± muscovite +± kaolinite. Chlorites, the main alteration minerals, are dioctahedral, d060 = 1.489-1-490/~,, of Ia polytype. The structural formulae indicate substitution of AI for Si from 0.61-0.78 atoms. The total octahedral occupancy ranges from 4.52-4-71 atoms, with 0.49-0-69 Li atoms per half cell unit. This composition indicates that the chlorites are intermediate members of the donbassite-cookeite series proposed by Sudo (1978). The mineralogical associations and textural relations suggest that after intensive silicification which produced alkali alteration under acid conditions, pyrophyllite was produced at the expense of muscovite and then Li-bearing donbassite formed from the pyrophyllite. The Li needed for the formation of the chlorites could be genetically related to granitic batholiths which occur close to the fluorite ores.

scholarly journals Characterization of hydrothermal alteration along geothermal wells using unsupervised machine-learning analysis of X-ray powder diffraction data

2021 ◽  
Author(s):  
Kazuya Ishitsuka ◽  
Hiroki Ojima ◽  
Toru Mogi ◽  
Tatsuya Kajiwara ◽  
Takeshi Sugimoto ◽  
...  
Keyword(s):  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Hydrothermal Alteration ◽  
Powder Diffraction ◽  
Gaussian Mixture ◽  
Geothermal Field ◽  
Classification Algorithms ◽  
Agglomerative Clustering ◽  
X Ray ◽  
Alteration Minerals

AbstractZonal distribution of hydrothermal alteration in and around geothermal fields is important for understanding the hydrothermal environment. In this study, we assessed the performance of three unsupervised classification algorithms—K-mean clustering, the Gaussian mixture model, and agglomerative clustering—in automated categorization of alteration minerals along wells. As quantitative data for classification, we focused on the quartz indices of alteration minerals obtained from rock cuttings, which were calculated from X-ray powder diffraction measurements. The classification algorithms were first examined by applying synthetic data and then applied to data on rock cuttings obtained from two wells in the Hachimantai geothermal field in Japan. Of the three algorithms, our results showed that the Gaussian mixture model provides classes that are reliable and relatively easy to interpret. Furthermore, an integrated interpretation of different classification results provided more detailed features buried within the quartz indices. Application to the Hachimantai geothermal field data showed that lithological boundaries underpin the data and revealed the lateral connection between wells. The method’s performance is underscored by its ability to interpret multi-component data related to quartz indices.

scholarly journals Petrographical and mineral chemistry characteristics of mafic dykes in Nhi Ha area, Ninh Thuan and its meaning

2020 ◽  
Vol 2 (6) ◽  
pp. 201-213
Author(s):  
Nguyen Minh Tai ◽  
Pham Trung Hieu
Keyword(s):  
Chemical Analysis ◽  
Hydrothermal Alteration ◽  
Mineral Chemistry ◽  
Block Type ◽  
Mafic Dyke ◽  
Quaternary Sediment ◽  
Mafic Dykes ◽  
Dyke Rock ◽  
Alteration Minerals ◽  
Opaque Minerals

The NE-SW and NW-SE mafic dyke rocks in Nhi Ha area intruded through Cretaceous granitoid Dinh Quan or overlapped by Quaternary sediment materials. It has block type and blue grey in color in the field. Under microscope, based on minerals and textures, divided into 2 types of mafic dyke rock, such as diabase and porphyritic diabase. Minerals chemical analysis by EPMA method: plagioclase almost are labradorite (An 60.80%), oligoclase (An from 12.31 to 14.29%), some grain had albitation (An from 6.75 to 8.46%); pyroxene with augite (Wo41,80 En44,22 Fs13,98 to Wo43,40 En37,50 Fs19,10) and diopsite composition (Wo45,45 En42,48 Fs12,07 to Wo48,16 En40,02 Fs11,81); amphiboles in basalt are magnesio-hastingsite (Ca-amphibole group). Popular alteration minerals are chlorite, epidote and sericite. Chlorite is pycnochlorite type, ratio Fe/(Fe+Mg) <0,6 show that it formed by hydrothermal alteration process with temperature from 150 to 3250C. Opaque minerals are pyrite, chalcopyrite, ilmenite, magnetite, titanomagnetite, titanite (sphene) and a little bit of rutile.  

scholarly journals Occurrence of Hydrothermal Alteration Minerals at the Jade Hydrothermal Field, in the Izena Hole, Mid-Okinawa Trough

2014 ◽  
pp. 567-583 ◽  
Author(s):  
Youko Miyoshi ◽  
Jun-ichiro Ishibashi ◽  
Kazuhiko Shimada ◽  
Mitsuhiro Ooki ◽  
Seiichiro Uehara ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Okinawa Trough ◽  
Hydrothermal Field ◽  
Alteration Minerals
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