察尔汗北部东陵湖Li、B资源分布特征与物质来源

Characterization of Lithium and Boron Resource Distribution and Material Sources in Dongling Lake,Located in the Northern Region of Qarhan

柴达木盆地盐湖锂、硼资源是青海省建设世界级盐湖产业基地的重要资源组成部分,盆地内接续性锂、硼资源储量的增加意义重大。柴达木盆地东南部的察尔汗盐湖锂、硼资源差异分布明显,位于察尔汗盐湖北部的东陵湖,近两年勘查工作揭露其湖表卤水和湖区晶间卤水LiCl品位(315.16 mg/L)和B_(2)O_(3)品位(429.32 mg/L)均超过边界品位。本文以东陵湖湖表卤水、钻孔晶间卤水、承压卤水、浅层钻孔(0~8 m)盐类沉积物为研究对象,分析研究了东陵湖不同卤水和钻孔沉积物的锂、硼含量特征,并与察尔汗盐湖锂、硼含量分布特征对比,结合盆地补给河流和尾闾盐湖的Li^(+)含量和δ^(11)B值,分析了东陵湖锂、硼资源元素分布特征与物质来源,主要得出如下结论:①东陵湖湖表卤水(61.91 mg/L)和湖区钻孔晶间卤水(27.05 mg/L)的Li^(+)含量最高,而与察尔汗盐湖别勒滩区段(204.48 mg/L)相比,其Li含量低3.3~7.6倍;东陵湖湖表卤水的B^(3+)平均含量为177.25 mg/L,钻孔晶间卤水和承压卤水的B^(3+)平均含量为81.65 mg/L,较之察尔汗盐湖,东陵湖不同卤水硼含量普遍较高。②东陵湖11个钻孔沉积物样品Li^(+)含量介于1×10^(-6)~8.24×10^(-6)之间,B3+含量在0.005%~0.024%之间,湖区钻孔沉积物锂含量高于凹地钻孔;钻孔沉积剖面石盐层和碎屑层沉积物Li、B含量无明显变化。③东陵湖与察尔汗盐湖锂、硼含量空间分布差异明显,东陵湖较察尔汗盐湖别勒滩区段明显贫锂,较达布逊、察尔汗和霍布逊区段更富硼,总体表现为富硼贫锂的特征。④东陵湖δ^(11)B介于+20.33‰~+29.17‰之间,平均为+24.23‰,与柴北缘补给河流和Ca-Cl水补给形成的盐湖均位于高δ^(11)B端元区,结合东陵湖不同卤水样品的Ca^(2+)与Li^(+)、B^(3+)相关性研究,认为东陵湖锂、硼资源元素与含盐溶质具有相似的物源,高硼低锂的元素分布特征和高δ^(11)B值显示东陵湖地区水文补给来源与柴北缘水文体系有关,主要物质来源受察尔汗盐湖北部断裂带Ca-Cl水的补给。

The lithium and boron resources in the Qaidam Basin are pivotal in establishing a world-class salt lake industry base in Qinghai province.The continuous augmentation of lithium and boron reserves in the basin holds significant importance.The disparity between lithium and boron resources in Qarhan Salt Lake,situated southeast of Qaidam Basin,is discernible.Dongling Lake,located to the north of Qarhan Salt Lake,has been subject to exploration efforts over the past two years,revealing that both LiCl grade(315.16 mg/L)and B_(2)O_(3) grade(429.32 mg/L)in the lake surface brines and intercrystalline brines of Dongling Lake surpass the threshold grades.This paper focuses on investigating surface brines,borehole intercrystalline brines,confined brines,and shallow borehole(0-8 m)salt sediments from Dongling Lake to analyze and compare their respective lithium and boron content characteristics with those found in Qarhan Salt Lake's distribution patterns,while considering the Li+contents and δ^(11)B values derived from basin recharge rivers and tail lakes.This study draws several conclusions by analyzing element distribution characteristics and material sources of lithium and boron resources within Dongling Lake.①The Li^(+)concentration in the surface brines of Dongling Lake(61.91 mg/L)and the intercrystalline brines from boreholes(27.05 mg/L)exhibit the highest values,which were 3.3-7.6 times lower than those observed in the Bieletan section of Qarhan Salt Lake(204.48 mg/L).The average boron concentration in the surface brines of Dongling Lake was 177.25 mg/L,whereas both intercrystalline brines and confined brines from boreholes had average boron concentrations of 81.65 mg/L,surpassing that found in Qarhan Salt Lake.②Sediments obtained from 11 boreholes within Dongling Lake displayed Li^(+)contents ranging from 1×10^(-6) to 8.24×10^(-6) and B^(3+)contents ranging from 0.005% to 0.024%.Lithium contents within these boreholes were significantly higher than sunken ones,whereas no significant variation was observed for Li and B contents within salt and detrital sediments along the sedimentary profile.③The spatial distribution of lithium and boron contents differed between Dongling Lake and Qarhan Salt Lake.Dongling Lake exhibited significantly lower lithium levels than the Bieletan section of Qarhan Salt Lake but displayed higher boron concentrations than the Dabuxun,Qarhan,and Huobuxun sections.These findings indicate a characteristic pattern of boron enrichment and lithium depletion.④The δ^(11)B values of Dongling Lake ranged from +20.33% to +29.17%,with an average of +24.23%,placing it within the highδ11B end-member region similar to salt lakes formed by replenishment rivers and Ca-Cl type water in the northern margin of Qaidam Basin.Based on correlation studies of Ca^(2+),Li^(+),and B^(3+)in various brine samples from Dongling Lake,it can be inferred that lithium and boron resources and salt-bearing solutions in Dongling Lake share a common origin.The distribution patterns of high boron,low lithium,and elevated δ^(11)B values suggest a hydrological recharge source for Dongling Lake that is linked to the hydrological system of the northern margin of the Qaidam Basin.The primary source material originates from the recharge of Ca-Cl type water within the northern fault zone of Qarhan Salt Lake.