Journal of Geological Research

Research Article

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

Table 2

Representative chemical analyses (recalculated to 100 wt% on anhydrous basis; in parentheses, standard deviation) of K-alkaline rocks (B-P suite, effusive and intrusive equivalents and dykes) from ASV [10, 13, 24]. Analysis of a silicobeforsitic flow, on anhydrous basis, is also shown [48, 74]. Ages as in [4].


Suite B-P
K-alkaline	Basanite	Tephrite	Phonotephrite	Phonolite	Silicobeforsite 22% dolomite	Silicobeforsite carb. fraction

No. of samples	(4)	(6)	(4)	(1)	(1)
Wt%
SiO₂	46.95 (2.14)	49.08 (1.31)	52.36 (1.64)	48.69	49.05	—
TiO₂	1.78 (0.19)	1.94 (0.26)	1.42 (0.19)	1.97	1.94	—
Al₂O₃	12.84 (1.63)	12.94 (1.17)	17.27 (1.24)	16.42	15.32	—
FeO_tot	10.20 (1.80)	10.02 (0.97)	7.39 (0.75)	8.45	9.60	—
MnO	0.18 (0.03)	0.17 (0.02)	0.15 (0.02)	0.15	0.17	—
MgO	9.95 (2.02)	7.88 (1.64)	3.66 (0.58)	3.86	5.28	—
CaO	11.31 (1.41)	9.36 (0.85)	7.00 (1.02)	6.96	8.81	—
Na₂O	2.42 (0.61)	2.99 (0.92)	4.34 (0.58)	3.79	3.50	—
K₂O	3.78 (1.18)	4.99 (1.24)	5.73 (0.17)	8.60	6.14	—
P₂O₅	0.59 (0.21)	0.66 (0.18)	0.58 (0.07)	0.69	0.34	—
Mg#	0.67	0.62	0.51	0.45	—	—
ppm
La	82.1 (19.0)	91.2 (13.0)	93.3 (13.6)	98	80	239.06
Ce	162.6 (30.4)	164.1 (18.1)	170.0 (25.0)	186	145	420.34
Nd	64.4 (10.9)	69.3 (4.9)	66.6 (12.1)	73.2	62	159.89
Sm	12.8 (2.4)	12.8 (3.6)	11.4 (1.6)	15.1	11.3	19.06
Eu	3.0 (0.6)	3.0 (0.4)	2.8 (0.3)	2.02	2.3	3.90
Gd	7.4 (1.9)	6.8 (1.1)	7.1 (0.6)	5.93	8.8	14.90
Dy	4.4 (0.6)	3.6 (0.2)	3.9 (0.4)	2.86	6.2	10.57
Er	1.9 (0.4)	1.7 (0.3)	1.9 (0.3)	1.59	3.3	5.40
Yb	1.6 (0.1)	1.4 (0.4)	1.5 (0.3)	1.59	1.9	3.16
Lu	0.25 (0.01)	0.21 (0.06)	0.26 (0.06)	0.23	0.28	0.32
Cr	275 (106)	378 (260)	36 (23)	53	51	—
Ni	81 (29)	111 (42)	28 (18)	22	18	—
Rb	88 (18)	117 (51)	111 (35)	260	148	0.21
Sr	1134 (279)	1661 (227)	1569 (10)	1626	1126	268
Ba	1179 (252)	1582 (147)	1462 (215)	1935	1350	—
Th	14.4 (9.9)	11.4 (3.5)	12.1 (1.6)	12.7	15.2	—
U	2.9 (1.0)	2.4 (0.7)	2.5 (0.1)	3.5	4.2	—
Ta	3.2 (0.2)	3.0 (0.7)	3.2 (0.3)	5.1	2.7	—
Nb	38.0 (7.0)	44 (10)	47 (1)	62	35	—
Zr	246 (42)	282 (91)	259 (35)	365	280	—
Y	14.0 (2.8)	17.3 (6.7)	18.9 (3.0)	13	18	23.75
Measured
(⁸⁷Sr/⁸⁶Sr)	0.70761 (4)	0.70774 (3)	0.70727 (4)	0.70752 (2)	0.70807 (2)	0.70762 (3)
(¹⁴³Nd/¹⁴⁴Nd)	0.51182 (4)	0.51171 (1)	0.51160 (4)	0.51187 (2)	0.511804 (6)	0.511371 (8)
Age	130	129	124	125	128	—
Initial ratio
(⁸⁷Sr/⁸⁶Sr)_i	0.70697	0.70716	0.70671	0.70645	0.70700	0.70717
(¹⁴³Nd/¹⁴⁴Nd)_i	0.51172	0.51162	0.51152	0.51177	0.51171	0.51131
	2049	2042	2043	2067	1884	1844
	1054	713	365		—	—
	1955	1646	1269	1258	—	—
Sr	34.31	37.04	30.58	26.88	34.7	34.17
Nd