discovery of columbite-tantalite in sonora, mexico

Bol. Depto.Geol. Uni-son. 1991,V.8. N'.1. p.7-11
DISCOVERY OF COLUMBITE-TANTALITE
IN SONORA, MEXICO
Luigi RADELLI, Ismael SOTo-V., Jess URRUTIA-B. aoo Griselda MACIAS-V.
Departamento de Geologra. Uni-Son, Herrrosilio. Sonora, Mexico.
ABSTRACT
The first discovery of a Sonoran Columbite- Tantalite mineralization is reported. It occurs in
two mica pegmatites associated to a peraluminous. two mica- garnet bearing eocene granite - the Huepac
granite
- of the Aconchi Massif.
RESUMEN
5e reporta el primer descubrimiento en Sonora de una mineralizaci6n de Columbita- Tantalita.
Esta mineralizaci6n se encuentra en pegmatitas de dos micas asociadas a un granito eoceno peraluminos,
de dos micas y granate - el granitode Huepac- del Macizo de Aronchi.
INTRODUCTION
The upper, allochthonous unit consists of an old
Precambrian basement, a 1100 Ma old granite
To our knowledge Nb- Ta minerals have
never been reported in Sonora. Thus, it seems
interesting to give notice of a recent discovery of a
Columbite- Tantalite mineralization, and
its
geological setting, in an area west of the town of
Huepac, in a massif generally known, in the
geological literature, as Sierra de Aconchi. And this
is the object of this paper.
(Anderson et al.. 1978; Anderson and Sliver.
1981) - the Aibo granite - and of a cover of
un metamorphosed quartzites and minor
dolomites; this last sequence has been usually
considered as Upper Precambrian, but in fact it
could be much younger (see Radelli, 1990 for
discussion). This upper, allochthonous unit has
recahedits present structural positk>nthere during
the Nevadian Orogeny (Figueroa and Grijalva,
1989; Radelli, 1989, 1990).
Intrusive into the hereabove mentioned
metarnorphics northwards: into the Laramide
granitoids south- and westwards: and divided
eastward from the detrital Miocene Baucarit
Formation by an east-dipping listric fault (Radelli,
1989), there occursalso a the two mlca-garnetbearing, about 40 Ma old (Mead et al. 1988)
peraluminous granite, a typical occurrence of
an Inner CordilleranBeh (Miller and Bradfish,1980;
Damon, 1989), the Huepac Granite (Roldan-a.
et al., 1989: Figueroaand Grijalva, 1989; Radelli,
1989). The emplacement of the Huepac Granite -
THE ACONCHI MASSIF (Fig. 1)
Most of the Aconchi Massif is a huge mass
of Laramide,57 Ma old granitoids(Andersonet al.
1980), that Intruded and contact-metamorphosed
Paleozoic limestone (e.g., EI Jaralito), older
metamorphicrocks (e.g., RanchoOquimonis)and
a Mesozoic (Jurassic?Cretaceous?)sedimentary
sequence that still shows some poorly preserved
fossils (Cerrode Ios Locos).
In the northernmost part of the Aconchi
Massifthere are two tectonicallysuperposedunits
(Figueroaand Grijalva,1989; Radelli,1989, 1990).
The lower unit consists of metamorphic
Precan'd>rlan
rocks with a Jurassicvolcanic cover.
the genesis of which is currently under study - has
been followed by that of two sets of pegmatitic
bodies:
(i) a set of :t NE-trending two mica
8
L RADEL et al.
~ .
.
.'
.
.
,.
..
~2
~3
~8
E,
~10
.
..
.'.
.
..
.
'.
.
4
~11
[SS]5
E:B. _1
0
5Km
Fig. 1 - Simplified geological map of the Aconchl . Huepac . Opodepe area.
1 - Neogeneclastic and volcanic rocks; 2 - Paleogeneand/or Late Cretaceousvolcanics;3 - 50 Ma old San
Felipe porphyry and remnants of its Cretaceousroof; 4 - Huepac granite; 5 - Pegmatites; 6 - Aconchi
Laramidegranitoids; 7- Cretaceous; 8 - Jurassicvolcanics; 9 - Skarn; 10 - "Aibo" Basementand its cover;
11 "Lobera" basement; 12 - Fault; 13 - Overthrust (Nevadian nappe).
-
pegmatites, that occurs at the northwestern
comerof that granite;and (ii) a set of generally
9
L. RADELL! et al.
larger, f: NNW-trending, zoned, two micagarnet-bearing
pegmatltes, that cross the
whole of the Huepac Granite and the pegmatites
of the first set as well.
THE COLUMBITE-TANTALITE
The Columbite- Tantalite object of this
paper is found in the two mica-pegmatitesof the
first set above, in the marginal part of the Huepac
Granite there, where it is in contact with the old
Table 1 -
X-ray diffractometer
Huepac, Sonora.
metamorphics (highly deformed gneisses in
particular), and in such gneisses themselves,
which contain also, there, some millimeter sized
crystals of Beryl/um .
The Co/umbite- Tanta/ite itself occurs as
well developped, millimeter to centimeter sized
black crystals. Its has been determined by X-ray
analysis (fig. 2). It copares (Table 1) fairly well with
the Columbite- Tantalite of Tinton, South Dakota
[(Fe, Mn) (Nb, Ta)206 - Iron, Manganese, Niobium,
Tantalium Oxide).
pattern of the Columblte-Tantallte
TINTON
dA
7.13
5.30
3.66
3.56
2.96
2.86
2.53
2.49
2.38
2.279
2.236
2.207
2.084
2.043
1.898
1.831
1.786
1.772
1.735
1.721
1.672
1.608
1.534
1.516
1.484
1.465
1.454
1.432
1.393
1.380
HUEPAC
dA
5.2937
3.6530
3.5597
2.9624
2.8599
2.5347
2.4902
2.3747
2.2362
2.2068
2.0837
1.8989
1 .8273
1.7695
1.7343
1.7197
1.6077
1.5347
1 .4839
of Tlnton, S. Dakota and
L. RADELLI et al
During our field and microscopic
researches Li-minerals have not been recognized
in either set of pegmatites of the Aconchi Massif.
This fact seem to suggest that the Nb-Ta-bearing
pegmatites belong either in the group of
pegmatitescharacterizedby the associationBe, Y,
REE,Nb>Ta, U and Th, or in that characterizedby
the associationBe, Nb>Ta or Nb<Ta,(5n) (:tB, P)
(Cemy and Ercit, 1985). However,as indicatedby
field evidences at the Alisos Mine (Rancho Las
Albondigas,West of La EstanciaVillage),where it
has been mined in the past, the Beryllumseems to
be related to the set of garnet-bearing pegmatites
only.
Thus, more work is needed, and is in
programme,
to define the geochemicalpetrographic environment of this ColumbiteTantalite of Sonora and to assess its geologic
significance.
REFERENCESCITED
ANDERSON, T.H., EELS, J.H., and SILVER, L.T.,
1978, Rocas precAmbricas y paleozoicas de Ia
regi6n de Caborca, Sonora, Mexico. -In
ROLDAN-C., J. y SALAS, G.A. Ed., Libreto
Guia, Primer Simposio sobre la geologra y
potencial minero en en Estado de Sonora,
Inst. Geol. UNAM, Hermosillo, Sonora, Mexico.
ANDERSON, T.H., SILVER, L.T. and SALAS,
G.A., 1980, Distribution and U-Pb isotope
ages of some lineated plutons, northwestern
Mexico. In Geological Society of America,
Memoir 153, pp. 269-283.
ANDERSON, T.H. and SILVER, L.T., 1981, An
overview of the Precambrian rocks in Sonora.
UNAM, Inst. Geol. Revista, 5, nR 2, pp. 131139.
CERNY, P. and ERCIT, T.S., 1985, Some recent
advances in the mineralogy and geochemistry
of Nb and Ta in rare-element
granitic
.pegmatites. Bull. Mineral., 108, pp. 499-532.
DAMON, P. E., 1989, Evidence for origin of the
Rhyolite-Andesite-Doreite
Series by crustal
melting during the Mid-Tertiary
Orogeny in
Southeastern Arizona In JENNEY, J.P. and
REYNOLDS,S.J., eds., Geologic evolution of
Arizona: Tucson, Arizona Geological Society
Digest 17, pp. 575-583.
FIGUEROA-V.,M.C. Y GRIJALVA-H.,A.S. , 1989,
Geologia de la Hoja Opodepe H12D12,
Municipio de Opodepe, Sonora, Mexico.
Tesis, Depto Geol. Uni-Son, Hermosillo,
Sonora, Mexico,51 p.
MEAD, R.D., KESLER, S.E., FOLAND, K.A. and
JONES, L.M., 1988, Relationshipof Sonoran
Tungsten Mineralization to the Metallogenic
Evolutionof Mexico.Econ. Geology,v. 83, pp.
1943-1965.
MILLER, C.F. and BRADFISH, L.J., 1980, An
inner Cordilleran belt of muscovite-bearing
plutons. Geology,v. 8, pp. 412- 416.
RADELLI, L., 1989, The Baucarit problem. Bol.
Depto Geol. Uni-Son,v. 6, n.D1 y 2, pp. 5557 HerrmosiDo,
Sonora,Mexico
.
RADELLI, L., 1990, La chaine nevadlenne
(gilienne) et ses deformations cretacees au
NW du Mexique (nappes d'origine
gondwanienne de Caborca et du Sonora
central). Geologie Alpine, t. 66, pp. 57-100.
Grenoble,France.
ROLDAN-C., J., LOZANO-S.C., R. Y ARRAZOLOR., S., 1989, Pegmatitas de la Sierra EI Jaralito
al Suroeste de Baviacora, Sonora. UNAM, Inst.
Geol., Revista, v. 8, n. 1, pp. 15-22.
Acknowledgments
This work has been supportedby the grant
CONACYTD 112- 904429. We are grateful to the
Laboratoire de Petrologie de I'Universite d'AixMarseille III and particularly to Dr. J.J. Cocheme for
the X-ray
determination of our Columbite Tantalite.We thank Ing. R. Amaya M. of the Depto
de Geologfa , Uni-Son for continuous logistical
support and encou-ragement.
Manuscritorecibidoel4 de Marzode 1991