Study On Metallogenic Regularity And Prediction Of Late Paleozoic Sedimentary Manganese Deposits Near The Junction Of West Kunlun Tectonic Belt And Southwest Tianshan Tectonic Belt

The study area is located in the junction of two tectonic belts:West Kunlun Mountain and Southwest Tianshan Mountain.The two study target zones are located in the north and south sides of these two zones.The Markansu ore belt in the south is distributed along the northeast Pamir margin in a near east-west direction and belongs to the West Kunlun tectonic belt.The Jiegen metallogenic area on the north side is located in the southwest Tianshan tectonic belt.In recent years,some late Paleozoic sedimentary manganese deposits?or sites?have been found in Kizilesukerkezi Autonomous Prefecture?kizhou for short?of Xinjiang Uygur Autonomous Region.Oltokanash,Markantu,Muhu and other manganese deposits along the Markansu region have become the most important manganese ore belt in Xinjiang.The manganese ore deposits such as Bosuoguonentao and Tieklek in Jigen area are distributed in belts and have great prospecting potential.However,due to the short period of discovery of these ore belts,research degree of both on basic geology and on deposit geology is low,especially,in the Jigen area it is basically blank.Thus,studing In the late Paleozoic lithofacies palaeogeography and sedimentary environment research,comparising of ore-hosting formations,as well as studing the structural framework in the study area,investigating,furtherly,the enrichment mechanism of manganese ore,metallogenic evolution,and metallogenic regularities,have important guiding significance to evaluation of manganese resources and to rich manganese ore prospecting exploration for xinjiang regional and adjacent countries.The sedimentary manganese ore deposits in the joint of West Kunlun Mountain and Southwest Tianshan Mountain are often occur in layers and strictly controlled by the manganese-bearing strata of a certain age?Lower Devonian in Jigen and Upper Carboniferous in Markansu?.There are various manganese-bearing rock series,some of which are mainly siliceous rocks and some carbonate rocks.After the manganese ores was deposited,the morphology and occurrence of ore body changed obviously under the influence of structural transformation.Volcanic-sedimentary manganese deposit?manganese formed internally and externally at the same time?is often accompanied by massive sulfide deposits?copper and zinc?in the Markansu ore belt.The Manganese deposits in Markansu manganese ore belt are occur mainly in the Upper Carboniferous Kalaatehe formation?C2k?.According to its lithology,it is divided into three lithological sections:bioclastic limestone,grey-green litharenite,and marlaceous limestone with thin layered limestone,which is the most important horizon for sedimentary manganese ore deposit in the area.The manganese deposits?spots?in the Jigen area occur in the lower devonian Savayardon Formation?D1s?,which is a set of slightly metamorphic flysch formation.The Savayarton formation is divided into four lithological sections:bottom coarse clastic rock section,lower slightly metamorphic mudstone-siliceous rock-fine clastic rock section,middle carbonate rock section,and upper slightly metamorphic siliceous rock-mudstone-fine clastic rock section,with some carbonate rocks.Manganese ore bodies are found in both the lower siliceous rocks and the middle carbonate rocks.The Fe/Ti ratio of the Ortokanash deposit is 29.79 on average.The Al/?Al+Fe+Mn?ratio of manganese ore is 0.14?0.19?the average is 0.165?,and the wallrock's is 0.29?0.74,showing the characteristics of hot water deposition.The Y/Ho ratio of the ore averaged 25.69,which was basically consistent with that of deep-sea hydrothermal fluids.The content of manganese in the early Carboniferous basalt under the manganese bearing rock series is between 1000×10^-6?1500×10^-6,and the background value of manganese is relatively high,indicating that the source of manganese is related to the deep source.The average total REE of ores was 99.03×10^-6,which was significantly lower,indicating hydrothermal activity in the mineralization process.The average LREE/HREE ratio of manganese carbonate ore and its top and bottom limestone is 3.25.The average value of?Ce of manganese ore is 1.15;The average value of?Ce of wallrock is 0.83.This may be caused by the frequent geological activities in the early Carboniferous and the eruption of basic volcanic rocks on the seabed.The value of?Eu of ore is 0.95 on average,and the value?Eu of rock is 0.89 on average.All showed weak Eu negative anomalies.Value of?¹³C of the surrounding rock of the upper and lower floors of the manganese ore bodies is between 0.26‰?-2.73‰,which is similar to the?¹³C value of Marine carbonate.The range of?¹³C of manganese carbonate ore is between-9.47‰?-21.67‰,indicating that organic matter degradation process exists during manganese mineralization,resulting in carbon isotope fractionation.The value of?¹³C_PDB is negative,so the formation of manganese ore is caused by organic matter.The value of?¹⁸O of manganese ore is between-5.2‰?-11.45.The calculated surrounding rock deposit temperature is concentrated in 68.1?78.2?.The temperature range of manganese ore is 42.7?84.1?,which also indicates that the formation of manganese ore deposit is characterized by hot water deposition.The average Fe/Ti value of the manganese ores in Jigen area is 24.60.The average Al/?Al+Fe+Mn?value was 0.24,and the average total REE was 57.99 PPM.The LREE/HREE ratio of manganese ore and its roof and floor the surrounding rock is 9.04on average.The average value of?Ce of manganese ore is 1.17,and the average value of?Ce of surrounding rock is 1.02,indicating that manganese behavior is affected by submarine volcanism in the sedimentation-mineralization process.The average value of ore?Eu is 1.09,and the average value of?Eu of wallrock is 0.96.It shows weak Eu positive anomaly,which reflects that the rock/ore precipitation is involved in the action of submarine hot water.Since the early Carboniferous period,the extremely thick basic-neutral volcanic rocks of the lower carboniferous Wuluate formation were formed under the continuous extensional environment,in the Markansu manganese ore belt.By the end of the late Carboniferous volcanic activities terminated,a set of marine carbonate rocks was developed in the tectonic sedimentary basin,and the paleogeographic environment was a shallow marine sedimentary basin.The mineralization of manganese can be divided into sedimentary diagenesis,hydrothermal modification,and supergenic oxidation.The metallogenic model is the evolution process of manganese polymetallic ore mineralization from crater?VMS?and proximal source?crater?dominated by volcanic-deposition to distal source?both sides of crater?dominated by chemical deposition.The lower and bottom of the lower devonian Savayardon Formation around Jigen in southwest Tianshan correspond to the sedimentary environment of estuarine delta.The middle part represents the shallow Marine sedimentary environment of deeper water.The upper part is a shallow Marine sedimentary environment.The formation of manganese deposits had undergone three stages:sedimentary diagenesis,metamorphic modification,and supergenic oxidation.The ore-bearing rocks have the characteristics of hydrothermal deposition.The source of manganese is closely related to it.Thus,these ores should belong to hydrothermal deposition-matemorphic reformation deposits.In order to realize the restriction of structures to ore bodies,The field investigation and study of the structural elements were carried out in and around the study area,and the structural framework of the study area was constructed.The Markansu manganese ore belt was placed in a anticlinorium,named as“Markansu River anticlinorium”.it contains,from north to south,Markansu river anticline-Markantu overturned syncline-Tandieer overturned anticline-Markanataqiaoku overturned anticline and other secondary folds,overturned fold axial plane are inclined to the south,reflecting the nappe power from south to north.Markantu syncline is the main ore-bearing structure in the study area.To the west of Muhu-Marcantu,the 12-line carboniferous structure style was determined,and the core of the Tandieer anticline was established.The south wing of the core extended to the east,dividing the new manganese bearing rock belt in the south and broadening the scope of manganese prospecting.In the Jigen manganese ore prospect area,the devonian system constitute a series of fold structures in NNE-SN direction.The carbonate rocks lower section of Tuogemaiti formation?D2?appear repeatedly on east and west wings of the central Aitike anticlinorium.The clastic rocks belonging to upper section of Tuogemaiti formation distributs on the west side of this anticlinorium.It reflects a pattern of the anticline:yonger on both sides,and older core of it.On east side of the anticlinorium,the upper part of the lower devonian Savayaerdun formation is in contact directly with the upper-top Silurian Tartekuli formation?S3-4?.identification of a series of synclinal structures presented by the lower part of the Tuogemaiti formation as the core is favorable for manganese prospecting.The sedimentary manganese deposits at the junction of West Kunlun mountains and Southwest Tianshan Mountains have the following characteristics:?1?The manganese mineralization related to Marine volcanism shows the characteristics of"endogenous source and exogenous deposit".The ore-forming material mainly comes from the deep-source hydrothermal?water?bearing hydrocarbons jet deposition caused by submarine volcanic eruption.?2?There are signs that hot water solution is involved in mineralization.Malkansu Manganese ore belt belongs to near volcanic-sedimentary formation,and the manganese bearing formation is accompanied by volcanic rocks and pyroclastic rocks.And Jiegen area belong to far from volcanic-sedimentary formation,the manganese-bearing formation is dominated by terrigenous clastic rocks with a small amount of volcanic material,but the geochemical characteristics show that the hydrothermal sedimenting was involved in ore formation.?3?The ore-hosting rocks may be all silicate rocks and carbonate rocks.The rock types are rich in carbonaceous and there are complex trace elements in siliceous rocks.Bosoguonentao in the north of Jigen manganese ore prospect area is a siliceous sand shale reservoir,while Kerkekunguoyishan in the south is a carbonate reservoir.The Tandieerl manganese deposit occurs in tuff on the top of volcanic rock construction.?4?Manganese ore types are rich ore in both belts,but there are Distinct differences in ore mineral composition.In the Markansu manganese ore belt manganese minerals are prodominated by primary manganese carbonates,with a small amount of secondary manganese oxide ore.The ore minerals are mostly rhodochrosite and Calcium rhodochrosite with a few caryopilite and alabandite.But silicate phase of manganese ore occupies a large proportion in the Jigen manganese ore prospect area.?5?Manganese ores are distributed in groups?zones?.The Jigen manganese ore prospect area is interpreted as an inter-arc depression-back-arc basin of an island arc sedimentary rock belt at the passive continental margin.The Markansu manganese ore belt might represent a shallow sea and a deep-water depression,belonging to an island arc volcanic-sedimentary rock belt at the active continental margin.Both of them belong to the subsea hydrothermal sedimentary of manganese deposit generated in the complex tensile tectonic environment.?6?After the formation of manganese ore body,it was obviously transformed by late tectonic movement,which is a change process of the structure and mineral composition of ore body from simple and complete to complex and damaged.Today's ore bodies are mostly located in the nucleus and two wings of syncline structure.?7?Manganese ore mineralization time belongs to late Paleozoic.Carboniferous period dominates,followed by Permian period,in the Markansu manganese ore belt.The age of manganese formation is early Devonian in Jigen area,and the accumulation of manganese has regional simultaneity.The comparison of regional geological background,types of manganese bearing structures,sedimentary facies and sedimentary environment of manganese forming stage,proved manganese rich ore resources and degree of structural transformation,as well as other ore-forming elements between Markansu manganese ore belt and Jigen manganese ore prospect area shows that the former has good conditions for forming large-and medium-sized manganese ore deposits,mong them,the long-term a large number of basic magma eruption and water-rock exchange of volcanic lava and tuff with paleoseawater provided plenty of Mn source,and relatively sedimentary sag area above volcanic rocks have very good gathering effect,and plenty of organic matter was in favour of manganese mineral precipitation and fixation,all of these ares particularly important elements.Thus,Markansu belt has great regional prospecting potential.The latter has more complex ore-forming conditions and makes less contribution to formation of manganese ore and the location of ore body in manganese source,manganese bearing structure,paleogeographic environment and post-mineralization tectonic transformation,which increases the difficulty of ore prospecting.Based on the above research results,combining with the geophysical,geochemical,and remote sensing information in the study area,the Markansu Mn belt,3?-level prospecting target areas and 1?-level prospecting target area is sketched.In Jigen manganese ore prospect area three worth for further mining sections are put forward:the target?-1,?-2,and?-1.