Structural deformation,ore-controlling characteristics and prospecting prognosis of Wuxu ore-field in the southern Nandan—Hechi metallogenic belt
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    Abstract:

    Wuxu ore-field is located in the southern part of Nandan—Hechi metallogenic belt,northern Guangxi,which is an important area of polymetallic mineralization in the southwestern part of the South China Block (SCB).However,the previous studies on the structural geology were relatively weak, which indirectly leads to the bottleneck of the exploration of this area in recent years.The aim of this paper is to provide guidance for prospecting of Wuxu orefield by analyzing the tectonic stress field and its tectonic evolution.Methods: In this paper,we present new structural data related to superimposed folds,fault and conjugated joints to define the paleo-stress regime with the aim to constrain the Mesozoic tectonic evolution of the Wuxu orefield.Furthermore,through the analysis of ore controlling structural style and ore controlling regularity of Bawang deposit,we put forward the prospecting strategies in the future.Results: Four stages of tectonic stress field and two types of ore-controlling structural styles have been identified through field scale geological structure survey and ore-controlling structural analysis.The four stages of tectonic stress fields are as follows: the first NE-trending compression (D1) was the product of the Indosinian movement,which was related to the closure of the Paleo-Tethys Ocean,i.e.the collision and amalgamation of the Indosinian Block and the South China Plate;the second stage of NWW—EW-trending compression (D2), formed in the early Yanshanian movement in the middle and late Middle Jurassic,which was driven by the collision of the Paleo Pacific Plate(or the Izanagi Plate) with the South China Plate;the third stage of SN-trending compression(D3)occurred in the early stage of Late Cretaceous,and its dynamic background may be N—NNW- trending subduction and collision of Paleo Pacific Plate or Izanagi Plate to South China Plate;the fourth stage of SN-trending tensility (D4) may be related to the back arc spreading caused by the high-angle subduction or retreat of the Paleo Pacific Plate.The two types of ore-controlling structural styles are NEE—NE-trending faults,fractures and bedding sliding fracture zones.The extensional activity of the cutting faults and fractures after the D4stage controlled the formation of the echelon vein orebody,which made the single orebody have a westward lateral tendency,while the ore belt presents an eastward lateral tendency.The stratified ore bodies were controlled by fold collapse spaces in D1 stage and tectonic compression in D3 stage,showing local swelling and pinch-out reappearance.Conclusions: According to the structural ore-controlling regularity and the characteristics of ore-controlling structural combination,it is considered that the SSE direction of No.1 main orebody (the lateral direction of ore belt) is the first choice for the next ore-prospecting section.The composite parts of the EW-trending folds and the NEE—NE-trending faults and the NNW—SN-trending bedding sliding fracture zones are important prospecting directions.The NNW—SN-trending sliding fracture zones have the characteristics of isometric ore-controlling,so the strike tracing should be strengthened.

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ZENG Guangqian, LIANG Enyun, LIU Gengyin, ZOU Guangjun, HUANG Yuanneng.2021. Structural deformation, ore-controlling characteristics and prospecting prognosis of Wuxu ore-field in the southern Nandan—Hechi metallogenic belt[J]. Geological Review,67(6):1727-1747.

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History
  • Received:April 21,2021
  • Revised:August 02,2021
  • Adopted:
  • Online: November 19,2021
  • Published: November 15,2021