Abstract
The Nopolo structure is located along the eastern margin of the Baja California peninsula and formed during the early stages (12-6 Ma) of development of the Gulf of California. The Nopolo structure is an ∼15-km-long series of two NW-striking, extensional monoclines produced by the upward propagation of normal faults. Where normal faults reach the surface, the footwall contains undisturbed, gently dipping strata, whereas the hanging wall is a highly deformed zone that contains fractured and faulted steep to subvertical strata. Long, narrow grabens with moderate to steep east-dipping strata are present in the hanging wall of the main normal faults. Initial monoclinal folding over blind normal faults produced a minimum of ∼300 m of structural relief. Once the faults propagated to the surface, they offset the monoclines ∼20-30 m before faulting ceased. We use an elastic dislocation model to invert fault geometry from bedding orientations around the Nopolo structure. The data are best matched by a listric normal fault that soles out at ∼5 km depth. The model suggests that the tip line of the fault was located ∼1 km below the surface prior to the breaching of the monocline. Because the offset along the main normal faults is minimal (∼20 m), the Nopolo structure is a unique example of an extensional faulted monocline and monocline system where faulting ended soon after the monoclines were breached and offset.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 651-669 |
| Number of pages | 19 |
| Journal | Journal of Structural Geology |
| Volume | 24 |
| Issue number | 4 |
| DOIs | |
| State | Published - 2002 |
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Keywords
- Extensional monocline
- Normal fault
- Upward propagation
ASJC Scopus subject areas
- Geology
Cite this
Early evolution of an extensional monocline by a propagating normal fault : 3D analysis from combined field study and numerical modeling. / Willsey, Shawn P.; Umhoefer, Paul J; Hilley, George E.
In: Journal of Structural Geology, Vol. 24, No. 4, 2002, p. 651-669.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Early evolution of an extensional monocline by a propagating normal fault
T2 - 3D analysis from combined field study and numerical modeling
AU - Willsey, Shawn P.
AU - Umhoefer, Paul J
AU - Hilley, George E.
PY - 2002
Y1 - 2002
N2 - The Nopolo structure is located along the eastern margin of the Baja California peninsula and formed during the early stages (12-6 Ma) of development of the Gulf of California. The Nopolo structure is an ∼15-km-long series of two NW-striking, extensional monoclines produced by the upward propagation of normal faults. Where normal faults reach the surface, the footwall contains undisturbed, gently dipping strata, whereas the hanging wall is a highly deformed zone that contains fractured and faulted steep to subvertical strata. Long, narrow grabens with moderate to steep east-dipping strata are present in the hanging wall of the main normal faults. Initial monoclinal folding over blind normal faults produced a minimum of ∼300 m of structural relief. Once the faults propagated to the surface, they offset the monoclines ∼20-30 m before faulting ceased. We use an elastic dislocation model to invert fault geometry from bedding orientations around the Nopolo structure. The data are best matched by a listric normal fault that soles out at ∼5 km depth. The model suggests that the tip line of the fault was located ∼1 km below the surface prior to the breaching of the monocline. Because the offset along the main normal faults is minimal (∼20 m), the Nopolo structure is a unique example of an extensional faulted monocline and monocline system where faulting ended soon after the monoclines were breached and offset.
AB - The Nopolo structure is located along the eastern margin of the Baja California peninsula and formed during the early stages (12-6 Ma) of development of the Gulf of California. The Nopolo structure is an ∼15-km-long series of two NW-striking, extensional monoclines produced by the upward propagation of normal faults. Where normal faults reach the surface, the footwall contains undisturbed, gently dipping strata, whereas the hanging wall is a highly deformed zone that contains fractured and faulted steep to subvertical strata. Long, narrow grabens with moderate to steep east-dipping strata are present in the hanging wall of the main normal faults. Initial monoclinal folding over blind normal faults produced a minimum of ∼300 m of structural relief. Once the faults propagated to the surface, they offset the monoclines ∼20-30 m before faulting ceased. We use an elastic dislocation model to invert fault geometry from bedding orientations around the Nopolo structure. The data are best matched by a listric normal fault that soles out at ∼5 km depth. The model suggests that the tip line of the fault was located ∼1 km below the surface prior to the breaching of the monocline. Because the offset along the main normal faults is minimal (∼20 m), the Nopolo structure is a unique example of an extensional faulted monocline and monocline system where faulting ended soon after the monoclines were breached and offset.
KW - Extensional monocline
KW - Normal fault
KW - Upward propagation
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U2 - 10.1016/S0191-8141(01)00120-1
DO - 10.1016/S0191-8141(01)00120-1
M3 - Article
VL - 24
SP - 651
EP - 669
JO - Journal of Structural Geology
JF - Journal of Structural Geology
SN - 0191-8141
IS - 4
ER -