Orbital forcing of climate 1.4 billion years ago

Abstract

Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe two patterns of climate fluctuations: On long time scales, over what amounts to tens of millions of years, sediments of the Xiamaling Formation record changes in geochemistry consistent with long-term changes in the location of the Xiamaling relative to the position of the Intertropical Convergence Zone. On shorter time scales, and within a precisely calibrated stratigraphic framework, cyclicity in sediment geochemical dynamics is consistent with orbital control. In particular, sediment geochemical fluctuations reflect what appear to be orbitally forced changes in wind patterns and ocean circulation as they influenced rates of organic carbon flux, trace metal accumulation, and the source of detrital particles to the sediment.

Remarkable Preservation of Microfossils and Biofilms in Mesoproterozoic Silicified Bitumen Concretions from Northern China

“…The age of the Xiamaling Formation has been constrained to 1392.2 ± 1.0 Ma for the bentonite layer at the top of unit 3 and 1384.4 ± 1.4 Ma for the tuff layer 52 m above the bentonite [22]. Sediments of the Xiamaling Formation began their deposition at ∼1,400 Ma at paleolatitude between 10 ∘ N and 30…”

“…We previously divided the Xiamaling Formation informally into 6 units [24]. Units 5 and 6 have yet to fully described, whereas unit 4 comprises alternating iron oxiderich and iron oxide-poor sediments or repeating bundles of alternating sediment type, grading upwards into alternating layers of black shale and chert of unit 3 and further upwards into unit 2 comprised predominantly of black shale alternating with grey and black silty mudstones [22,24]. Uppermost unit 1 is composed of alternating layers of black and green shales.…”

“…Black shales are very common in all of the Xiamaling Formation, except for the lowermost 2 units. The total organic carbon (TOC) of the Xiamaling Formation ranges from less than 1 wt% in the green and red sandy mudstones to over 10 wt% in the black shales [22]. Our previous work suggests that the sediment geochemical fluctuations reflect the orbital forced changes, known as Milankovitch cycles, controlled the wind patterns, rainfall, and ocean circulation, and then translated into sediment geochemistry [22].…”

The Late Cryogenian Warm Interval, NE Svalbard: Chemostratigraphy and genesis

“…Study of such cyclicity in pelagic sediments has provided a calibration of 40 Ar/ 39 Ar geochronology and the definitive age of the Mesozoic-Cenozoic boundary (Kuiper et al, 2008). Older successions are subject to more uncertainty, but there exist a large number of successful studies in the Mesozoic and increasingly in the Palaeozoic (Hinnov, 2013) and even the Mesoproterozoic (Zhang et al, 2015) where multiple frequencies have been identified and assigned to particular bands. One source of change is the effect of increasing Earth-Moon distance over time, which is incompletely known.…”

Effects of U-ore on the chemical and isotopic composition of products of hydrous pyrolysis of organic matter

“…The kerogen samples used in our pyrolysis experiments were separated from the organic-rich immature source rocks from Xiamaling Formation, Xiahuayuan Area, Hebei Province, North China, with an age of 1384.4 ± 1.4 Ma (Zhang et al 2015). The uranium ore was collected from a depth of 170 m below the surface of the Zoujiashan Deposit, Xiangshan Uranium Field, South China.…”