唐菊興, 丁 帥, 孟 展, 胡古月, 高一鳴, 謝富偉, 李 壯,袁 梅, 楊宗耀, 陳國榮, 李于海, 楊洪鈺, 付燕剛

1)中國地質(zhì)科學(xué)院礦產(chǎn)資源研究所, 國土資源部成礦作用與資源評價(jià)重點(diǎn)實(shí)驗(yàn)室, 北京 100037;

2)成都理工大學(xué)地球科學(xué)學(xué)院, 四川成都 610059;

3)西藏中瑞礦業(yè)發(fā)展有限責(zé)任公司, 西藏拉薩 850000; 4)中國地質(zhì)大學(xué)(北京), 北京 100083

西藏林子宗群火山巖中首次發(fā)現(xiàn)低硫化型淺成低溫?zé)嵋盒偷V床
——以斯弄多銀多金屬礦為例

唐菊興1), 丁 帥2), 孟 展2), 胡古月1), 高一鳴1), 謝富偉2), 李 壯2),袁 梅2), 楊宗耀2), 陳國榮3), 李于海3), 楊洪鈺3), 付燕剛4)

1)中國地質(zhì)科學(xué)院礦產(chǎn)資源研究所, 國土資源部成礦作用與資源評價(jià)重點(diǎn)實(shí)驗(yàn)室, 北京 100037;

2)成都理工大學(xué)地球科學(xué)學(xué)院, 四川成都 610059;

3)西藏中瑞礦業(yè)發(fā)展有限責(zé)任公司, 西藏拉薩 850000; 4)中國地質(zhì)大學(xué)(北京), 北京 100083

西藏岡底斯成礦帶分布著大面積古近紀(jì)(70–40 Ma)林子宗群火山巖。但如此強(qiáng)烈的火山-巖漿作用,與安第斯成礦帶相比(如馬力昆帶(Franja de Maricunga)、印地—帕斯瓜帶(Franja El Indio-Pascua)), 除了碰撞伸展階段形成的驅(qū)龍、甲瑪?shù)劝邘r-矽卡巖型銅多金屬礦床外(23–13 Ma), “缺位”資源規(guī)模大、經(jīng)濟(jì)價(jià)值高的淺成低溫?zé)嵋盒偷V床成礦亞系列。該類礦床是剝蝕了, 還是沒有發(fā)現(xiàn)？本文在前人工作基礎(chǔ)上, 通過詳細(xì)的地質(zhì)勘探、地質(zhì)填圖、地質(zhì)編錄、鏡下鑒定、能譜和電子探針分析, 在南木林盆地斯弄多地區(qū)林子宗群陸相火山巖中識別出低硫化淺成低溫?zé)嵋盒豌y鉛鋅(銦鎘金)礦床。礦體由產(chǎn)于流紋斑巖中的隱爆角礫巖型銀鉛鋅礦體、火山機(jī)構(gòu)旁側(cè)的熱液脈型銀鉛鋅礦體及斷裂上盤的銀(鉛鋅)礦體組成, 目前控制Pb+Zn資源量超過30萬噸(331+332為主)@Pb+Zn＞5％, Ag資源量超過400噸@Ag＞50 g/t。主要金屬礦物為方鉛礦、閃鋅礦、輝銀礦、硫砷銅銀礦、黃鐵礦, 微量黃銅礦, 主要蝕變組合為: 石英-玉髓-碧玉, 重晶石-螢石, 冰長石-伊利石-絹云母, 菱鐵礦-菱錳礦; 礦石構(gòu)造以脈狀、角礫狀、網(wǎng)脈狀、條帶狀、層紋狀、皮殼狀、塊狀、浸染狀等, 發(fā)育結(jié)晶作用和交代作用形成的礦石結(jié)構(gòu); 近地表發(fā)育古熱泉噴口, 堆積條帶狀、層紋狀硅質(zhì)沉積物。綜合上述地質(zhì)信息, 確定該礦床為典型低硫化淺成低溫?zé)嵋盒豌y多金屬礦床。這一重要礦床類型的發(fā)現(xiàn)和確定在岡底斯成礦帶乃至西藏特提斯成礦省尚屬首例, 對岡底斯成礦帶廣泛發(fā)育形成于70～40 Ma的林子宗群火山巖地區(qū)區(qū)域找礦具有積極和重要的指導(dǎo)意義, 其重要性不容低估。

斯弄多; 林子宗群火山巖; 冰長石-絹云母-伊利石; 低硫化型; 淺成低溫?zé)嵋恒y多金屬; 岡底斯

“淺成低溫?zé)嵋骸边@一術(shù)語最初由Lindgren (1922)對熱液礦床按其形成的溫度和深度進(jìn)行分類研究時(shí)首次提出。其后, 許多研究者不斷對淺成低溫?zé)嵋盒偷V床含義及分類進(jìn)行著補(bǔ)充和完善, 目前定義為含礦熱液上升至淺地表(＜2 km)、在中低壓(＜100 Pa)、中低溫度(200～300℃)條件下形成的一類礦床(Lindgren, 1922, 1933; Hendenquist, 1987; White and Hendenquist, 1990; Hendenquist et al., 2000; Corbett, 2002; Simmons et al., 2005)。并根據(jù)流體中硫的氧化還原態(tài)與蝕變礦物組合劃分為高硫化(明礬石-高嶺石型)和低硫化(冰長石-絹云母型)兩種端元類型(Hendenquist, 1987; Heald et al., 1987; Einaudi et al., 2003; Sillitoe and Hedenquist, 2003)。同時(shí),隨著全球范圍內(nèi)大量淺成低溫?zé)嵋盒偷V床相繼被發(fā)現(xiàn), 這類礦床逐漸成為全球金、銀、銅、鉛、鋅等有色資源重要礦床類型之一(Corbett, 2002; 江思宏等, 2004; Sidorov et al., 2015; Páez et al., 2016), 地質(zhì)學(xué)家們逐漸認(rèn)識到這類礦床主要產(chǎn)于板塊俯沖帶邊緣的島弧、陸緣弧中(Hendenquist et al., 2000; Corbett, 2002; Richards, 2013), 與同期陸相火山-次火山活動(dòng)在時(shí)空上有著密切聯(lián)系, 并強(qiáng)調(diào)火山作用對成礦的貢獻(xiàn)(Sidorov et al., 2015; Nadeau et al., 2016)。

西藏岡底斯帶發(fā)育的多條不同時(shí)期、線性分布的火山-巖漿巖帶是形成大-超大型礦床的有利條件,現(xiàn)已發(fā)現(xiàn)多個(gè)具有重要經(jīng)濟(jì)價(jià)值的斑巖-矽卡巖型銅多金屬礦(如: 甲瑪、驅(qū)龍、雄村、幫浦等)、矽卡巖型鉛鋅礦(龍瑪拉、洞中拉—洞中松多、亞貴拉等)及熱液脈型銀鉛鋅礦床, 使得該區(qū)成為我國一條重要銅多金屬成礦帶(Hou et al., 2009; 郎興海等, 2012; 唐菊興等, 2012, 2014a, b; Tang et al., 2015; Zheng et al., 2016)。作為岡底斯構(gòu)造-巖漿-成礦帶中規(guī)模最大的林子宗群火山巖, 其東西展布大于1 200 km, 分布范圍占岡底斯巖漿帶面積的一半以上(圖1a)(Mo et al., 2008), 與岡底斯大巖基一起構(gòu)成岡底斯帶最重要的巖漿巖組合, 代表著白堊紀(jì)晚期—早新生代(70—40 Ma)青藏高原南部的一次大規(guī)模的構(gòu)造巖漿事件(Ding et al., 2003, 2005; 侯增謙等, 2006)。然而, 如此強(qiáng)烈的火山-巖漿活動(dòng)是否伴有重要的成礦作用？與安第斯成礦帶相比(如馬力昆帶(La Franja de Maricunga)、印地—帕斯瓜帶(Franja El Indio-Pascua)), 是否形成與之類似的淺成低溫?zé)嵋盒唾F金屬礦床？盡管近年來南木林盆地相繼發(fā)現(xiàn)了諸如納如松多、則學(xué)等多個(gè)中-大型礦床,但產(chǎn)于林子宗群中的礦床至今尚未引起足夠的重視。賦存于林子宗群火山巖中的斯弄多銀多金屬礦床的發(fā)現(xiàn), 為深入研究及剖析該套火山巖的形成與成礦關(guān)系提供了良好的契機(jī)。為此, 本文以新發(fā)現(xiàn)的斯弄多銀多金屬礦為研究對象, 通過詳細(xì)的地質(zhì)勘探、地質(zhì)填圖、地質(zhì)編錄、鏡下鑒定、能譜和電子探針分析, 確定礦床類型, 對岡底斯成礦帶廣泛發(fā)育林子宗群火山巖地區(qū)的區(qū)域找礦具有積極和重要的指導(dǎo)意義。

圖1 西藏地區(qū)構(gòu)造分區(qū)圖(a) (根據(jù)Hou et al., 2004修改)和岡底斯北帶區(qū)域地質(zhì)及礦床分布圖(b) (根據(jù)Zheng et al., 2016修改)Fig. 1 Sketch tectonic map (a) (modified after Hou et al., 2004) and simplified regional geological map of northeastern Gangdese belt with ore deposits (b) (modified after Zheng et al., 2016)

圖2 斯弄多礦區(qū)地質(zhì)圖(a)和斯弄多礦區(qū)剖面(b)Fig. 2 Geological map of the Sinongduo deposit (a) and section A-A’ of the Sinongduo deposit (b)

1 礦床地質(zhì)

1.1 成礦地質(zhì)背景

斯弄多礦區(qū)位于西藏自治區(qū)謝通門縣境內(nèi), 大地構(gòu)造位置處于拉薩地體隆格爾—工布江達(dá)弧背斷隆帶上, 屬于岡底斯北緣Pb-Zn-Ag成礦帶中段(圖1a)。區(qū)域地層主要以火山-沉積建造為主, 研究區(qū)出露石炭—二疊系碳酸鹽-碎屑巖建造, 中生界(J3-K1)淺海相至海陸交互相碎屑巖、碳酸鹽巖建造, 新生界林子宗群(E1-2)陸相火山巖(圖1b), 該套火山巖自下而上劃分為典中組、年波組和帕那組, 成巖年齡集中在64.43～61.45 Ma、54.07 Ma、48.72～43.93 Ma(董國臣等, 2005), 其中典中組表現(xiàn)為弧火山巖特征, 年波組顯示為陸緣弧、碰撞和板內(nèi)環(huán)境特征, 帕那組顯示為大陸碰撞、板內(nèi)環(huán)境特征, 由南向北巖石堿度增高, 由東向西由偏基性過渡為偏酸性, 反應(yīng)了由南向北大洋向大陸轉(zhuǎn)換, 巖漿源區(qū)具有不均一性的特征(Lee et al., 2009 Chen et al., 2014)。斯弄多礦區(qū)含礦圍巖為古新統(tǒng)典中組(E1d),其形成時(shí)代在60～62 Ma(丁帥等, 未刊數(shù)據(jù)), 巖性主要包括流紋斑巖、晶屑凝灰?guī)r、火山角礫巖等(圖2a)。鄰區(qū)納如松多隱爆角礫巖型銀鉛鋅、則學(xué)熱液脈型鉛鋅銀礦則產(chǎn)于典中組火山巖中(紀(jì)現(xiàn)華等, 2012), 拉宗熱液脈型銀鉛鋅礦產(chǎn)于帕那組火山巖。區(qū)內(nèi)發(fā)現(xiàn)多個(gè)火山機(jī)構(gòu), 具有典型火山角礫巖-流紋斑巖-凝灰?guī)r巖相分帶, 火山機(jī)構(gòu)旁側(cè)發(fā)育多條張性斷裂, 是熱液脈型礦體主要賦存空間。礦區(qū)巖漿巖主要為黑云母花崗斑巖, 呈巖脈、巖枝分布在13–15號勘探線附近(圖2a), 與典中組火山巖接觸帶多形成熱液隱爆角礫巖。

1.2 礦體特征

新發(fā)現(xiàn)銀鉛鋅礦體產(chǎn)于典中組火山巖中(前人認(rèn)為是年波組火山巖), 2013—2014年西藏地質(zhì)二隊(duì)開展了卓有成效的地質(zhì)工作, 初步圈定了礦體, 但在礦床類型確定、礦體特征等方面研究程度較低。通過對鉆孔和探礦坑道詳細(xì)地質(zhì)編錄, 根據(jù)賦礦圍巖及成礦元素共劃分出三種類型礦體, 即: 產(chǎn)于流紋斑巖中隱爆角礫巖型銀鉛鋅礦體、火山機(jī)構(gòu)旁側(cè)受斷層破碎帶控制的熱液脈型鉛鋅銀礦體及斷裂上盤的獨(dú)立銀礦體。

隱爆角礫巖型礦體: 位于礦區(qū)西側(cè), 近直立筒狀, 目前控制長60 m, 寬約30 m, 厚度約50 m(圖2b)。角礫成分主要為流紋斑巖及火山碎屑巖, 呈三角狀、板狀、橢圓狀及不規(guī)則狀, 大小0.5～10 cm之間, 占整個(gè)角礫巖體積約30％～50％, 膠結(jié)物主要為巖粉、石英、長石、絹云母、伊利石、菱鐵礦、菱錳礦及黃鐵礦、方鉛礦、閃鋅礦等硫化物(圖3a)。除了筒狀角礫巖型礦體以外, 還在脈狀礦體中發(fā)育大量脈狀、板狀隱爆角礫巖型礦石, 與塊狀、網(wǎng)脈狀礦石一同構(gòu)成脈狀礦體。

脈狀礦體: 近南北向位于礦區(qū)中部, 是礦區(qū)規(guī)模最大、品位高的銀鉛鋅礦體, 主要產(chǎn)于火山機(jī)構(gòu)旁側(cè)張性斷裂中, 呈板狀陡傾斜, 礦體走向長度超過300 m, 傾向延伸200 m, 厚度在2～30 m之間(圖2b)。方鉛礦、閃鋅礦等硫化物多呈塊狀、網(wǎng)脈狀、細(xì)脈狀集合體, 系含礦熱液沿構(gòu)造裂隙充填交代作用形成(圖3b)。

獨(dú)立銀(鉛鋅)礦體: 分布在脈型礦體上盤, 多與紅色碧玉及含鐵錳碳酸鹽礦物密切共生(圖3c), Ag平均品位可達(dá)400～1 000 g/t。

截止目前, 斯弄多銀多金屬礦共探明Pb+Zn金屬量大于30萬噸, Ag金屬量超過400噸(331+332類別), 遠(yuǎn)景規(guī)模可達(dá)大型。

1.3 礦石特征

礦區(qū)礦石呈典型熱液礦床的構(gòu)造, 以塊狀、角礫狀、網(wǎng)脈狀為主, 局部發(fā)育脈狀-網(wǎng)脈狀、浸染狀礦石, 金屬礦物由方鉛礦、閃鋅礦、黃鐵礦、黃銅礦、輝銀礦、硫砷銅銀礦、黃鉀鐵礬、赤鐵礦和菱鐵礦、菱錳礦等組成(據(jù)丁帥等, 未刊電子探針數(shù)據(jù))。其中方鉛礦多呈中細(xì)粒自形-半自形與黃鐵礦、閃鋅礦等礦物產(chǎn)出(圖3d); 閃鋅礦中多發(fā)育固溶體分離結(jié)構(gòu)的黃銅礦(圖3e); 銀礦物主要為輝銀礦、硫砷銅銀礦, 除部分以類質(zhì)同象形式產(chǎn)于方鉛礦中外(圖3f), 多數(shù)輝銀礦、硫砷銅銀礦等獨(dú)立銀礦物賦存于碧玉及鐵錳碳酸鹽裂隙中或呈粒間銀分布于早期硫化物晶隙間(圖3g, h), 與我國江西冷水坑及環(huán)太平洋地區(qū)淺成低溫?zé)嵋盒虯g礦床極為類似(盧燃等, 2012; Chinchilla et al., 2016)。黃鐵礦呈浸染狀、脈狀, 在隱爆角礫巖中呈團(tuán)斑狀, 粒徑以1～2 mm為主, 具有多階段形成特征, 早期黃鐵礦被方鉛礦、閃鋅礦等硫化物交代, 晚期黃鐵礦交代閃鋅礦。非金屬礦物可見石英、斜長石、絹云母、伊利石、玉髓、冰長石、方解石、重晶石, 螢石等(據(jù)丁帥等, 未刊電子探針數(shù)據(jù))。根據(jù)鉆孔編錄、高光譜測量、光薄片鑒定和礦物能譜分析, 蝕變礦物組合有石英-玉髓-碧玉(圖3i, j), 重晶石-螢石, 冰長石-伊利石-絹云母(圖3k, l), 碳酸鹽礦物組合(包括鐵錳碳酸鹽巖(圖3m)及葉片狀方解石(圖3n))及表生硅華(圖3o)。其中石英-玉髓化分布在1號勘探線附近, 冰長石-伊利石-絹云母化疊加在石英-玉髓化之上, 鐵錳碳酸鹽分布在5–13號勘探線, 空間上與獨(dú)立銀礦物密切共生。

2 討論

2.1 低硫化淺成低溫?zé)嵋旱V床的確定

Hendenquist(1987)依據(jù)流體中硫的氧化還原狀態(tài)將淺成低溫?zé)嵋盒偷V床劃分出高硫化和低硫化兩種類型(Hendenquist, 1987)。前者主要與安山質(zhì)和流紋質(zhì)巖漿活動(dòng)有關(guān), 由酸性、氧化的熱液流體形成(White and Hendenquist, 1990; Corbett, 2002; 張德全等, 2005), 以高含量的金銅硫化物及高價(jià)硫的明礬石+高嶺土等硫酸鹽礦物組合為主(Heald, 1987; Hendenquist, 1987; Sillitoe and Hedenquist, 2003; 唐菊興等, 2014b), 常見硅帽(由塊狀石英和多孔狀石英組合)(Corbett, 2002; 張?jiān)竦? 2009; Elizabeth, 2012); 后者與堿性和偏堿性玄武質(zhì)-流紋質(zhì)巖漿活動(dòng)有關(guān), 由近中性、還原的熱流體形成(Corbett,2002; Taylor, 2007), 發(fā)育熱泉及隱爆角礫巖(Kouhestani et al., 2012), 常見刃片狀/葉片狀/板狀碳酸鹽及條帶狀、層紋狀、梳狀石英+玉髓+冰長石+絹云母+伊利石組合的蝕變, 以 金、銀、鉛、鋅礦化為主, 伴生銅、銻、硒等元素(Hendenquist, 1987; Simmons et al., 2000; Sillitoe and Hedenquist, 2003;Moncada et al., 2012)。

圖3 斯弄多礦區(qū)礦石、礦物及蝕變特征Fig. 3 The characteristics of ores, minerals and alterations in the Sinongduo deposita-角礫巖型礦體, 膠結(jié)物為黃鐵礦、方鉛礦及閃鋅礦等硫化物; b-熱液脈型礦體; c-高品位銀礦石; d-半自形粒狀方鉛礦; e-固溶體分離結(jié)構(gòu)的閃鋅礦與黃銅礦; f-輝銀礦, 與方鉛礦共生體; g, h-碧玉等脈石礦物裂隙中的輝銀礦及硫砷銅銀礦; i-石英及玉髓脈; j-紅色碧玉,發(fā)育大量赤鐵礦; k-絹云母交代冰長石; l-鱗片狀伊利石; m-環(huán)狀鐵菱錳礦; n-葉片狀方解石; o-條帶狀熱泉噴口硅華; Py-黃鐵礦; Gn-方鉛礦; Sph-閃鋅礦; Ccp-黃銅礦; Arn-輝銀礦; Pe-硫砷銅銀礦; Hem-赤鐵礦; Q-石英; Cha-玉髓; Jas-碧玉; Ser-絹云母; Aul-冰長石; Ili-伊利石; Sd-菱錳礦; Cal-方解石; Si-硅質(zhì)礦物a-breccia-type ores with the cement of pyrite, galena, sphalerite and other sulfides; b-hydrothermal vein-type orebody; c-high-grade silver ore; d-subhedral granular galena; e-exsolution texture of sphalerite and chalcopyrite; f-association of argentite and galena; g, h-argentite and proustite in the fissures of jasper and other gangue minerals; i-quartz and chalcedony veins; j-lots of hematites in red jasper; k-adularia replaced by sericite; l-flake illite; m-annular iron-rhodochrosite; n-bladed calcite; o-banded supergene geyserite; Py-pyrite; Gn-galena; Sph-sphalerite; Ccp-chalcopyrite; Arn-argentite; Pe-proustite; Hem-hematite; Q-quartz; Cha-chalcedony; Jas-jasper; Ser-sericite; Aul-adularia; Ili-illite; Sd-rhodochrosite; Cal-calcite; Si-siliceous minerals

斯弄多銀多金屬礦體賦存于林子宗群火山巖中, 包括產(chǎn)于流紋斑巖中隱爆角礫巖型銀鉛鋅礦體、火山機(jī)構(gòu)旁側(cè)的熱液脈型鉛鋅銀礦體及斷裂上盤的獨(dú)立銀礦體。與世界上低硫化淺成低溫?zé)嵋盒偷V床有相似的礦化特征, 發(fā)育典型淺成低溫?zé)嵋合到y(tǒng)中硅化-冰長石-碳酸鹽(鐵錳碳酸鹽+方解石)蝕變。硅化表現(xiàn)為石英+硅華+玉髓+碧玉等礦物組合(圖3i, j), 且表現(xiàn)出自上而下垂直分帶特征: 由淺部熱泉噴口附近的硅華→中部微細(xì)粒石英+玉髓脈→深部梳狀、脈狀石英。其中這些非晶質(zhì)硅質(zhì)礦物大多形成于相對高pH和中低溫(＜300℃)環(huán)境中(James, 1994), 反映了沸騰熱液在淺地表環(huán)境下快速冷卻沉淀?xiàng)l件(張?jiān)竦? 2009)。冰長石形成溫度為180～320℃(Pirajno, 1992), 在近中性-堿性條件下大量鉀質(zhì)蝕變而成(張?jiān)竦? 2009), 后期多受絹云母等含水硅酸鹽礦物所交代(圖3k)。斯弄多礦區(qū)碳酸鹽化表現(xiàn)兩種形式: 鐵錳碳酸鹽和方解石(圖3m, n), 其中鐵錳碳酸鹽礦物在空間上與銀礦體相伴產(chǎn)出, 與我國江西冷水坑和浙東地區(qū)淺成低溫?zé)嵋盒豌y礦床極為相似(魏元柏和趙宇, 1996; 盧燃等, 2012)。一般認(rèn)為這種鐵錳碳酸鹽形成于低溫(200℃左右), 中性環(huán)境中(pH在6.7左右)(Wei and Chen, 1993), 其形成加速了銀的沉淀速度, 促進(jìn)了銀礦物(主要是自然銀)的析出(魏元柏和趙宇, 1996)。此外,礦區(qū)常見葉片狀方解石(圖3n), 這種方解石多因富揮發(fā)分流體快速沸騰, CO2較其他揮發(fā)分溶解度偏低, 而從液相中優(yōu)先強(qiáng)烈分離進(jìn)入氣水相, 促使方解石快速結(jié)晶并按扁平習(xí)性生長形成(Canet et al., 2011), 是低硫化淺成低溫?zé)嵋盒偷V床形成過程中存在流體沸騰的有利證據(jù)(Simon et al., 1999; Etoh et al., 2002)。以上這些礦物均反映了斯弄多礦區(qū)成礦流體具有淺成、低溫、中-還原性特征, 具有典型低硫化淺成低溫?zé)嵋盒偷V床成礦特征(Hendenquist et al., 2000; Corbett, 2002; Sillitoe and Hedenquist, 2003), 這在岡底斯成礦帶乃至西藏特提斯成礦省尚屬首例。

2.2 區(qū)域成礦前景

淺成低溫?zé)嵋盒偷V床的形成與深部巖漿作用形成的熱液體系密切相關(guān), 其深部常發(fā)育斑巖型銅多金屬礦, 它們共同組成一個(gè)完整的火山-巖漿成礦系統(tǒng)(Sillitoe, 2010)。如在我國西藏多龍礦集區(qū),鐵格隆南(榮那)礦段由淺部高硫化淺成低溫?zé)嵋号c深部斑巖型銅(金、銀)型礦體組成, 這是我國目前已發(fā)現(xiàn)的規(guī)模最大的高硫型淺成低溫?zé)嵋?斑巖型礦床(唐菊興等, 2014b; 楊超等, 2014; 方向等, 2015;李光明等, 2015)。此外, 唐菊興等(2014a)按照斑巖礦床成礦系列的“缺位理論”, 提出雄村礦集區(qū)具有低硫化淺成低溫?zé)嵋盒偷V床找礦潛力, 并根據(jù)雄村外圍洞嘎金礦礦物組合認(rèn)為其具有淺成低溫?zé)嵋盒偷V床特征。然而, 近年來在廣泛分布的陸相火山巖地區(qū)大量淺成低溫?zé)嵋盒虯u、Ag、Pb、Zn礦床(低硫型)相繼被發(fā)現(xiàn), 地質(zhì)學(xué)家們逐漸重視火山作用對成礦的貢獻(xiàn), 同時(shí)強(qiáng)調(diào)火山作用中火山熱液體系是成礦關(guān)鍵因素(Sidorov et al., 2015; Nadeau et al., 2016)。

林子宗群火山巖是岡底斯成礦帶乃至青藏高原發(fā)育的最大規(guī)模的火山巖帶, 該套火山巖東西展布大于1 200 km, 分布范圍占岡底斯巖漿帶面積的一半以上(Mo et al., 2008), 代表著白堊紀(jì)晚期—早新生代(70～40 Ma)青藏高原南部的一次大規(guī)模的構(gòu)造巖漿事件(Ding et al., 2003, 2005; 侯增謙等, 2006)。同時(shí)也是岡底斯Ag-Pb-Zn礦床重要賦礦層位, 包括納如松多、斯弄多、則學(xué)、扎扎龍等多個(gè)中-大型礦床均產(chǎn)于該套火山巖中。斯弄多銀多金屬礦是林子宗群火山巖中首次確定的低硫化淺成低溫?zé)嵋盒偷V床, 盡管這套火山巖對成礦作用影響尚未展開深入研究, 但其成礦環(huán)境可媲美安第斯成礦帶(如馬力昆成礦帶(La Franja de Maricunga)(John et al., 2001; Richards et al., 2013)、印地—帕斯瓜成礦帶(Franja El Indio-Pascua) (Deyella et al., 2005; Bissiga et al., 2015)等火山巖地區(qū), 此外, 斯弄多礦區(qū)外圍還發(fā)現(xiàn)有多個(gè)熱液隱爆角礫巖筒及古熱泉噴口,是斑巖-淺成低溫?zé)嵋盒豌y、金礦床形成的有利條件,有望在該地區(qū)實(shí)現(xiàn)淺部未被剝蝕的獨(dú)立金礦體找礦突破。另一方面, 就整個(gè)岡底斯成礦帶上林子宗群火山巖而言, 其出露區(qū)域均與地球化學(xué)異常套合較好, Au、Ag等成礦元素均具有明顯的濃度分帶, 較高的峰值, 指示了林子宗群火山巖具有良好的找礦前景(李光明等, 2004; 譚鋼等, 2011), 是尋找斑巖-淺成低溫?zé)嵋盒?、隱爆角爍巖型、熱液脈型金、銀、鉛、鋅多金屬礦的有利地段。

3 結(jié)論及地質(zhì)意義

1)斯弄多銀多金屬礦產(chǎn)于岡底斯成礦帶中段南木林火山盆地, 是在林子宗群陸相火山巖中新發(fā)現(xiàn)的中大型銀多金屬礦床, 由產(chǎn)于流紋斑巖中隱爆角礫巖型銀多金屬礦體、火山機(jī)構(gòu)旁側(cè)的熱液脈型鉛鋅銀礦體及斷裂上盤的銀(鉛鋅)礦體組成。

2)礦石發(fā)育典型的條帶狀、層紋狀、皮殼狀、角礫狀、網(wǎng)脈狀礦石構(gòu)造, 以石英-玉髓-碧玉-伊利石-絹云母-碳酸鹽等蝕變礦物組合為主, 顯示該礦床具有典型的低硫化淺成低溫?zé)嵋盒偷V床典型的礦石組構(gòu)和蝕變礦物組合。

3)產(chǎn)于林子宗群火山巖中的低硫化淺成低溫?zé)嵋盒偷V床在岡底斯成礦帶上尚屬首次識別, 不僅豐富和完善了該區(qū)礦床類型, 同時(shí)對岡底斯成礦帶廣泛發(fā)育林子宗群火山巖地區(qū)的區(qū)域找礦具有積極和重要的指導(dǎo)意義, 對于1 200 km帶狀分布的林子宗群出露區(qū)的銀(金)多金屬礦找礦勘查其意義非同小可。

致謝:感謝西藏中瑞礦業(yè)發(fā)展有限責(zé)任公司黃若朝董事長、李祥總經(jīng)理為筆者的野外工作和室內(nèi)工作提供的資助。同時(shí)對編輯老師以及審稿專家為本文提出的寶貴意見, 在此深表謝意!

Acknowledgements:

This study was supported by China Geological Survey (No. 12120114068401), and Zhongrui Mining Co., Ltd. (No. XZZR-2015).

董國臣, 莫宣學(xué), 趙志丹, 王亮, 周肅. 2005. 拉薩北部林周盆地林子宗火山巖層序新議[J]. 地質(zhì)通報(bào), 24(6): 549-557.

方向, 唐菊興, 宋楊, 楊超, 丁帥, 王藝云, 王勤, 孫興國, 李玉彬, 衛(wèi)魯杰, 張志, 楊歡歡, 高軻, 唐攀. 2015. 西藏鐵格隆南超大型淺成低溫?zé)嵋恒~(金、銀)礦床的形成時(shí)代及其地質(zhì)意義[J]. 地球?qū)W報(bào), 36(2): 168-176.

侯增謙, 楊竹森, 徐文藝, 莫宣學(xué), 丁林, 高永豐, 董方瀏, 李光明, 曲曉明, 李光明, 趙志丹, 江思宏, 孟祥金, 李振清,秦克章, 楊志明. 2006. 青藏高原碰撞造山帶: I. 主碰撞造山成礦作用[J]. 礦床地質(zhì), 25(4): 337-358.

紀(jì)現(xiàn)華, 楊竹森, 于玉帥, 申俊峰, 田世洪, 孟祥金, 李振清,劉英超. 2012. 西藏納如松多鉛鋅礦床成礦巖體形成機(jī)制:巖漿鋯石證據(jù)[J]. 礦床地質(zhì), 31(4): 758-774.

江思宏, 聶風(fēng)軍, 張義, 胡朋. 2004. 淺成低溫?zé)嵋盒徒鸬V床研究最新進(jìn)展[J]. 地學(xué)前緣, 11(2): 401-411.

郎興海, 唐菊興, 陳毓川, 李志軍, 黃勇, 王成輝, 陳淵, 張麗,周云. 2012. 西藏岡底斯成礦帶南緣新特提斯洋俯沖期成礦作用: 來自雄村礦集區(qū)Ⅰ號礦體的Re-Os同位素年齡證據(jù)[J]. 地球科學(xué)-中國地質(zhì)大學(xué)學(xué)報(bào), 37(3): 515-525.

李光明, 潘棒棠, 于高明, 黃志英, 高大發(fā). 2004. 西藏岡底斯成礦帶礦產(chǎn)資源遠(yuǎn)景評價(jià)與展望[J]. 成都理工大學(xué)學(xué)報(bào)(自然科學(xué)版), 31(1): 22-27.

李光明, 張夏楠, 秦克章, 孫興國, 趙俊興, 印賢波, 李金祥,袁華山. 2015. 羌塘南緣多龍礦集區(qū)榮那斑巖-高硫型淺成低溫?zé)嵋篊u-(Au)套合成礦: 綜合地質(zhì)、熱液蝕變及金屬礦物組合證據(jù)[J]. 巖石學(xué)報(bào), 31(8): 2307-2324.

盧燃, 毛景文, 高建京, 蘇慧敏, 鄭佳浩. 2012. 江西冷水坑礦田下鮑Ag-Pb-Zn礦床地質(zhì)特征及銀的賦存狀態(tài)研究[J]. 巖石學(xué)報(bào), 28(1): 105-121.

譚鋼, 佘宏全, 常幗雄, 李光明, 董英君, 潘桂棠, 李進(jìn)文, 張德全, 豐成友. 2011. 西藏岡底斯多金屬成礦帶鉛鋅礦定位預(yù)測與資源潛力評價(jià)[J]. 巖石礦物學(xué)雜志, 30(1): 83-96.

唐菊興, 多吉, 劉鴻飛, 郎興海, 張金樹, 鄭文寶, 應(yīng)立娟. 2012.岡底斯成礦帶東段礦床成礦系列及找礦突破的關(guān)鍵問題研究[J]. 地球?qū)W報(bào), 33(4): 393-410.

唐菊興, 孫興國, 丁帥, 王勤, 王藝云, 楊超, 陳紅旗, 李彥波,李玉彬, 衛(wèi)魯杰, 張志, 宋俊龍, 楊歡歡, 段吉琳, 高軻,方 向, 譚江云. 2014b. 西藏多龍礦集區(qū)發(fā)現(xiàn)淺成低溫?zé)嵋盒豌~(金銀)礦床[J]. 地球?qū)W報(bào), 35(1): 6-10.

唐菊興, 王立強(qiáng), 鄭文寶, 鐘康惠. 2014a. 岡底斯成礦帶東段礦床成礦規(guī)律及找礦預(yù)測[J]. 地質(zhì)學(xué)報(bào), 88(12): 2545-2555.

魏元柏, 趙宇. 1996. 浙東地區(qū)銀鉛鋅礦床菱錳礦的形成與銀的礦化關(guān)系初探[J]. 南京大學(xué)學(xué)報(bào)(自然科學(xué)版), 32(4): 717-721.

楊超, 唐菊興, 王藝云, 馮軍, 印賢波, 丁帥, 方向, 張志, 李玉彬. 2014. 西藏鐵格隆南淺成低溫?zé)嵋盒?斑巖型Cu-Au礦床流體及地質(zhì)特征研究[J]. 礦床地質(zhì), 33(6): 1287-1305.

張德全, 豐成友, 李大新, 佘宏全, 董英君. 2005. 紫金山地區(qū)斑巖-淺成熱液成礦系統(tǒng)的成礦流體演化[J]. 地球?qū)W報(bào), 26(2): 127-136.

張?jiān)? 毛景文, 李宗彥, 喬翠杰, 張孝民, 張向衛(wèi). 2009. 巖漿熱液系統(tǒng)中礦床類型、特征及其在勘探中的應(yīng)用[J]. 地質(zhì)學(xué)報(bào), 83(3): 399-425.

References:

BISSIGA T, CLARKB A H, RAINBOWB A, MONTGOMERYC A. 2015. Physiographic and Tectonic Settings of High-Sulfidation Epithermal Gold-Silver Deposits of The Andes and Their Controls on Mineralizing Processes[J]. Ore Geology Reviews, 65(1): 327-364.

CANET C, FRANCO S I, PROL-LEDESMA R M, GONZáLEZ-PARTIDA E, VILLANUEVA-ESTRADA R E. 2011. A model of Boiling for Fluid Inclusion Studies: Application to the Bolanos Ag-Au-Pb-Zn Epithermal Deposit, Western Mexico[J]. Journal of Geochemical Exploration, 110(2): 118-125.

CHEN J S, HUANG B C, YI Z Y, YANG L K, CHEN L W. 2014. Paleomagnetic And40Ar/39Ar Geochronological Results from The Linzizong Group, Linzhou Basin, Lhasa Terrane, Tibet: Implications to Paleogene Paleolatitude and Onset of The India–Asia Collision[J]. Journal of Asian Earth Sciences, 96: 162-177.

CHINCHILLA D, ORTEGA L, PI?A R, MERINERO R, DANIEL MONCADA D, BODNARD R J, QUESADA C, VALVERDE A, LUNAR R. 2016. The Patricia Zn–Pb–Ag Epithermal Ore Deposit: An Uncommon Type of Mineralization in northeastern Chile[J]. Ore Geology Reviews, 73(1): 104-126.

CORBETT G. 2002. Epithennal Gold for Explorationists[J]. AIG Journal-Applied Geoscientifie Practice and Research in Anstralia, 1: 1-26.

DEYELLA C L, RYEB R O, LANDISB G P, BISSIGC T. 2005. Alunite and the Role of Magmatic Fluids in the Tambo High-Sulfidation Deposit, El Indio-Pascua Belt, Chile[J]. Chemical Geology, 215(1-4): 185-218.

DING L, KAPP P, WAN X Q. 2005. Paleocene-Eocene Record of Ophilite Obduction and Initial India-Asia collision, south central Tibet[J]. Tectonic, 24: 1-18.

DING L, KAPP P, ZHONG D, DENG W M. 2003. Cenozoic Volcanism in Tibet: Evidence for a Transition from Oceanic to Continental Subduction[J]. Journal of Petrology, 44: 1833-1865.

DONG Guo-chen, MO Xuan-xue, ZHAO Zhi-dan, WANG Liang, ZHOU Su. 2005. A new understanding of the stratigraphic successions of the Linzizong volcanic rocks in the Linzhou Basin, northern Lhasa, Tibet, China[J]. Geology Bulletin of China, 24(6): 549-557(in Chinese with English abstract).

EINAUDI M T, HEDENQUIST J W, INAN E. 2003. Sulfidation State of Fluids in Active and Extinct Hydrothermal System: Transitions from Porphyry to Epithermal Environments[J]. Society of Economic Geologists Special Publication, 10: 28-314.

ELIZABETH A H. 2012. The Veladero High-Sulfidation Epithermal Au-Ag Deposit, Argentina Volcanic Stratigraphy, Alteration, Mineralization and Quartz Paragenesis[D]. Golden, Colorado: the Colorado School of Mines: 55-140.

ETOH J, IZAWA E, TAGUCHI S. 2002. A Fluid Inclusion Study on Columnar Adularia From the Hishikari Low-Sulfidation Epithermal Gold Deposit, Japan[J]. Resource Geology, 52(1): 73-78.

FANG Xiang, TANG Ju-xing, SONG Yang, YANG Chao, DING Shuai, WANG Yi-yun, WANG Qin, SUN Xing-guo, LI Yu-bin, WEI Lu-jie, ZHANG Zhi, YANG Huan-huan, GAO Ke, TANG Pan. 2015. Formation Epoch of the South Tiegelong Supelarge Epithermal Cu (Au-Ag) Deposit in Tibet and Its Geological Implications[J]. Acta Geoscientica Sinica, 36(2): 168-176(in Chinese with English abstract).

HEALD P, FOLEY N K, HAYBA D O. 1987. Comparative Anatomy of Volcanic Hosted Epithermal Deposits-Acid Sulphate and Adularia-Sericite Types[J]. Economic Geology, 80: 1-26.

HENDENQUIST J W. 1987. Volcanic-Related Hydrothennal Systenrs in the Circum-Pacifie Basin and Their Potential for Mineralization[J]. Mining Geology, 37(3): 347-364.

HENDENQUIST J W, ARRIBAS R A, GONZALEZ U E. 2000. Exploration for Epithermal Gold Deposit[J]. Reviews in Economic Geology, 13: 245-277.

HOU Z Q, GAO Y F, QU X M, RUI Z Y, MO X X. 2004. Origin of Adakitic Intrusives Generated During Mid-Miocene East–West Extension in Southern Tibet[J]. Earth and Planetary Science Letters, 220: 139-155.

HOU Z Q, YANG Z M, QU X M, MENG X J, LI Z Q, BEAUDOIN G, RUI Z Y, GAO Y F, ZAW K. 2009. The Miocene Gangdese Porphyry Copper Belt Generated During Post-Collisional Extension in The Tibetan Orogen[J]. Ore Geology Reviews, 36(1-3): 25-51.

HOU Zeng-qian, YANG Zhu-sen, XU Wen-yi, MO Xuan-xue, DING Li , GAO Yong-feng, DONG Fang-liu, LI Guang-ming, QU Xiao-ming, LI Guang-ming, ZHAO Zhi-dan, JIANG Si-hong, MENG Xiang-jin, LI Zhen-qing, QIN Ke-zang, YANG Zhi-ming. 2006. Metallogenesis in Tibetan collisional orogenic belt: I. Mineralization in main collisional orogenic setting[J]. Mineral Deposite, 25(4): 337-358(in Chinese with English abstract).

JAMES A S. 1994. Silica and Gold Textures in Bonanza Ores of the Sleeper Deposit, Humboldt County, Nevada: Evidence for Colloids and Implications for Epithermal Ore-Forming Processes[J]. Economic Geology, 89(3): 628-638.

JI Xian-hua, YANG Zhu-sen, YU Yu-shuai, SHEN Jun-feng, TIAN Shi-hong, MENG Xiang-jin, LI Zhen-qing, LIU Ying-chao. 2012. Formation Mechanism of Magmatic Rocks in Narusongduo Lead-Zinc Deposit of Tibet: Evidence From Magmatic Zircon[J]. Mineral Deposit, 31(4): 758-774(in Chinese with English abstract).

JIANG Si-hong, NIE Feng-jun, ZHANG Yi, HU Peng. 2004. The Latest Advances in The Research of Epithermal Deposits[J]. Earth Science Frontiers, 11(2): 401-411(in Chinese with English abstract).

JOHN L, MUNTEAN, EINAUDI M T. 2001. Porphyry-Epithermal Transition: Maricunga Belt, Northern Chile[J]. Economic Geology, 96(4): 743-772.

KOUHESTANI H, GHADERI M, ZAW K, MEFFRE S, EMAMI M H. 2012. Geological Setting and Timing of The Chah Zard Breccia-Hosted Epithermal Gold-Silver Deposit in the Tethyan Belt of Iran[J]. Mineralium Deposita, 47(4): 425-440.

LANG Xing-hai, TANG Ju-xing, CHEN Yu-chuan, LI Zhi-jun, HUANG Yong, WANG Cheng-hui, CHEN Yuan, ZHANG Li, ZHOU Yun. 2012. Neo-Tethys Mineralization on the Southern Margin of the Gangdise Metallogenic Belt, Tibet, China: Evidence from Re-Os Ages of Xiongcun Ore body No.Ⅰ[J]. Earth Science-Journal of China University of Geosciences, 37(3): 515-525(in Chinese with English abstract).

LEE H Y, CHUNG S L, LO C H, JI J Q, LEE T Y, QIAN Q, ZHANG Q. 2009. Eocene Neotethyan Slab Breakoff in Southern Tibet Inferred from The Linzizong[J]. Tectonophysics, 477: 20-35.

LI Guang-ming, PAN Gui-tang, WANG Gao-ming, HUANG Zi-ying, GAO Da-fa. 2004. Evaluation and Prospecting Value of Mineral Resources in Gangdise Metallogenic Belt, Tibet, China[J]. Journal of Chengdu University of Technology(Science and Technology Edition), 31(1): 22-27(in Chi-nese with English abstract)．

LI Guang-ming, ZHANG Xia-nan, QIN Ke-zhang, SUN Xing-guo, ZHAO Ju-xing, YIN Xian-bo, LI Jin-xiang, YUAN Hua-shan. 2015. The Telescoped Porphyry–High Sulfidation Epithermal Cu(–Au) Mineralization of Rongna Deposit in Duolong Ore Cluster at the Southern Margin of Qiangtang Terrane, Central Tibet: Integrated Evidence from Geology, Hydrothermal Alteration and Sulfide Assemblages[J]. Acta Petrologica Sinica, 31(8): 2307-2324(in Chinese with English abstract).

LINDGREN W. 1922. A Suggestion for a Terminology of Certain Mineral Deposits[J]. Economic Geology, 17: 292-294.

LINDGREN W. 1933. Mineral Deposits[M]. 4th Ed. NewYork: McGraw Hill: l-930.

LU Ran, MAO Jing-wen, GAO Jian-jing, SU Hui-min, ZHEN Jia-hao. 2012. Geological Characteristics and Occurrence of Silver in Xiabao Ag-Pb-Zn Deposit, Lengshuikeng Ore Field, Jiangxi Province, East China[J]. Acta Petrologica Sinica, 28(1): 105-121(in Chinese with English abstract).

MO X X, NIU Y L, DONG G C, ZHAO Z D, HOU Z Q, ZHOU S, KE S. 2008. Contribution of Syncollisional Felsic Magmatism to Continental Crust Growth: A Case Study of The Paleogene Linzizong Volcanic Succession in Southern Tibet[J]. Chemical Geology, 250: 49-67.

MONCADA D, MUTCHLER S, NIETO A, REYNOLDS T J, RIMSTIDT J D, BODNAR R J. 2012. Mineral Textures and Fluid Inclusion Petrography of the Epithermal Ag-Au Deposits at Guanajuato, Mexico: Application to Exploration[J]. Journal of Geochemical Exploration, 114: 20-35.

NADEAU O, STIX J, WILLIAMS-JONES A E. 2016. Links Between Arc Volcanoes and Porphyry-Epithermal Ore Deposits[J]. Geology, 44(1): 11-14.

PáEZ G N, RUIZ R, GUIDO D M, RíOS F J, SUBIAS I, RECIO C, SCHALAMUK I B. 2016. High-Grade Ore Shoots at The Martha Epithermal Vein System, Deseado Massif, Argentina: The Interplay of Tectonic, Hydrothermal and Supergene Processes in Ore Genesis[J]. Ore Geology Reviews, 72: 546-561.

PIRAJNO F. 1992. Hydrothermal Mineral Deposits: Principles and Fundamental Concepts for The Exploration Geologist[M]. Berlin: SpringerVerlag: 325-442.

RICHARDS J P. 2013. Giant Ore Deposits Formed By Optimal Alignments and Combinations of Geological Processes[J]. Nature Geoscience, 6(11): 911-916.

SIDOROV A A, VOLKOV A V, SAVVA N E. 2015. Volcanism and Epithermal Deposits[J]. Journal of Volcanology and Seismology, 9(6): 349-357.

SILLITOE R H, HEDENQUIST J W. 2003. Linkages Between Volcanotectonic Settings, Ore Fluid Compositions, and Epithermal Precious Metal Deposits[J]. Society of Economic Geologists Special Publication, 10: 315-343.

SILLITOE R H. 2010. Porphyry Copper Systems[J]. Economic Geology, 105(1): 3-41.

SIMMONS S F, AREHART G, SIMPSON M P, MAUK J L. 2000. Origin of Massive Calcite Veins in the Golden Cross Low-Sulfidation, Epithermal Au-Ag Deposit, New Zealand[J]. Economic Geology, 95(1): 99-112.

SIMMONS S F, WHITE N C, JOHN D A. 2005. Geological Characteristics of Epithermal Precious and Base Metal Deposits[J]. Economic Geology 100th Anniversary Volume, 485-522.

SIMON G, KESLER E S, RUSSELL N, HALL M C, BELL D, PINERO E. 1999．Epithermal Gold Mineralization in an Old Volcanic Arc, the Jacinto Deposit, Camagueey District, Cuba[J]. Economic Geology, 94(4): 487-506.

TAN Gang, SHE Hong-quan, CHANG Guo-xiong, LI Guang-ming, DONG Ying-jun, PAN Gui-tang, LI Jin-wen, ZHANG De-quan, FENG Cheng-you. 2011. Regional Metallogenic Predication and Mineral Reserves Evaluation of Lead and Zinc Deposits in the Gangdise Polymetallic Ore-Forming Belt, Tibet[J]. Acta Petrologica Et Mineralogica, 30(1): 83-96(in Chinese with English abstract)．

TANG J X, LANG X H, XIE F W, GAO Y M, LI Z J, HANG Y, DING F, YANG H H, ZHANG L, WANG Q, ZHOU Y. 2015. Geological Characteristics and Genesis of the Jurassic No. I Porphyry Cu-Au Deposit in The Xiongcun District, Gangdese Porphyry Copper Belt, Tibet[J]. Ore Geology Reviews, 70: 438-456.

TANG Ju-xing, DUO Ji, LIU Hong-fei, ZHANG Jin-shu, ZHENG Wen-bao, YING Li-juan. 2012. Minerogenetic Series of Ore Deposits in the East Part of the Gangdise Metallogenic Belt[J]. Acta Geoscientica Sinica, 33(4): 393-410(in Chinese with English abstract).

TANG Ju-xing, WANG Li-qiang, ZHENG Wen-bao, ZHONG Kang-hui. 2014a. Ore Deposits Metallogenic Regularity and Prospecting in the Eastern Section of the Gangdese Metallogenic Belt[J]. Acta Geologica Sinica, 88(12): 2545-2555(in Chinese with English abstract).

TANG Ju-xing, SUN Xing-guo, DING Shuai, WANG Qin, WANG Yi-yun, YANG Chao, CHEN Hong-qi, LI Yan-bo, LI Yu-bin, WEI Lu-jie, ZHANG Zhi, SONG Jun-long, YANG Huan-huan, DUAN Ji-lin, GAO Ke, FANG Xiang, TAN Jiang-yun. 2014b. Discovery of the epithermal deposit of Cu (Au–Ag) in the Duolong ore concentrating area, Tibet[J]. Acta Geoscientica Sinica, 35(1): 6-10(in Chinese with English abstract).

TAYLOR B E. 2007. Epithermal gold deposits[J]//Goodfellow W D., ed., Mineral Deposits of Canada: A Synthesis of Major Deposit-Types, District Metallogeny, the Evolution of Geological Provinces, and Exploration Methods: Geological Association of Canada, Mineral Deposits Division, Special Publication, 5: 113-139.

WEI Y B, CHEN W. 1993. Physicochemical Conditions during theFormation of Dalingkou Ag-Pb-Zn Deposit in Zhejiang Province[J]. Chinese Journal of Geochemistry, 12(3): 252-260.

WEI Yuan-bai, ZHAO Yu. 1996. Preliminary Studies on the Relationship of the Silver Mineralization and the Forming of Rhodochrosite from the Ag-Pb-Zn Ore Deposit in East Zhejiang Province[J]. Journal of Nanjing University (Natural Sciences), 32(4): 717-721(in Chinese with English abstract).

WHITE N C, HENDENQUIST J W. 1990. Epithermal Environment and Styles of Mineralization: Variations and Their Causes and Guidelines for Exploration[J]. Journal of Geochemical Exploration, 36(3): 445-474.

YANG Chao, TANG Ju-xing, WANG Yi-yun, YANG Huan-huan, WANG Qin, SUN Xing-guo, FENG Jun, YIN Xian-bo, DING Shuai, FANG Xiang, ZHANG Zhi, LI Yu-bin. 2014. Fluid and Geological Characteristics Researches of Southern Tiegelong Epithermal Porphyry Cu-Au Deposit in Tibet[J]. Mineral Deposits, 33(6): 1287-1305(in Chinese with English abstract).

ZHANG De-quan, FENG Cheng-you, LI Da-xin, SHE Hong-quan, DONG Ying-jun. 2005. The Evolution of Ore-forming Fluids in the Porphyry-Epithermal Metallogenic System of Zijinshan Area[J]. Acta Geoscientica Sinica, 26(2): 127-136(in Chinese with English abstract).

ZHANG Yuan-hou, MAO Jing-wen, LI Zong-yan, QIAO Cui-jie, ZHANG Xiao-min, ZHANG Xiang-wei. 2009. Ore Deposit Types and Characteristics of Magmatic-Hydrothermal Systems and Implication for Exploration[J]. Acta Geologica Sinica, 83(3): 399-425(in Chinese with English abstract).

ZHENG Y C, FU Q, HOU Z Q, YANG Z S, HUANG K X, WU C D, SUN Q Z. 2016. Metallogeny of The Northeastern Gangdese Pb-Zn-Ag-Fe-Mo-W Polymetallic Belt in The Lhasa Terrane, Southern Tibet[J]. Ore Geology Reviews, 70: 510-532.

The First Discovery of the Low Sulfidation Epithermal Deposit in Linzizong Volcanics, Tibet: A Case Study of the Sinongduo Ag Polymetallic Deposit

TANG Ju-xing1), DING Shuai2), MENG Zhan2), HU Gu-yue1), GAO Yi-ming1), XIE Fu-wei2), LI Zhuang2), YUAN Mei2), YANG Zong-yao2), CHEN Guo-rong3), LI Yu-hai3), YANG Hong-yu3), FU Yan-gang4)
1) MLR Key Laboratory of Metallogeny and Mineral Resource Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037; 2) College of Earth Sciences, Chengdu University of Technology, Chengdu, Sichuan 610059; 3) Zhongrui Mining Co., Ltd., Lhasa, Tibet 850000; 4) China University of Geosciences(Beijing), Beijing 100083

Sinongduo; Linzizong group volcanic rock; valencianite-illite-sericite; low sulfidation; epithermal Ag polymetallic deposit; Gangdise

P317.3; P618.4

A

10.3975/cagsb.2016.04.08

本文由中國地質(zhì)調(diào)查局地質(zhì)調(diào)查項(xiàng)目“西藏雄村-普桑果斑巖-矽卡巖型銅多金屬礦成礦地質(zhì)背景與找礦潛力調(diào)查”(編號: 12120114068401)和西藏中瑞礦業(yè)發(fā)展有限責(zé)任公司項(xiàng)目(編號: XZZR-2015)聯(lián)合資助。

2016-02-27; 改回日期: 2016-04-02。責(zé)任編輯: 魏樂軍。

唐菊興, 男, 1964年生。博士, 研究員。主要從事礦床學(xué)和固體礦產(chǎn)勘查與評價(jià)研究工作。通訊地址: 100037, 北京市西城區(qū)百萬莊大街26號。E-mail: tangjuxing@126.com。

Abstract:Since the Paleogene (70–40 Ma), volcanic rocks of Linzizong Group have been distributed in a large area in Gangdise metallogenic belt, Tibet; nevertheless, there is an “absence” of mass resource and high economic value epithermal deposit except for the Qulong and Jiama porphyry-skarn copper polymetallic deposit (23–13 Ma) formed in the collision-stretch phase, in contrast with the Andean metallogenic belt (such as La Franja de Maricunga, Franja El Indio-Pascua) formed under the condition of extensive volcanic -magmatism. Are these deposits denudated or even not found yet? The authors have recognized a type of low sulfidation epithermal lead-zinc (In-Cd-Au) deposit in Linzizong continental volcanic rock group in Sinongduo of Namling basin, based on the detailed exploration, geological mapping, geological logging, microscopic examination, energy spectrometer analysis, electron microprobe analysis (EPMA) and the result of previous researchers. The orebodies consist of cryptoexplosion breccia type Ag-Pb-Zn orebody hosted in liparophyre, hydrothermal vein type Ag-Pb-Zn orebody beside volcanic edifice, and Ag (Pb-Zn) orebody on the hanging side of the fault. The amount of the controlled resource of Pb+Zn is over 0.3 million tons (331+332)@Pb+zinc＞5％, and resource amount of Ag@Ag＞50g/t is more than 400 tons. The major metallic minerals are galena, sphalerite, and argentite, pearceite, and pyrite together with rare chalcopyrite. Quartz-chalcedonite-jasper, siderite-rhodochrosite, barite-fluorite, and valencianite-illite-sericite are main associations of alteration. The main structures include veined sturcture, brecciated, mesh-veined, banded and laminated, crustified, massive and disseminated structures, the ore textures of this deposit are developed on the basis of crystallization and metasomatism. The authors found a vent of ancient hot spring near the surface, around which there are some banded and laminated siliceous sediments. These geological findings led the authors to believe that this is a typical low-sulfidation epithermal Ag polymetallic deposit. This is for the first time a deposit of this significant type was found and verified in Gangdise belt and even in Tethys metallogenic province. The essentiality for guiding exploration in the area where Linzizong Group volcanic rock was developed in 70–40 Ma in Gangdise belt would be very obvious.