Journal of Geological Research

Research Article

Magmatism in the Asunción-Sapucai-Villarrica Graben (Eastern Paraguay) Revisited: Petrological, Geophysical, Geochemical, and Geodynamic Inferences

Table 1

Averages of representative chemical analyses (recalculated to 100 wt% on anhydrous basis; in parentheses, standard deviation) of tholeiites from ASV [33, 34, 44]. L-Ti and H-Ti tholeiites according to [2, 45]. The time-integrated notations are calculated using the present day Bulk Earth parameters [50], that is, UR = 0.7047 (⁸⁷Rb/⁸⁶Sr = 0.0816) and CHUR = 0.512638 (¹⁴⁷Sm/¹⁴⁴Nd = 0.1967. Mg#: molar ratio MgO/(MgO + FeO)).


Suite:	L-Ti	L-Ti	H-Ti	H-Ti
tholeiite	basalt	andesite-basalt	basalt	Andesite-basalt

No. of samples	(3)	(3)	(6)	(5)
Wt%
SiO₂	50.20 (0.79)	53.06 (0.40)	50.83 (0.84)	50.52 (0.60)
TiO₂	1.40 (0.06)	1.36 (0.11)	2.58 (0.36)	3.19 (0.60)
Al₂O₃	14.64 (0.21)	13.78 (0.09)	13.98 (0.45)	14.25 (0.63)
FeO_tot	12.73 (0.39)	13.42 (0.49)	13.54 (0.56)	14.55 (1.13)
MnO	0.19 (0.05)	0.25 (0.05)	0.21 (0.02)	0.21 (0.02)
MgO	7.36 (0.22)	5.53 (0.08)	5.13 (0.44)	4.19 (0.65)
CaO	10.63 (0.66)	8.55 (0.05)	9.65 (0.62)	8.56 (0.44)
Na₂O	2.36 (0.11)	2.66 (0.20)	2.61 (0.15)	2.49 (0.29)
K₂O	0.33 (0.05)	1.07 (0.18)	1.10 (0.17)	1.14 (0.10)
P₂O₅	0.15 (0.02)	0.19 (0.01)	0.37 (0.09)	0.36 (0.04)
Mg#	0.66	0.55	0.54	0.48
ppm
La	6.2 (0.8)	9.0 (1.0)	25.3 (6.3)	26.0 (6.0)
Ce	16.0 (1.7)	21.0 (2.9)	60.4 (12.2)	50.0 (2.0)
Nd	11.1 (1.3)	14.1 (2.2)	28.3 (3.6)	25.0 (3.0)
Sm	3.4 (0.3)	4.3 (0.4)	7.7 (1.5)	6.8 (1.1)
Eu	1.2 (0.1)	1.5 (0.1)	2.2 (0.2)	1.9 (0.2)
Gd	4.3 (0.6)	5.4 (0.8)	7.7 (1.2)	6.9 (1.1)
Dy	4.8 (0.5)	6.0 (0.9)	6.3 (1.5)	5.7 (1.3)
Er	2.9 (0.4)	3.6 (0.6)	3.9 (1.3)	3.5 (0.9)
Yb	2.6 (0.4)	3.2 (0.4)	3.4 (1.2)	3.2 (1.0)
Lu	0.34 (0.07)	0.42 (0.09)	0.49 (0.15)	0.50 (0.19)
Cr	325 (27)	62 (1)	119 (15)	48 (2)
Ni	103 (18)	55 (7)	60 (15)	54 (12)
Rb	13 (4)	13 (1)	24 (3)	33 (11)
Sr	188 (42)	187 (2)	386 (90)	334 (15)
Ba	154 (19)	190 (4)	409 (78)	347 (37)
Th	1.1 (0.1)	1.7 (0.2)	2.0 (0.1)	3.0 (0.2)
U	0.24 (0.05)	0.37 (0.08)	0.43 (0.08)	0.65 (0.04)
Ta	0.28 (0.04)	0.42 (0.07)	1.2 (0.3)	1.8 (0.4)
Nb	4.0 (1.0)	6.1 (1.0)	13 (2)	20 (1)
Zr	83 (10)	113 (2)	190 (36)	197 (6)
Y	28 (2)	42 (1)	33 (4)	36 (3)
Measured
(⁸⁷Sr/⁸⁶Sr)	0.70548 (20)	0.70535 (20)	0.70617 (21)	0.70620 (18)
(¹⁴³Nd/¹⁴⁴Nd)	0.51271 (9)	0.51272 (10)	0.51239 (2)	0.51240 (1)
Age (Ma): 131.6
Initial ratio
(⁸⁷Sr/⁸⁶Sr)_i	0.70502	0.70456	0.70576	0.70554
(¹⁴³Nd/¹⁴⁴Nd)_i	0.51256	0.51256	0.51225	0.51226
	1991	1976	2127	2037
	2037	1929	1758	1722
	1789	1459	1561	1403
Sr	6.70	0.12	17.16	14.12
Nd	1.60	1.79