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The Collision Between Indochina and South China Blocks in Northwestern Vietnam and its Controversy

Hung Khuong The, Golonka Jan, Du Nguyen Khac

Inżynieria Mineralna

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2023

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no. 2, vol. 1

103--112

EN

The Indosinian orogeny, which was regarded as the collision event between the South China and Indochina blocks that occurred in Southeast Asia, including Vietnam, resulting in the formation of the Indosinian mountain range. However, the question of how many times collision between these blocks occurred in the past and during which period remains unanswered. Furthermore, the closure of the ancient ocean and the evidence of its remnants between the South China and Indochina Blocks are still the subjects of serious debate. The underlying origin of the Indosinian thermo-tectonism is uncertain. The entire region was affected by the thermal-tectonic processes in the west, caused by the collision of the Sibumasu plate and Indochina block. The absence of evidence supporting the Indosinian as a significant mountain-building event is highlighted through an examination of regional paleogeography, as well as palaeontological and thermochronological data. There is no conclusive evidence to suggest that the Indochina and South China blocks collided during the Triassic times. A plate tectonic scenario that describes the Indosinian orogeny as a reactivation event triggered by the accretion of the Sibumasu block to Indochina is favored.

2

The eastern extension of the Avalonian terranes, the Prototethys and Paleotethys oceans

Golonka Jan, Hung Khuong The, Du Nguyen Khac, Krobicki Michał

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

23--24

EN

Avalonia was an archipelago of microcontinents divided into West and East Avalonia. West Avalonia included south-eastern parts of Nova Scotia, eastern Newfoundland, New Brunswick, Florida(?), and New England, while East Avalonia included southern Ireland, southern Scotland, England, northern France, the Brabant Massif, Lusatia, northern Germany, and north-western Poland. Several crustal fragments such as the Bruno–Silesia terrane, Moesian terranes, Istanbul/Zonguldak terrane constituted an extension of East Avalonia (Golonka et al., 2023). These microcontinents detached from Gondwana during the Early Paleozoic times. Golonka et al. (2023) also portrayed a chain of microcontinents moving away from Gondwana across the Palaeoasian (Protothetys) Ocean. These chain included Scythian, Turan, South Kazakhstan, Junggar, Tarim and Indochina. The Rheic-Palaeotethys Ocean opened behind these microcontinents. Collision occurred between Avalonia, Laurentia and Baltica during Caledonian Orogeny. This collision also included Bruno–Silesia, Moesia terranes, Istanbul/Zonguldak, Scythian and Turan terranes (Golonka & Gawęda, 2012). The events involving Junggar, South Kazakhstan and Tarim are more speculative. Indochina collided with South China along Song Ma– Truong Song–Ailaoshan suture during latest Silurian–earliest Devonian times. In northwestern Vietnam, the Late Silurian Song Chay complex granitoid is connected to this event. Moreover, the deep-water deposits such as Pa Ham formation were later replaced by shallow-water sedimentary formations, including the continental Lower Devonian red beds and Lower Devonian Nam Pia Formation composed mainly of terrigenous sediments and marl, medium-bedded to massive fine-grained limestone, representing shallow water sediments. The Lower Paleozoic greenschists of deepsea origin were unconformably covered in many localities by Devonian redbeds (Son et al., 1978; Hung, 2010; Hung et al., 2023).

3

Sulfur and lead isotope geochemical characteristics of Pb-Zn deposits in the Khau Loc zone, northeastern Vietnam, and their significance

Hung Khuong The, Tung Ta Dinh, Binh Do Quoc, Sang Pham Nhu, Cuc Nguyen Thi, Linh Nguyen Thi Hoang, Tin Quach Duc

Geology, Geophysics and Environment

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2021

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Vol. 47, no. 3

143--157

EN

In northeastern Vietnam, the Khau Loc zone is considered to have high potential for lead-zinc mineralization. The lead isotope data for 18 galena samples and 18 ones of δ34S isotope data (including galena and pyrite samples) were collected from lead-zinc ore deposits in some areas in the Khau Loc zone, including Phia Dam, Khuoi Man, Ban Lin, Lung Dam, and Ta Pan. These were employed to investigate the sulfur and lead isotope geochemical characteristics of Pb-Zn deposits and their significance in this study. The samples were analyzed using the LA-ICP-MS to show that the Pb isotopic ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in the galena samples range from 17.8908 to 18.6012, 15.5794 to 16.1025, 38.4420 to 39.2118, with the average values of 18.296, 15.749, and 38.812, respectively. The pyrite and galena samples had the δ34S isotope, ranging from 9.0 to 15.106. The sulfur isotope systematics implies that most of the lead-zinc ore formations originated from marine sedimentary evaporation deposits and magmatic intrusion-volcanic eruption sources rich in silica. The distribution of lead isotopic ratios had a well-defined cluster for each deposit, indicating the formation of lead-zinc deposits and lower crust and orogen trends. In addition, these findings of lead isotopic ratios and δ34S isotopes proved that the Khau Loc zone is an activated structure with continuous growth in continental crust thickness during the early Proterozoic and Cenozoic periods. Furthermore, the study results also presented the evolution of material sources involved in the formation of lead-zinc ores in the Khau Loc zone.

4

Polymetallic Nodules Resource Estimation in the Suoi Thau-Sang Than Area, Northeastern Vietnam

Hung Khuong The, Sang Pham Nhu, Phuong Nguyen, Dung Nguyen Tien, Bui Hoang‑Bac, Nguyen Quoc Phi, Bui Viet Sang

Inżynieria Mineralna

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2020

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no. 2, vol. 1

7--14

EN

1,720 chemical, mineral, and petrography samples in the Suoi Thau-Sang Than area, northeastern Vietnam were collected to investigate polymetallic nodules resource. The similarity-analogy in ore geology, direct calculation method for metallization parameters, and mineral resource estimation based on cutoff grade change methods are employed to estimate polymetallic nodules resource from the Suoi Thau, Sang Than, and Ban Kep areas in northeastern Vietnam. The similarity-analogy in ore geology indicates 1,785,000 tons Cu, 12,005,000 tons Pb+Zn, and 195 kg Au in total. The direct calculation method for metallization parameters shows 2,060,000 tons Cu, 13,648,000 tons Pb+Zn, and 224 kg Au in total. These methods display that the Sang Than area contains mainly polymetallic nodules in the studied area. Following the mineral resource estimation based on cutoff grade changes, estimation results indicate potential Pb-Zn nodules resource in the Ban Kep and Cu nodules resource in the Sang Than, while no potential Au nodules resource in the Suoi Thau and the Sang Than as well as the Ban Kep. The estimation results obtained from mineral resource estimation based on cutoff grade changes are suitable with the results from the traditional geometric block methods. Our study suggests that the Sang Than area can be considered as a potential Cu nodules resource, and the Ban Kep area is potential Pb-Zn nodules resource in northeastern Vietnam for future exploitation, while there is no potential polymetallic nodules resource in the Suoi Thau area. Furthermore, the one resource estimation based on cutoff grade changes method displays an overview of the prospect on polymetallic nodules resources, indicating that this method can serve as a basis for the proposed selection of the prospective areas for effective Cu, Pb-Zn, and Au mineral exploration in the Suoi Thau-Sang Than area, northeastern Vietnam.

PL

W celu zbadania zasobów konkrecji polimetalicznych zebrano 1,720 próbek substancji chemicznych, minerałów i petrografii z obszaru Suoi Thau-Sang Than w północno-wschodnim Wietnamie. Podobieństwo-analogia w geolo-gii rudy, metoda bezpośredniego obliczania parametrów metalizacji i szacowania zasobów mineralnych w opar-ciu o metody zmian zawartości granicznej są wykorzystywane do szacowania zasobów konkrecji polimetalicz-nych w obszarze Suoi Thau, Sang Than i Ban Kep w północno-wschodnim Wietnamie. Podobieństwo-analogia w geologii rudy wskazuje łącznie na 1,785,000 ton Miedzi, 12,005,000 ton Ołowiu + Cynków i 195 kg Żłota. Meto-da bezpośredniego obliczania parametrów metalizacji pokazuje łącznie 2 060 000 ton Miedzi, 13,648,000 ton Ołowiu + Cynków i 224 kg Żłota. Te metody pokazują, że obszar Sang Than zawiera głównie konkrecje polimeta-liczne na badanym obszarze. Po oszacowaniu zasobów mineralnych na podstawie zmian zawartości granicznej, wyniki oszacowań wskazują na potencjalny zasobów konkrecji Ołowiu - Cynków w Ban Kep i Miedzi w Sang Than, natomiast nie ma potencjalnego zasobu konkrecji Żłota w Suoi Thau i Sang Than, a także w Ban Kep. Wy-niki uzyskane z szacowania zasobów mineralnych na podstawie zmian zawartości granicznej są zgodne z wyni-kami tradycyjnymi metodami bloków geometrycznych. Nasze badanie sugeruje, że obszar Sang Than można uznać za potencjalny zasób konkrecji Miedzi, a obszar Ban Kep jest potencjalnym zasobem konkrecji Ołowiu + Cynków w północno-wschodnim Wietnamie do przyszłej eksploatacji, natomiast w obszarze Suoi Thau nie ma potencjalnego zasobu konkrecji polimetalicznych. Co więcej, oszacowanie zasobu w oparciu o metody zmian zawartości granicznej przedstawia przegląd perspektyw dotyczących zasobów konkrecji polimetalicznych, wska-zując, że metoda ta może służyć jako podstawa do proponowanego wyboru perspektywicznych obszarów efek-tywnych Miedzi, Ołowiu-Cynków i Żłota poszukiwanie minerałów w obszarze Suoi Thau-Sang Than w północno-wschodnim Wietnamie.

5

Statistical evaluation of the geochemical data for prospecting polymetallic mineralization in the Suoi Thau–Sang Than region, Northeast Vietnam

Hung Khuong The, Sang Pham Nhu, Phuong Nguyen, Linh Vu Thai, Sang Bui Viet

Geology, Geophysics and Environment

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2020

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Vol. 46, no. 4

285--299

EN

In Northeast Vietnam, Suoi Thau-Sang Than is considered as a high potential area of polymetallic deposits. 1,720 geochemical samples were used to investigate polymetallic mineralization; thereby polymetallic ore occurrences in this study region were discovered and the statistical and multivariate analysis helps to define geochemical anomalies in some northeastern regions, namely Suoi Thau, Sang Than, and Ban Kep. The statistical method and cluster analysis of geochemical data indicate that the Cu, Pb, and Zn elements are good indicators, and most of them comply with the lognormal or gamma distribution. Based on the third-order threshold, the geochemical anomalies of the content of the Cu, Pb, and Zn elements reflect the concentration of copper forming ore bodies in the mineralized zone, and clearly show the concentration in three distinct zones. The trend surface analysis which was employed to determine spatial variations and relationships among these good indicator elements and anomalous areas revealed relative changes in the content of the indicator elements, and they can be considered as regular. Moreover, the goodness of fit obtained trend functions of Pb and Zn, and Cu elements is a third-degree trend surface model. These results indicate that the models can be useful in studying geochemical anomalies and analyzing the tendency of the concentration of indicator elements in the Suoi Thau-Sang Than region. Additionally, it is suggested that the statistical analysis shows a remarkable potential to use the bottom river sediments in the region to investigate polymetallic mineralization. Moreover, geochemical data can help to evaluate geochemical anomalies of the pathfinder elements and potential mineral mapping of the Suoi Thau-Sang Than region in Northeast Vietnam.