Role of thermal subsidence, flexure, and eustasy in evolution of early Paleozoic carbonate platforms in Appalachian and Cordilleran miogeoclines

Conference · Fri May 01 04:00:00 EDT 1987 · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)

OSTI ID:6206169

Bond, G C; Grotzinger, J P; Kominz, M A

Modeling of early Paleozoic passive margins (miogeoclines) in the Cordilleran and Appalachian orogenes suggests that factors controlling growth of early Paleozoic carbonate platforms were thermal-controlled subsidence, time-dependent flexure of the lithosphere, and at least two orders of eustatic sea level changes. Initiation of the carbonate platforms in the Middle Cambrian followed reduction in supply of Lower Cambrian coarse siliciclastic materials to the passive margins. Two-dimensional modeling of palinspastically restored cross sections implies that significant reduction in relief of onshore sediment sources would have occurred in the Middle Cambrian when increased time-dependent flexural rigidity extended the area of subsidence into the craton. Evidence of controls on subsequent growth of the platforms is obtained from one-dimensional analyses of post-rift subsidence of the margins. The effects of sediment loading and lithification are removed from cumulative subsidence curves, producing reduced cumulative curves, designated R1. Model cooling curves (exponential) are then fit to the R1 curves and subtracted from them, producing a second set of curves, designated R2. The form of the R2 curves is not significantly affected by uncertainties in time scales, delithification factors and models of post-rift subsidence. Therefore, R2 curves contain evidence of deviations from the thermal-controlled subsidence of the margins. R2 curves from the southern Canadian Rockies, Utah, and Virginia Appalachians indicate two orders of events superimposed on the thermal-controlled subsidence of the margins. One event is a single long-term rise and fall of sea level more than 40 m.y. in duration, and the other consists of multiple short-term sea level changes lasting from 2 to 10 m.y. The long-term event has the same timing in all three areas, and it coincides temporally with the Sauk transgression-regression on the craton.

• Research Organization: Lamont-Doherty Geological Observatory, Palisades, NY
• OSTI ID: 6206169
• Report Number(s): CONF-870606-
• Conference Information: Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 71:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CAMBRIAN PERIOD
CARBONATE ROCKS
DIAGENESIS
GEOLOGIC AGES
GEOLOGIC HISTORY
PALEOZOIC ERA
RESERVOIR ROCK
ROCKS
SEDIMENTARY ROCKS