A Plausibility Test for Neoproterozoic Correlations Based on Global Climate Episodes: The Case History of the Kingston Peak Accommodation Paradox, Panamint Range, California

For many Neoproterozoic successions, estimates of duration depend upon correlating diamictite-cap carbonate couplets with global climate episodes. The Sturtian (771-667 Ma) and Marinoan (635 Ma) glacials are candidates to explain two such couplets (Surprise-Sourdough; Wildrose-Noonday) for Kingston Peak time. Three global correlation hypotheses have been published: two Sturtian couplets, two Marinoan couplets, or one couplet for each episode. The third interpretation allots at least 100 m.y. to Kingston Peak time.

Because the thickness of the local stratigraphic interval is known, an hypothesis of duration implies accumulation and accommodation rates. These may be compared with average rates drawn from scaling laws based upon thousands of empirical rate determinations from similar environments. Scaling laws for rates of eustatic change, subsidence in comparable tectonic settings, and accumulation in analogous depositional environments may be combined to generate envelopes of expected accommodation rate.

The Kingston Peak Formation is the product of glaciomarine deposition in a syn-rift tectonic setting – rapid potential sediment delivery and fast subsidence. Paradoxically, less than 300 m of diamictite-bearing strata are attributable to the time interval from Sturtian to Marinoan and sedimentologic indications of hiatus are not obvious. Glaciomarine systems could deliver this much sediment in less than 100,000 yr. Mean rift subsidence rates might accommodate as much in about 2 m.y. Typical post-rift passive margins can accommodate this thickness in about 5 m.y.

Thus, comparison with empirical accommodation envelopes reveals more implications of global climate correlations. Either the Kingston Peak Formation accumulated in far less than 100 m.y. or, if it indeed includes both Sturtian and Marinoan climate episodes, then 1) tectonic subsidence rates were much slower than in other rift systems, 2) sediment delivery was anomalously less efficient than Cenozoic glaciomarine settings, and 3) the formation must include cryptic surfaces of hiatus, cumulatively amounting to 90 m.y. or more.