Sequence and timing of deformation in the footwall of the Funeral Mountains metamorphic core complex, California

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5806729

Applegate, J D.R.; Hodges, K V ^[1]; Walker, J D ^[2]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States)
2. Univ. of Kansas, Lawrence, KS (United States). Dept. of Geology

The metamorphic infrastructure of the Funeral Mountains has undergone a polygenetic sequence of deformation associated with Mesozoic-Tertiary burial and unroofing. The first two episodes of deformation are displayed as isoclinal, recumbent folds (F1 and F2) that have been highly attenuated by subsequent deformation, and as associated axial planar schistosities. The minimum age of D1-2 deformational features is constrained as 72 Ma by U-Pb zircon data for cross-cutting granitic pegmatites. Attenuation of older structures occurred during D3, a deformation episode that produced the dominant foliation (S3) and well-defined, WNW-ESE stretching and mineral lineations (L3). D3 deformation has been dated at 70--72 Ma. The next episode of deformation (D4) is represented by NW-vergent, tight to isoclinal folds (F4) which fold the S3 foliation. The age of this folding is bracketed between 72 Ma and 65Ma. Southwest-vergent, tight folds that involve S3 and F4 are the dominant structures of D5 deformation. These folds, which range in size from mm-scale to hundreds of meters in amplitude, are associated with a regionally developed, NW-SE crenulation lineation (L5). The age of D5 is not tightly constrained but is considered to be Tertiary. They associate D1--2 deformation with Mesozoic thrust faulting which buried the core rocks. D3 and D4 deformation are clearly Late Cretaceous and represent initial unroofing of the core. They ascribe subsequent deformational events to episodic Tertiary unroofing. D5 deformation in particular may represent an isostatic response to unroofing on the core-bounding Boundary Canyon Detachment, while D6--7 deformation may be related to late-stage doming of the core.

• OSTI ID: 5806729
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
CALIFORNIA
DEFORMATION
DEVELOPED COUNTRIES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GROUND SUBSIDENCE
GROUND UPLIFT
METAMORPHIC ROCKS
MOUNTAINS
NORTH AMERICA
ROCKS
USA