Journal of Geological Research

Research Article

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

Table 3

Representative chemical analyses (recalculated to 100 wt% on anhydrous basis; in parentheses, standard deviation) of K-alkaline rocks (AB-T suite, effusive and intrusive equivalents and dykes) from ASV [13, 74]. Ages as in [4].


Suite AB-T
K-alkaline	Alkaline basalt	Trachybasalt	Trachyandesite	Trachyphonolite	Trachyte

No. of samples	(3)	(3)	(7)	(5)	(1)
Wt%
SiO₂	48.69 (1.50)	50.90 (1.56)	53.16 (1.18)	58.25 (1.44)	58.95
TiO₂	1.69 (0.48)	1.49 (0.31)	1.42 (0.21)	0.91 (0.23)	1.94
Al₂O₃	15.17 (1.86)	17.07 (1.06)	16.99 (1.45)	18.39 (1.01)	19.03
FeO_tot	10.31 (0.76)	9.04 (0.57)	7.96 (0.75)	4.87 (1.51)	4.49
MnO	0.19 (0.01)	0.16 (0.02)	0.15 (0.02)	0.16 (0.01)	0.12
MgO	6.71 (0.89)	5.01 (0.24)	4.03 (0.58)	0.89 (0.90)	1.69
CaO	11.09 (0.63)	8.58 (1.11)	6.95 (0.66)	4.59 (1.09)	3.37
Na₂O	3.16 (0.42)	3.64 (0.44)	4.10 (0.38)	5.89 (1.38)	4.21
K₂O	2.46 (0.42)	3.65 (0.72)	4.61 (1.06)	5.76 (1.13)	7.00
P₂O₅	0.55 (0.36)	0.50 (0.17)	0.55 (0.09)	0.29 (0.10)	0.25
Mg#	0.58	0.53	0.51	0.32	0.40
ppm
La	51.2 (16.0)	54.0 (18.6)	82.8 (29.7)	154.0 (33.9)	136
Ce	106.7 (24.4)	109.0 (21.0)	154.2 (55.7)	261.1 (44.2)	206
Nd	52.7 (19.7)	47.9 (12.9)	64.7 (15.7)	84.0 (17.7)	78
Sm	10.5 (1.6)	9.4 (30.5)	10.8 (2.1)	12.7 (3.5)	15.1
Eu	2.8 (1.0)	2.5 (0.3)	2.8 (0.5)	3.28 (0.8)	3.9
Gd	6.8 (2.4)	6.0 (1.2)	6.4 (1.0)	5.70 (1.6)	9.4
Dy	4.1 (0.7)	4.2 (0.6)	4.2 (0.7)	5.44 (1.1)	6.3
Er	1.7 (0.1)	1.8 (0.3)	1.6 (0.4)	2.59 (0.58)	2.3
Yb	1.5 (0.1)	1.6 (0.4)	1.6 (0.4)	2.25 (0.46)	2.0
Lu	0.22 (0.05)	0.24 (0.03)	0.28 (0.08)	0.35 (0.08)	0.31
Cr	143 (24)	92 (59)	38 (34)	10 (6)	8
Ni	49 (6)	31 (18)	17 (12)	6 (2)	2
Rb	53 (13)	98 (16)	87 (20)	7 (3)	133
Sr	1573 (263)	1389 (407)	1474 (194)	77 (34)	600
Ba	1033 (321)	1280 (170)	1211 (168)	1377 (215)	1726
Th	4.3 (2.1)	7.9 (1.5)	14.6 (8.5)	31.7 (8.5)	—
U	1.3 (0.5)	1.7 (0.6)	3.4 (3.0)	9.5 (3.3)	—
Ta	2.3 (1.1)	1.6 (0.4)	2.8 (0.7)	2.6 (0.6)	2.5
Nb	18.1 (9.0)	25.0 (6.0)	40 (12)	62 (18)	61
Zr	260 (31)	220 (33)	268 (14)	411 (128)	392
Y	14.5 (9.2)	14.6 (6.5)	19.5 (3.2)	25 (4)	23
Measured
(⁸⁷Sr/⁸⁶Sr)	0.70717 (4)	0.70721 (5)	0.70753 (4)	0.70752 (2)	0.70807 (2)
(¹⁴³Nd/¹⁴⁴Nd)	0.51185 (4)	0.51170 (3)	0.51160 (4)	0.51187 (2)	0.51181 (6)
Age	125	119	129	125	128
Initial ratio
(⁸⁷Sr/⁸⁶Sr)_i	0.70693	0.70673	0.70709	0.70708	0.70639
(¹⁴³Nd/¹⁴⁴Nd)_i	0.51175	0.51161	0.51151	0.51179	0.51171
	2009	2199	1999	1530	2001
	1215	954	749	545	649
	1817	1501	1277	1014	818
Sr	33.68	30.74	36.09	35.85	26.0
Nd