中太平洋海山区富钴结壳地质特征

Geological characteristics of Co-rich crusts from the Mid-Pacific Seamounts Area

应用 X射线衍射分析、穆斯堡尔谱分析、X荧光光谱分析以及超微生物化石定年等方法对 1 998年和 1 999年“大洋一号”调查船 DY95 - 8和 DY95 - 1 0航次采集的富钴结壳样品进行了地质特征综合研究与分析 ,结果表明 :( 1 )该区富钴结壳可划分为板状结壳、砾状结壳和钴结核三类 ,均具有微晶质结构。 ( 2 )该区富钴结壳宏观构造主要呈板层状和圈层状构造 ;显微构造在形态上可大体分为柱状构造、平行纹理状构造和致密块状构造三种基本类型。 ( 3)该区富钴结壳主要由三类矿物组成 :锰矿物、铁矿物和杂质矿物。其中锰矿物为水羟锰矿和少量的钡镁锰矿 ,铁矿物主要为 β-羟铁矿 ,偶见赤铁矿和磁铁矿等 ,杂质矿物有石英、斜长石等。( 4 )该区富钴结壳主要成矿元素含量 :Fe为 1 6.86% ,Mn为 2 1 .2 6% ,Cu为 1 1 0 2 .0 9× 1 0 - 6 ,Co为 62 5 2 .72× 1 0 - 6 ,Ni为 40 64.62× 1 0 - 6 。 ( 5 )该区东部海山 ( N1～ N4海山 )比西部海山( N5、 N6海山 ) Fe元素含量高 ,Mn、 Cu、 Co、 Ni元素含量则低 ,这一差异源于海水中 Fe、 Mn等成矿元素的分离作用 ,其分离程度与海底火山作用时代以及相应的玄武岩海解风化时间长短有密切关系。 ( 6)结壳形成于第三纪古新世至第四纪更新世 :第一阶段从第三纪古新世到中新世 ,?

Geological characteristics of Co\|rich crusts sampled by 'DA YANG YI HAO' scientific investigation vessel in 'DY95\|8 & DY95\|10' cruises of 1998 and 1999 in the Mid\|Pacific Seamounts Area are studied and analyzed comprehensively with varied methods including XRD analysis, Mssbauer analysis, XRF analysis and ultra\|microfossil biostratigraphic dating. Results show: crusts in the Mid\|Pacific Seamounts Area can be divided into three types in shape, which are board\|like, gravel\|like and nodule\|like crusts respectively. It has biological, colloidal and microcrystalline texture; The main structure of crusts in macroscopical observation is board\|stratified and ring\|stratified structure; in microscopical indentification, it can be divided into three fundamental kinds in shape, which are columnar, parallel\|laminae and compact structure. The crust consists of three types of crystalline minerals, which are Mn minerals, Fe minerals and impurity minerals; The Mn minerals are vernadite mainly, and todorokite a few; the Fe minerals are β\|amakinite primary and hematite, magnetite in serendipitous; the impunity minerals are quartzes, feldspars and so on. The elements Fe(16 86%), Mn(21 26%),Cu(1 102 09×10\+\{-6\}),Co(6 252 72×10\+\{-6\}) and Ni(4 064 62×10\+\{-6\}) are rich in crusts. Fe is more in crusts of eastern area (N1,N2,N3,N4) than that of western area (N5,N6) averagely, while Mn, Cu, Co and Ni are contrary. The difference above\|mentioned is derived from the separation of Fe, Mn and other metallogenetic elements in sea water, and the degree of separation is relative closely with the time of volcanic action and the corresponding length of basalts halmyrolysis. The crusts in Mid\|Pacific came into being between Paleocene in Tertiary and Pleistocene in Quaternary, the first stage is from Paleocene to Miocene, the second one is from Pliocene to Pleistocene.