‘Indicator’ carbonaceous phyllite/graphitic schist in the Archean Kundarkocha gold deposit, Singhbhum orogenic belt, eastern India: Implications for gold mineralization vis-a-vis organic matter

Sahoo, Prabodha Ranjan; Venkatesh, A. S.

doi:10.1007/s12040-014-0488-y

Cited by 16 publications

(3 citation statements)

References 41 publications

(72 reference statements)

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“…Organic rich metasedimentary rocks act as a trap as well as a source of valuable elements such as Au, Ag and Bi (Large et al 2011;Hazarika et al 2013;Sahoo and Venkatesh 2014). The organic matter within carbonaceous metasedimentary rocks indicates reducing conditions favourable for the formation of diagenetic pyrites.…”

Section: Role Of Organic Mattermentioning

confidence: 99%

Trace-element systematics of pyrite and its implications for refractory gold mineralisation within the carbonaceous metasedimentary units of Palaeoproterozoic South Purulia shear zone, eastern India

et al. 2019

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Globally, refractory gold occurs in significant proportions in many types of gold deposits. The present work reports the occurrence of sulphide-hosted refractory gold within the carbonaceous phyllites of the South Purulia shear zone in the Singhbhum crustal province, eastern India. Detailed textural characteristics, paragenesis and trace-element concentrations of different generations of pyrites were studied to understand their evolutionary stages and the mechanism of gold incorporation in pyrites. Four types of pyrites, which are closely associated with gold mineralisation were identified in the host rock, i.e., carbonaceous phyllite. Py I is of diagenetic origin, whereas Py II, Py III and Py IV are of hydrothermal origin. Laser ablation inductively coupled plasma mass spectrometry studies confirm the presence of invisible/refractory gold concentration up to 110.55 ppm within these pyrites. The positive correlation between Au and As in pyrite indicates the significant role of As in the incorporation of gold in pyrite. Fourier transform infrared spectroscopy confirms the presence of organic matter that provided suitable redox conditions for the precipitation of auriferous pyrites. The refractory gold mineralisation is attributed to widespread sulphidation during both sedimentation and hydrothermal ore-forming processes. Transformation of diagenetic pyrite to pyrrhotite during prograde metamorphism of carbonaceous rocks promoted the liberation of sulphur and Au from the lattice of abundant diagenetic pyrites to the hydrothermal fluid which later precipitated sulphides in the quartz ± carbonate veins.

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Section: Role Of Organic Mattermentioning

confidence: 99%

Trace-element systematics of pyrite and its implications for refractory gold mineralisation within the carbonaceous metasedimentary units of Palaeoproterozoic South Purulia shear zone, eastern India

et al. 2019

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“…More over, or ganic mat ter dispersed within phyllite was ana lysed for the first time in search for biomarkers to de ter mine its or i gin. While car bo na ceous phyllites are rel a tively com mon, there are only few pa pers on organic mat ter in those rocks fo cused on the or ganic mat ter role in the ore-form ing pro cesses (Sahoo and Venkatesh, 2014;da Silva Nogueira de Matos et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Mineralogy and organic geochemistry of phyllite from the Dewon–Pokrzywna deposit, the Opava Mountains (SW Poland)

Sawicka¹,

Janeczek²,

Fabiańska³

et al. 2018

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As so ci ate ed i tor: Tadeusz Peryt Phyllites from the Dewon-Pokrzywna de posit in the Opava Mts., SW Po land, were in ves ti gated by XRD (Rietveld method), XRF, EPMA, SEM, and ATR-FTIR from the per spec tive of their po ten tial us age as a buffer and/or back fill ma te rial in a geolog i cal re pos i tory of ra dio ac tive waste. Or ganic mat ter dis persed in the phyllite ma trix was ana lysed by GC-MS. Fine-grained Mg-Fe-mus co vite (13 to 29 wt.%), Fe-ripidolite (10 to 25 wt.%), de tri tal quartz (20 to 46 wt.%), and al bite (7 to 28 wt.%) ± microcline, illite or illite/smectite, and kaolinite are ma jor min er als in phyllite sam ples. The chlorite/mus co vite ra tio ranges from 0.65 to 1.1. Mg-annite in her ited from the pre cur sor rock is a mi nor con stit u ent. De tri tal il men ite is a dom i nant ac ces sory min eral. Ancylite-(Ce) oc curs in quartz-cal cite-ripidolite veins. Two types of phyllite have been dis tin guished based on the pro por tion of phyllosilicates to silt frac tion: ar gil la ceous (47 to 55 wt.% phyllosilicates) and silt-rich (28 wt.% phyllosilicates). Ar gil la ceous phyllite shows el e vated con tent of alu mina and mod er ate con cen tra tion of sil ica. It is highly en riched in Fe compared to phyllites from other lo cal i ties world wide. The BET spe cific sur face area of ar gil la ceous phyllite ranges from 1.73 to 3.64 m 2 /g. Whole-rock chem i cal com po si tion, min eral as sem blages, chlorite geothermometry, and the oc cur rence of aliphatic hy dro car bons sug gest that ar gil la ceous phyllite orig i nated from a pe lagic pelite protolith un der low-tem per a ture (260-370°C) greenschist to subgreenschist fa cies con di tions. Per sis tent biomarkers are in dic a tive of bac te rial deg ra da tion of plank tonic or ganic mat ter sus pended in a high wa ter col umn. En rich ment in Fe-rich chlorite and Mg,Fe-mus co vite, low volume of in ter con nected pores with dom i nant mesopores sug gest that ar gil la ceous phyllite from the Dewon-Pokrzywna deposit is a po ten tial can di date for a buffer and/or back fill ma te rial.

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“…The other important greenstone schist belt of DhV enriched with gold (Au) and other mineralization is located in the Singhbhum Craton of the Eastern India (Mazumder 2005). Kundarkocha gold deposit (22 • 10 N, 86 • 16 E) has proven evidences of gold mineralization within the Precambrian Singhbhum orogenic belt in the Eastern India (Sahoo and Venkatesh 2014). Recently, Jha et al (2015) reported the occurrence of invisible gold within the North Singhbhum Mobile Belt of Singhbhum crustal province by petrographic, SEM and EPMA studies.…”

Section: Introductionmentioning

confidence: 99%

Audio-magnetotelluric investigation of sulfide mineralization in Proterozoic–Archean greenstone belts of Eastern Indian Craton

et al. 2018

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Greenstone belts are well known for gold occurrences at different regions of the world. The Dhanjori basin in the eastern Singhbhum region shows major characteristics of a rifted greenstone belt. Initially, we conducted 14 audio-magnetotelluric (AMT) measurements for a profile of ∼20 km in the frequency range of 1 kHz to 10 Hz over this rather complex geologic environment covering Dhanjori Volcanics (DhV) and Kolhan Group (KG). Subsequently, gravity and magnetic surveys were also conducted over this AMT profile. The purpose of the survey was to identify and map conductive features and to relate them to metallogeny of the area along with the mapping of the basement of Dhanjori basin. The strike analysis showed N30 • W strike for DhV for all the frequencies and for sites over KG domain in the frequency range of 100-10 Hz, but for KG domain, the obtained strike in 1 kHz to 100 Hz is N45 • E. As the combination of transverse electric (TE), transverse magnetic (TM) and tipper (Tzy) can recover the electrical signature in complex geological environment, we discuss the conductivity model obtained from TE+TM+Tzy only. The inversion was carried for the regional profile with 14 sites and for 7 sites over KG domain. Conductivity model shows two well resolved conductors, one each in KG and Quartz Pebble Conglomerate Dhanjori (QPCD) domains respectively showing common linked concordant features between these regional and KG profiles. The conductors are interpreted as sulfide mineralization linked with QPCD group of rocks which may host gold. These conductors are also horizontally disposed due to the intrusive younger Mayurbhanj Granite. These intrusives correlate well with the gravity modeling as well. The thickness of the Dhanjori basin at the central is about 3.0 km, similar to that from gravity modeling. The conductivity model also indicates the presence of shallow conductors, but could not be resolved due to lack of high frequency data. However, the results from the close-by drill site indicate the presence of shallow sulfide mineralization hosting gold. The deep level conductors delineated from AMT studies are associated with gravity high and low magnetic. ICP-AES results of Dhanjori samples show significant concentration of gold ∼5.0 g/t, which is of economic consideration. Thus, it can be inferred that the conductors have evidences of sulfide mineralization which host gold.

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‘Indicator’ carbonaceous phyllite/graphitic schist in the Archean Kundarkocha gold deposit, Singhbhum orogenic belt, eastern India: Implications for gold mineralization vis-a-vis organic matter

Cited by 16 publications

References 41 publications

Trace-element systematics of pyrite and its implications for refractory gold mineralisation within the carbonaceous metasedimentary units of Palaeoproterozoic South Purulia shear zone, eastern India

Trace-element systematics of pyrite and its implications for refractory gold mineralisation within the carbonaceous metasedimentary units of Palaeoproterozoic South Purulia shear zone, eastern India

Mineralogy and organic geochemistry of phyllite from the Dewon–Pokrzywna deposit, the Opava Mountains (SW Poland)

Audio-magnetotelluric investigation of sulfide mineralization in Proterozoic–Archean greenstone belts of Eastern Indian Craton

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