Internal geology and evolution of the Redondo Dome, Valles Caldera, New Mexico

Nielson, Dennis L.; Hulen, Jeffrey B.

doi:10.1029/jb089ib10p08695

Cited by 87 publications

(93 citation statements)

References 15 publications

(9 reference statements)

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“…These are characterized by resurgent domes, with an amount of uplift varying from a few tens of meters (Rabaul; Saunders 2001) to ∼1 km (Valles, Long Valley, USA; Bailey et al 1976;Nielson and Hulen 1984;Hill et al 1985). These resurgent domes are related to a significant hydrothermal system and surface deformation accompanied with seismicity (e.g., Heiken and Goff 1983;Mori and McKee 1987;Langbein et al 1995;Battaglia et al 1999).…”

Section: Possible Relations To Resurgencementioning

confidence: 97%

Evaluating fracture patterns within a resurgent caldera: Campi Flegrei, Italy

Acocella

2010

Bull Volcanol

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Understanding deformation of active calderas allows their dynamics to be defined and their hazard mitigated. The Campi Flegrei resurgent caldera (Italy) is one of the most active and hazardous volcanoes in the world, characterized by post-collapse resurgence, eruptions, ground deformation, and seismicity. An original structural analysis provides an overview of the main fracture zones. NW-SE and NE-SW fractures (normal or transtensive faults and extensional fractures) predominate along the rim and within the caldera, suggesting a regional control, both during and after the collapses. While the NE-SW fractures are ubiquitous in the deposits of the last ∼37 ka, NW-SE fractures predominate in the last 4.5 ka, during resurgence. The most recently (<4.5 ka) strained area lies in the caldera center (Solfatara area), where the faults, with an overall ∼ENE-WSW extension direction, appear to be associated with the bending due to resurgence. Solfatara lies immediately to the east of the most uplifted part of the caldera (Pozzuoli area), where domes form and culminate both on the long-term (resurgence, accompanied by volcanic activity) and short-term deformation (1982)(1983)(1984) bradyseism, accompanied by seismic and hydrothermal activity). Similar volcano-tectonic behavior characterizes the short-and long-term uplifts, and only the intensity of the tectonic and volcanic activity varies, being related to varying amounts of uplift. Seismicity and hydrothermal manifestations occur during the bradyseisms, with moderate uplift, while surface faulting and eruptions occur during resurgence, with higher uplift. The features observed at Campi Flegrei are found at other major calderas, suggesting consistent behavior of large magmatic systems.

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Section: Possible Relations To Resurgencementioning

confidence: 97%

Evaluating fracture patterns within a resurgent caldera: Campi Flegrei, Italy

Acocella

2010

Bull Volcanol

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“…In cross section, the amount of displacement upon the individual faults can vary considerably. Drilling into the Valles caldera, New Mexico, revealed this type of asymmetry; multiple step-down faults were documented to the west, and a principal fault was inferred to the east (Nielson and Hulen, 1984).…”

Section: Caldera Asymmetrymentioning

confidence: 97%

Controls on caldera structure: Results from analogue sandbox modeling

Kennedy

Stix

Vallance

et al. 2004

Geo. Society Am. Bull.

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We conducted scaled analogue sandbox models of caldera formation in order to understand the effects of chamber depth and orientation on the spatial and temporal development of calderas. Dry sand contained in a 1-m-diameter cylinder served as a crustal rock analogue, and a water-filled 0.6-m-diameter rubber bladder served as an analogue magma chamber. Scaling parameters included a length ratio (L*) of 2.5 ؋ 10 -5 and a stress ratio (*) of 1.8-2.4 ؋ 10 -5 . In contrast to some previous analogue models, the viscosity of the fluid in the chamber and its withdrawal rate were properly scaled. Generally, deformation began with broad sagging, followed by an arcuate or linear outward-dipping fault that formed on one side of the caldera. This fault propagated laterally around the caldera in both directions, sometimes joining other faults, and typically forming an overall polygonal structure. As subsidence continued, the caldera grew incrementally outward and progressively formed a series of concentric outward-dipping faults. Lastly, a peripheral zone of extension and pronounced sagging, and commonly an inwarddipping outer fault related to extension, developed at the surface. As the depth of the chamber increased, (1) the area of faulting † E-mail: ben@eps.mcgill.ca. ‡ Present address: U.S. Geological Survey, 1300 SE Cardinal Court, Building 10, Suite 100, Vancouver, Washington 98683-9589, USA. decreased, (2) the symmetry of the caldera was affected, and (3) the coherence of the subsiding block decreased. Tilting the chamber caused highly asymmetric subsidence to occur. In this case, faults formed first where the bladder was shallowest. Subsidence then shifted rapidly to where the bladder was deepest, producing an elongate trapdoor caldera that was deepest where the bladder was deepest. Our experiments highlight the roles of sagging and faulting during caldera subsidence. Surface fault patterns both in our experiments and at natural calderas are frequently not circular. The aspect ratio of the block above the magma chamber controls the shape of the caldera, which is frequently polygonal. The faults at natural calderas determine locations and migration of eruptive vents, the degree of subsidence, the style of postcaldera resurgent magmatism, and the extent of hydrothermal circulation. Our experiments reveal details of how calderas grow outward incrementally and demonstrate that asymmetric subsidence along linear and arcuate faults is common to many calderas.

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“…According to Nielson and Hulen (1984) these listric faults are a result of surface extension and deeper compression of the block (i.e. a stress regime that would be consistent with ring dyke driven uplift).…”

Section: Criticisms Of Previously Suggested or Implied Resurgent Mechmentioning

confidence: 96%

The possible contribution of circumferential fault intrusion to caldera resurgence

Saunders

2004

Bull Volcanol

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In the geological record, the intrusion of substantial amounts of magma into circumferential faults and ring fractures is commonly observed. Finite element modelling is used here to investigate the strain field that may be expected from such intrusive events. Two simple vertical scenarios are explored, one for a caldera with a central block of thickness to diameter ratio of~1:1 (similar to Rabaul) and one with a ratio much less than 1:1 (similar to the 'Valles type'). Surface deformation in both cases is similar with central uplift, the development of a moat (or trough) like feature just outside of the intersection of the azimuth of the intruded ring fault and the free surface, and broader scale tumescence at a scale several times larger than the caldera's radius. The response of the block and sub-caldera magma chamber for the two scenarios, however, is different. The blocks are in effect squeezed; the high aspect ratio one deforms upwards at the surface and downwards at its base, whereas the low aspect ration one experiences up arching (or bending) of the central part of the caldera block. Central uplift still occurs when only a short arc of a ring fracture system or a circumferential fault is intruded. In both models, tumescence in the centre of the caldera from single ring dyke intrusion can only account for decimetres to metres of surface uplift. Repeated intrusions over tens to hundreds of thousands of years, however, may cause incremental up doming of the caldera block leading to larger scale resurgent features. The amount of uplift possible due to squeezing of a high aspect ratio block is limited. It is proposed, however, that where bending of plate-like blocks occur above a decompressible and/or malleable magma body, ring fault intrusion may be a significant contributor to resurgence. In the simple conceptual models shown here, the amount of ring dykeinduced central uplift will be >40-50% of the width of the ring complex. In the geological record the accumulation of intrusions into some ring fractures has led to annular or arcuate plutons of hundreds of meters to several kilometres in thickness. At certain calderas such intrusions may be a control on the marked concentration of uplift within the restricted area defined by the caldera faults. The complex nature of the horizontal displacements associated with the intrusion of ring and arcuate dykes is also explored. Intrusion into ring fracture zones will tend to take place into those sectors of the annular zone which are perpendicular to the least compressive stress vector. This may be a factor in the observed difference for caldera evolution in extensional and compressional areas. The unrest at several modern calderas is tentatively related to circumferential fault intrusion.

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Internal geology and evolution of the Redondo Dome, Valles Caldera, New Mexico

Cited by 87 publications

References 15 publications

Evaluating fracture patterns within a resurgent caldera: Campi Flegrei, Italy

Evaluating fracture patterns within a resurgent caldera: Campi Flegrei, Italy

Controls on caldera structure: Results from analogue sandbox modeling

The possible contribution of circumferential fault intrusion to caldera resurgence

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