周錫強(qiáng) 遇 昊 黃泰譽(yù),3 張力鈺,3 張恭境,3 付 勇 陳代釗

(1.中國科學(xué)院地質(zhì)與地球物理研究所油氣資源研究室 北京 100029；2.中國五礦集團(tuán)公司 北京 100007；3.中國科學(xué)院大學(xué) 北京 100049；4.貴州大學(xué)資源與環(huán)境工程學(xué)院 貴陽 550025)

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重晶石沉積類型及成因評述
——兼論揚子地區(qū)下寒武統(tǒng)重晶石的富集機(jī)制

周錫強(qiáng)1遇 昊2黃泰譽(yù)1,3張力鈺1,3張恭境1,3付 勇4陳代釗1

(1.中國科學(xué)院地質(zhì)與地球物理研究所油氣資源研究室 北京 100029；2.中國五礦集團(tuán)公司 北京 100007；3.中國科學(xué)院大學(xué) 北京 100049；4.貴州大學(xué)資源與環(huán)境工程學(xué)院 貴陽 550025)

重晶石沉積類型豐富，具有多種成因過程。通常，沉積型重晶石可分為生物、熱液、成巖和冷泉重晶石四種類型。富鋇與富硫酸鹽的流體(海水、早成巖孔隙水或熱液流體)及其相互作用過程(水柱、熱液系統(tǒng)、沉積柱、沉積物—水界面附近)決定了重晶石的沉積環(huán)境、宏微觀產(chǎn)出方式、同位素組成及相應(yīng)的地質(zhì)意義。另外，根據(jù)揚子地區(qū)下寒武統(tǒng)富重晶石沉積的地質(zhì)特征，簡述了其各種富集機(jī)制的適用性及爭論。據(jù)此建議，結(jié)合埃迪卡拉紀(jì)—寒武紀(jì)轉(zhuǎn)折時期的古海洋背景，對其進(jìn)行詳細(xì)的沉積學(xué)及地球化學(xué)分析，有助于深化成因認(rèn)識，彌合分歧。

重晶石 古海洋 下寒武統(tǒng)

0 引言

重晶石(BaSO4)是沉積巖(物)里的常見礦物，自太古宙至今時有發(fā)育，并具有層狀、條帶狀、結(jié)核狀、以及彌散狀等多種產(chǎn)出形式[1-4]。重晶石具有高密度(～ 4.5 g/cm3)的物理特性，在化工添加劑、油氣勘探鉆井液等方面具有廣泛的工業(yè)應(yīng)用。因此，重晶石的顯著富集，具有重要的經(jīng)濟(jì)價值。

另一方面，在地質(zhì)歷史時期，重晶石產(chǎn)出豐度具有非均勻的時空分布特征[1,5-6]，并可能響應(yīng)了海洋環(huán)境的變化[7]。在礦物成分方面，重晶石富含S、O元素，其相關(guān)同位素(δ34S、δ18O及δ17O)可用于解譯硫循環(huán)或古氣候特征[3,8-12]。同時，重晶石具有高Sr、低Rb含量特征，是獲取87Sr/86Sr同位素比值的重要礦物[2]。由于分布廣、易保存，重晶石的同位素特征已廣泛應(yīng)用于流體演化[13-16]、全球海水Sr、S同位素組分重建等方面的研究[17-19]。此外，重晶石可以作為古生產(chǎn)力指標(biāo)[20-22]、硫酸鹽—甲烷轉(zhuǎn)換帶沉積指示物[23-24]或冷泉流體的活動的記錄者等[25-27]，具有廣泛的地質(zhì)應(yīng)用。然而，沉積型重晶石可能源于多種形成過程，并具有不同的成因類型和地質(zhì)意義。因此對沉積型重晶石的地質(zhì)特征和成因類型進(jìn)行對比認(rèn)識，有助于合理解讀其在古海洋、古環(huán)境及古地理方面的意義。

本文擬從鋇的海洋地球化學(xué)循環(huán)，并根據(jù)重晶石的沉積過程、形成環(huán)境、宏微觀特征(產(chǎn)出形式、晶體形態(tài))、同位素組成(Sr和S)、以及地質(zhì)意義等方面對沉積型重晶石進(jìn)行分類和評述。在此基礎(chǔ)上，針對揚子地區(qū)下寒武統(tǒng)黑色巖系重晶石富集程度差異、地質(zhì)特征，對其富集機(jī)理進(jìn)行對比、評述，并指出下一步研究中需注意的問題。

1 海洋鋇的循環(huán)與分布

2 重晶石沉積分類

海洋里的重晶石可形成于多種地質(zhì)過程，并最終保存于沉積物里(或富集為沉積型礦床)；在此概稱為沉積型重晶石。沉積型重晶石有多種分類方案[2]。根據(jù)構(gòu)造背景和產(chǎn)出特征，Maynardetal.[45]和Maynardetal.[46]將沉積型層狀重晶石礦床分為兩大類：①大陸邊緣類型，純重晶石礦床，不伴生Pb、Zn礦床；②克拉通裂谷型，可能伴生Pb、Zn礦床。根據(jù)產(chǎn)出形式、流體來源和現(xiàn)今實例，層狀重晶石可也分為成巖交代、熱液噴流和生物成因類型[1,47]。根據(jù)富鋇流體來源及與硫酸鹽相互作用過程，最新研究成果將海洋重晶石分為四類：生物重晶石、熱液重晶石、成巖重晶石和冷泉重晶石(圖1)[48-50]。各類型重晶石在地層沉積記錄里廣泛報道。由于形成環(huán)境和過程差異，如水柱、熱液系統(tǒng)、沉積物—水界面附近、或者沉積物柱孔隙環(huán)境等，重晶石具有多種晶體習(xí)性和結(jié)構(gòu)、產(chǎn)出形式，以及Sr、S同位素特征(表1)[48-49,51]。為了便于科研實踐，本文將據(jù)此對海洋重晶石沉積類型進(jìn)行詳細(xì)介紹。

2.1 生物重晶石

生物重晶石是指在生物直接誘導(dǎo)(胞內(nèi)合成)或間接調(diào)控(有機(jī)質(zhì)降解微環(huán)境)作用下形成的重晶石[20,35-36,54](圖1A)。重晶石微晶顆粒形成于不飽和海水，普遍認(rèn)為與生物有關(guān)。研究發(fā)現(xiàn)，為維持定向或深度而調(diào)節(jié)身體密度，海洋部分底棲原生動物(如有孔蟲類xenophyophore)可直接在細(xì)胞內(nèi)生成重晶石[55-56]。另一方面，培養(yǎng)實驗顯示，海洋細(xì)菌能夠提供晶體成核點并促進(jìn)重晶石晶體的生長[57-58]。目前而言，這類海洋生物報道數(shù)量或?qū)嵗邢?，有待進(jìn)一步探索；它們可能對整個重晶石儲庫的貢獻(xiàn)份額有限。

圖1 A. 海洋沉積型重晶石的產(chǎn)出環(huán)境；B. 熱液重晶石形成模式(修改自文獻(xiàn)[52])，圖A中b框細(xì)節(jié)圖；C. 成巖重晶石形成模式，圖A中c框細(xì)節(jié)圖；D. 冷泉重晶石形成模式(修改自文獻(xiàn)[53])，圖A中d框細(xì)節(jié)圖。注意成巖重晶石與冷泉重晶石的成因聯(lián)系。Fig.1 A. The occurrences of sedimentary barites in marine environments. B. Formation of hydrothermal barite (details of inset box b in Fig. 1A), modified from reference[52]. C. Formation of diagenetic barite (details of inset box c in Fig. 1A). D. Formation of cold seeps barite (details of inset box d in Fig. 1A), modified from reference[53]. Note the genetic connection between the diagenetic and cold seeps barites

重晶石成因類型生物重晶石熱液重晶石成巖重晶石冷泉重晶石沉積過程生物直接胞內(nèi)合成,或有機(jī)質(zhì)降解微環(huán)境里生成富Ba2+熱流體與含SO2-4流體混合富Ba2+(或和CH4)孔隙水與含SO2-4孔隙水混合富Ba2+(或和CH4)孔隙水與含SO2-4海水(或孔隙水)混合鋇源海水及含鋇有機(jī)質(zhì)淋濾洋殼、陸殼及富鋇沉積物早期沉積物(原生生物重晶石等)早期沉積物(原生生物重晶石等)硫酸鹽源海水海水或熱液H2S氧化產(chǎn)物孔隙水(經(jīng)BSR改造后的殘余海水硫酸鹽)經(jīng)BSR改造后的孔隙水或海水形成地點水柱熱液系統(tǒng)(通道、噴口、熱液羽)沉積物—水界面之下沉積物孔隙環(huán)境沉積物—水界面附近孔隙環(huán)境及水柱產(chǎn)出形式微晶顆粒,散布于水柱和沉積物熱液羽微顆粒、煙囪體、結(jié)殼、海底熱液網(wǎng)脈彌散的重晶石微顆粒,或膠結(jié)物、結(jié)核、透鏡、薄層條帶狀煙囪體、丘體、海底結(jié)殼,膠結(jié)物、結(jié)核、層狀等沉積或構(gòu)造環(huán)境非特定海域(高生產(chǎn)力海區(qū)更為顯著)熱液噴流及熱液羽區(qū)域,常見于洋中脊、弧后盆地等擴(kuò)張中心、斷裂帶,陸架邊緣斷裂帶,以及克拉通內(nèi)部裂谷區(qū)等高生產(chǎn)力海區(qū)(如陸架邊緣上升流地區(qū))高生產(chǎn)力海區(qū)、陸架邊緣陡坡帶、構(gòu)造及斷層發(fā)育的主動、被動大陸邊緣及復(fù)雜構(gòu)造背景的海盆生物群落浮游生物、原生動物xenophyophore等熱液生物群冷泉生物群代表性伴生礦物無特定伴生礦物多金屬硫化物、非晶質(zhì)硅質(zhì)沉積等富有機(jī)質(zhì)沉積物,黃鐵礦、方解石、白云石等黃鐵礦、方解石、白云石等粒度亞微米級晶粒(普遍<5μm)數(shù)十至數(shù)百微米,可達(dá)毫米級數(shù)十至數(shù)百微米,可達(dá)厘米級數(shù)十至數(shù)百微米,可達(dá)厘米級晶體形態(tài)常為啞鈴形、橢球形晶型,或不具有晶體習(xí)性自形、棱柱形、板片狀等晶型,放射針束狀、扇狀自形晶集合體,或者玫瑰花狀結(jié)構(gòu)片狀板柱狀等自形晶型,有時可見交切板狀雙晶,以及樹枝狀、玫瑰狀集合體螺旋狀、菱柱等晶型,以及樹枝狀和結(jié)核環(huán)帶等生長模式;有時可見交切板狀雙晶和玫瑰花狀結(jié)構(gòu)S同位素近似同時期海水值(Δδ34S≈0)常介于同時期海水值與熱液硫化物值之間(Δδ34S<0),但有時Δδ34S>0較同時期海水值不同程度偏高(Δδ34S>0,可達(dá)+50‰)較同時期海水值不同程度偏高(Δδ34S>0,可達(dá)+50‰)Sr同位素近似同時期海水值(Δ87Sr/86Sr≈0)顯著偏離同時期海水值(通常-0.006<Δ87Sr/86Sr<-0.002;或Δ87Sr/86Sr>+0.002)稍微偏離同時期海水值(通常-0.002<Δ87Sr/86Sr<+0.002)稍微偏離同時期海水值(通常-0.002<Δ87Sr/86Sr<+0.002)地質(zhì)意義記錄海水Sr、S同位素組成,重建海洋生產(chǎn)力指示熱液活動、并記錄熱液流體化學(xué)特征,指導(dǎo)伴生的沉積噴流礦床的勘探指示SMTZ和下伏甲烷輸入,反映沉積速率變化,制約鋇古生產(chǎn)力指標(biāo)指示甲烷釋放和冷泉滲流事件,可能影響局部海域Ba(和/或碳)循環(huán),指導(dǎo)層狀重晶石勘探

注：Δδ34S=δ34S重晶石-δ34S同時期海水硫酸鹽；Δ87Sr/86Sr=87Sr/86Sr重晶石-87Sr/86Sr同時期海水

另一方面，有機(jī)質(zhì)降解時的微環(huán)境可促進(jìn)重晶石的形成。許多海洋浮游生物直接從周圍海水吸收鋇進(jìn)入生物結(jié)構(gòu)，較海水相對富集鋇[59]。例如，等幅骨蟲(Acantharians)殼體由天青石(SrSO4)構(gòu)成，常含有數(shù)千ppm的Ba[60]。因此，它們含有相當(dāng)規(guī)模的活性鋇儲庫，在水柱里降解時可向臨近微環(huán)境提供鋇源，促進(jìn)重晶石的形成[20,35,54]。例如，Ganeshrametal.[61]發(fā)現(xiàn)，海岸浮游生物以及實驗室培養(yǎng)的硅藻和顆石藻在降解實驗中可沉淀重晶石。此外，Dehairsetal.[62]推測，富有機(jī)質(zhì)沉降顆粒里高強(qiáng)度細(xì)菌活動可能有助于海洋中層水柱高含量鋇顆粒的生成。然而由于現(xiàn)今海洋處于重晶石未飽和狀態(tài)，浮游生物降解時釋放的鋇能否被有效維存于微環(huán)境，對于重晶石沉淀至關(guān)重要[61]。目前認(rèn)為，糞球粒和有機(jī)質(zhì)團(tuán)塊等，雖然不是重晶石沉淀的必要條件，但能顯著促進(jìn)重晶石的生成[20,61]。理論上只要存在有機(jī)質(zhì)集合體，重晶石可以生成于任何水深，甚至沉積物—水界面附近[63]。

生物重晶石生成于水柱，呈現(xiàn)亞微米級晶粒(普遍<5 μm)，常為啞鈴形、橢球形晶型，或者不具有晶體習(xí)性[36,54,57]。由于形成于水柱，生物重晶石Sr、S和O同位素主要記錄了同時期海水的特征，并可用于重建海水組分的長期演化趨勢[17-19,49,64]?，F(xiàn)今海洋水柱溶解Ba含量與重晶石顆粒和有機(jī)碳含量，以及上覆海水的生物生產(chǎn)力具有顯著相關(guān)性，表明生物或有機(jī)質(zhì)降解控制著水柱Ba循環(huán)[21,65-69]。因此，遠(yuǎn)洋氧化環(huán)境沉積物里生物重晶石與表層生物生產(chǎn)力之間存在顯著的相關(guān)性[21]，據(jù)此可作為重建海洋生物生產(chǎn)力的指標(biāo)[20,22,70-71]。然而值得注意的是，在硫酸鹽虧損的缺氧海水或沉積物孔隙水中(由于細(xì)菌硫酸鹽還原作用)，重晶石可能會經(jīng)歷不同程度的溶解；這種背景下沉積物里的Ba含量并不能有效指示海洋的初始生產(chǎn)力。

2.2 熱液重晶石

熱液重晶石是指深部富鋇熱流體沿斷層或裂隙向海底運移或噴發(fā)至水柱過程中，與富硫酸鹽流體相互作用而生成的重晶石(圖1B)[50,72-73]。熱液流體里的鋇離子可淋濾自洋殼、陸殼基底或長英質(zhì)巖石(尤其是長石)、或者遠(yuǎn)洋富鋇沉積物[50]。熱液重晶石常源于火山島弧、洋脊、弧后盆地擴(kuò)張中心的巖漿熱源驅(qū)動的富硫化物中高溫集中流體(150℃～250℃)或中低溫彌散流體(<120℃)的活動，如東北太平洋布蘭科(Blanco)斷裂帶[74]、沖繩海槽JADE熱液區(qū)[75]、北冰洋洋中脊南部Loki’s Castle熱液區(qū)[52]、馬里亞納島弧[72,76-77]、克馬德克島弧[78-79]、湯加島弧[80]、巴布亞新幾內(nèi)亞的富蘭克林(Franklin)海山[73]、以及加那利群島亨利(Henry)海山[81]。此外，在構(gòu)造和減薄地殼導(dǎo)致的高熱流背景下，陸架邊緣的中低溫?zé)嵋毫黧w也可發(fā)育熱液重晶石，如南加利福尼亞大陸邊緣[50]。

由于熱流體運移速率差異，熱液重晶石具有多種產(chǎn)出形式：①網(wǎng)脈狀充填于海底面之下的熱液通道[75]，②在海底面之上形成煙囪體、丘體或結(jié)殼[72-73,77,82]，③以細(xì)小顆粒形式隨熱液羽飄散，并散布于沉積物中[83-85]。洋脊或弧后擴(kuò)張中心火山熱液系統(tǒng)里的重晶石常伴生多金屬硫化物(方鉛礦、閃鋅礦、黃銅礦、黃鐵礦等)和非晶質(zhì)硅質(zhì)沉積[72-73,78,86]?？死▋?nèi)部裂谷或者陸架邊緣的熱液系統(tǒng)沉積的重晶石既可與塊狀硫化物礦床共生，也可伴生于塊狀硫化物礦床上部或毗鄰區(qū)，形成獨立的沉積型重晶石礦床，如阿拉斯加地區(qū)的Red Dog礦床[87]。熱液重晶石呈現(xiàn)自形(如棱柱形、板片狀等)晶型，粒度較大，為數(shù)十微米至毫米級。它們有時生長于開闊孔洞，構(gòu)成放射針束狀、扇狀自形晶集合體[77]，或者玫瑰花狀結(jié)構(gòu)[49]。

熱液重晶石的生成常源于熱液端元流體(熱液成因H2S氧化而來的硫酸鹽δ34S值為+1‰至+2‰)與海水(現(xiàn)今海水硫酸鹽δ34S值約為+20‰)不同程度的混合，因此具有不同程度偏低或類似于同時期海水硫酸鹽的δ34S值[49,88-89]。值得注意的是，如果上覆局限盆地海水或者海底熱液系統(tǒng)里的硫酸鹽處于相對封閉環(huán)境(即硫酸鹽補(bǔ)充不足)時，細(xì)菌硫酸鹽還原作用可使殘余硫酸鹽的硫同位素值不斷增高。在此背景下，部分熱液重晶石也可能具有較同時期海水值偏重的δ34S值[52,75,81,90]。由于受到熱液活動的影響，熱液重晶石87Sr/86Sr同位素值通常不同程度偏離同時期海水值，記錄了熱液流體淋濾洋殼或者陸殼的特征[91-92]。洋脊擴(kuò)張中心和洋脊翼部的熱液重晶石的87Sr/86Sr值通常介于同時期海水值(現(xiàn)今海水87Sr/86Sr = 0.709 17)與萃取自洋殼的端元熱液流體值(87Sr/86Sr = 0.703 05)之間[51]；而克拉通內(nèi)部裂谷或者陸架邊緣的沉積噴流型熱液重晶石則常具有高于同時期海水值的殼源Sr同位素特征[45,47]。

沉積物里熱液重晶石的發(fā)育，指示存在熱液活動，有助于加深對古海洋的認(rèn)識。此外，熱液重晶石是獲取Sr、S同位素及流體包裹體測溫的理想對象[75]，可用于解析熱液流體地球化學(xué)性質(zhì)。因此，作為海底火山型塊狀硫化物礦床及沉積噴流型礦床里常見的伴生礦物，熱液重晶石有助于認(rèn)識相應(yīng)的成礦過程，并促進(jìn)硫化物礦床的勘探[87,90]。

2.3 成巖重晶石

成巖重晶石是指沉積物—水界面之下，原生生物重晶石在硫酸鹽虧損帶溶解后形成富鋇孔隙水，遷移至硫酸鹽—甲烷轉(zhuǎn)換帶(Sulfate-methane transition zones，SMTZ)附近與孔隙水殘余硫酸鹽相互作用而再沉淀的重晶石(圖1C)[24,38,93-95]。通常隨著深度的增加，沉積物孔隙水里的硫酸鹽由于來自上覆海水的擴(kuò)散補(bǔ)充受限，并且經(jīng)細(xì)菌硫酸鹽還原作用而不斷消耗[96-98]。隨著硫酸鹽的完全耗盡，沉積物里有機(jī)質(zhì)在產(chǎn)甲烷細(xì)菌作用下進(jìn)一步發(fā)酵產(chǎn)生甲烷，該區(qū)帶稱為產(chǎn)甲烷帶(methanogenesis zone)。因此，沉積物—水界面之下一定深度可形成硫酸鹽—甲烷轉(zhuǎn)換帶。SMTZ之上為硫酸鹽還原帶，孔隙水含有硫酸鹽，重晶石礦物性質(zhì)穩(wěn)定。SMTZ之下為產(chǎn)甲烷帶，硫酸鹽完全虧損，重晶石礦物將逐漸溶解，使得孔隙水具有高含量溶解鋇[38,93,99]。SMTZ附近甲烷和硫酸鹽近完全虧損，存在一個陡變的鋇離子梯度(圖1C)。下伏富鋇(和甲烷)孔隙水向上擴(kuò)散遷移，在SMTZ附近與向下擴(kuò)散的殘余硫酸鹽匯合，導(dǎo)致形成自生成巖重晶石前鋒帶[38,93]。成巖重晶石前鋒在現(xiàn)今水深數(shù)百米至上千米的海洋沉積物里時有發(fā)育，如環(huán)太平洋陸架邊緣[38]、墨西哥灣[53]、美國東南海岸Blake Ridge[24,99]、納米比亞陸架[93]、以及黑海[100]等地。

成巖重晶石的富集程度取決于SMTZ在特定深度的持續(xù)時間及溶解鋇的輸入情況。這又受到沉積速率[101]、下伏甲烷輸入量[24]、沉積物里原生海洋生物重晶石含量等因素的影響[99]。通常，高生產(chǎn)力海區(qū)沉積物里可積累較豐富的生物重晶石，其大量溶解后有助于提升孔隙水鋇離子含量，促進(jìn)成巖重晶石的形成[38,94]。因此，成巖重晶石在富有機(jī)質(zhì)巖層里更為常見。它們以彌散狀重晶石晶粒、厘米至分米級重晶石結(jié)核或者薄層重晶石條帶等多種形式產(chǎn)出[7,102-103]。由于具有相對穩(wěn)定的生長條件，成巖重晶石常形成片狀、板柱狀等自形晶型，有時可見交切板狀雙晶，粒度常為數(shù)十至數(shù)百微米，有時可達(dá)厘米級[48-49]。它們可呈現(xiàn)樹形生長、玫瑰狀集合體等形態(tài)結(jié)構(gòu)[38]。由于SMTZ里發(fā)育甲烷厭氧氧化作用(AOM)，成巖重晶石可能也伴生黃鐵礦、方解石、白云石等礦物[95,104-105]。

成巖重晶石形成于沉積物，主要記錄了孔隙水Sr、S同位素特征。孔隙水環(huán)境里，細(xì)菌硫酸鹽還原作用(BSR)優(yōu)先將富32S硫酸鹽還原為H2S，導(dǎo)致殘余硫酸鹽逐漸富集34S(Rayleigh分餾效應(yīng))[97,106-107]。由于記錄了孔隙水殘余硫酸鹽重硫同位素特征，成巖重晶石較同時期海水不同程度的富集34S(Δδ34S可達(dá)+50‰)[49,103]。另一方面，沉積柱中孔隙水主要繼承或擴(kuò)散自上覆海水，二者87Sr/86Sr值通常比較接近。但如果存在早期海洋沉積物、富放射性成因Sr的陸源物質(zhì)及虧損87Sr的洋殼物質(zhì)等的改造時，孔隙水Sr同位素將不同程度的偏離同時期海水值[27,108]。因此，成巖重晶石的87Sr/86Sr反映了孔隙水與各種沉積物質(zhì)的相互作用，接近或小幅度偏離同時期海水值(Δ87Sr/86Sr介于±0.002)[49,51]。

成巖重晶石及其富集情況能夠指示烴類輸入和SMTZ的位置[24,93,95,109-111]，以及沉積速率顯著變化[101]等地質(zhì)過程。此外，成巖重晶石的發(fā)育，表明沉積物里的生物重晶石經(jīng)歷了溶解、遷移和再沉淀，這將制約鋇含量在古生產(chǎn)力指標(biāo)方面的應(yīng)用[20,30,94]。值得注意的是，成巖重晶石及相關(guān)礦化作用在前寒武紀(jì)僅有少量報道[112-113]，至顯生宙其豐度和規(guī)模則有顯著增加[16,90,101-103,105,111,114-115]。因此最近研究認(rèn)為，這種情形可能響應(yīng)了埃迪卡拉紀(jì)—寒武紀(jì)轉(zhuǎn)折時期古海洋硫酸鹽濃度及生態(tài)系統(tǒng)的轉(zhuǎn)變[7]。

2.4 冷泉重晶石

冷泉重晶石是指富鋇(或/和烴類)孔隙水沿裂隙運移至沉積物—水界面附近(冷泉滲流地)，與富硫酸鹽孔隙水或海水相互作用而形成的重晶石(圖1D)[25-27,51,116]。冷泉重晶石與成巖重晶石在流體來源、沉積過程、同位素組成等多方面具有相似性。在斷層、側(cè)向擠壓構(gòu)造作用或者高沉積速率形成的沉積加載下，孔隙水可獲得超壓并垂向向上遷移。這將導(dǎo)致位于沉積物SMTZ里的成巖重晶石前鋒帶遷移至沉積物—水界面附近，轉(zhuǎn)化為冷泉重晶石體系(圖1C和D)[26,51,53]。冷泉流體的鋇源與成巖重晶石類似，主要為沉積物里堆積的活性生物重晶石[51]；因此冷泉重晶石常出現(xiàn)在高生產(chǎn)力背景下的富有機(jī)質(zhì)沉積環(huán)境。冷泉重晶石在現(xiàn)今海洋時有報道，如加尼福尼亞陸架[27,116]、秘魯陸架上升流地區(qū)[117]、阿拉斯加附近阿留申海槽[118]等匯聚型大陸架邊緣，墨西哥灣[25,119]等被動大陸邊緣，以及鄂霍茲克海[26]、日本海[120]等復(fù)雜構(gòu)造背景的大陸邊緣。此外，墨西哥、中國南方、美國阿拉斯加和內(nèi)華達(dá)地區(qū)古生代大型層狀重晶石礦床[51]，以及非洲西北部Taoudéni Basin新元古代蓋帽碳酸鹽巖里的重晶石沉積等也被認(rèn)為與冷泉活動有關(guān)[121]。

冷泉重晶石的產(chǎn)出形式受制于重晶石前鋒帶的深度(圖1D)，而這又受控于冷泉流體滲流速率[23,53]：低滲流速率時，重晶石沉積于沉積物—水界面附近的孔隙環(huán)境，形成微晶膠結(jié)物或結(jié)核(類似成巖重晶石)；高滲流速率時，重晶石沉積于海底面或水柱，形成結(jié)殼、多孔丘體以及大型煙囪體等典型的冷泉滲流結(jié)構(gòu)[25-27,116,119]。冷泉重晶石呈現(xiàn)螺旋狀、菱柱狀等晶型，可見交切板狀雙晶；有時形成玫瑰花狀、樹枝狀和結(jié)核環(huán)帶等生長模式[26,119-120]。由于常伴生AOM作用，冷泉重晶石沉積?？晒采妓猁}巖及少量黃鐵礦。其中，重晶石和碳酸鹽巖的相對含量受控于孔隙水里甲烷與鋇離子含量的比例[23]：低甲烷/鋇離子比值條件下，以重晶石沉淀為主；高比值條件下，硫酸鹽受到AOM的消耗，以碳酸鹽巖沉淀為主。因此，冷泉重晶石和冷泉碳酸鹽巖普遍共生，但也可以相互獨立而存在[51,90]。值得注意的是，現(xiàn)今海底冷泉重晶石沉積區(qū)也可能伴生相應(yīng)的冷泉生物群，如微生物席，以及貝類、管狀蠕蟲、腹足等大型生物[25-27,118]。

冷泉重晶石的Sr和S同位素主要記錄了孔隙水與海水的混合信號。若海水混合比例較低時，冷泉重晶石與成巖重晶石具有相似的孔隙水Sr、S同位素特征，即與同時期海水值相比具有相近的87Sr/86Sr比值(Δ87Sr/86Sr介于±0.002)，以及顯著偏重的δ34S值[15,49,51]。若海水混合顯著時，冷泉重晶石的Sr、S同位素將更為接近同時期海水值。需要指出的是，冷泉重晶石的δ34S/δ18O比值可提供滲流速率和硫酸鹽還原速率信息：該值大于4∶1(代表微生物硫酸鹽還原作用斜率值)被認(rèn)為指示了低滲流速率背景下高微生物硫酸鹽還原速率(硫酸鹽相對封閉體系)，反之則指示高滲流速率背景下低微生物還原速率(硫酸鹽相對開放體系)[25]。

冷泉是陸架邊緣重要的地質(zhì)過程，其釋放大量低溫富鋇(和甲烷流體)流體，可能顯著影響半封閉海洋盆地[116,122]，甚至地質(zhì)歷史時期全球海洋鋇(和碳)循環(huán)[28]。此外，地質(zhì)歷史里的冷泉重晶石也直接指示甲烷輸入和冷泉滲流事件[109,123-125]，并可能是古生代層狀重晶石礦床的成因機(jī)制[15,51,126]。

3 揚子地區(qū)下寒武統(tǒng)重晶石

華南揚子地區(qū)下寒武統(tǒng)黑色頁巖—硅質(zhì)巖地層普遍富含重晶石，具有顯著的高鋇含量特征(常高于1 000 ppm，有時甚至可達(dá)數(shù)萬ppm)[127-128]。其中，揚子地區(qū)湘黔相鄰區(qū)牛蹄塘組和秦嶺大巴山地區(qū)洞河群發(fā)育大型層狀重晶石成礦帶，是沉積型重晶石礦床的典型代表[1,47,129-132]。重晶石在沉積物里異常富集，通常需要特殊的地質(zhì)條件(如高生產(chǎn)力背景下生物重晶石或者富鋇流體的大量輸入等)[133]，而這通常反映了重要的地質(zhì)事件。在此，我們以揚子地區(qū)下寒武統(tǒng)重晶石為例，分析其沉積特征，討論富集機(jī)制和地質(zhì)意義。

3.1 地質(zhì)特征

揚子地區(qū)下寒武統(tǒng)富重晶石巖系在地理圖上呈帶狀分布[129,132]?；谥魑⒘康鹊厍蚧瘜W(xué)特征，目前普遍認(rèn)為下寒武統(tǒng)富重晶石的黑色巖系主要沉積于缺氧環(huán)境[132,134-137]。重晶石礦床的硫酸鋇含量一般為85%～95%，并伴生毒重石、鋇解石、黃鐵礦、鋇冰長石、斜鋇鈣石、閃鋅礦、硫釩銅礦和膠磷礦等礦物[130,138]。重晶石呈現(xiàn)彌散、層狀、透鏡狀、條帶狀、結(jié)核狀、玫瑰花狀等多種沉積結(jié)構(gòu)。重晶石圍巖里可見藻類、海綿骨針、管狀生物等化石[139]。同位素地球化學(xué)方面，層狀重晶石δ34S值一般為+25‰至+60‰[132,138,140-143]，其中重晶石結(jié)核δ34S值可達(dá)74‰[103]；較早寒武世海水(35‰～40‰)[144]顯著富集34S。揚子地區(qū)下寒武統(tǒng)重晶石87Sr/86Sr分布較窄，普遍介于0.708 0至0.709 0之間[132,145-146]，總體接近早寒武世海水值(0.708 2～0.709 0)[147]。少量重晶石樣品可能受陸源雜質(zhì)的影響，87Sr/86Sr比值可達(dá)0.709 5～0.716 7[146]。

3.2 富集機(jī)制

根據(jù)下寒武統(tǒng)重晶石富集的地質(zhì)特征，研究者們提出了多種成因機(jī)制，如生物富集[1,148]、富鋇冷泉流體釋放[15,51]、或者熱液活動[47,129-130,142,145,149]等地質(zhì)作用。

生物富集模式支持者認(rèn)為，早寒武世揚子地區(qū)陸架邊緣上升流發(fā)育，富營養(yǎng)水體促進(jìn)生物繁盛，高生產(chǎn)力背景下生成大量海洋生物重晶石[1,148]。它們可能直接導(dǎo)致層狀重晶石的沉積，或者在缺氧海盆或沉積物里經(jīng)溶解、遷移再沉淀形成富重晶石沉積。該模式得到重晶石及其圍巖(黑色頁巖—硅質(zhì)巖)富含有機(jī)質(zhì)、Si和P元素證據(jù)的支持，暗示沉積時水柱處于高生產(chǎn)力背景或者缺氧環(huán)境[137,149]。然而，重晶石的Sr、S同位素特征均不同程度偏離同時期海水值，這顯著不同于水柱直接生成的生物成因重晶石。同時，單一的生物作用模式難以解釋揚子地區(qū)下寒武統(tǒng)重晶石富集的形態(tài)、規(guī)模和品位，且缺乏古今實例。

冷泉作用模式認(rèn)為，揚子地區(qū)下寒武統(tǒng)大型層狀重晶石沉積可能受益于陸架邊緣富鋇(和烴)的冷泉活動[15,51,132]。揚子地區(qū)下寒武統(tǒng)重晶石的Sr同位素比值在同時期海水值附近小幅度波動[146]，表明可能源于受沉積物改造的孔隙水。它們的硫同位素較同時期海水顯著偏重[140]，可能記錄了沉積物孔隙水里殘余硫酸鹽(富集34S同位素)的信號。因此，下寒武統(tǒng)重晶石的Sr和S同位素特征與現(xiàn)今成巖或冷泉重晶石相似[51,132]。此外，下寒武統(tǒng)重晶石富集的冷泉模式也得到其他地質(zhì)證據(jù)的支持：①重晶石具有成巖和海底生長特征[139]，表明隨著孔隙水流體向上運移強(qiáng)弱的變化，重晶石前鋒帶深度不斷波動；②圍巖里的化石疑似冷泉生物群；③牛蹄塘組早成巖重晶石—黃鐵礦結(jié)核顯示沉積物里發(fā)育冷泉流體[103]；④重晶石未見伴生的大規(guī)模的賤金屬硫化物沉積；⑤富重晶石沉積帶狀分布，表明受控于斷層相關(guān)的冷泉流體通道；⑥現(xiàn)今大陸邊緣可見冷泉重晶石顯著富集的實例[51,117]。值得注意的是，揚子地區(qū)下寒武統(tǒng)部分重晶石(毒重石)也不同程度經(jīng)歷了早成巖作用的富集[103,132]。

熱液活動模式認(rèn)為，前寒武紀(jì)—寒武紀(jì)轉(zhuǎn)折時期揚子地區(qū)廣泛發(fā)育海底熱液活動[128,150]，并促進(jìn)了下寒武統(tǒng)硅質(zhì)巖和Ni-Mo多金屬的沉積[151]。在此背景下，下寒武統(tǒng)重晶石富集也可能源于熱液活動，并得到大量地質(zhì)證據(jù)的支持：①重晶石具有網(wǎng)脈結(jié)構(gòu)及熱水噴流沉積結(jié)構(gòu)[130]；②硅質(zhì)巖、黑色頁巖等重晶石圍巖的地球化學(xué)特征顯示有熱液流體的影響[142,152]；③重晶石Sr同位素值偏離同時期海水值，反映了熱液流體的貢獻(xiàn)[47,129,145-146]；④伴生少量黃銅礦、環(huán)帶鋇冰長石等熱液礦物[135,153-154]；⑤流體包裹體數(shù)據(jù)揭示中等溫度條件[131]；⑥圍巖里的化石疑似海底熱液生物群[139]；⑦重晶石成礦帶線性排列，表明似乎受控于斷層相關(guān)的熱液流體通道。

3.3 討論

由此可見，揚子地區(qū)下寒武統(tǒng)重晶石的各種富集機(jī)制均能得到地質(zhì)證據(jù)不同程度的支持。然而，有些證據(jù)并非特定成因模式的必要條件。比如，重晶石較海水顯著較重的δ34S值，顯示了在硫酸鹽虧損環(huán)境里、微生物硫酸鹽還原的分餾作用。這種環(huán)境可能是海洋生物富集模式里硫酸鹽供給不足的局限海盆環(huán)境[129,135,140,143]，也可以是冷泉模式里海洋沉積物中的孔隙水環(huán)境[15,132]。同時，重晶石Sr同位素相對于早寒武世海水值一定程度的偏移，也分別被解釋為熱液[135,145]，或者海水來源的證據(jù)[132]。另一方面，揚子地區(qū)下寒武統(tǒng)重晶石富集帶的線性分布特征，既可能是受控于陸架邊緣沿岸上升流高生產(chǎn)力條件，也可能受控于斷層相關(guān)的冷泉或熱液流體通道。此外，重晶石富集帶是否伴生硫化物礦床、是否發(fā)育烴類流體及相關(guān)的碳酸鹽巖沉積、滲(噴)流流體溫度特征及Sr同位素解釋等，也可以是冷泉模式和熱液模式的重要分歧[51,91,151]。

因此，揚子地區(qū)下寒武統(tǒng)重晶石的顯著富集可能涉及各種成因過程。例如，高生產(chǎn)力背景下，陸架邊緣沉積物里初步富集海洋生物重晶石。早成巖階段，這些重晶石不斷溶解，提升孔隙流體鋇含量，一方面可遷移至SMTZ附近再沉淀而不斷富集，另一方面也可為冷泉或熱液重晶石提供鋇源。反之，大量富鋇冷泉或熱液流體釋放至海水，也可能促進(jìn)水柱里海洋(生物)重晶石的生成。值得注意的是，埃迪卡拉紀(jì)—寒武紀(jì)轉(zhuǎn)折時期海洋生態(tài)(后生動物及糞球粒的到來)[155-156]，以及海洋地球化學(xué)(硫酸鹽濃度的增高)[157]的轉(zhuǎn)變，可能是理解下寒武統(tǒng)普遍具有高鋇含量及富集重晶石的一個新思路[7]。總之，揚子地區(qū)下寒武統(tǒng)黑色巖系富重晶石沉積的成因機(jī)制仍然懸而未決。結(jié)合該時期古海洋背景，在詳細(xì)的沉積學(xué)基礎(chǔ)上，綜合地球化學(xué)特征，有助于深化對該層段重晶石的沉積類型和成因機(jī)制的認(rèn)識，并彌合分歧。

4 結(jié)論

沉積型重晶石在地質(zhì)歷史里分布廣泛、類型豐富，具有重要的經(jīng)濟(jì)和地質(zhì)意義。基于形成環(huán)境、宏微觀沉積特征、Sr和S同位素組成等特點，沉積型重晶石可分為生物、熱液、成巖和冷泉重晶石四個端元類型。通過地質(zhì)特征，識別重晶石成因類型，是合理解讀相應(yīng)地質(zhì)意義的關(guān)鍵。揚子地區(qū)下寒武統(tǒng)重晶石不同程度體現(xiàn)了生物、冷泉(及成巖)和熱液重晶石的地質(zhì)特征，相關(guān)研究有待進(jìn)一步深化。

References)

1 Jewell P W. Bedded barite in the geologic record[M]//Glenn C R, Prévt L, Lucas J. Marine Authigenesis: from Global to Microbial. Society Economic Paleontologists Mineralogists Special Publication, 2000, 66(1): 147-161.

2 Hanor J S. Barite-celestine geochemistry and environments of formation[J]. Reviews in Mineralogy and Geochemistry, 2000, 40(1): 193-275.

3 Shen Yanan, Buick R, Canfield D E. Isotopic evidence for microbial sulphate reduction in the early Archaean era[J]. Nature, 2001, 410(6824): 77-81.

4 McClung C R, Gutzmer J, Beukes N J, et al. Geochemistry of bedded barite of the Mesoproterozoic Aggeneys-Gamsberg Broken Hill-type district, South Africa[J]. Mineralium Deposita, 2007, 42(5): 537-549.

5 Lyons T W, Gellatly A M, McGoldrick P J, et al. Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry[J]. Geological Society of America Memoirs, 2006, 198: 169-184.

6 Huston D L, Logan G A. Barite, BIFs and bugs: evidence for the evolution of the Earth's early hydrosphere[J]. Earth and Planetary Science Letters, 2004, 220(1/2): 41-55.

7 Zhou Xiqiang, Chen Daizhao, Dong Shaofeng, et al. Diagenetic barite deposits in the Yurtus Formation in Tarim Basin, NW China: implications for barium and sulfur cycling in the earliest Cambrian[J]. Precambrian Research, 2015, 263: 79-87.

8 Peng Yongbo, Bao Huiming, Zhou Chuanming, et al. Oxygen isotope composition of meltwater from a Neoproterozoic glaciation in South China[J]. Geology, 2013, 41(3): 367-370.

9 Killingsworth B A, Hayles J A, Zhou Chuanming, et al. Sedimentary constraints on the duration of the Marinoan Oxygen-17 Depletion (MOSD) event[J]. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110(44): 17686-17690.

10 Peng Yongbo, Bao Huiming, Zhou Chuanming, et al.17O-depleted barite from two Marinoan cap dolostone sections, South China[J]. Earth and Planetary Science Letters, 2011, 305(1/2): 21-31.

11 Zhou Chunming, Bao Huiming, Peng Yongbo, et al. Timing the deposition of17O-depleted barite at the aftermath of Nantuo glacial meltdown in South China[J]. Geology, 2010, 38(10): 903-906.

12 Bao Huiming, Rumble III D, Lowe D R. The five stable isotope compositions of Fig Tree barites: implications on sulfur cycle in ca. 3.2 Ga oceans[J]. Geochimica et Cosmochimica Acta, 2007, 71(20): 4868-4879.

13 Staude S, G?b S, Pfaff K, et al. Deciphering fluid sources of hydrothermal systems: a combined Sr- and S-isotope study on barite (Schwarzwald, SW Germany)[J]. Chemical Geology, 2011, 286(1/2): 1-20.

14 Shen Yanan, Farquhar J, Masterson A, et al. Evaluating the role of microbial sulfate reduction in the early Archean using quadruple isotope systematics[J]. Earth and Planetary Science Letters, 2009, 279(3/4): 383-391.

15 Johnson C A, Emsbo P, Poole F G, et al. Sulfur- and oxygen-isotopes in sediment-hosted stratiform barite deposits[J]. Geochimica et Cosmochimica Acta, 2009, 73(1): 133-147.

16 Magnall J M, Gleeson S A, Stern R A, et al. Open system sulphate reduction in a diagenetic environment-isotopic analysis of barite (δ34S and δ18O) and pyrite (δ34S) from the Tom and Jason Late Devonian Zn-Pb-Ba deposits, Selwyn Basin, Canada[J]. Geochimica et Cosmochimica Acta, 2016, 180: 146-163.

17 Paytan A, Kastner M, Campbell D, et al. Sulfur isotopic composition of Cenozoic seawater sulfate[J]. Science, 1998, 282(5393): 1459-1462.

18 Paytan A, Kastner M, Martin E E, et al. Marine barite as a monitor of seawater strontium isotope composition[J]. Nature, 1993, 366(6454): 445-449.

19 Bottrell S H, Newton R J. Reconstruction of changes in global sulfur cycling from marine sulfate isotopes[J]. Earth-Science Reviews, 2006, 75(1/2/3/4): 59-83.

20 Paytan A, Griffith E M. Marine barite: recorder of variations in ocean export productivity[J]. Deep Sea Research Part II: Topical Studies in Oceanography, 2007, 54(5/6/7): 687-705.

21 Dymond J, Suess E, Lyle M. Barium in deep-sea sediment: a geochemical proxy for paleoproductivity[J]. Paleoceanography, 1992, 7(2): 163-181.

22 Schoepfer S D, Shen Jun, Wei Hengye, et al. Total organic carbon, organic phosphorus, and biogenic barium fluxes as proxies for paleomarine productivity[J]. Earth-Science Reviews, 2015, 149: 23-52.

23 Aloisi G, Wallmann K, Bollwerk S M, et al. The effect of dissolved barium on biogeochemical processes at cold seeps[J]. Geochimica et Cosmochimica Acta, 2004, 68(8): 1735-1748.

24 Dickens G R. Sulfate profiles and barium fronts in sediment on the Blake Ridge: present and past methane fluxes through a large gas hydrate reservoir[J]. Geochimica et Cosmochimica Acta, 2001, 65(4): 529-543.

25 Feng Dong, Roberts H H. Geochemical characteristics of the barite deposits at cold seeps from the northern Gulf of Mexico continental slope[J]. Earth and Planetary Science Letters, 2011, 309(1/2): 89-99.

26 Greinert J, Bollwerk S M, Derkachev A, et al. Massive barite deposits and carbonate mineralization in the Derugin Basin, Sea of Okhotsk: precipitation processes at cold seep sites[J]. Earth and Planetary Science Letters, 2002, 203(1): 165-180.

27 Naehr T H, Stakes D S, Moore W S. Mass wasting, ephemeral fluid flow, and barite deposition on the California continental margin[J]. Geology, 2000, 28(4): 315-318.

28 Dickens G R, Fewless T, Thomas E, et al. Excess barite accumulation during the Paleocene-Eocene thermal Maximum: Massive input of dissolved barium from seafloor gas hydrate reservoirs[J]. Geological Society of America Special Papers, 2003, 369: 11-23.

29 Gonneea M E, Paytan A. Phase associations of barium in marine sediments[J]. Marine Chemistry, 2006, 100(1/2): 124-135.

30 McManus J, Berelson W M, Klinkhammer G P, et al. Geochemistry of barium in marine sediments: implications for its use as a paleoproxy[J]. Geochimica et Cosmochimica Acta, 1998, 62(21/22): 3453-3473.

31 Monnin C. A thermodynamic model for the solubility of barite and celestite in electrolyte solutions and seawater to 200°C and to 1 kbar[J]. Chemical Geology, 1999, 153(1/2/3/4): 187-209.

32 Monnin C, Cividini D. The saturation state of the world's ocean with respect to (Ba,Sr)SO4solid solutions[J]. Geochimica et Cosmochimica Acta, 2006, 70(13): 3290-3298.

33 Monnin C, Jeandel C, Cattaldo T, et al. The marine barite saturation state of the world's oceans[J]. Marine Chemistry, 1999, 65(3/4): 253-261.

34 Rushdi A I, McManus J, Collier R W. Marine barite and celestite saturation in seawater[J]. Marine Chemistry, 2000, 69(1/2): 19-31.

35 Bishop J K B. The barite-opal-organic carbon association in oceanic particulate matter[J]. Nature, 1988, 332(6162): 341-343.

36 Dehairs F, Chesselet R, Jedwab J. Discrete suspended particles of barite and the barium cycle in the open ocean[J]. Earth and Planetary Science Letters, 1980, 49(2): 528-550.

37 McManus J, Berelson W M, Klinkhammer G P, et al. Remobilization of barium in continental margin sediments[J]. Geochimica et Cosmochimica Acta, 1994, 58(22): 4899-4907.

38 Torres M E, Brumsack H J, Bohrmann G, et al. Barite fronts in continental margin sediments: a new look at barium remobilization in the zone of sulfate reduction and formation of heavy barites in diagenetic fronts[J]. Chemical Geology, 1996, 127(1/2/3): 125-139.

39 Steele J H, Thorpe S A, Turekian K K. Encyclopedia of Ocean Sciences[M]. 2nd ed. Amsterdam: Academic Press, 2011: 255-260.

40 Falkner K K, Klinkhammer G P, Bowers T S, et al. The behavior of barium in anoxic marine waters[J]. Geochimica et Cosmochimica Acta, 1993, 57(3): 537-554.

41 Coffey M, Dehairs F, Collette O, et al. The behaviour of dissolved barium in estuaries[J]. Estuarine, Coastal and Shelf Science, 1997, 45(1): 113-121.

42 Stecher III H A, Kogut M B. Rapid barium removal in the Delaware estuary[J]. Geochimica et Cosmochimica Acta, 1999, 63(7/8): 1003-1012.

43 Douville E, Charlou J L, Oelkers E H, et al. The rainbow vent fluids (36°14'N, MAR): the influence of ultramafic rocks and phase separation on trace metal content in Mid-Atlantic Ridge hydrothermal fluids[J]. Chemical Geology, 2002, 184(1/2): 37-48.

44 Elderfield H, Schultz A. Mid-ocean ridge hydrothermal fluxes and the chemical composition of the ocean[J]. Annual Review of Earth and Planetary Sciences, 1996, 24(1): 191-224.

45 Maynard J B, Morton J, Valdes-Nodarse E L, et al. Sr isotopes of bedded barites; guide to distinguishing basins with Pb-Zn mineralization[J]. Economic Geology, 1995, 90(7): 2058-2064.

46 Maynard J B, Okita P M. Bedded barite deposits in the United States, Canada, Germany, and China; two major types based on tectonic setting[J]. Economic Geology, 1991, 86(2): 364-376.

47 Clark S H B, Poole F G, Wang Zhongcheng. Comparison of some sediment-hosted, stratiform barite deposits in China, the United States, and India[J]. Ore Geology Reviews, 2004, 24(1/2): 85-101.

48 Griffith E M, Paytan A. Barite in the ocean-occurrence, geochemistry and palaeoceanographic applications[J]. Sedimentology, 2012, 59(6): 1817-1835.

49 Paytan A, Mearon S, Cobb K, et al. Origin of marine barite deposits: Sr and S isotope characterization[J]. Geology, 2002, 30(8): 747-750.

50 Hein J R, Zierenberg R A, Maynard J B, et al. Barite-forming environments along a rifted continental margin, Southern California Borderland[J]. Deep Sea Research Part II: Topical Studies in Oceanography, 2007, 54(11/12/13): 1327-1349.

51 Torres M E, Bohrmann G, Dubé T E, et al. Formation of modern and Paleozoic stratiform barite at cold methane seeps on continental margins[J]. Geology, 2003, 31(10): 897-900.

52 Eickmann B, Thorseth I H, Peters M, et al. Barite in hydrothermal environments as a recorder of subseafloor processes: a multiple-isotope study from the Loki's Castle vent field[J]. Geobiology, 2014, 12(4): 308-321.

53 Castellini D G, Dickens G R, Snyder G T, et al. Barium cycling in shallow sediment above active mud volcanoes in the Gulf of Mexico[J]. Chemical Geology, 2006, 226(1/2): 1-30.

54 Bertram M A, Cowen J P. Morphological and compositional evidence for biotic precipitation of marine barite[J]. Journal of Marine Research, 1997, 55(3): 577-593.

55 Gooday A J, Nott J A. Intracellular barite crystals in two xenophyophores,AschemonellaramuliformisandGalatheamminasp. (Protozoa: Rhizopoda) with comments on the taxonomy ofA.ramuliformis[J]. Journal of the Marine Biological Association of the United Kingdom, 1982, 62(3): 595-605.

56 Swinbanks D D, Shirayama Y. High levels of natural radionuclides in a deep-sea infaunal xenophyophore[J]. Nature, 1986, 320(6060): 354-358.

58 González-Munoz M T, Fernández-Luque B, Martínez-Ruiz F, et al. Precipitation of barite byMyxococcusxanthus: possible implications for the biogeochemical cycle of barium[J]. Applied and Environmental Microbiology, 2003, 69(9): 5722-5725.

59 Fisher N S, Guillard R R L, Bankston D C. The accumulation of barium by marine phytoplankton grown in culture[J]. Journal of Marine Research, 1991, 49(2): 339-354.

60 Bernstein R E, Byrne R H. Acantharians and marine barite[J]. Marine Chemistry, 2004, 86(1/2): 45-50.

61 Ganeshram R S, Fran?ois R, Commeau J, et al. An experimental investigation of barite formation in seawater[J]. Geochimica et Cosmochimica Acta, 2003, 67(14): 2599-2605.

62 Dehairs F, Jacquet S, Savoye N, et al. Barium in twilight zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific[J]. Deep Sea Research Part II: Topical Studies in Oceanography, 2008, 55(14/15): 1673-1683.

63 van Beek P, Fran?ois R, Conte M, et al.228Ra/226Ra and226Ra/Ba ratios to track barite formation and transport in the water column[J]. Geochimica et Cosmochimica Acta, 2007, 71(1): 71-86.

64 Markovic S, Paytan A, Li Hong, et al. A revised seawater sulfate oxygen isotope record for the last 4Myr[J]. Geochimica et Cosmochimica Acta, 2016, 175: 239-251.

65 Dehairs F, Baeyens W, Goeyens L. Accumulation of suspended barite at mesopelagic depths and export production in the Southern Ocean[J]. Science, 1992, 258(5086): 1332-1335.

66 Dehairs F, Stroobants N, Goeyens L. Suspended barite as a tracer of biological activity in the Southern Ocean[J]. Marine Chemistry, 1991, 35(1/2/3/4): 399-410.

67 Dymond J, Collier R. Particulate barium fluxes and their relationships to biological productivity[J]. Deep Sea Research Part II: Topical Studies in Oceanography, 1996, 43(4/5/6): 1283-1308.

68 Cardinal D, Savoye N, Trull T W, et al. Variations of carbon remineralisation in the Southern Ocean illustrated by the Baxsproxy[J]. Deep Sea Research Part I: Oceanographic Research Papers, 2005, 52(2): 355-370.

69 Jeandel C, Tachikawa K, Bory A, et al. Biogenic barium in suspended and trapped material as a tracer of export production in the tropical NE Atlantic (EUMELI sites)[J]. Marine Chemistry, 2000, 71(1/2): 125-142.

70 Francois R, Honjo S, Manganini S J, et al. Biogenic barium fluxes to the deep sea: implications for paleoproductivity reconstruction[J]. Global Biogeochemical Cycles, 1995, 9(2): 289-303.

71 Ma Zhongwu, Ravelo A C, Liu Zhonghui, et al. Export production fluctuations in the eastern equatorial Pacific during the Pliocene-Pleistocene: reconstruction using barite accumulation rates[J]. Paleoceanography, 2015, 30(11): 1455-1469.

72 Urabe T, Kusakabe M. Barite silica chimneys from the Sumisu Rift, Izu-Bonin Arc: possible analog to hematitic chert associated with Kuroko deposits[J]. Earth and Planetary Science Letters, 1990, 100(1/2/3): 283-290.

73 Binns R A, Parr J M, Gemmell J B, et al. Precious metals in barite-silica chimneys from Franklin Seamount, Woodlark Basin, Papua New Guinea[J]. Marine Geology, 1997, 142(1/2/3/4): 119-141.

74 Hein J R, Koski R A, Embley R W, et al. Diffuse-flow hydrothermal field in an oceanic fracture zone setting, Northeast Pacific: deposit composition[J]. Exploration and Mining Geology, 1999, 8(3/4): 299-322.

75 Lüders V, Pracejus B, Halbach P. Fluid inclusion and sulfur isotope studies in probable modern analogue Kuroko-type ores from the JADE hydrothermal field (Central Okinawa Trough, Japan)[J]. Chemical Geology, 2001, 173(1/2/3): 45-58.

76 Stüben D, Taibi N E, McMurtry G M, et al. Growth history of a hydrothermal silica chimney from the Mariana backarc spreading center (southwest Pacific, 18°13'N)[J]. Chemical Geology, 1994, 113(3/4): 273-296.

77 Moore W S, Stakes D. Ages of barite-sulfide chimneys from the Mariana Trough[J]. Earth and Planetary Science Letters, 1990, 100(1/2/3): 265-274.

78 Herzig P M, Becker K P, Stoffers P, et al. Hydrothermal silica chimney fields in the Galapagos spreading center at 86°W[J]. Earth and Planetary Science Letters, 1988, 89(3/4): 261-272.

79 de Ronde C E, Faure K, Bray C J, et al. Hydrothermal fluids associated with seafloor mineralization at two southern Kermadec arc volcanoes, offshore New Zealand[J]. Mineralium Deposita, 2003, 38(2): 217-233.

80 Stoffers P, Worthington T J, Schwarz-Schampera U, et al. Submarine volcanoes and high-temperature hydrothermal venting on the Tonga arc, southwest Pacific[J]. Geology, 2006, 34(6): 453-456.

81 Klügel A, Hansteen T H, van den Bogaard P, et al. Holocene fluid venting at an extinct Cretaceous seamount, Canary archipelago[J]. Geology, 2011, 39(9): 855-858.

82 Petersen S, Herzig P M, Schwarz-Schampera U, et al. Hydrothermal precipitates associated with bimodal volcanism in the Central Bransfield Strait, Antarctica[J]. Mineralium Deposita, 2004, 39(3): 358-379.

83 Mottl M J, McConachy T F. Chemical processes in buoyant hydrothermal plumes on the East Pacific Rise near 21°N[J]. Geochimica et Cosmochimica Acta, 1990, 54(7): 1911-1927.

84 Feely R A, Geiselman T L, Baker E T, et al. Distribution and composition of hydrothermal plume particles from the ASHES vent field at Axial Volcano, Juan de Fuca Ridge[J]. Journal of Geophysical Research, 1990, 95(B8): 12855-12873.

85 Peters M, Strauss H, Petersen S, et al. Hydrothermalism in the Tyrrhenian Sea: inorganic and microbial sulfur cycling as revealed by geochemical and multiple sulfur isotope data[J]. Chemical Geology, 2011, 280(1/2): 217-231.

86 Halbach M, Halbach P, Lüders V. Sulfide-impregnated and pure silica precipitates of hydrothermal origin from the central Indian Ocean[J]. Chemical Geology, 2002, 182(2/3/4): 357-375.

87 Kelley K, Jennings S. A special issue devoted to barite and Zn-Pb-Ag deposits in the Red Dog district, Western Brooks Range, Northern Alaska[J]. Economic Geology, 2004, 99(7): 1267-1280.

88 Rye R O. A review of the stable-isotope geochemistry of sulfate minerals in selected igneous environments and related hydrothermal systems[J]. Chemical Geology, 2005, 215(1/2/3/4): 5-36.

89 Herzig P M, Hannington M D, Arribas A, Jr. Sulfur isotopic composition of hydrothermal precipitates from the Lau back-arc: implications for magmatic contributions to seafloor hydrothermal systems[J]. Mineralium Deposita, 1998, 33(3): 226-237.

90 Johnson C, Kelley K, Leach D L. Sulfur and oxygen isotopes in barite deposits of the western Brooks Range, Alaska, and implications for the origin of the Red Dog massive sulfide deposits[J]. Economic Geology, 2004, 99(7): 1435-1448.

91 Emsbo P, Johnson C A. Formation of modern and Paleozoic stratiform barite at cold methane seeps on continental margins: comment and reply comment[J]. Geology, 2004, 32(1): e64.

92 Noguchi T, Shinjo R, Ito M, et al. Barite geochemistry from hydrothermal chimneys of the Okinawa Trough: insight into chimney formation and fluid/sediment interaction[J]. Journal of Mineralogical and Petrological Sciences, 2011, 106(1): 26-35.

93 Riedinger N, Kasten S, Gr?ger J, et al. Active and buried authigenic barite fronts in sediments from the Eastern Cape Basin[J]. Earth and Planetary Science Letters, 2006, 241(3/4): 876-887.

94 Hendy I L. Diagenetic behavior of barite in a coastal upwelling setting[J]. Paleoceanography, 2010, 25(4): PA4103.

95 Snyder G T, Hiruta A, Matsumoto R, et al. Pore water profiles and authigenic mineralization in shallow marine sediments above the methane-charged system on Umitaka Spur, Japan Sea[J]. Deep Sea Research Part II: Topical Studies in Oceanography, 2007, 54(11/12/13): 1216-1239.

96 Goldhaber M B, Kaplan I R. Mechanisms of sulfur incorporation and isotope fractionation during early diagenesis in sediments of the Gulf of California[J]. Marine Chemistry, 1980, 9(2): 95-143.

97 Canfield D E. Biogeochemistry of sulfur isotopes[J]. Reviews in Mineralogy and Geochemistry, 2001, 43(1): 607-636.

98 J?rgensen B B, Weber A, Zopfi J. Sulfate reduction and anaerobic methane oxidation in Black Sea sediments[J]. Deep Sea Research Part I: Oceanographic Research Papers, 2001, 48(9): 2097-2120.

99 Snyder G T, Dickens G R, Castellini D G. Labile barite contents and dissolved barium concentrations on Blake Ridge: new perspectives on barium cycling above gas hydrate systems[J]. Journal of Geochemical Exploration, 2007, 95(1/2/3): 48-65.

100 Henkel S, Mogollón J M, N?then K, et al. Diagenetic barium cycling in Black Sea sediments-a case study for anoxic marine environments[J]. Geochimica et Cosmochimica Acta, 2012, 88: 88-105.

101 Bréhéret J G, Brumsack H J. Barite concretions as evidence of pauses in sedimentation in the Marnes Bleues Formation of the Vocontian Basin (SE France)[J]. Sedimentary Geology, 2000, 130(3/4): 205-228.

103 Goldberg T, Mazumdar A, Strauss H, et al. Insights from stable S and O isotopes into biogeochemical processes and genesis of Lower Cambrian barite-pyrite concretions of South China[J]. Organic Geochemistry, 2006, 37(10): 1278-1288.

104 Moore T S, Murray R W, Kurtz A C, et al. Anaerobic methane oxidation and the formation of dolomite[J]. Earth and Planetary Science Letters, 2004, 229(1/2): 141-154.

105 Raiswell R, Bottrell S H, Dean S P, et al. Isotopic constraints on growth conditions of multiphase calcite-pyrite-barite concretions in Carboniferous mudstones[J]. Sedimentology, 2002, 49(2): 237-254.

106 B?ttcher M E, Khim B K, Suzuki A, et al. Microbial sulfate reduction in deep sediments of the Southwest Pacific (ODP Leg 181, Sites 1119-1125): evidence from stable sulfur isotope fractionation and pore water modeling[J]. Marine Geology, 2004, 205(1/2/3/4): 249-260.

107 Borowski W S, Rodriguez N M, Paull C K, et al. Are34S-enriched authigenic sulfide minerals a proxy for elevated methane flux and gas hydrates in the geologic record?[J]. Marine and Petroleum Geology, 2013, 43: 381-395.

108 Dia A N, Aquilina L, Boulègue J, et al. Origin of fluids and related barite deposits at vent sites along the Peru convergent margin[J]. Geology, 1993, 21(12): 1099-1102.

109 Kasten S, N?then K, Hensen C, et al. Gas hydrate decomposition recorded by authigenic barite at pockmark sites of the northern Congo Fan[J]. Geo-Marine Letters, 2012, 32(5/6): 515-524.

110 Arndt S, Hetzel A, Brumsack H J. Evolution of organic matter degradation in Cretaceous black shales inferred from authigenic barite: a reaction-transport mode[J]. Geochimica et Cosmochimica Acta, 2009, 73(7): 2000-2022.

111 Niu D, Renock D, Whitehouse M, et al. A relict sulfate-methane transition zone in the mid-Devonian Marcellus Shale[J]. Geochimica et Cosmochimica Acta, 2016, 182: 73-87.

112 Heinrichs T, Reimer T. A sedimentary barite deposit from the Archean Fig Tree Group of the Barberton Mountain Land (South Africa)[J]. Economic Geology, 1977, 72(8): 1426-1441.

113 Reimer T O. Archean sedimentary baryte deposits of the Swaziland Supergroup (Barberton Mountain Land, South Africa)[J]. Precambrian Research, 1980, 12(1/2/3/4): 393-410.

114 Lash G G. Authigenic barite nodules and carbonate concretions in the Upper Devonian shale succession of western New York-a record of variable methane flux during burial[J]. Marine and Petroleum Geology, 2015, 59: 305-319.

115 Hendry J P, Pearson M J, Trewin N H, et al. Jurassic septarian concretions from NW Scotland record interdependent bacterial, physical and chemical processes of marine mudrock diagenesis[J]. Sedimentology, 2006, 53(3): 537-565.

116 Torres M E, McManus J, Huh C A. Fluid seepage along the San Clemente Fault scarp: basin-wide impact on barium cycling[J]. Earth and Planetary Science Letters, 2002, 203(1): 181-194.

117 Aquilina L, Dia A N, Boulégue J, et al. Massive barite deposits in the convergent margin off Peru: implications for fluid circulation within subduction zones[J]. Geochimica et Cosmochimica Acta, 1997, 61(6): 1233-1245.

118 Suess E, Bohrmann G, von Huene R, et al. Fluid venting in the eastern Aleutian subduction zone[J]. Journal of Geophysical Research, 1998, 103(B2): 2597-2614.

119 Fu Baoshan, Aharon P, Byerly G, et al. Barite chimneys on the Gulf of Mexico slope: Initial report on their petrography and geochemistry[J]. Geo-Marine Letters, 1994, 14(2): 81-87.

120 Torres M E, Bohrmann G, Suess E. Authigenic barites and fluxes of barium associated with fluid seeps in the Peru subduction zone[J]. Earth and Planetary Science Letters, 1996, 144(3/4): 469-481.

121 Shields G A, Deynoux M, Strauss H, et al. Barite-bearing cap dolostones of the Taoudéni Basin, northwest Africa: Sedimentary and isotopic evidence for methane seepage after a Neoproterozoic glaciation[J]. Precambrian Research, 2007, 153(3/4): 209-235.

122 McQuay E L, Torres M E, Collier R W, et al. Contribution of cold seep barite to the barium geochemical budget of a marginal basin[J]. Deep Sea Research Part I: Oceanographic Research Papers, 2008, 55(6): 801-811.

123 馮東，陳多福. 海底沉積物孔隙水鋇循環(huán)對天然氣滲漏的指示[J]. 地球科學(xué)進(jìn)展，2007，22(1)：49-57. [Feng Dong, Chen Duofu. Barium cycling in pore water of seafloor sediment: Indicator of methane fluxes[J]. Advances in Earth Science, 2007, 22(1): 49-57.]

124 Bhatnagar G, Chapman W G, Dickens G R, et al. Sulfate-methane transition as a proxy for average methane hydrate saturation in marine sediments[J]. Geophysical Research Letters, 2008, 35(3): L03611.

125 Shields G A. A normalised seawater strontium isotope curve: possible implications for Neoproterozoic-Cambrian weathering rates and the further oxygenation of the Earth[J]. Earth, 2007, 2(2): 35-42.

126 Canet C, Anadón P, González-Partida E, et al. Paleozoic bedded barite deposits from Sonora (NW Mexico): evidence for a hydrocarbon seep environment of formation[J]. Ore Geology Reviews, 2014, 56: 292-300.

127 Guo Qingjun, Shields G A, Liu Congqiang, et al. Trace element chemostratigraphy of two Ediacaran-Cambrian successions in South China: implications for organosedimentary metal enrichment and silicification in the Early Cambrian[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2007, 254(1/2): 194-216.

128 Wang Jianguo, Chen Daizhao, Wang Dan, et al. Petrology and geochemistry of chert on the marginal zone of Yangtze Platform, western Hunan, South China, during the Ediacaran-Cambrian transition[J]. Sedimentology, 2012, 59(3): 809-829.

129 Wang Zhongcheng, Li Guizhi. Barite and witherite deposits in Lower Cambrian shales of South China; stratigraphic distribution and geochemical characterization[J]. Economic Geology, 1991, 86(2): 354-363.

130 楊瑞東，魏懷瑞，鮑淼，等. 貴州天柱上公塘—大河邊寒武紀(jì)重晶石礦床海底熱水噴流沉積結(jié)構(gòu)、構(gòu)造特征[J]. 地質(zhì)論評，2007，53(5)：675-680. [Yang Ruidong, Wei Huairui, Bao Miao, et al. Submarine hydrothermal venting—Flowing sedimentary characters of the Cambrian Shanggongtang and Dahebian barite deposits, Tianzhu county, Guizhou province[J]. Geological Review, 2007, 53(5): 675-680.]

131 劉家軍，吳勝華，柳振江，等. 南秦嶺大型鋇成礦帶中毒重石礦床成因新認(rèn)識——來自單個流體包裹體證據(jù)[J]. 地學(xué)前緣，2010，17(2)：222-238. [Liu Jiajun, Wu Shenghua, Liu Zhenjiang, et al. A discussion on the origin of witherite deposits in large-scale barium metallogenic belt, southern Qinling Mountains, China: evidence from individual fluid inclusion[J]. Earth Science Frontiers, 2010, 17(2): 222-238.]

132 Xu Lingang, Lehmann B, Mao Jingwen, et al. Strontium, sulfur, carbon, and oxygen isotope geochemistry of the Early Cambrian strata-bound barite and witherite deposits of the Qinling-Daba Region, Northern Margin of the Yangtze Craton, China[J]. Economic Geology, 2016, 111(3): 695-718.

133 Elswick E R, Maynard J B. Bedded barite deposits: environments of deposition, styles of mineralization, and tectonic settings[M]//Holland H D, Turekian K K, Holland H D.Treatise on Geochemistry. 2nd ed. Amsterdam: Elsevier, 2014: 629-656.

134 Pi Daohui, Jiang Shaoyong, Luo Li, et al. Depositional environments for stratiform witherite deposits in the Lower Cambrian black shale sequence of the Yangtze Platform, southern Qinling region, SW China: evidence from redox-sensitive trace element geochemistry[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2014, 398: 125-131.

135 Han Shanchu, Hu Kai, Cao Jian, et al. Origin of early Cambrian black-shale-hosted barite deposits in South China: mineralogical and geochemical studies[J]. Journal of Asian Earth Sciences, 2015, 106: 79-94.

136 孫澤航，胡凱，韓善楚，等. 湘黔新晃—天柱重晶石礦床微量稀土元素和硫同位素研究[J]. 高校地質(zhì)學(xué)報，2015，21(4)：701-710. [Sun Zehang, Hu Kai, Han Shanchu, et al. Trace and rare earth elements and sulfur isotope analysis of barite deposits in West Hunan and East Guizhou[J]. Geological Journal of China Universities, 2015, 21(4): 701-710.]

137 吳朝東，陳其英，雷家錦. 湘西震旦—寒武紀(jì)黑色巖系的有機(jī)巖石學(xué)特征及其形成條件[J]. 巖石學(xué)報，1999，15(3)：453-462. [Wu Chaodong, Chen Qiying, Lei Jiajin. The genesis factors and organic petrology of black shale series from the Upper Sinian to the Lower Cambrian, southwest of China[J]. Acta Petrologica Sinica, 1999, 15(3): 453-462.]

138 劉家軍，吳勝華，柳振江，等. 揚子地塊北緣大型鋇成礦帶中硫同位素組成及其意義[J]. 礦物巖石地球化學(xué)通報，2008，27(3)：269-275. [Liu Jiajun, Wu Shenghua, Liu Zhenjiang, et al. Sulfur isotopic compositions of the large barium metallogenic belt in the northern Yangtze Block and its significance[J]. Bulletin of Mineralogy, Petrology and Geochemistry, 2008, 27(3): 269-275.]

139 楊瑞東，鮑淼，魏懷瑞，等. 貴州天柱寒武系底部重晶石礦床中熱水生物群的發(fā)現(xiàn)及意義[J]. 自然科學(xué)進(jìn)展，2007，17(9)：1304-1309. [Yang Ruidong, Bao Miao, Wei Huairui, et al. Discovery of hydrothermal venting community at the base of Cambrian barite in Guizhou province, western China: implication for the Cambrian biological explosion[J]. Progress in Natural Science, 2007, 17(9): 1304-1309.]

140 王忠誠，儲雪蕾，李仲. 高δ34S值重晶石礦床的成因解釋[J]. 地質(zhì)科學(xué)，1993，28(2)：191-192. [Wang Zhongcheng, Chu Xuelei, Li Zhong. Original explanation on the highδ34S values of a barite deposit[J]. Scientia Geologica Sinica, 1993, 28(2): 191-192.]

141 吳勝華，劉家軍，張鼐，等. 南秦嶺鋇成礦帶重晶石與毒重石成礦特征[J]. 現(xiàn)代地質(zhì)，2010，24(2)：237-244. [Wu Shenghua, Liu Jiajun, Zhang Nai, et al. Metallogenic characteristics of barite and witherite of the Barium Metallogenic Belt in Southern Qinling Mountains[J]. Geoscience, 2010, 24(2): 237-244.]

142 吳朝東，楊承運，陳其英. 新晃貢溪—天柱大河邊重晶石礦床熱水沉積成因探討[J]. 北京大學(xué)學(xué)報：自然科學(xué)版，1999，35(6)：774-785. [Wu Chaodong, Yang Chengyun, Chen Qiying. The hydrothermal sedimentary genesis of barite deposits in west Hunan and East Guizhou[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 1999, 35(6): 774-785.]

143 吳衛(wèi)芳，潘家永，夏菲，等. 貴州天柱大河邊重晶石礦床硫同位素研究[J]. 東華理工大學(xué)學(xué)報：自然科學(xué)版，2009，32(3)：205-208. [Wu Weifang, Pan Jiayong, Xia Fei, et al. Sulfur isotope of the Dahebian barite deposit, Tianzhu, Guizhou province[J]. Journal of East China Institute of Technology, 2009, 32(3): 205-208.]

144 Goldberg T, Poulton S W, Strauss H. Sulphur and oxygen isotope signatures of late Neoproterozoic to early Cambrian sulphate, Yangtze Platform, China: diagenetic constraints and seawater evolution[J]. Precambrian Research, 2005, 137(3/4): 223-241.

145 夏菲，馬東升，潘家永，等. 貴州天柱大河邊和玉屏重晶石礦床熱水沉積成因的鍶同位素證據(jù)[J]. 科學(xué)通報，2004，49(24)：2592-2595. [Xia Fei, Ma Dongsheng, Pan Jiayong, et al. Strontium isotopic signature of hydrothermal sedimentation from Early Cambrian barite deposits in east Guizhou, China[J]. Chinese Science Bulletin, 2004, 49(24): 2592-2595.]

146 王忠誠，儲雪蕾. 早寒武世重晶石與毒重石的鍶同位素比值[J]. 科學(xué)通報，1993，38(16)：1490-1492. [Wang Zhongcheng, Chu Xuelei. Strontium isotopic composition of the Early Cambrian Barite and witherite deposits[J]. Chinese Science Bulletin, 1993, 38(16): 1490-1492.]

147 Maloof A C, Porter S M, Moore J L, et al. The earliest Cambrian record of animals and ocean geochemical change[J]. Geological Society of America Bulletin, 2010, 122(11/12): 1731-1774.

148 呂志成，劉叢強(qiáng)，劉家軍，等. 南秦嶺毒重石成礦帶礦床中的生物成因重晶石及其意義[J]. 自然科學(xué)進(jìn)展，2004，14(8)：892-897. [Lü Zhicheng, Liu Congqiang, Liu Jiajun, et al. Biogentic barite in the large barium metallogenic belt, southern Qingling Mountains and its significance[J]. Progress in Natural Science, 2004, 14(8): 892-897.]

149 吳朝東. 湘西震旦—寒武紀(jì)交替時期古海洋環(huán)境的恢復(fù)[J]. 地學(xué)前緣，2000，7(增刊Ⅰ)：45-57. [Wu Chaodong. Recovery of the paleoocean environment in the alternating epoch of Late Sinian and Early Cambrian in the west Hu'nan[J]. Earth Science Frontiers, 2000, 7(Suppl.Ⅰ): 45-57.]

150 Chen Daizhao, Wang Jianguo, Qing Hairuo, et al. Hydrothermal venting activities in the Early Cambrian, South China: petrological, geochronological and stable isotopic constraints[J]. Chemical Geology, 2009, 258(3/4): 168-181.

151 Emsbo P, Hofstra A H, Johnson C A, et al. Lower Cambrian metallogenesis of south China: interplay between diverse basinal hydrothermal fluids and marine chemistry[M]//Mao Jingwen, Bierlein F P. Mineral Deposit Research: Meeting the Global Challenge: Proceedings of the 8th Biennial SGA Meeting. Berlin Heidelberg: Springer, 2005: 115-118.

152 方維萱，胡瑞忠，蘇文超，等. 大河邊—新晃超大型重晶石礦床地球化學(xué)特征及形成的地質(zhì)背景[J]. 巖石學(xué)報，2002，18(2)：247-256. [Fang Weixuan, Hu Ruizhong, Su Wenchao, et al. Geochemical characteristics of Dahebian-Gongxi Superlarge barite deposits and analysis on its background of tectonic geology, China[J]. Acta Petrologica Sinica, 2002, 18(2): 247-256.]

153 韓善楚，胡凱，曹劍. 華南早寒武世黑色巖系重晶石礦床環(huán)帶鋇冰長石新發(fā)現(xiàn)及其意義[J]. 地質(zhì)論評，2013，59(6)：1143-1149. [Han Shanchu, Hu Kai, Cao Jian. First discovery of zoned hyalophane in the barite deposits hosted in early cambrian black shales of south china and its geological implications[J]. Geological Review, 2013, 59(6): 1143-1149.]

154 夏菲，馬東升，潘家永，等. 天柱大河邊—新晃重晶石礦床礦物組成特征的電子探針研究[J]. 礦物學(xué)報，2005，25(3)：289-294. [Xia Fei, Ma Dongsheng, Pan Jiayong, et al. EMP study of Early Cambrian barite deposits in eastern Guizhou, China[J]. Acta Mineralogica Sinica, 2005, 25(3): 289-294.]

155 Butterfield N J. Animals and the invention of the Phanerozoic Earth system[J]. Trends in Ecology & Evolution, 2011, 26(2): 81-87.

156 Butterfield N J. Oxygen, animals and oceanic ventilation: an alternative view[J]. Geobiology, 2009, 7(1): 1-7.

157 Canfield D E, Farquhar J. Animal evolution, bioturbation, and the sulfate concentration of the oceans[J]. Proceedings of the National Academy of Sciences of the United States of America, 2009, 106(20): 8123-8127.

Genetic Classification of Sedimentary Barites and Discussion on the Origin of the Lower Cambrian Barite-rich Deposits in the Yangtze Block, South China

ZHOU XiQiang1YU Hao2HUANG TaiYu1,3ZHANG LiYu1,3ZHANG GongJing1,3FU Yong4CHEN DaiZhao1

(1. Key Lab of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; 2. China Minmetals Corporation, Beijing 100007, China; 3. University of Chinese Academy of Sciences, Beijing 100049, China; 4. College of Resource and Environmental Engineering, Guizhou University, Guiyang 550025, China)

Barites are widely distributed in sedimentary records with various geological characteristics and formation processes. In general, sedimentary barites can be subdivided into marine (or biogenic), hydrothermal, diagenetic and cold seeps barites. The sedimentary environments, macro- and micro-occurrences, geochemical features (especially Sr and S isotopes) and corresponding geological implications of these four barite subtypes are controlled by the origin of barium- and sulfate- fluids (seawater, diagenetic porewater or hydrothermal fluids) and related interaction process (in seawater column, sediment column, sediment-water interface or hydrothermal system). In addition, this study further introduces the geological features of the Lower Cambrian barite-rich sediments in the Yangtze Block, South China, and summarizes the enrichment mechanisms having been proposed for these barite deposits and argues on their reconciliation and biases with geological features and processes. Based on the paleo-oceanic context during the Ediacaran-Cambrian transitional period, integrated sedimentological and geochemical researches together would provide better constrains on the origins of the Lower Cambrian barium-rich deposits in the Yangtze Block.

Barite; Paleo-ocean; the Lower Cambrian

1000-0550(2016)06-1044-13

10.14027/j.cnki.cjxb.2016.06.004

2016-05-19； 收修改稿日期： 2016-07-04

國家自然科學(xué)基金面上項目(41472089，41502117)；中國博士后科學(xué)基金資助項目(2015M581166)[Foundation: National Narural Science Foundation of China, No. 41472089, 41502117; China Postdoctoral Science Foundation Funded Project, No. 2015M581166]

周錫強(qiáng) 男 1985年出生 博士 沉積學(xué) E-mail: zhouxiqiang123@163.com

P619.25+1

A