地球学报
地毬學報
지구학보
ACTA GEOSCIENTIA SINICA
2014年
4期
445-453
,共9页
胡古月%范昌福%李延河%侯可军%刘燚%陈贤
鬍古月%範昌福%李延河%侯可軍%劉燚%陳賢
호고월%범창복%리연하%후가군%류일%진현
辽河群%里尔峪组%砖庙硼矿区%硼同位素%硫同位素%碳同位素
遼河群%裏爾峪組%磚廟硼礦區%硼同位素%硫同位素%碳同位素
료하군%리이욕조%전묘붕광구%붕동위소%류동위소%탄동위소
Liaohe Group%Lieryu Formation%Zhuanmiao Mg-borate ore district%boron isotope%sulfur isotope%carbon isotope
辽宁砖庙硼矿区的硼矿体呈层状或透镜状赋存于辽河群里尔峪组火山-沉积建造下部的蛇纹石化大理岩中,内部含有大量镁橄榄岩包裹体。本研究利用LA-MC-ICP-MS技术对砖庙硼矿区内的硼矿石硼同位素进行了微区原位分析,对矿石及大理岩围岩的硫、碳稳定同位素进行了系统研究。硼矿石的δ11BNIST SRM-951为12.6‰~13.9‰,具海相蒸发沉积特征;硼矿石和大理岩的δ34SV-CDT为11.6‰~24.3‰,具海相沉积成因特征;矿体上下层位中蛇纹石化大理岩的δ13CV-PDB为-5.0‰~-0.5‰,部分未蛇纹石化大理岩的δ13CV-PDB为4.1‰~4.6‰,具有古元古代海相碳酸盐岩特有的碳同位素正异常现象。据此提出,砖庙矿区的硼矿床可能形成于海相蒸发沉积和火山喷发旋回交替的滨海环境,随后同期喷发的超基性火山岩覆盖于海相蒸发沉积成因硼矿体之上,保护了易溶的硼酸盐矿物,经后期变质和热液改造,形成目前独特的硼酸盐矿物,碳酸盐岩与超基性岩岩石组合。
遼寧磚廟硼礦區的硼礦體呈層狀或透鏡狀賦存于遼河群裏爾峪組火山-沉積建造下部的蛇紋石化大理巖中,內部含有大量鎂橄欖巖包裹體。本研究利用LA-MC-ICP-MS技術對磚廟硼礦區內的硼礦石硼同位素進行瞭微區原位分析,對礦石及大理巖圍巖的硫、碳穩定同位素進行瞭繫統研究。硼礦石的δ11BNIST SRM-951為12.6‰~13.9‰,具海相蒸髮沉積特徵;硼礦石和大理巖的δ34SV-CDT為11.6‰~24.3‰,具海相沉積成因特徵;礦體上下層位中蛇紋石化大理巖的δ13CV-PDB為-5.0‰~-0.5‰,部分未蛇紋石化大理巖的δ13CV-PDB為4.1‰~4.6‰,具有古元古代海相碳痠鹽巖特有的碳同位素正異常現象。據此提齣,磚廟礦區的硼礦床可能形成于海相蒸髮沉積和火山噴髮鏇迴交替的濱海環境,隨後同期噴髮的超基性火山巖覆蓋于海相蒸髮沉積成因硼礦體之上,保護瞭易溶的硼痠鹽礦物,經後期變質和熱液改造,形成目前獨特的硼痠鹽礦物,碳痠鹽巖與超基性巖巖石組閤。
료녕전묘붕광구적붕광체정층상혹투경상부존우료하군리이욕조화산-침적건조하부적사문석화대리암중,내부함유대량미감람암포과체。본연구이용LA-MC-ICP-MS기술대전묘붕광구내적붕광석붕동위소진행료미구원위분석,대광석급대리암위암적류、탄은정동위소진행료계통연구。붕광석적δ11BNIST SRM-951위12.6‰~13.9‰,구해상증발침적특정;붕광석화대리암적δ34SV-CDT위11.6‰~24.3‰,구해상침적성인특정;광체상하층위중사문석화대리암적δ13CV-PDB위-5.0‰~-0.5‰,부분미사문석화대리암적δ13CV-PDB위4.1‰~4.6‰,구유고원고대해상탄산염암특유적탄동위소정이상현상。거차제출,전묘광구적붕광상가능형성우해상증발침적화화산분발선회교체적빈해배경,수후동기분발적초기성화산암복개우해상증발침적성인붕광체지상,보호료역용적붕산염광물,경후기변질화열액개조,형성목전독특적붕산염광물,탄산염암여초기성암암석조합。
Zhuanmiao Mg-borate ore bodies exhibit layered or lenticular structure in the wall rocks of serpentinized marbles, which are located in the lower strata of volcanic-sedimentary Lieryu Formation in Kuandian County of eastern Liaoning Province. The authors applied LA-MC-ICP-MS in-situ technology to analyze the B isotopic composition of borate ores in the Zhuangmiao Mg-borate ore district, and systematically studied the S and C stable isotopic compositions of the ores and marbles. Theδ11BNIST SRM-951 values of Mg-borate ores vary from 12.6‰ to 13.9‰, showing marine evaporative characteristics; the δ34SV-CDT values of Mg-borate ores and serpentinized marble vary from 11.6‰to 24.3‰, suggesting marine sedimentary characteristics;(3) theδ13CV-PDB values of serpentinized marble vary from -4.6‰ to -0.5‰, while those of marble vary from 4.1‰ to 4.6‰, exhibiting positive carbon isotopic anomaly of Paleoproterozoic marine carbonates. Therefore, the ore-forming environment of the Mg-borate deposit in Zhuanmiao area was probably an alternate cycle of marine sedimentation and volcanism of the littoral facies, while a suite of homochronous Mg-rich ultrabasic volcanic rocks covered the borate deposits and preserved the borate ores during hydrothermalism and metamorphism at late stages, and formed a unique rock unit of borate minerals, carbonates and ultrabasic minerals.