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NW Section of the Tamboril-Santa Quiteria Complex, Ceara, Brazil




Roberto Weinberg and Cae Araujo,
School of Geosciences, Monash University, Australia
and Universidade de Sao Paulo, Brazil






This page is part II of our study of the Santa Quiteria Complex Part I. Here the focus is the area NW and W of Santa Quiteria , between the towns of Itapipoca, Amontada and Miraima. This page also documents two outcrops of the Transbrasiliano Lineament.


We define the Itapipoca-Amontada structural domain that is characterized by two deformation phases, contemporaneous with water-fluxed melting and the production of hornblende leucosomes.


a) D1 is characterized by N-S shear foliation with a well developed lineation plunging genlty to S-SSE. Outcrops DKE 600-602 and 605 shows D1 overprinted to different degrees by D2. In these, S1 dips to the west and the movement combines dextral and normal components. Elsewhere, S1 dips to the east and has a similar lineation but the movement sense combines dextral and reverse components DKE 606 and 609). These define large scale folds plunging south. Within S1 there are isoclinal folds. Rocks typically have undergone anatexis and leucosomes contain Hbl and Bt and lack anhydrous pertitectic phases.


b) D2 is characterized by folds and thrusts with a small dextral component. It overprints D1 and is characterized by asymmetric upright plunging folds trending NE-SW. These are commonly small scale folds (50cm scale) associated with axial planar leucosomes with Hbl or Bt and lacking anhydrous peritectic minerals.


c) Overprinting of D1 by D2 gives rise to small scale domes and basins.


We also define the Forquilha-Miraima structural domain characterized by normal movement to E and ESE on shallow dipping foliations.


The conclusion in Part I that the core area of the Santa Quiteria pluton went down in relation to its surroundings during a generalized extension is further supported here.


geological map, Santa Quiteria granite
1a) Geological Map of the Santa Quiteria granite in red and surroundings with hand written field stations.

DKE605 W404035 S9630232 UTM WGS84, close to Amontada on road westward towards Morrinhos. Stromatic orthogneiss with Hbl in leucosomes: a good example of D1 interference with D2. D1 is defined by a gently south plunging folds with a strong parallel stretching lineation. F1 limbs are overprinted by N50E-trending D2 folds and thrusts with leucosomes with a dextral component. Both deformation events occurred during anatexis. Hbl in leucosomes are oriented parallel to S1 (010-190).
migmatite migmatite
1b) D1 fold in 3D showing the strong lineation parallel to axis. Lax=Lx=180/18, S1 axial plane N-S/60-80E. 1c) F1 folds plunging S, photo looking S at low angle to fold axis creating an exagerated pattern.
migmatite migmatite
1d) Steep wall showing D2 asymmetric folds N50E/60W, with a thrusting component. 1e) Tighter version of D2 folds (steep wall).
syn-anatectic thrust syn-anatectic thrust
1f) Vertical wall with a D2 thrust plane with leucosome. 1h) same as f.
fold interference fold interference
1i) Horizontal plane showing dextral component on D2 thrust plane and interference pattern with south plunging F1 folds, forming domes and basins. 1j) Inclined wall showing interference pattern between F1 gently south plunging folds and drag folds on the margins of S2 dextral-thrust.
fold interference
1k) domes and basins forming complex patterns. This was interpreted as a result of D1 sheath folds as there is no evidence of a D2 thrust plane in the immediate vicinity.

DKE606 399747 9636486 by house on road towards Morrinhos from Amontada. Stromatic migmatite after orthogneiss with Hbl in leucosomes: another good example of D1 interference with D2. Here, there is a clear dexttral-reverse movement associated with D1 and interference between F1, with isoclinal folds around S1=355/30-50W lx=175/20, and F2 upright plunging to S50W. Hbl in lecuosome is sheared in S1.
sigma clasts sigma clasts
2a) Hbl leucosomes sheared into sigma clasts: dextral movement on shear plane related to D1, nearly horizontal plane parallel to Lx 2b) Same as previous, notice asymmetric fold with vergence to the right. Notice also two sigma shaped Hbl grains left of the lens cap.
sigma clasts parasitic folds
2c) Same as above, Hbl grains sheared into sigma clasts indicative of dextral movement. 2d) Long limb of F1 showing parasitic asymmetric folds in leucosome with vergence to the right: dextral shearing.
fold interference fold interference
2e) F2 folds treniding NE-SW causing undulations of S1 at metre scale. 2f) Deatail of previous one showing an F1 closure on the hinge of F2..
fold interference
2g) F1 isoclinal fold refolded by F2.

DKE602 Lajedao, close to Amontada on road to Miraima. Stromatic migmatite in orthogneiss, 30-40% Hbl leucosome, D2 folds such as in DKE601 , plunging gently south) overprinting a pre-exisitng S1 foliation trending 340, gently south dipping.
migmatite migmatite
3a) Broad D2 hinge zone, plunging gently SW (245-250), with the envoltoria trending 340. Layer with few leucosomes, has few and low amplitude folds. Layers with lots of melt have high amplitude folds (close to down plunge view). Notice axial planar leucosomes. 3b) Asymmetric F2 folds with vergence to the left (south). This fold style is typical of F2 (see Figs 1d-1e above). Looking down plunge to SW on subhorizontal plane.
migmatite migmatite
3c) Partial and chaotic transposition of pre-existing stromata by S2 axial plane filled with leucosome. 3d) More advanced transposition of pre-exisitng foliation (S1) into S2.

DKE45 Miraima river bed in town. Two lineations 060 and 110 developed in paragneiss with Gnt-Sil. The latter overprints intrusive pegmatites and is associated with normal shearing (top-to-ESE) and is folded around a south plunging fold. Normal movement to the east is typical of a domain between Miraima and Forquilha, with several small outcrops (DKE612-615) documented (plus one on BR222 near Forquilha).
migmatite migmatite
4a) Two stretching lineations: 110 (parallel to the length of the photograph) and 60 (oblique to the photograph). Foliation parallel plane dipping gently east (right). 4b) Normal movement parallel to Lx=110. Vertical wall.
migmatite migmatite
4c) Normal movement parallel to Lx=110. Vertical wall. 4d) Disruption of psammites into mobile pelitic layers. The whole package is isoclinally folded (with rootless folds of psammite blocks) within the gently E-dipping foliation. This foliation is also gently folded defining upright, south-plunging folds.

DKE610-611 Transbrasiliano Lineament, W353577 S9601612. Past the town of Remedios towards Sobral. C=N28E/76W, Lx= 40 towards NE, shear senses dextral with west side down.
migmatite migmatite
5a) Mylonitic Part of the Transbrasiliano Lineament. 5b) zoom in.