CRETACEOUS CONTRACTION IN THE LEES CAMP ANTICLINE: INYO MINE AND VICINITY, FUNERAL MOUNTAINS, DEATH VALLEY, CALIFORNIA

The Lees Camp (Winters Peak) anticline, in the central Funeral Mountains of Death Valley, consists of a doubly east and west-vergent fold and is both shallowly northeast and southwest-plunging. Folded strata include inter-layered argillite, calcareous schist/phyllite, marble, quartzite and meta-conglomerate of the Stirling Quartzite Member A and upper Johnnie Formation (Wright and Troxel, 1993). Preliminary structural data indicate the fold grew during two phases of post-metamorphic, Cretaceous contraction. Both the timing of metamorphism relative to deformation and the structural history place important constraints upon correlation of contractional structures across Death Valley.

Primary bedding structures (So) are defined by alternating grain size in the argillites and cross-bedding in the quartzite units. A bedding-parallel metamorphic foliation (S1) is defined by the preferred orientation of platy minerals. Both bedding and S1 are deformed by D2, characterized by southeast-vergent shortening. S2 cleavage is sub-parallel to bedding on fold limbs, but axial planar to isoclinal, east-vergent, F2 folds. East-vergent, D2 thrust faults duplicate Johnnie Formation meta-conglomerate and marble units. By contrast, D3 is distinguished by northwest-vergent shortening. F3 west-vergent folds and west-vergent thrust faults overprint F2 folds and D2 thrust faults. D4 Keane-Wonder brittle, right lateral, down to the southwest, oblique normal faulting cuts all previous deformation.

Snow and Wernicke (1989, 2000) correlated the Lees Camp anticline with the White Top Mountain backfold, based on regional structural similarities. While the gross structure of both folds is indeed similar, the White Top Mountain backfold formed during only one episode of pre-early Triassic, west-vergent shortening. The Lees Camp anticline formed during two episodes of contraction that post-dated metamorphism, dated by Labotka and Albee (1988) at ~135 Ma in the northern Funeral range. If these observations are correct, then correlations between the Lees Camp Anticline and the Permian White Top Mountain backfold in the Cottonwood Mountains are not likely.