坦桑尼亚乌本迪活动带西北部元古宙沉积盆地 碎屑锆石 u-pb...
TRANSCRIPT
坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石U-Pb年龄及其地质意义
刘晓阳1,2,龚鹏辉1,2,许康康1,2,吴兴源1,2,孙凯1,2,何胜飞1,2,贺福清1,2
(1.中国地质调查局天津地质调查中心,300170 天津;2.中国地质调查局华北地质科技创新中心,天津 300170)
摘 要:坦桑尼亚西北部卡拉戈维-安科连活动带和玛拉嘎拉西台地发育一系列元古宙沉积盆地,由于沉积岩性和
变质程度相近,地层层序的界定存在争议。本文通过对原划分的卡盖拉超群和玛拉嘎拉西超群乌哈群上部马攸攸
组碎屑锆石铀铅年龄的测试,获得了坦桑尼亚西北部基戈马附近中元古代沉积盆地碎屑锆石207Pb/206Pb年龄集中分
布于1 276~1 562 Ma、1 735~2 156 Ma和2 505~2 836 Ma三个年龄区间;坦桑尼亚西北部基戈马附近玛拉嘎拉西台
地乌哈群上部马攸攸组碎屑锆石207Pb/206Pb年龄集中分布于735~1 400 Ma、1 793~2 094 Ma和2 554~2 934 Ma三个
年龄区间;坦桑尼亚西北部卡雷马附近玛拉嘎拉西台地乌哈群上部的马攸攸组两个样品碎屑锆石U-Pb不一致线上
交点年龄分别为2 654 ± 29 Ma和 2 671 ± 13 Ma。结合已有的地质资料可以推断坦桑尼亚西北部基戈马附近中元
古代沉积盆地沉积时代不早于1 400 Ma;坦桑尼亚西北部基戈马附近玛拉嘎拉西台地乌哈群上部马攸攸组沉积时代
不早于735 Ma;坦桑尼亚西北部卡雷马附近乌哈群上部的马攸攸组与基戈马附近的马攸攸组碎屑成分来源存在明显
差异,建议重新划分。
关键词:坦桑尼亚;乌本迪活动带;卡盖拉超群;乌哈群;碎屑锆石铀铅年龄
中图分类号:P588.12 文献标识码:A 文章编号:1672-4135(2019)03-0005-14
收稿日期:2019-03-22
资助项目:中国地质调查局项目“海上丝绸之路非洲中东部7国矿产资源潜力评价(DD20160108)”;商务部援外项目:“援卢旺
达地质矿产调查(WKZB811BJB301389)”
作者简介:刘晓阳(1977-),男,正高级工程师,长期从事矿产地质勘查工作,E-mail:[email protected]。
坦桑尼亚主体为元古宙活动带包围的太古宙地
盾。古元古代的乌本迪-乌萨伽仁活动带环绕在太
古宙地盾的周围,被认为是坦桑尼亚克拉通和班韦
卢地块相互作用的结果。近期研究结果表明乌本迪
活动带经历了元古代不同时期的构造演化阶段,并
于乌本迪带内的乌菲帕地体内获得了590~520 Ma
的榴辉岩地质年龄数据[1],代表了乌本迪活动带最终
结束年龄。乌本迪活动带西北部被一套轻微-中等
程度变质的碎屑沉积岩所覆盖,被称为玛拉嘎拉西
(Malagarazi)台地。早期研究资料[2-7]表明玛拉嘎拉
西台地形成于新元古时期,其北部为卡拉戈维-安科
连(Karagwe-Ankolean)活动带(基巴拉活动带的一
部分)(图1)。为研究这套变质沉积岩与乌本迪活动
带的演化关系,本文采集了玛拉嘎拉西台地和卡拉
戈维-安科连活动带内不同地区、不同岩性的沉积岩
样品,获得了一批碎屑锆石铀铅年龄数据,为本地区
地层层序的划分提供佐证。
1地质背景玛拉嘎拉西台地位于坦桑尼亚西北部,呈北北
东向展布(图1中的nv和kg)。其西北部为中元古代
卡拉戈维-安科连活动带(图1中的bk和ka),南部为
乌本迪活动带,西部为坦噶尼噶湖,东部为新近系覆
盖。新元古代玛拉嘎拉西台地出露的地层为玛拉嘎
拉西超群,它出露于坦桑尼亚西北部边境的基戈马
(Kigoma)地区,主要分布在一系列孤立的盆地中,这
些沉积盆地是古元古代乌本迪带中的断层在新元古
代活化时发生活动形成的[2-3]。
早期的玛拉嘎拉西超群在坦桑尼亚境内被称为
布科班超群,时代为新元古代。自上至下分别为乌
哈(Uha)群、克格尼弗莱(kigonero Flags)群、步森多
(Busondo)-马森瓦(Masontwa)群、布科班砂岩和艾
索塔(ltiaso)群。其中艾索塔群为一套粉砂质页岩或
泥岩,出露于玛拉嘎拉西台地南端,坦桑尼亚太古宙
地盾和乌本迪活动带之间。艾索塔群见有层状侵入
体,获得的K-Ar年龄为1 239±50 Ma[4],而侵入到布
科班砂岩内的镁铁质基性岩也获得了1 360±20 Ma
和1 379±10 Ma的Ar-Ar年龄[5],证明此两套地层均
远早于新元古代。为此Legler等[6]首次提出将坦桑
尼亚境内原属布科班超群中的马森瓦-步森达群、克
第43卷 第1期 地 质 调 查 与 研 究 Vol.43 No.1
2020年03月 GEOLOGICAL SURVEY AND RESEARCH Mar. 2020
格尼弗莱群及乌哈群划为新元古代,并且为了保证
一贯的延续性,决定采用玛拉嘎拉西超群来加以命
名(图2)。
马森瓦群下部为一套灰绿色板岩和砂岩、粉砂岩
互层,上部为浅灰色或红色石英岩。该群厚度非常
薄,一般不超过300 m,而且局部消失。步森多群标准
剖面由3个组组成,Uruwira组、Nyanza组、Malagarazi
组。Uruwira组上覆于马森瓦群或角度不整合于艾
索塔群或乌本迪变质杂岩之上,其下部为红色页岩、
粉砂岩、杂砂岩,上部为交错层理的石英岩。其厚度
在典型剖面内只有 60 m,但在其他地区可以达到
300 m,并可见灰岩的互层。在Mwendo山地区可见
红色的杂砂岩可达440 m厚,包括巨大的鹅卵石状砂
岩、石英岩和其他岩石。Nyanza组(60~230 m)由灰
色的条带状页岩和粉砂岩组成。Malagarazi组(350
m)下部为灰白色粗粒局部具有交错层理的石英岩,
上部为棕色页岩和与下部相同的石英岩,局部见有鹅
卵石状砂岩组成。马森瓦群和步森多群内可见微生
物的化石。克格尼弗莱群大约250 m厚,整合覆盖于
Malagarazi组之上,由红色变质细砂岩、页岩、石英岩
图1 坦桑尼亚区域地质简图(据Pinna等(2004)修改)
Fig.1 Regional geological map of Tanzania (modified from Pinna et al. (2004))
1.新近纪至第四纪陆相和湖相沉积地层;2.新近纪-第四纪火山岩层;3.白垩纪沉积物;4.卡鲁岩系;5.新元古代火山沉积
地层;6.新元古界沉积岩层;7.莫桑比克带;8.新元古代镁铁质和长英质岩浆岩,具高级变质作用,中间夹有角闪石,大理
石,石英岩,片岩;9.中元古界Karagwe-Ankolean沉积;10.中元古代布科班碎屑沉积物;11.中元古代长英质花岗岩,受新
元古代高级变质作用影响(约1.19~0.094 5 Ga)(Songea和Kimambi组);12.乌本迪或乌萨伽仁带;13.古元古代-新太古
代未分花岗岩、花岗片麻岩;14.多多玛群(约2.90~2.50 Ga);15.Isangani花岗岩、花岗片麻岩(约3.0~2.85 Ga);16.卡维
隆迪超群;17.新-中太古未分的花岗岩、辉石、镁铁质和超镁铁质岩石;18.图2大致位置
6 地 质 调 查 与 研 究 第43卷
和灰色含叠层石白云岩组成。乌哈(Uha)群覆盖在
克格尼弗莱群不同层位岩石之上。其下部为Gagwe
杏仁状玄武岩(总厚度700 m),中间为凝灰岩和灰岩
互层。Gagwe 杏仁状玄武岩 K-Ar 等值线年龄 900
Ma[7],其上部为马攸攸(Manyouo)组红色地层不整合
覆盖在灰岩之上,局部直接覆盖在玄武岩或前期基
底包括艾索塔群之上,其厚度大约700 m。马攸攸组
红色地层主要为红色细粒砂岩和具交错层理的页
岩。在马攸攸组底部中-粗粒的石英岩中局部可见
铜的矿化。
基巴拉活动带位于玛拉嘎拉西台地西北,完整
的基巴拉活动带位于乌干达西南部和坦桑尼亚西北
部,经过布隆迪和卢旺达,直至刚果(金)东南部,呈
NE-SW 走向展布,总长约 1 300 km,最宽可达 400
km。在基巴拉带中部,古元古代的乌本迪-如斯安活
动带将基巴拉带分隔为南西(SW)基巴拉带和北东
(NE)基巴拉带2个部分。Tack等[8]据此将传统基巴
拉带的南西部分(基巴拉带命名地,位于刚果(金)境
内)重新定义为基巴拉带(Kibara
Belt,即KIB),而将传统基巴拉带的
北东段(主要位于布隆迪、卢旺达、坦
桑尼亚境内)称为卡拉戈维-安科连
带(Karagwe- Ankolean belt,即
KAB)。其中,卡拉戈维-安科连带又
被NE-SW走向、断续出露的卡邦加
(Kabanga)-穆松盖蒂(Musongati)
镁铁-超镁铁质层状杂岩体分为两
部分,Tack等[8]分别称为东部沉积
区域(Eastern Domain)和西部沉积
区域两部分(Western Domain)。
东部沉积区域包括乌干达西南缘、
坦桑尼亚西北部及布隆迪东部,分
布的地层为卡盖拉超群(Kagera
Supergroup);西部沉积区域包括乌
干达西南部、卢旺达和布隆迪西
部,分布的地层为阿卡亚鲁超群
(Akanyaru Supergroup)。
坦桑尼亚境内出露的基巴拉带
地层为卡盖拉超群(Kagera Super
group),卡盖拉超群直接角度不整
合覆盖于下伏基底片麻岩之上,基
底可能为太古宙坦桑尼亚克拉通,
也可能为古元古代鲁文佐里褶皱带岩石,这套地层
表现出自西向东变质-变形程度逐渐减弱的特征[9]。
卡盖拉超群的沉积时限为1.37 Ga~1.78 Ga,之前普
遍被认为是一套造山晚期的磨拉石沉积建造[10]。卡
盖拉超群的露头分别位于东、西2个不同的次级沉积
盆地之中,西部次级沉积盆地的地层称为:Muyaga
群、Ruvubu群,而东部次级沉积盆地的地层称为布科
巴砂岩(Bukoba Sandstone)群(图 2)。Muyaga群不
整合覆盖于古元古代结晶基底之上,由下至上依次
为底砾岩、砂岩或石英岩、页岩与长石砂岩互层、碳酸
盐岩、黑色泥岩及泥质页岩;Ruvubu群位于Muyaga群
之上,岩石类型主要由砂岩、石英岩、泥岩、泥质页
岩等组成 [10]。布科巴砂岩群属于原来新元古代布
科班超群(Bukoban Supergroup)的一部分,岩层未遭
受明显变质,却经历了弱变形作用。
2取样位置本文共采集碎屑沉积岩样品 5 个(图 3),其中
图2 卡盖拉超群和玛拉嘎拉撕超群地层柱状图简图(非标准比例)Fig.2 Histogram of Kagera Supergroup and Maragara Supergroup Strata
(Non-standard ratio)1.泥质粉砂质页岩;2.页岩;3.含碳质页岩、板岩;4.砂岩;
5.灰岩、白云岩;6.玄武岩;7.基性火山岩\侵入岩
第1期 刘晓阳等:坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石铀铅年龄及其地质意义 7
D6459TW1和D6460TW1位于中元古代卡拉戈维-
安科连活动带内的卡盖拉超群内,地理坐标分别为
29.609 4,-4.917 4和29.613 4,-4.915 0。D6459TW1
为 一 套 轻 微 变 质 的 中 细 粒 长 石 石 英 砂 岩 ;
D6460TW1则为一套含砾砂岩,砾石粒度2~3 cm,含
量5%~10%,磨圆度较高。其余3个样品均位于乌哈
群上部马攸攸组,分别为D6457TW1、D6355TW1和
D6356TW1。其岩性分别为细粒长石石英砂岩、粗
粒长石石英砂岩和中粒长石石英砂岩;地理坐标分
别为 29.870 1,-4.886 3;29.877 6,-5.509 5和 29.891
4,-5.539 2。野外可以观测到乌哈群上部马攸攸组同
卡盖拉超群呈断层接触。
3分析方法
锆石是在河北廊坊物化勘察研究所采用浮选和
电磁选方法获得的。锆石阴极发光(CL)显微照相、
锆石U-Pb定年测试在北京锆年领航科技有限公司完
成。锆石U-Pb定年利用LA-MC-ICPMS完成,该套
系统的多接收器电感耦合等离子体质谱仪为Ther-
mo Fisher 公司制造的 Neptune,
激光器为美国 ESI 公司生产的
UP193nm,FX ArF 准分子激光
器。利用193 nm 激光器对锆石
进行剥蚀,通常采用的激光剥蚀
的斑束直径为35 或50 μm。采用
的激光能量密度为13~14 J/cm,
频率为8~10 Hz,激光剥蚀物质
以He为载气送入Neptune, 利用
动态变焦扩大色散可以同时接
收质量数相差很大的U-Pb同位
素从而进行锆石U-Pb同位素原
位测定。采用TEMORA 作为外
部锆石年龄标准。采用中国地
质 大 学 刘 勇 胜 博 士 研 发 的
ICPMSDataCal 程序和 Kenneth
R. Ludwig 的 Isoplot程序进行数
据处理,采用Tom Andersen的方
法对普通铅进行校正 [9]。利用
NIST612 玻璃标样作为外标计
算锆石样品的Pb、U、Th含量。
4 测试结果
本文对 D6459TW1、D6460TW1、D 6457TW1、
D6355TW1和D6356TW1 5个样品分别进行了测试,
测试结果分别见表1、表2、表3。所测试的5个样品锆
石为典型的碎屑锆石特征,锆石晶型不完整,多为破
损的长柱状锆石,部分具有磨圆,代表锆石经历了搬
运过程。阴极发光图片表明部分锆石还保留了原有
的核和震荡环带,部分碎屑锆石仅保留了外部震荡环
带,无明显增生边(图4)。样品D6459TW1共测试了
80个点,其中有44个点为近协和年龄(谐和度95%~
110%),33 个点为不协和年龄(图 5a)。获得的锆
石 207Pb/206Pb(谐和度95%~110%)呈三个明显的集中
分布区间:1 371~1 562 Ma(10个点)、1 796~2 156
Ma(22个点)和 2 505~2 768 Ma(12个点)(图 5b)。
样品D6460TW1共测试了80个点,其中有56个点为
近协和年龄(谐和度98%~110%),34个点为不协和
年龄(图 5c)。测得的锆石 207Pb/206Pb(谐和度 98~
110%)位于1 276~1 441 Ma(5个点),1 735~2 152
Ma(44 个点)和 2 597~2 836 Ma(5 个点)区间(图
5d)。样品D6457TW1共测试了 80个点,其中有 73
图3 取样位置平面示意图
Fig.3 Simplified map of sampling location
1.古元古代乌本迪杂岩;2.中元古代安科瑞安群;3.古-中元古代艾塔索群;4.新元古
代马森瓦群;5.新元古代步森多群;6.新元古代乌哈群;7.新近系;8.取样位置及编号
8 地 质 调 查 与 研 究 第43卷
测点号
D6459TW1,长石石英砂岩,80个年龄测点:D6459TW1.01D6459TW1.02D6459TW1.03D6459TW1.04D6459TW1.05D6459TW1.06D6459TW1.07D6459TW1.08D6459TW1.09D6459TW1.10D6459TW1.11D6459TW1.12D6459TW1.13D6459TW1.14D6459TW1.15D6459TW1.16D6459TW1.17D6459TW1.18D6459TW1.19D6459TW1.20D6459TW1.21D6459TW1.22D6459TW1.23D6459TW1.24D6459TW1.25D6459TW1.26D6459TW1.27D6459TW1.28D6459TW1.29D6459TW1.30D6459TW1.31D6459TW1.32D6459TW1.33D6459TW1.34D6459TW1.35D6459TW1.36D6459TW1.37D6459TW1.38D6459TW1.39D6459TW1.40D6459TW1.41D6459TW1.42D6459TW1.43D6459TW1.44D6459TW1.45D6459TW1.46D6459TW1.47D6459TW1.48D6459TW1.49D6459TW1.50D6459TW1.51D6459TW1.52D6459TW1.53D6459TW1.54D6459TW1.55D6459TW1.56D6459TW1.57D6459TW1.58D6459TW1.59D6459TW1.60D6459TW1.61D6459TW1.62D6459TW1.63D6459TW1.64D6459TW1.65D6459TW1.66D6459TW1.67D6459TW1.68D6459TW1.69D6459TW1.70D6459TW1.71D6459TW1.72D6459TW1.73
含量(x10-6)U
4040964087619052
17026
140523219182778
12330
10113308458301163689
1089624889830
14482
103765370
153143138188251938
1398611011324130974
1491022111815038349311894528082
1822161
1363886
Pb
8597
34418728413029783
93767
3659483474174
2531 064
804774578
23616610122581
21922123688
20421111827425934220014512263672837939410168
13998414822422247672220564736480
2673266368
18823316194
162228
1 49083
153301125273
同位素比值207Pb*/206Pb*
0.129 00.116 40.123 20.093 00.120 40.121 80.118 10.193 00.176 10.109 80.178 90.188 90.134 40.123 60.125 10.116 50.118 30.129 00.116 40.121 80.096 70.113 00.114 10.112 70.087 50.187 10.119 30.124 90.185 10.180 60.090 10.121 50.180 10.091 90.179 40.118 30.131 00.121 60.110 80.184 70.130 80.125 70.162 70.176 10.093 40.099 30.094 70.129 60.184 00.182 20.187 50.197 40.197 70.115 60.134 00.119 30.089 00.176 00.174 40.179 80.182 20.189 80.164 80.185 80.125 30.171 00.129 00.136 80.093 50.116 90.182 20.089 40.132 4
1σ
0.001 90.001 70.001 80.001 40.001 70.001 80.001 70.002 80.002 60.001 60.002 60.002 70.002 00.001 80.001 90.001 80.001 70.001 90.001 70.001 70.001 80.001 70.001 70.001 70.001 30.002 70.001 80.001 80.002 70.002 60.001 40.001 70.002 60.001 60.002 60.001 70.001 90.001 70.001 60.002 70.001 90.001 80.002 30.002 50.001 40.001 60.001 40.001 90.002 60.002 60.002 70.002 90.002 80.001 70.001 90.001 70.001 40.002 50.002 50.002 60.002 60.002 70.002 40.002 70.001 80.002 50.001 80.001 90.001 40.001 70.002 60.001 30.001 9
207Pb*/235U
7.138 25.466 63.721 62.415 24.639 15.951 33.932 913.987 43.642 74.556 16.895 112.364 36.548 25.852 15.860 24.753 33.998 77.138 25.466 62.814 92.836 85.182 14.500 04.672 32.765 411.938 15.538 25.839 011.662 19.022 02.772 95.766 59.402 42.574 710.948 13.889 13.965 45.370 64.316 512.093 43.663 52.734 66.986 29.877 52.825 02.896 72.992 71.819 111.611 59.956 111.325 410.597 210.063 34.896 23.969 33.824 32.789 49.263 29.106 611.471 910.006 610.406 710.129 811.946 75.960 310.303 35.582 81.641 32.691 44.831 09.399 62.762 34.968 6
1σ
0.131 40.099 50.072 20.046 20.079 50.103 40.072 10.245 10.062 30.080 20.118 40.221 60.114 30.103 30.105 10.085 10.072 00.131 40.099 50.051 60.062 10.093 70.080 80.086 50.052 00.212 90.099 30.100 70.198 40.210 10.049 10.098 00.163 10.049 30.183 00.070 60.069 20.089 80.073 50.204 90.062 90.047 70.135 20.178 00.049 50.055 80.051 30.031 30.197 10.193 60.192 70.182 00.169 60.082 90.067 60.065 90.050 40.158 30.183 90.193 60.171 00.189 30.170 10.203 90.101 20.177 60.103 20.041 20.048 00.082 00.165 10.047 80.086 6
206Pb*/238U
0.401 30.340 60.219 10.188 40.279 40.354 50.241 50.525 50.150 00.300 90.279 60.474 80.353 40.343 40.339 70.295 90.245 10.401 30.340 60.167 60.212 70.332 70.286 00.300 80.229 30.462 70.336 60.339 10.457 00.362 30.223 10.344 10.378 70.203 20.442 60.238 50.219 60.320 30.282 50.474 90.203 10.157 80.311 50.406 70.219 30.211 50.229 30.101 80.457 80.396 30.438 10.389 40.369 20.307 10.214 90.232 40.227 30.381 70.378 60.462 80.398 30.397 70.445 90.466 30.345 00.436 90.313 80.087 00.208 70.299 60.374 20.224 00.272 1
1σ
0.005 50.004 60.003 50.002 90.003 60.004 70.003 60.007 00.001 90.003 90.003 70.006 60.004 70.004 50.004 40.003 80.003 50.005 50.004 60.002 40.002 90.004 40.003 70.004 00.003 00.005 90.004 40.004 30.005 80.007 30.002 90.004 40.005 20.002 60.005 60.003 50.003 00.004 00.003 60.006 10.002 70.002 10.004 70.005 80.002 80.002 70.002 90.001 40.005 90.006 10.005 70.005 00.004 70.003 90.002 70.003 00.002 90.004 90.005 70.005 80.005 20.005 70.005 60.006 00.004 40.005 60.004 70.002 00.002 70.003 80.005 10.002 80.003 7
表面年龄值(Ma)207Pb*/206Pb*
2 0851 9022 0031 4871 9621 9821 9282 7682 6171 7962 6432 7322 1562 0092 0301 9031 9312 0851 9021 9831 5621 8481 8661 8431 3712 7171 9462 0272 6992 6581 4281 9792 6541 4652 6471 9302 1111 9801 8132 6952 1092 0392 4842 6171 4971 6121 5222 0922 6892 6732 7202 8052 8071 8902 1501 9461 4042 6162 6012 6512 6732 7402 5052 7062 0332 5682 0852 1871 4981 9102 6731 4142 131
1σ
26262628262626242427242426272828262626263527272730242626242429262433242625252624252524242931282524242324232625263024242424242424262425252926242825
207Pb*/235U
2 1291 8951 5761 2471 7561 9691 6202 7491 5591 7412 0982 6322 0521 9541 9551 7771 6342 1291 8951 3601 3651 8501 7311 7621 3462 6001 9071 9522 5782 3401 3481 9412 3781 2932 5191 6111 6271 8801 6972 6121 5631 3382 1102 4231 3621 3811 4061 0522 5742 4312 5502 4882 4411 8021 6281 5981 3532 3642 3492 5622 4352 4722 4472 6001 9702 4621 9139 86
1 3261 7902 3781 3451 814
1σ
39353124303430482731364736343532293935253033313325463434445524334125422928312944272341442427241844474343413128282440474342454144334235252430422332
206Pb*/238U
2 1751 8901 2771 1131 5881 9561 3942 7239 01
1 6961 5892 5051 9511 9031 8851 6711 4132 1751 8909 99
1 2431 8511 6221 6951 3312 4511 8701 8822 4261 9931 2981 9062 0701 1922 3621 3791 2801 7911 6042 5051 1929 44
1 7482 2001 2781 2371 3316 25
2 4302 1522 3422 1202 0261 7271 2551 3471 3202 0842 0702 4522 1612 1582 3772 4671 9112 3371 759538
1 2221 6892 0491 3031 551
1σ
30262017202621361222213526252421203026141724212218312424314017242815302017232132161327311616178
31333027262216171727313128313032243026131622281621
谐和度
1049964758199729834946092909593887330935080
100879297909693907591967881897161908893574670848577873090808676729158699480809281799591949184258288779273
表1 样品锆石U-Pb测年结果表
Tab.1 Results of U-Pb dating of samples
第1期 刘晓阳等:坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石铀铅年龄及其地质意义 9
测点号
D6459TW1.74D6459TW1.75D6459TW1.76D6459TW1.77D6459TW1.78D6459TW1.79D6459TW1.80
D6460TW1,含砾砂岩,80个年龄测点:D6460TW1.1D6460TW1.2D6460TW1.3D6460TW1.4D6460TW1.5D6460TW1.6D6460TW1.7D6460TW1.8D6460TW1.9
D6460TW1.10D6460TW1.11D6460TW1.12D6460TW1.13D6460TW1.14D6460TW1.15D6460TW1.16D6460TW1.17D6460TW1.18D6460TW1.19D6460TW1.20D6460TW1.21D6460TW1.22D6460TW1.23D6460TW1.24D6460TW1.25D6460TW1.26D6460TW1.27D6460TW1.28D6460TW1.29D6460TW1.30D6460TW1.31D6460TW1.32D6460TW1.33D6460TW1.34D6460TW1.35D6460TW1.36D6460TW1.37D6460TW1.38D6460TW1.39D6460TW1.40D6460TW1.41D6460TW1.42D6460TW1.43D6460TW1.44D6460TW1.45D6460TW1.46D6460TW1.47D6460TW1.48D6460TW1.49D6460TW1.50D6460TW1.51D6460TW1.52D6460TW1.53D6460TW1.54D6460TW1.55D6460TW1.56D6460TW1.57D6460TW1.58D6460TW1.59D6460TW1.60D6460TW1.61D6460TW1.62D6460TW1.63D6460TW1.64D6460TW1.65D6460TW1.66D6460TW1.67D6460TW1.68
含量(x10-6)U
191602450
12669
141
4250323081923245511105652423238267743144736608030579482272
2570213344
1337
2946145796
1296260427369426
512
6121
102433736223219225349217317
130
Pb67
10216278
404201604
1021117893
23224059
128112924
12485
103787558
25110436
10823018520780
153175457135
470
2006281
102693237511637
176410527173131157166138133
31182
14354
36996909864744252
1468155
30658
709
同位素比值207Pb*/206Pb*
0.091 40.122 10.115 20.180 10.116 10.115 00.128 4
0.113 40.114 40.115 00.121 20.169 50.182 50.178 70.114 80.118 20.116 60.088 40.115 10.179 40.117 30.116 30.117 70.115 10.117 20.115 60.115 30.116 10.105 30.179 10.181 60.112 20.116 10.185 00.118 00.118 10.468 70.113 20.116 30.115 90.113 80.114 30.162 80.115 40.115 90.115 30.115 00.117 60.118 00.125 50.116 40.117 40.084 80.123 50.174 00.116 10.412 20.192 00.282 90.114 20.113 50.116 50.134 10.114 40.115 30.106 20.115 10.115 80.110 30.115 20.192 40.116 60.116 80.086 10.083 3
1σ0.001 40.001 70.001 70.002 60.001 70.001 70.001 9
0.001 50.001 50.001 50.001 60.002 10.002 30.002 30.001 50.003 30.002 30.002 30.001 50.002 30.001 50.001 50.001 50.001 50.001 50.001 50.001 60.001 50.001 40.002 30.002 50.001 50.001 50.002 30.001 50.001 60.409 40.001 50.001 50.001 50.001 50.001 50.002 10.002 00.001 50.001 50.001 60.001 50.001 50.001 60.001 50.001 50.001 10.001 60.002 30.001 50.039 60.002 40.050 40.001 50.001 50.001 50.001 70.001 50.001 50.001 40.001 50.001 60.001 50.001 50.002 80.001 60.001 50.001 90.001 1
207Pb*/235U2.880 01.756 15.228 712.035 74.813 94.409 43.721 5
5.429 95.444 85.504 94.643 57.056 08.399 511.809 14.644 45.377 85.060 12.701 25.072 512.747 25.362 75.347 85.329 45.234 43.808 55.045 85.087 05.315 72.174 26.560 48.246 84.710 14.641 112.945 31.972 22.724 021.885 64.704 93.601 14.689 25.099 75.080 53.992 73.674 45.152 84.565 25.052 13.575 63.339 53.652 74.907 65.317 42.286 75.668 210.249 94.098 948.157 910.163 125.870 14.640 45.029 54.036 17.069 05.130 45.186 24.148 44.906 55.069 74.421 94.843 013.389 64.951 82.799 32.445 12.107 8
1σ0.052 10.040 60.089 80.203 70.082 40.075 50.067 3
0.088 90.082 50.085 60.071 30.105 10.135 70.179 30.090 10.155 10.111 60.073 50.076 10.194 40.081 40.081 70.084 10.081 80.061 90.076 90.082 10.081 30.060 40.103 70.147 50.071 90.075 50.198 50.029 60.067 84.996 10.072 90.058 10.071 50.077 30.076 40.062 60.073 80.079 30.069 70.080 80.064 30.061 70.081 00.085 60.079 00.034 60.089 70.159 20.063 39.623 20.153 74.455 00.068 60.077 10.061 20.106 80.076 70.077 30.063 40.073 30.078 30.068 60.074 50.246 30.077 60.058 50.055 30.031 6
206Pb*/238U0.228 60.104 30.329 00.484 70.300 70.278 00.210 2
0.347 20.345 30.347 20.277 90.301 90.333 90.479 30.293 40.330 00.314 80.221 50.319 70.515 40.331 50.333 50.328 50.329 80.235 60.316 60.320 00.332 20.149 70.265 70.329 30.304 50.290 00.507 50.121 20.167 30.338 70.301 30.224 70.293 40.324 90.322 40.177 80.230 90.322 40.287 20.318 60.220 50.205 30.211 00.305 90.328 50.195 60.333 00.427 20.256 00.847 40.384 00.663 30.294 70.321 40.251 20.382 40.325 40.326 30.283 40.309 30.317 60.290 80.304 80.504 80.307 90.173 80.205 90.183 5
1σ0.002 90.002 20.004 20.006 10.003 90.003 50.002 9
0.004 80.004 30.004 40.003 50.003 70.004 50.006 00.005 20.004 20.004 10.002 70.003 90.006 50.004 10.004 10.004 20.004 10.003 30.004 00.004 00.004 20.003 60.003 50.004 80.003 70.004 10.006 40.001 50.004 10.050 60.003 80.003 00.003 50.004 00.003 90.002 30.003 20.004 00.003 60.003 80.003 50.003 40.004 80.004 60.003 90.002 40.004 10.005 20.003 20.109 30.004 70.058 50.003 50.003 90.003 10.004 60.003 90.003 90.003 40.003 70.003 80.003 50.003 90.006 50.003 70.003 30.002 50.002 3
表面年龄值(Ma)207Pb*/206Pb*
1 4551 9881 8842 6541 8971 8802 076
1 8551 8701 8801 9742 5532 6752 6411 8771 9291 9041 3921 8812 6471 9161 9001 9211 8821 9141 8891 8851 8961 7202 6452 6681 8351 8962 6981 9261 9284 1461 8521 8991 8941 8611 8682 4851 8861 8941 8841 8801 9201 9262 0361 9011 9171 3102 0072 5971 8973 9542 7593 3791 8671 8561 9032 1521 8701 8841 7351 8811 8921 8041 8842 7631 9051 9081 3411 276
1σ30252724262626
2323232321212123503550232123232324232325232421222423212324
129524232423232131232325232323232325242223
14421
27823242323232324232425232424234225
207Pb*/235U1 3771 0291 8572 6071 7871 7141 576
1 8901 8921 9011 7572 1192 2752 5891 7571 8811 8291 3291 8322 6611 8791 8771 8741 8581 5951 8271 8341 8711 1732 0542 2581 7691 7572 6761 1061 3353 1791 7681 5501 7651 8361 8331 6331 5661 8451 7431 8281 5441 4901 5611 8041 8721 2081 9272 4581 6543 9552 4503 3421 7571 8241 6412 1201 8411 8501 6641 8031 8311 7161 7922 7081 8111 3551 2561 151
1σ25243244312929
3129302732373934544036274129293029262830293332402729411733
72627252728282631282729282835312818303826
79037
57526282532282825272827285028282817
206Pb*/238U1 327639
1 8342 5481 6951 5811 230
1 9211 9121 9211 5811 7011 8572 5241 6581 8381 7641 2901 7882 6801 8461 8551 8311 8381 3641 7731 7891 849899
1 5191 8351 7141 6422 646738997
1 8801 6981 3061 6581 8141 8021 0551 3391 8021 6271 7831 2851 2031 2341 7201 8311 1521 8532 2931 4703 9572 0953 2801 6651 7971 4452 0871 8161 8201 6081 7371 7781 6451 7152 6341 7301 0331 2071 086
1σ17132332222017
2724252021253229232316223423232323192222232220272123349
2428121172022221419222021202028262214232819
51026
28920221825222219212120223421201413
谐和度
91329796898459
104102102806769968895939395
101969895987194959852576993879838524592698897964271958695676261909688928877
100769789977697979793929491919591549085
续表1
10 地 质 调 查 与 研 究 第43卷
测点号
D6460TW1.69D6460TW1.70D6460TW1.71D6460TW1.72D6460TW1.73D6460TW1.74D6460TW1.75D6460TW1.76D6460TW1.77D6460TW1.78D6460TW1.79D6460TW1.80
含量(x10-6)U
54581113827
1036342
104403528
Pb18113278911171
39016876
27813393
108
同位素比值207Pb*/206Pb*
0.116 20.115 20.121 50.115 20.119 10.117 50.115 50.201 20.114 40.128 70.115 00.090 7
1σ0.001 50.001 50.001 60.001 50.001 60.001 50.001 50.002 60.001 40.001 90.001 50.001 2
207Pb*/235U3.986 04.958 51.888 24.342 05.330 43.534 14.869 613.804 54.656 64.345 75.020 62.886 1
1σ0.069 20.073 30.032 90.066 20.080 70.055 90.071 80.205 70.068 40.070 10.075 10.043 6
206Pb*/238U0.248 70.312 10.112 70.273 30.324 60.218 20.305 80.497 50.295 30.244 90.316 50.230 7
1σ0.003 80.003 70.001 80.003 40.003 90.002 90.003 60.006 00.003 50.003 10.003 80.002 8
表面年龄值(Ma)207Pb*/206Pb*
1 8991 8831 9791 8841 9431 9181 8882 8361 8702 0811 8801 441
1σ232323232323232123272325
207Pb*/235U1 6311 8121 0771 7011 8741 5351 7972 7361 7591 7021 8231 378
1σ282719262824264126272721
206Pb*/238U1 4321 751688
1 5571 8121 2721 7202 6031 6681 4121 7731 338
1σ222111192217203220182116
谐和度
759335839366919289689493
续表1
注:*Pb代表放射成因Pb,普通Pb校正采用204Pb。
测点号
D6457TW1,细粒长石石英砂岩,80个年龄测点:D6457TW1.01D6457TW1.02D6457TW1.03D6457TW1.04D6457TW1.05D6457TW1.06D6457TW1.07D6457TW1.08D6457TW1.09D6457TW1.10D6457TW1.11D6457TW1.12D6457TW1.13D6457TW1.14D6457TW1.15D6457TW1.16D6457TW1.17D6457TW1.18D6457TW1.19D6457TW1.20D6457TW1.21D6457TW1.23D6457TW1.24D6457TW1.25D6457TW1.26D6457TW1.27D6457TW1.28D6457TW1.29D6457TW1.30D6457TW1.31D6457TW1.32D6457TW1.33D6457TW1.34D6457TW1.35D6457TW1.36D6457TW1.37D6457TW1.38D6457TW1.39D6457TW1.40D6457TW1.41D6457TW1.42D6457TW1.43D6457TW1.44D6457TW1.45D6457TW1.46D6457TW1.47D6457TW1.48D6457TW1.49D6457TW1.50D6457TW1.51D6457TW1.52D6457TW1.53D6457TW1.54D6457TW1.55D6457TW1.56D6457TW1.57
含量(x10-6)U
633821254375255449359943279
7310178152233
21912268
10419
125102153367212221272847162633132764276849242926
18468522234271674
Pb
50012513222921318610899
3502362193585852
18630422011795
16733718516723748
24024866
1893314293616767
107116577095
12315165
34811075
15722946311185
21089
17361
199
同位素比值207Pb*/206Pb*
0.081 30.095 50.071 30.067 50.076 30.110 30.083 90.181 60.069 30.095 30.127 60.064 70.116 20.072 10.128 90.189 90.115 20.068 30.077 70.077 10.213 70.178 40.116 80.122 80.118 90.169 70.127 70.081 90.076 70.075 00.120 40.074 70.103 10.118 20.119 40.123 60.066 20.121 50.122 70.068 80.079 10.121 60.116 80.073 10.125 60.112 90.074 00.064 10.117 70.174 30.202 20.070 00.109 60.072 90.087 60.110 6
1σ
0.001 20.001 30.001 00.000 90.001 00.001 40.001 10.002 40.000 90.001 50.001 60.000 90.001 60.001 40.001 80.002 40.001 50.001 10.001 10.001 10.002 70.002 30.001 50.001 60.001 60.002 20.001 60.001 70.001 20.001 00.001 70.001 10.001 40.001 90.001 60.001 60.001 00.001 70.001 60.001 20.001 10.001 60.001 60.000 90.001 60.001 50.001 00.000 90.001 50.002 20.002 70.001 20.001 50.001 00.001 40.001 4
207Pb*/235U
1.362 33.163 51.474 01.003 31.937 94.358 82.461 8
12.236 11.312 51.677 26.595 31.055 65.185 01.622 06.096 76.841 74.859 01.162 91.886 41.761 3
15.590 311.841 84.857 65.784 85.252 410.811 76.598 42.169 71.531 91.826 65.939 81.849 44.442 25.838 55.872 96.288 91.234 16.060 75.845 51.111 52.276 55.877 95.009 41.705 96.355 24.632 51.710 10.978 74.763 811.696 014.737 01.009 04.671 11.476 12.776 44.611 5
1σ
0.026 20.050 00.024 30.016 30.029 90.065 30.039 60.191 40.020 40.032 20.100 10.016 40.081 60.033 40.094 40.115 90.079 40.020 60.031 00.026 80.233 10.178 30.072 90.087 70.084 00.162 00.100 90.046 80.026 00.028 60.096 90.031 40.070 70.098 80.090 20.095 90.021 50.112 20.089 70.021 70.036 60.088 40.079 60.025 90.095 70.070 90.027 10.016 10.070 90.175 00.223 60.018 60.071 60.023 80.049 20.069 6
206Pb*/238U
0.121 60.240 30.149 80.107 80.184 10.286 60.212 80.488 80.137 40.127 70.374 80.118 30.323 70.163 10.343 20.261 30.305 80.123 40.176 10.165 70.529 10.481 30.301 60.341 70.320 50.462 20.374 90.192 20.144 80.176 60.357 70.179 50.312 50.358 20.356 80.369 10.135 20.361 90.345 50.117 10.208 80.350 60.311 00.169 20.366 90.297 50.167 60.110 70.293 50.486 60.528 60.104 60.309 00.146 90.229 90.302 4
1σ
0.001 70.003 00.001 90.001 40.002 30.003 50.002 70.006 30.001 70.001 70.004 70.001 50.004 10.002 00.004 30.003 70.003 90.001 50.002 20.002 00.006 50.005 90.003 60.004 20.004 00.005 70.004 80.002 40.001 80.002 20.004 60.002 30.004 10.004 80.004 40.004 60.001 70.004 70.004 30.001 40.002 70.004 30.004 10.002 10.004 50.003 60.002 10.001 40.003 60.006 00.006 40.001 30.003 80.001 80.002 80.003 7
表面年龄值(Ma)207Pb*/206Pb*
1 2281 537967853
1 1041 8041 2912 667907
1 5342 065764
1 898989
2 0822 7411 884879
1 1401 1232 9342 6381 9081 9971 9392 5542 0661 2421 1141 0691 9631 0611 6801 9291 9472 008813
1 9781 996893
1 1741 9801 9081 0182 0371 8471 042746
1 9222 6002 844928
1 7931 0101 3731 809
1σ
2925292826232621282923282439242124332927212123232521234030262429252823233225233727232426232428302321213524283124
207Pb*/235U
8731 448920705
1 0941 7051 2612 623851
1 0002 059732
1 850979
1 9902 0911 795783
1 0761 0312 8522 5921 7951 9441 8612 5072 0591 171943
1 0551 9671 0631 7201 9521 9572 017816
1 9851 953759
1 2051 9581 8211 0112 0261 7551 012693
1 7792 5802 798708
1 762921
1 3491 751
1σ
1723151117262041131931112920313529141816433927293038312516173218273330311437301519292915312716112639421327152426
206Pb*/238U
7401 388900660
1 0891 6251 2442 565830774
2 052721
1 808974
1 9021 4971 720750
1 045988
2 7382 5331 6991 8951 7922 4492 0521 133872
1 0481 9711 0641 7531 9741 9672 025818
1 9911 913714
1 2231 9381 7461 0082 0151 679999677
1 6592 5562 735641
1 736884
1 3341 703
1σ
1017128
142016331010269
23122421229
1312343121232230261411132514232624251126249
162423132521139
2031338
21111621
谐和度
609093779990969692509994959891559185928893968995929699917898
1001001041021011011011019680
104989199999196918698966997879794
表2 样品锆石U-Pb测年结果表
Tab.2 Results of U-Pb dating of samples
第1期 刘晓阳等:坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石铀铅年龄及其地质意义 11
测点号
D6457TW1.58D6457TW1.59D6457TW1.60D6457TW1.61D6457TW1.62D6457TW1.63D6457TW1.64D6457TW1.65D6457TW1.66D6457TW1.67D6457TW1.68D6457TW1.69D6457TW1.70D6457TW1.71D6457TW1.72D6457TW1.73D6457TW1.74D6457TW1.75D6457TW1.76D6457TW1.77D6457TW1.78D6457TW1.79D6457TW1.80
含量(x10-6)U
130245238
12636266
67455729
10311486
15382324720695115
Pb20489
13422633993
12826
17517416614724327418224829216325096
17043857
同位素比值207Pb*/206Pb*
0.205 40.101 80.114 80.083 90.124 00.111 30.081 80.074 80.115 70.087 30.110 40.077 30.126 40.128 20.129 70.174 90.088 60.082 20.075 10.076 40.114 50.063 80.088 8
1σ0.002 60.001 90.001 50.001 10.001 70.001 50.001 20.002 40.001 50.001 10.001 40.001 10.001 60.001 70.001 70.002 30.001 10.001 10.001 10.001 20.001 50.000 80.001 3
207Pb*/235U15.304 32.184 15.005 91.559 85.344 44.642 02.140 71.673 55.049 62.967 14.801 92.008 96.228 06.294 46.733 111.906 63.089 12.113 01.509 11.783 85.410 60.982 72.929 8
1σ0.237 50.047 80.075 90.025 20.085 00.070 90.035 20.055 10.075 20.046 20.076 20.032 10.094 10.103 90.118 20.181 70.048 30.034 10.025 30.031 60.082 90.015 90.049 9
206Pb*/238U0.540 40.155 60.316 20.134 90.312 70.302 60.189 80.162 30.316 60.246 50.315 60.188 50.357 40.356 10.376 50.493 70.252 80.186 50.145 70.169 30.342 70.111 70.239 3
1σ0.006 90.002 00.003 90.001 70.003 80.003 70.002 30.002 00.003 80.003 20.004 10.002 40.004 40.005 10.005 00.006 10.003 30.002 30.001 80.002 20.004 30.001 50.003 0
表面年龄值(Ma)207Pb*/206Pb*
2 8701 6571 8771 2892 0141 8201 2411 0631 8901 3671 8051 1282 0482 0732 0942 6051 3961 2501 0721 1071 872735
1 400
1σ2135232724242864232524282323242225272831232828
207Pb*/235U2 8341 1761 820954
1 8761 7571 162999
1 8281 3991 7851 1192 0082 0182 0772 5971 4301 153934
1 0401 887695
1 390
1σ4426281530271933272228183033364022191618291124
206Pb*/238U2 785933
1 771816
1 7541 7041 120970
1 7731 4211 7681 1131 9701 9642 0602 5871 4531 102877
1 0081 900683
1 383
1σ3612221021211412211823142428273219141113249
17
谐和度
975694638794909194
104989996959899
104888291
1019399
续表2
注:*Pb代表放射成因Pb,普通Pb校正采用204Pb。
测点号
D6355TW1,粗粒长石石英砂岩,80个年龄测点:D6355TW1.01D6355TW1.02D6355TW1.03D6355TW1.04D6355TW1.05D6355TW1.06D6355TW1.07D6355TW1.08D6355TW1.09D6355TW1.10D6355TW1.11D6355TW1.12D6355TW1.13D6355TW1.14D6355TW1.15D6355TW1.16D6355TW1.17D6355TW1.18D6355TW1.19D6355TW1.20D6355TW1.21D6355TW1.22D6355TW1.23D6355TW1.24D6355TW1.25D6355TW1.26D6355TW1.27D6355TW1.28D6355TW1.29D6355TW1.30D6355TW1.31D6355TW1.32D6355TW1.33D6355TW1.34D6355TW1.35D6355TW1.36D6355TW1.37D6355TW1.38D6355TW1.39D6355TW1.40D6355TW1.41D6355TW1.42D6355TW1.43D6355TW1.44D6355TW1.45
含量(x10-6)U
1772021561602631273069111114622020515020722426290
24417950
16987
15583
12522117614098
30818023218015923921722819632017
19266
2364943
Pb
353968267273
1 411213
1 639163210271490544477477
1 9521 07515693145586
305202
2 589191225486687253233
2 872384455468961613783
1 956626
2 03039
2 10212560713477
同位素比值207Pb*/206Pb*
0.177 30.164 90.178 90.185 50.142 00.178 80.154 30.179 20.181 20.178 70.173 10.178 40.169 50.172 60.155 50.153 80.184 50.173 60.178 50.185 40.186 60.180 20.146 80.182 90.178 40.173 60.163 60.176 70.176 80.136 90.178 80.177 30.174 50.171 40.184 90.168 20.164 30.154 10.137 70.117 80.148 10.181 90.162 90.127 20.178 6
1σ
0.002 40.002 20.002 30.002 40.001 90.002 30.002 00.002 40.002 40.002 30.002 30.002 30.002 20.002 40.002 00.002 00.002 40.002 30.002 30.002 40.002 40.002 40.002 00.002 40.002 30.002 30.002 10.002 30.002 30.001 80.002 40.002 40.002 30.002 30.002 50.002 20.002 30.002 10.001 90.002 50.001 90.002 40.002 10.001 70.002 3
207Pb*/235U
10.656 34.170 8
12.636 012.891 13.449 5
12.616 03.330 3
12.262 211.771 212.288 79.323 48.287 76.546 69.389 32.183 84.674 2
12.896 45.296 39.118 6
12.068 112.559 08.931 21.072 29.641 2
12.319 59.914 15.161 011.814 98.934 61.976 3
10.000 911.117 07.915 23.458 28.377 45.804 22.359 05.911 82.975 85.427 71.809 211.893 68.139 75.691 611.473 3
1σ
0.234 00.086 80.202 00.208 10.074 10.191 00.110 40.198 40.205 30.193 70.202 10.124 50.109 50.234 80.053 70.074 20.199 70.158 90.197 60.191 90.188 00.176 70.030 50.217 60.196 50.186 90.122 20.183 50.150 90.039 40.152 20.175 30.128 30.155 80.144 20.160 00.112 10.121 70.077 90.118 40.031 90.183 50.124 10.088 50.171 0
206Pb*/238U
0.435 80.183 40.512 30.504 10.176 20.511 70.156 50.496 30.471 10.498 80.390 60.336 90.280 10.394 60.101 90.220 40.506 90.221 30.370 60.472 10.488 20.359 40.053 00.382 40.500 90.414 20.228 70.484 80.366 50.104 70.405 60.454 70.328 90.146 40.328 50.250 30.104 10.278 20.156 70.334 20.088 60.474 10.362 30.324 40.465 9
1σ
0.008 20.003 50.006 80.006 70.003 20.006 20.005 00.006 50.006 80.006 40.007 50.004 10.004 00.008 20.002 30.002 80.006 20.006 10.007 10.006 10.005 90.006 80.001 30.007 80.006 50.006 50.004 60.006 10.005 20.001 60.004 80.005 70.004 30.006 00.004 50.006 30.004 60.005 20.003 30.004 10.001 40.005 90.004 50.004 10.005 5
表面年龄值(Ma)207Pb*/206Pb*
2 6282 5072 6422 7022 2512 6422 3952 6452 6642 6412 5882 6382 5532 5832 4072 3892 6942 5922 6392 7022 7122 6552 3092 6792 6382 5932 4942 6232 6232 1892 6422 6282 6022 5712 6982 5392 5012 3922 1991 9232 3242 6712 4862 0602 640
1σ
232222222322222222222222222322232222222221222322222222222223222222232222242324382222222322
207Pb*/235U
2 4941 6682 6532 6721 5162 6511 4882 6252 5862 6272 3702 2632 0522 3771 1761 7632 6721 8682 3502 6102 6472 331740
2 4012 6292 4271 8462 5902 3311 1072 4352 5332 2211 5182 2731 9471 2301 9631 4011 8891 0492 5962 2471 9302 562
1σ
553542433340494245415134345929284156514140462154424644403922374036683954584037411840343038
206Pb*/238U
2 3321 0862 6672 6311 0462 664937
2 5982 4882 6092 1251 8721 5922 144625
1 2842 6431 2892 0322 4932 5631 979333
2 0872 6182 2341 3282 5482 0136 42
2 1952 4161 833881
1 8311 440639
1 583938
1 859547
2 5021 9931 8112 466
1σ
442135351932303436334123234414163236393231378
43343527322910263024362536283020238
31252329
谐和度
8943
1019746
101399893998271628326549850779295751478998653977729839270346857266643972494808893
表3 样品锆石U-Pb测年结果表
Tab.3 Results of U-Pb dating of samples
注:*Pb代表放射成因Pb,普通Pb校正采用204Pb。
12 地 质 调 查 与 研 究 第43卷
测点号
D6355TW1.46D6355TW1.47D6355TW1.48D6355TW1.49D6355TW1.50D6355TW1.51D6355TW1.52D6355TW1.53D6355TW1.54D6355TW1.55D6355TW1.56D6355TW1.57D6355TW1.58D6355TW1.59D6355TW1.60D6355TW1.61D6355TW1.62D6355TW1.63D6355TW1.64D6355TW1.65D6355TW1.66D6355TW1.67D6355TW1.68D6355TW1.69D6355TW1.70D6355TW1.71D6355TW1.72D6355TW1.73D6355TW1.74D6355TW1.75D6355TW1.76D6355TW1.77D6355TW1.78D6355TW1.79D6355TW1.80
D6356TW1,中粒长石石英砂岩,80个年龄测点:D6356TW1.01D6356TW1.02D6356TW1.03D6356TW1.04D6356TW1.05D6356TW1.06D6356TW1.07D6356TW1.08D6356TW1.09D6356TW1.10D6356TW1.11D6356TW1.12D6356TW1.13D6356TW1.14D6356TW1.15D6356TW1.16D6356TW1.17D6356TW1.18D6356TW1.19D6356TW1.20D6356TW1.21D6356TW1.22D6356TW1.23D6356TW1.24D6356TW1.25D6356TW1.26D6356TW1.27D6356TW1.28D6356TW1.29D6356TW1.30D6356TW1.31D6356TW1.32D6356TW1.33D6356TW1.34D6356TW1.35D6356TW1.36D6356TW1.37D6356TW1.38D6356TW1.39D6356TW1.40
含量(x10-6)U
22899
207709311848
228280155245148250126154215806439
26612419837
16313512913414328344
17020147113329
2008940
240104482957
1064036776241
1351601098993623251173458
10250
1626043215747543921195459463
Pb624171
4 08811016221385
674732
2 009540312
1 04221129395114613169
1 67823255765
37410 253
25627738356276
304360123176
1 040
45115063
5681728145
1011766760
1279662
2293221791291571075289305298
17610842099693311282
12660
33121574
153108
同位素比值207Pb*/206Pb*
0.160 10.176 90.146 70.183 70.191 00.177 30.177 80.175 50.164 60.165 50.208 30.178 80.181 00.176 70.180 50.146 20.176 90.191 00.177 70.160 60.183 60.156 50.173 60.172 30.075 70.185 70.174 80.173 90.176 30.186 80.177 80.177 10.116 80.191 40.166 1
0.178 60.179 00.186 30.178 30.179 80.178 40.179 80.182 90.175 80.176 20.186 90.181 10.186 90.210 80.182 20.182 60.182 90.183 10.179 90.177 60.180 60.179 20.187 60.177 00.178 00.175 80.116 10.183 80.177 40.188 80.194 00.178 40.178 60.127 70.187 40.178 80.178 80.191 90.180 10.187 6
1σ0.002 10.002 30.002 00.002 40.002 50.002 30.002 30.002 30.002 20.002 20.002 70.002 40.002 40.002 30.002 50.001 90.002 30.002 50.002 40.002 10.002 40.002 00.002 30.002 20.001 00.002 40.002 30.002 30.002 30.002 50.002 30.002 30.001 50.002 50.002 2
0.002 30.002 30.002 40.002 30.002 30.002 30.002 30.002 30.002 30.002 30.002 40.002 30.002 40.003 00.002 30.002 30.002 30.002 30.002 30.002 30.002 30.002 30.002 70.002 30.002 30.002 20.001 50.002 50.002 30.002 50.003 70.002 30.002 30.001 60.002 50.002 30.002 30.002 70.002 30.002 4
207Pb*/235U7.734 6
12.057 50.957 1
12.403 512.213 911.487 511.740 76.774 86.643 41.477 811.191 110.603 85.070 0
12.087 312.258 64.326 511.944 811.664 112.159 53.046 911.777 97.088 511.972 49.341 60.126 9
10.908 89.633 37.900 3
10.935 312.394 712.251 412.133 35.460 3
12.820 06.294 9
9.075 212.647 212.837 78.451 8
12.761 712.360 612.616 512.101 112.018 212.580 012.884 612.864 112.983 016.089 712.578 610.586 212.655 712.864 312.150 712.408 612.694 212.802 912.797 012.669 212.488 911.781 05.619 47.658 5
12.354 713.004 713.585 511.492 811.991 86.734 0
13.051 512.467 79.028 0
13.335 812.472 712.790 9
1σ0.116 80.179 70.029 60.189 10.189 80.173 10.177 50.113 80.103 00.052 50.200 30.165 00.204 40.196 50.193 50.104 30.178 50.234 10.198 50.095 60.188 10.107 00.199 00.143 60.001 90.178 40.151 60.149 00.163 70.190 60.184 00.184 00.081 70.191 10.149 4
0.139 70.194 40.199 40.138 90.192 10.182 40.187 60.177 60.175 80.188 90.192 60.193 20.193 90.315 60.186 00.161 30.188 50.192 20.181 00.188 40.192 30.196 40.206 70.194 60.199 50.178 10.089 70.123 10.184 30.197 30.297 10.174 20.181 90.102 40.200 50.209 00.204 20.216 20.184 50.189 4
206Pb*/238U0.350 40.494 50.047 30.489 80.463 80.470 00.478 90.279 90.292 70.064 80.389 70.430 00.203 20.496 10.492 50.214 70.489 70.442 90.496 20.137 60.465 30.328 60.500 10.393 30.012 20.426 00.399 80.329 50.449 90.481 20.499 90.496 80.338 90.485 80.274 8
0.368 50.512 40.499 80.343 80.514 70.502 60.509 00.479 90.495 90.517 70.500 10.515 30.503 70.553 50.500 80.420 50.501 90.509 50.489 90.506 70.509 70.518 20.494 80.519 10.508 90.486 00.351 00.302 30.505 10.499 70.507 90.467 30.487 00.382 50.505 20.505 60.366 10.504 00.502 20.494 4
1σ0.004 20.005 90.001 20.006 00.005 90.005 70.005 70.003 80.003 50.002 20.005 80.005 40.007 60.006 70.006 40.004 30.00580.007 80.006 70.004 10.006 10.004 00.006 80.005 00.000 10.005 80.005 10.005 40.005 40.005 90.006 00.006 10.004 00.005 80.005 7
0.004 80.006 60.006 20.004 90.006 50.006 10.006 20.005 80.006 00.006 50.006 20.006 50.006 30.007 90.006 10.005 30.006 20.006 30.006 10.006 50.006 40.006 70.006 00.006 60.006 80.006 10.004 70.003 90.006 20.006 10.007 40.005 80.006 10.004 80.006 10.007 40.007 60.006 30.006 20.006 0
表面年龄值(Ma)207Pb*/206Pb*
2 4562 6242 3082 6862 7512 6272 6332 6112 5042 5122 8922 6422 6622 6222 6582 3022 6242 7512 6322 4622 6862 4182 5932 5801 0862 7052 6042 5952 6182 7142 6322 6261 9082 7542 519
2 6402 6442 7102 6372 6512 6382 6512 6792 6132 6182 7152 6632 7152 9122 6732 6772 6792 6812 6522 6312 6592 6452 7212 6252 6342 6141 8972 6872 6292 7312 7762 6382 6402 0662 7192 6422 6422 7592 6542 722
1σ2222232221222222222221222222232322222222222222222622222222222222242222
21212221212121212121212121232121212121212121242221212322212232212223222121232121
207Pb*/235U2 2012 609682
2 6352 6212 5642 5842 0822 065921
2 5392 4891 8312 6112 6241 6982 6002 5782 6171 4192 5872 1232 6022 372121
2 5152 4002 2202 5182 6352 6242 6151 8942 6672 018
2 3462 6542 6682 2812 6622 6322 6512 6122 6062 6492 6712 6702 6782 8822 6492 4882 6542 6702 6162 6362 6572 6652 6652 6552 6422 5871 9192 1922 6322 6802 7212 5642 6042 0772 6832 6402 3412 7042 6412 664
1σ3339214041393935323345397442414139524345413243362
41384238413940284048
36414137403939383840404040573938404039404041434142393135394160394032414453443939
206Pb*/238U1 9372 590298
2 5702 4562 4842 5221 5911 655405
2 1212 3061 1922 5972 5811 2542 5702 3642 597831
2 4631 8312 6142 138
782 2882 1681 8362 3952 5332 6132 6001 8822 5521 565
2 0222 6672 6131 9052 6772 6252 6522 5272 5962 6892 6142 6792 6302 8402 6172 2632 6222 6542 5702 6432 6552 6922 5912 6952 6522 5531 9401 7022 6362 6122 6482 4722 5582 0882 6362 6382 0112 6312 6232 590
1σ23318
3231303021201431294535332531423525322235271
31283029313232223033
27343227343232303134323433413229323332343335323436322622333239313226323842333232
谐和度
79991396899596616616738745999754988699349276
101837
85837191939999999362
861009884
10110010097
10010298
10098999991999998
10010010197
10210099
10178
10097979698
10198
10086979997
续表3
第1期 刘晓阳等:坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石铀铅年龄及其地质意义 13
测点号
D6356TW1.41D6356TW1.42D6356TW1.43D6356TW1.44D6356TW1.45D6356TW1.46D6356TW1.47D6356TW1.48D6356TW1.49D6356TW1.50D6356TW1.51D6356TW1.52D6356TW1.53D6356TW1.54D6356TW1.55D6356TW1.56D6356TW1.57D6356TW1.58D6356TW1.59D6356TW1.60D6356TW1.61D6356TW1.62D6356TW1.63D6356TW1.64D6356TW1.65D6356TW1.66D6356TW1.67D6356TW1.68D6356TW1.69D6356TW1.70D6356TW1.71D6356TW1.72D6356TW1.73D6356TW1.74D6356TW1.75D6356TW1.76D6356TW1.77D6356TW1.78D6356TW1.79D6356TW1.80
含量(x10-6)U
454955526298367760758956112162277159107604559514397347249
169785180
227593580
10344
213555384
Pb7384928798
17661
13110812617999
209285
1 42726718411681
15386
1091705311688
34313192
15339410960
14819473
4659995
161
同位素比值207Pb*/206Pb*
0.192 40.180 40.179 40.179 40.178 50.175 50.177 80.178 90.178 90.179 40.184 60.179 70.179 20.180 50.163 70.181 20.179 60.171 10.175 00.116 90.187 30.116 40.177 70.178 70.181 90.187 10.184 10.190 90.190 20.172 10.185 10.180 10.180 40.181 40.189 50.202 40.181 20.178 30.178 40.176 4
1σ0.002 60.002 30.002 30.002 30.002 30.002 20.002 30.002 30.002 30.002 30.002 30.002 30.002 30.002 30.002 20.002 30.002 30.002 20.002 20.001 50.002 40.001 50.002 30.002 30.002 30.002 40.002 40.002 50.002 40.002 20.002 40.002 30.002 30.002 30.002 40.002 60.002 30.002 30.002 30.002 3
207Pb*/235U13.471 512.860 812.478 712.546 612.150 211.496 811.872 212.063 711.512 512.125 410.343 111.962 011.581 112.135 24.170 8
12.276 112.275 89.556 711.298 05.069 511.849 15.405 2
12.229 312.022 511.914 812.723 010.454 012.366 012.480 010.825 211.415 312.302 412.250 411.672 911.379 814.306 89.146 211.539 511.762 911.694 2
1σ0.217 40.192 70.186 40.190 10.180 60.170 50.178 40.181 00.172 30.180 60.160 60.176 70.171 70.179 80.199 80.180 50.189 50.140 10.172 00.076 00.177 50.080 70.183 70.181 50.185 80.189 20.207 50.184 80.185 60.160 50.175 40.214 80.198 60.173 00.167 00.215 40.175 60.169 80.174 20.173 3
206Pb*/238U0.507 90.517 20.504 40.507 20.493 70.475 00.484 30.489 00.466 60.490 20.406 30.482 70.468 80.487 60.184 80.491 40.495 70.405 10.468 30.314 60.458 80.336 70.499 30.488 10.475 00.493 10.411 90.469 90.475 80.456 30.447 30.495 30.492 60.466 80.435 60.512 80.366 00.469 30.478 30.480 8
1σ0.006 50.006 50.006 30.006 40.006 10.005 80.006 00.006 10.005 80.006 10.005 40.005 90.005 80.006 00.008 40.005 90.006 40.004 90.005 80.004 00.005 50.004 20.006 30.006 10.006 20.006 10.007 00.005 70.005 90.005 60.005 80.007 50.006 60.005 70.005 20.006 50.006 10.005 70.005 90.005 9
表面年龄值(Ma)207Pb*/206Pb*
2 7632 6562 6482 6472 6392 6112 6322 6432 6432 6472 6952 6502 6452 6572 4942 6642 6492 5682 6061 9092 7191 9022 6312 6402 6702 7172 6902 7502 7442 5782 6992 6542 6562 6652 7372 8452 6642 6372 6382 619
1σ22212121212121212121212121212321212121232223212121212121212121212221212121212121
207Pb*/235U2 7132 6702 6412 6462 6162 5642 5942 6092 5662 6142 4662 6012 5712 6151 6682 6262 6262 3932 5481 8312 5931 8862 6222 6062 5982 6592 4762 6332 6412 5082 5582 6282 6242 5792 5552 7702 3532 5682 5862 580
1σ44403940393839393839383838398039413539273928393941404939393739464338374245383838
206Pb*/238U2 6482 6872 6332 6452 5872 5052 5462 5662 4692 5712 1982 5392 4782 5601 0932 5772 5952 1932 4761 7632 4341 8712 6112 5622 5062 5842 2242 4832 5092 4232 3832 5942 5822 4692 3312 6682 0112 4812 5202 531
1σ34343334323032323132293130325031342631222923333233323830313031393530283434303131
谐和度
98101100100999898989698899896986698999297969499
1009896979094959793999896919685979798
续表3
注:*Pb代表放射成因Pb,普通Pb校正采用204Pb。
个点为近协和年龄(谐和度 98%~108%),7个点为
不协和年龄(图 5e)。所获得的锆石U-Pb207Pb/206Pb
(谐和度 98%~108%)年龄呈三个集中分布区间:
735~1 400 Ma(32 个点)、1 793~2 094 Ma(31 个
点)和 2 554~2 934 Ma(8 个点)(图 5f)。样品
D6355TW1共测试了80个点,测试的80个测试点有
44个点为近协和年龄(谐和度 90%~100%),36个
点为不协和年龄,拟合的不一致线与谐和线的上交
点年龄为 2 654±29 Ma,下交点年龄为 290±110 Ma
(MSWD=17)(图 5g);所测得的锆石 207Pb/206Pb(谐
和度 90%~100%)位于 1 908~2 060 Ma(3个点),
2 580~2 754 Ma(40 个点)区间(图 5h)。样品
D6356TW1共测试了80个点,其中有72个点为近协
和年龄(谐和度91%~102%),8个点为不协和年龄,
测试的 80个测试点拟合的不一致线与谐和线上交
点年龄为2 671±13 Ma(MSWD=4.0)(图5i);所测得
的锆石 207Pb/206Pb(谐和度91%~102%)位于1 897~
2 066 Ma(3个点),2 568~2 912 Ma(68个点)区间
(图5j)。
5讨论5.1地层成岩时代
(1)样品D6459TW1和D6460TW1位于中元古
代基巴拉活动带内的卡盖拉超群,其中样品
D6459TW1获得的锆石年龄信息集中分布在三个区
间:(1)1 371~1 562 Ma,峰值为1 425 Ma;(2)1 796~
2 156 Ma,峰值为1 900 Ma;(3)2 505~2 768 Ma,峰
值为2 690 Ma。D6460TW1锆石年龄信息集中分布
在三个区间:(1)1 276~1 441 Ma,数据较少,无明
显峰值;(2)1 735~2 152 Ma,峰值为 1 890 Ma;(3)
2 597~2 836 Ma,峰值为 2 727 Ma。从测试结果来
看,卡盖拉超群内的中细粒长石石英变砂岩和含砾
变砂岩可能都接受了来自新太古代 2 505~2 836
Ma、古元古时期的1 735~2 156 Ma和中元古时期的
1 276~1 562 Ma的碎屑沉积物。两个样品中年轻的
锆石均具有明显的震荡环带,而无明显加大增生边,
14 地 质 调 查 与 研 究 第43卷
而且年轻锆石获得的年龄是协和的,因此推断该地
区沉积盆地的形成应该晚于1 276 Ma。值得注意的
是侵入于卡盖拉超群的基性岩年龄为1 375 Ma[10],因
此可能存在这样的解释,即该组数据点数少、不够集
中,没有形成明显的峰,因此其对地层形成时代的约
束力不强,或者卡盖拉超群形成时间由于产出盆地
不同而略有差异。如果侵入这套地层的基性岩的年
龄 1 375 Ma 是可靠,则这套地层应该早于 1 375
Ma。结合本文数据推断该地区地层的形成总体应该
在1 400 Ma左右,而且沉积事件与第一期岩浆事件
相隔的时间间断很短。
样品D6457TW1位于新元古代玛拉嘎拉西超群
乌哈群上部马攸攸组。获得的锆石年龄信息集中分
布在三个区间,即细粒长石石英砂岩碎屑物分别来自
太古代2 554~2 934 Ma、古元古时期的1 793~2 094
Ma和中元古代-新元古代 735~1 400 Ma,说明该地
区地层形成时间要晚于735 Ma。
样品 D6355TW1 和 D6356TW1 在现有的地质
图上也被划分为新元古代玛拉嘎拉西超群乌哈群
上部马攸攸组。从测试结果来看,D6355TW1样品
有3个测试点落在谐和线上,位于中元古代1 908~
2 060 Ma;其余测试点虽然部分存在铅丢失,但均可
拟合不一致线,获得的不一致线上交点年龄为2 654±
29 Ma。相邻层位的D6356TW1的锆石年龄信息有
4个测试点落在谐和线上,位于1 897~2 066 Ma的
年龄区间,其余测试点获得的不一致线上交点年龄
为2 671±13 Ma。从测试结果看,样品D6355TW1和
D6356TW1的碎屑沉积物可能主要来自新太古代的
2 650 Ma左右,二者在误差范围内一致,其次可能存
在古元古1 897~2 066 Ma的碎屑沉积。由于二者为
相邻层位的地层,二者之间呈整合接触,因此可以推
断该两种岩性地层之间碎屑物质来源时间上应该差
异不大,该地区盆地的沉积时间晚于1 897 Ma。这
与同群组的D6457TW1样品反映的碎屑沉锆石年龄
信息有很大不同,该地区的乌哈群上部马攸攸组与
基戈马附近的乌哈群上部(样品D6457TW1)马攸攸
组物质来源存在明显差异,建议重新划分。
5.2 地质意义
基于本次测试的5个沉积岩碎屑锆石所反映的
年龄信息,可以发现无论是中元古代的沉积地层还
是新元古代的沉积地层都包含了太古代陆壳的碎
屑,这些碎屑形成时间在 2 560~2 760 Ma之间(图
图4 测试样品部分阴极发光图片
Fig.4 Cathode luminescence picture of the test sample
(a.D6459TW1; b.D6460TW1; c.D6457TW1;
d.D6355TW1; e.D6356TW1)
第1期 刘晓阳等:坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石铀铅年龄及其地质意义 15
5),表明新太古代时期为坦桑
尼亚克拉通新生花岗质岩浆作
用和广泛的地壳再循环的主要
时期[11],特别是2 650 Ma在4个
样品中作为峰值出现,另一个峰
值为2 720 Ma,这两个时期也是
坦桑尼亚太古宙绿岩型金矿主要
产出期。同时5个样品的碎屑锆
石年龄也反映了沉积岩的碎屑成
分部分来源于古元古代,这些碎
屑形成时间在1 800~2 120 Ma
之间,峰值为 1 900 Ma,与乌本
迪-乌萨伽仁活动带主构造期时
间一致[12-23]。这些碎屑锆石的年
龄信息间接证明了乌本迪活动
带是在坦桑尼亚太古宙克拉通
活动边缘基础上演化而来,而后
期的中元古代和新元古代盆地
在原乌本迪活动带的基础上演
化的地质事实。
新元古代地层样品 D6
457TW1 出现多个年龄峰值包
括 880 Ma、1 100 Ma、1 400 Ma、
1 900 Ma、2 600 Ma和2 860 Ma,
其中中元古代出现1 100 Ma和
1 400 Ma两个峰值,与中部非洲
地区中元古代两期主要的岩浆
构造热事件一致 [8- 10]。样品 D6
457TW1 沉积上限为 735 Ma,
晚于下伏Gagwe杏仁状玄武岩
K-Ar等值线年龄 900 Ma,与卢
菲利安弧内加丹加超群沉积上
限 800 Ma[24-28]近一致。结合在
马攸攸组底部中-粗粒石英岩
中局部可见铜的矿化的地质特
征,推测此地区该套地层内可
能是坦桑尼亚境内寻找与卢菲
利安弧内类似的砂页岩型铜矿
的最佳地段,但该地区可能未
经历与卢菲利安弧演化过程中
的后期的变质变形,其矿化规模
有待商榷。图5 测试样品锆石U-Pb测年结果
Fig.5 U-Pb dating results of zircon of the tested samples
16 地 质 调 查 与 研 究 第43卷
6结论(1)坦桑尼亚西北部基戈马附近中元古代沉积
盆地的形成最早起始于1 400 Ma。
(2)坦桑尼亚西北部基戈马附近玛拉嘎拉西台
地乌哈群上部马攸攸组沉积上限为735 Ma。
(3)坦桑尼亚西北部卡雷马附近乌哈群上部的
马攸攸组与基戈马附近的马攸攸组碎屑成分来源存
在明显差异,建议重新划分。
(4)坦桑尼亚西北部基戈马附近玛拉嘎拉西台地
乌哈群上部马攸攸组可能是坦桑尼亚境内寻找与卢
菲利安弧内类似的砂页岩型铜矿的最佳有利地段。
参考文献:
[1] Boniface, Nelson, Volker Schenk, et al. Paleoproterozoic
eclogites of MORB- type chemistry and three Proterozoic
orogenic cycles in the Ubendian Belt (Tanzania): Evidence
from monazite and zircon geochronology, and geochemistry
[J]. Precambrian Research, 2012, 192: 16-33.
[2] Theunissen K, Klerkx J, Melnikov A, et al. Mechanisms of
inheritance of rift faulting in the western branch of the East
African Rift, Tanzania[J]. Tectonics, 1996,15(4), 776-790.
[3] Klerkx J, K Theunissen, D Delvaux. Persistent fault con-
trolled basin formation since the Proterozoic along the West-
ern Branch of the East African Rift[J]. Journal of African
Earth Sciences1998, 26.3: 347-361.
[4] Cahen L, Snelling N J, Delhal J, et al. The geochronology and
evolution of Africa[M]. Oxford:Oxford Univ. Press, 1984:181-
183.
[5] Deblond A, Punzalan L E, Boven A, et al. The Malagarazi
Supergroup of southeast Burundi and its correlative Bukoba
Supergroup of northwest Tanzania: Neo-and Mesoproterozoic
chronostratigraphic constraints from Ar-Ar ages on mafic in-
trusive rocks[J]. Journal of African Earth Sciences, 2001,
32.3: 435-449.
[6] Legler C, Barth A, Knobloch A, et al. Minerogenic Map of
Tanzania and Explanatory Notes for the Minerogenic Map of
Tanzania 1: 1.5 M[J]. Geological Survey of Tanzania, 2015.
[7] Bozhko N A, Pykhova N G, Raaben M E. Biostratigraphy of
upper precambrian of africa[J]. Doklady Akademii Nauk
SSSR, 1974, 214(3), 643.
[8] Tack L, Wingate M T D, De Waele B, et al. The 1375 Ma
“Kibaran event”in Central Africa: Prominent emplacement
of bimodal magmatism under extensional regime[J]. Precam-
brian research, 2010,180(1-2), 63-84.
[9] Tack L, Liégeois J P, Deblond A, et al. Kibaran A- type
granitoids and mafic rocks generated by two mantle sources
in a late orogenic setting (Burundi). Precambrian research,
1994, 68(3-4), 323-356.
[10] Fernandez- Alonso M, Cutten H, De Waele B, et al. The
Mesoproterozoic Karagwe-Ankole Belt (formerly the NE Ki-
bara Belt): The result of prolonged extensional intracratonic
basin development punctuated by two short- lived far-field
compressional events[J]. Precambrian Research, 2012, 216,
63-86.
[11] Sun K, Zhang L, Zhao Z, et al. Episodic crustal growth in
the Tanzania Craton: evidence from Nd isotope compositions
[J]. China Geology, 2018, 1(2): 210-224.
[12] Sanislav I V, Wormald R J, Dirks P, et al. Zircon U-Pb ag-
es and Lu-Hf isotope systematics from late-tectonic gran-
ites, Geita Greenstone Belt: Implications for crustal growth
of the Tanzania Craton[J]. Precambrian research, 2014, 242:
187-204.
[13] Kabete J M, McNaughton N J, Groves D I, et al. Reconnais-
sance SHRIMP U-Pb zircon geochronology of the Tanzania
Craton: evidence for Neoarchean granitoid-greenstone belts
in the Central Tanzania Region and the Southern East Afri-
can Orogen[J]. Precambrian Research, 2012, 216: 232-266.
[14] Rino S, Komiya T, Windley B F, et al. Major episodic in-
creases of continental crustal growth determined from zircon
ages of river sands; implications for mantle overturns in the
Early Precambrian[J]. Physics of the Earth and Planetary
Interiors, 2004, 146(1-2): 369-394.
[15] Lenoir J L, Liégeois J P, Theunissen K, et al. The Palaeo-
proterozoic Ubendian shear belt in Tanzania: geochronology
and structure[J]. Journal of African Earth Sciences, 1994, 19
(3): 169-184.
[16] Hanson R E. Proterozoic geochronology and tectonic evolu-
tion of southern Africa[J]. Geological Society, London, Spe-
cial Publications, 2003, 206(1): 427-463.
[17] Boniface N, Appel P. Stenian-Tonian and Ediacaran meta-
morphic imprints in the southern Paleoproterozoic Ubendi-
an Belt, Tanzania: Constraints from in situ monazite ages[J].
Journal of African Earth Sciences, 2017, 133: 25-35.
[18] De Waele B, Johnson S P, Pisarevsky S A. Palaeoproterozo-
ic to Neoproterozoic growth and evolution of the eastern
Congo Craton: its role in the Rodinia puzzle[J]. Precambrian
Research, 2008, 160(1-2): 127-141.
[19] Black R, Liegeois J P. Cratons, mobile belts, alkaline rocks
and continental lithosphericmantle: the Pan-African testimo-
ny[J]. Journal of theGeological Society, 1993, 150(1): 89-98.
[20] Abdelsalam M G, Liégeois J P, Stern R J. The saharan
metacraton[J]. Journal of African Earth Sciences, 2002, 34
(3-4): 119-136.
[21] Liégeois J P, Abdelsalam M G, Ennih N, et al. Metacraton:
nature, genesis and behavior[J]. Gondwana Research, 2013,
第1期 刘晓阳等:坦桑尼亚乌本迪活动带西北部元古宙沉积盆地碎屑锆石铀铅年龄及其地质意义 17
23(1): 220-237.
[22] De Waele B, Mapani B. Geology and correlation of the cen-
tral Irumide belt[J]. Journal of African Earth Sciences,
2002, 35(3): 385-397.
[23] Andersen L S, Unrug R. Geodynamic evolution of the Ban-
gweulu Block, northern Zambia[J]. Precambrian Research,
1984, 25(1-3): 187-212.
[24] Armstrong R A, Master S, Robb L J. Geochronology of the
Nchanga Granite, and constraints on the maximum age of
the Katanga Supergroup, Zambian Copperbelt[J]. Journal of
African Earth Sciences, 2005, 42(1-5): 32-40.
[25] Master S, Rainaud C, Armstrong R A, et al. Provenance
ages of the Neoproterozoic Katanga Supergroup(Central
African Copperbelt), with implications for basin evolution
[J]. Journal of African Earth Sciences, 2005, 42(1-5): 41-
60.
[26] Master S, Wendorff M. Neoproterozoic glaciogenic diamic-
tites of the Katanga Supergroup, Central Africa[J]. Geologi-
cal Society, London, Memoirs, 2011, 36(1): 173-184.
[27] Cailteux J L H, De Putter T. The Neoproterozoic Katanga
Supergroup(DR Congo): State-of-the-art and revisions of
the lithostratigraphy, sedimentary basin and geodynamic
evolution[J]. Journal of African Earth Sciences, 2019, 150:
522-531.
[28] Mambwe P, Kipata L, Chabu M, et al. Sedimentology of the
Shangoluwe breccias and timing of the Cu mineralisation
(Katanga Supergroup, DR of Congo) [J]. Journal of African
Earth Sciences, 2017, 132: 1-15.
U-Pb Age of detrital Ziron and its geological significance in the Pro-terozoic sediments basin in the northwestern Ubendian belt of Tanzania
LIU Xiao-yang1,2, GONG Peng-hui1,2, XU Kang-kang1,2, WU Xing-yuan1,2,
SUN Kai1,2, HE Sheng-fei1,2, HE Fu-qing1,2
(1.Tianjin Center, China Geological Survey, Tianjin 300170, China;2.North China Center for Geoscience Innovation, China Geological Survey, Tianjin 300170, China)
Abstract: Karagwe- Ankolean active zone and Malagarazi platform in northwestern Tanzania are a series of
Proterozoic sedimentary basins developed in the later period of the Ubendian belt. Due to the similarity of
sedimentary lithology and metamorphism, the definition of stratigraphic sequence is controversial. In this paper,
the U-Pb ages from detrial zircons in the upper part of the Manyouo Formation in the upper Uha group in the
Kagala supergroup and the Malagasi supergroup were obtained. The detrital zircon 207Pb /206Pb ages are
concentrated in the three peak ranges of 1 276~1 562 Ma, 1 735~2 156 Ma and 2 505~2 836 Ma; the 207Pb
/ 206Pb ages from detrital zircon in the manyouo group in the upper Uha group of the Malagarazi platform near
Kigoma in northwestern Tanzania are concentrated in the three peak intervals of 735~1 400 Ma, 1 793~2 094
Ma and 2 554~2 934 Ma; the U-Pb ages from two samples detrital zircon in the manyouo group in the upper part
of the Uha group on the Malagarazi platform near Kalimain northwestern Tanzania are 2 654 ± 29 Ma and 2 671
± 13 Ma. Based on the available geological data, it can be concluded that the sedimentary age of the
Mesoproterozoic sedimentary basin near Kigoma in northwestern Tanzania is not earlier than 1 400 Ma; the
sedimentary age of the manyouo group in the upper Uha group of the Malagarazi platform near Kigoma in
northwestern Tanzania is not earlier than 735 Ma; The manyouo group in the upper part of the Uha group on the
Malagarazi platform near kalimais diffrent with the same group near Kigoma, and re-division is recommended.
Key words: Tanzania; Ubendian belt; Uha group; detrital zircon U-Pb age
18 地 质 调 查 与 研 究 第43卷