Stage | Facies ID | DESCRIPTON | INTERPETATION |
1 | LP-fn+1-ps | Pleistocene sediments (poorly compacted) cropping out west of Lagoa do Peixe escarpment (Barrier III). | Pleistocene sediments cropping out at the footwall top west of fault escarpment (Barrier III). |
1a | LP-fn+1-pf | Radarfacies underlying the lower lagoonal unit, displays regular reflections which are truncated (toplap-offlap) by its upper boundary. | Pre-fault radarfacies undergone hangingwall collapse and erosion. |
LP-sn+1-gf | Upward concave listric geometry surface that truncate Pleistocene sediments (west) and lower lagoonal unit (east). | Listric gravitational growth fault. See also associated branching normal faults. | |
LP-sn+2-et | Offlap-toplap for reflectors underlying lower lagoonal unit; maybe an erosional truncation. | An erosional surface developed on the down-throwing hangingwall before fault controlled lagoonal accumulation. | |
2 | LP-fn+2-pe | Convex upward arcuted lower lagoonal unit, displaying onlap for lowermost reflections in the thickest zones, close to listric surface, and parallel reflections for uppermost strata. | Lagoonal accumulation during the first stage of fault displacement resulted in its convex geometry and greater thickness close to fault surface. |
LP-sn+3-ol | Surface at the top of the lower lagoonal unit, in the outcropping peat layer, showing onlap reflections for overlying radarfacies. | An increase in water depth giving rise to onlap of horizontal sedimentary layer on both sides in the lagoon depocenter. | |
3 | LP-fn+3-lag | Horizontal reflections in a hangingwall triangular area close to listric surface, showing onlap upon lower lagoonal unit and listric surface. | Localized sediment accumulation while fault displacement advanced, during a second stage of fault displacement, clogging Lagoa do Peixe depocenter (triangular wedge). |
LP-sn+4-dl | Discrete onlap-downlap features upon previous radarfacies on both margins of the Lagoa do Peixe. | Surface defining the vanishing stage of fault displacement, and the third stage of sediment accumulation in the Lagoa do Peixe. | |
4 | LP-fn+4-lag | Upward arcuated reflections at both Lagoa do Peixe margins, showing alternating onlap-downlap and toplap-offlap features. | Third stage of lagoonal sediment accumulation, characterized by the interbedding of lagoon sediments and sands from emersed areas on both sides of the Lagoa do Peixe. |
5 | LP-fn+5-es | Dipping sinuous reflections in the Lagoa do Peixe escarpment, showing discrete downlap with lagoon sediment reflections. | Erosional degradation of the fault escarpment and deposition as interbedded layer of sands and lagoon sediments. |
LP-sn+n-df | Minor truncation of inner reflections of radarfacies. | Minor listric normal faults merging into master one, or diachronic synthetic and antithetic normal faults. | |
LP-sn+5-dl | Irregular surface underlying recent dune sediments. | Surface upon which recent dune sediments prograde. | |
6 | LP-fn+6-dm | Horizontal and steeply dipping sigmoidal reflections, as also as thin horizontal reflection near the topographic surface. | Recent dunes and thin wind cover overlying previous sedimentary radarfacies: 6a—steeply dipping reflections: lateral limbs of recent dunes; 6b—horizontal reflections: frontal dune strata, and thin wind covers. |
Types of radarfacies (f) | Types of boundary surfaces ( s ) | ||
ps = Pleistocene sediments | gf = growth fault | ||
pf = pre-fault unit underlaying lower lagoonal | et = erosional truncation | ||
pe = lower lagoonal, underlying peat layer | ol = onlap | ||
lag = sediments clogging the lagoon | dl = downlap | ||
es = erosional sediments close to escarpment | df = diachronic normal faults | ||
dm = recent dunes and thin wind covers (Upper Holocene) |