Table 1

87Sr/86Sr ratios, major and trace ion compositions (in 10-6 moles/l for Ca, Na, K, Mg Si, Cl, SO4, Sr and HCO3) of dissolved solids for samples from the Oubangui watersheds. Monthly mean discharge for the Oubangui river in m3/s; S + and S - in 10-6 eq/l.

Sample

87Sr/86Sr

2 S

Cl

SO4

Ca

Na

Mg

K

Si

Rb

Sr

Q m3/s

HCO3

S +

S -

OUBANGUI

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

06/89

0.719315

3.2E-05

18

19

115

66

104

49

197

0.04

0.343

1520

460

553

516

07/89

0.719274

4.9E-05

18

11

87

70

60

35

220

0.03

0.272

2020

350

399

390

08/89

0.719889

3.0E-05

15

18

72

34

54

76

227

0.07

0.220

3470

250

362

301

09/89

0.720849

4.9E-05

11

11

65

36

40

22

227

0.02

0.191

4000

250

268

283

10/89

0.720325

2.7E-05

10

15

66

31

39

34

205

0.03

0.179

6530

210

265

250

02/11/89

0.719682

2.9E-05

22

13

65

50

41

28

222

0.03

0.169

4920

238

290

286

18/11/89

0.719128

5.5E-05

24

13

77

51

-

26

-

0.03

0.188

-

-

-

-

12/89

0.718993

3.6E-05

22

11

76

56

52

20

217

0.02

0.224

2500

300

332

344

01/90

0.718927

3.0E-05

22

22

87

66

68

25

215

0.03

0.233

1300

400

401

444

02/90

0.718656

3.0E-05

24

7

109

87

113

22

217

0.03

0.272

630

460

553

498

SPRINGS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mpoko 02/89

0.728293

3.0E-05

-

-

25

16

14

-

-

-

0.061

-

-

-

-

Mpoko 1 11/89

0.728657

6.0E-05

-

-

52

67

62

-

-

-

0.194

-

-

-

-

Mpoko 2 11/89

0.719676

3.1E-05

-

-

115

74

82

-

-

-

0.221

-

-

-

-

ORSTOM 11/89

0.719199

2.8E-05

-

-

262

55

21

-

-

-

0.410

-

-

-

-

DRILL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

02/89

0.740882

4.7E-05

61

3

780

856

270

-

-

-

2.195

-

-

-

-

07/89

0.740996

3.5E-05

35

2

775

819

268

-

-

-

2.160

-

-

-

-

02/90

-

-

-

-

771

810

265

-

-

-

-

-

-

-

-

TRIBUTARIES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mpoko 11/88

0.726345

2.6E-05

23

12

134

82

104

-

-

-

0.215

 

-

-

-

Mpoko 02/89

0.721992

3.1E-05

23

13

367

65

255

-

-

-

0.313

 

-

-

-

Mpoko 11/89

0.724202

2.4E-05

8

7

157

87

107

80

-

0.05

0.249

 

545

595

567

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mbali 11/88

0.716879

2.9E-05

23

7

86

24

65

-

-

-

0.190

 

 

 

 

Mbali 02/89

0.714546

3.0E-05

22

14

290

34

206

-

-

-

0.288

 

 

 

 

Mbali 11/89

0.716332

2.1E-05

12

5

130

42

78

138

-

0.07

0.239

 

479

596

501

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mandjo 02/89

0.711884

3.8E-05

 

-

579

25

353

-

-

-

0.820

 

-

-

-

Mandjo 11/89

0.713782

3.1E-05

9

7

284

25

131

-

-

-

0.399

 

-

-

-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bili 11/89

0.725484

3.1E-05

21

21

48

66

49

-

-

-

0.169

 

-

-

-

Tomi 11/89

0.726559

2.7E-05

8

19

175

110

124

-

-

-

0.248

 

-

-

-

Uele 11/89

0.717353

5.4E-05

21

20

55

105

53

-

-

-

0.187

 

-

-

-

Kotto 11/89

0.720056

4.6E-05

8

11

67

39

53

-

-

-

 

 

-

-

-

Bamba 11/89

0.728124

2.5E-05

16

22

120

100

112

-

-

-

0.199

 

-

-

-

Oumba 11/89

0.723665

2.6E-05

8

5

257

56

210

-

-

-

0.207

 

-

-

-

Ombella 11/89

0.722831

2.6E-05

9

21

450

78

278

-

-

-

0.372

 

-

-

-

Oubangui 11/89

0.721671

2.8E-05

12

17

70

49

68

-

-

-

0.170

 

-

-

-

Mbomou 11/89

0.721261

1.9E-05

12

11

71

46

68

-

-

-

0.154

 

-

-

-

Ouaka 11/89

0.725455

3..3E-05

6

14

30

44

39

-

-

-

0.118

 

-

-

-