Anomalously High Cretaceous Paleobrine Temperatures: Hothouse, Hydrothermal or Solar Heating?

Abstract

Elevated surface paleobrine temperatures (average 85.6 • C) are reported here from Cretaceous marine halites in the Maha Sarakham Formation, Khorat Plateau, Thailand. Fluid inclusions in primary subaqueous "chevron" and "cumulate" halites associated with potash salts contain daughter crystals of sylvite (KCl) and carnallite (MgCl 2 ·KCl·6H 2 O). Petrographic textures demonstrate that these fluid inclusions were trapped from the warm brines in which the halite crystallized. Later cooling produced supersaturated conditions leading to the precipitation of sylvite and carnallite daughter crystals within fluid inclusions. Dissolution temperatures of daughter crystals in fluid inclusions from the same halite bed vary over a large range (57.9 • C to 117.2 • C), suggesting that halite grew at different temperatures within and at the bottom of the water column. Consistency of daughter crystal dissolution temperatures within fluid inclusion bands and the absence of vapor bubbles at room temperature demonstrate that fluid inclusions have not stretched or leaked. Daughter crystal dissolution temperatures are reproducible to within 0.1 • C to 10.2 • C (average of 1.8 • C), and thus faithfully document paleobrine conditions. Microcrystalline hematite incorporated within halite crystals also indicate high paleobrine temperatures. We conclude that halite crystallized from warm brines rich in K-Mg-Na-Cl; sylvite and carnallite daughter crystals were nucleated during cooling of the warm brines sometime after deposition. Hothouse, hydrothermal, and solar-heating hypotheses are compared to explain the anomalously high surface paleobrine temperatures. Solar radiation stored in shallow density stratified brines is the most plausible explanation for the observed paleobrine temperatures and the progressively higher temperatures downward through the paleobrine column. The solar-heating hypothesis may also explain high paleobrine temperatures documented from fluid inclusions in other ancient halites.

Practical Application of the Mineralogical Mapping Method for Stratigraphy of the Cretaceous Deposits of Southern Primorye (Russian Far East)

“…The formation interval of the reddish-colored sediments of the Korkinskaya Series (upper part of the Romanovskaya suite) is 93-95 Ma (the epoch of lateritic weathering), which coincides with the Cenomanian-Turonian events (OAEs-Bonarelli event, C/T OAE, OAE2,~93 Ma, [41,42,46]). Similar stratification was also noted for the Cretaceous deposits of Europe [47][48][49], Venezuela [45], Northern Iraq [50], Japan [51][52][53][54], Polynesia [55], Tibet [56,57], the Arctic [58], and other regions of the world [59][60][61][62][63][64].…”

Improvement of sylvite flotation from halite by starvation feeding the collector octadecylamine

“…Octadecylamine hydrochloride (ODA) which was used as collector in this research was supplied by Sichuan Tianyu fat chemical Co., Ltd. A 2 wt% dispersion of ODA was prepared by melting ODA by heating at 70 C, then it was mixed with a certain amount of diluted HCl solution with a molar ratio of 2 : 1. 10,11 Moreover, in order to maintain the dispersion stability of ODA, the ODA solution was kept in a thermostat water bath (HH-4D, Shanghai Leiyin Scientic Instrument Co., Ltd.) at 70 C. Terpenic oil which was used in this work was purchased from Dongying Shengdou Oil Co., Ltd. Hydrochloric acid (HCl, 36%) and all of the other reagents used in this work were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd (China).…”

Ore-Forming Fluid Evolution of Shallow Polyhalite Deposits in the Kunteyi Playa in the North Qaidam Basin

“…The results show that the fluid inclusion temperature gradually decreased from the bottom to the top of the section (Table 2). A possible explanation might be related to the effect of the solar pool event due to brine delamination or extreme surface heat from the inland desert (Zambito and Benison, 2013;Wang and Lowenstein, 2017). Many fluid inclusions were found in chevron-type halite crystals (Figure 6), which can form at the bottom of salt lakes that are less than 60 cm in depth as a result of competitive growth (Handford, 1990;Meng et al, 2013).…”