Ordovician seawater composition: evidence from fluid inclusions in halite

Abstract

Fluid in clu sions in ha lite can di rectly re cord the ma jor com po si tion of evap o rated sea wa ter; how ever, Or do vi cian ha lite is very rare. The Or do vi cian is a key time dur ing the evo lu tion his tory be cause pro found changes oc curred in the planet's ecosys tems. Ma rine life was char ac ter ized by a ma jor di ver si fi ca tion, the Great Or do vi cian Biodiversification Event and the Late Or do vi cian Mass Ex tinc tion, the first of the "big five" mass ex tinc tions. How ever, so far there is no data on the Or do vi cian sea wa ter. Data from the Or do vi cian-Si lu rian bound ary were avail able only. In this study, we re port the ma jor com po si tions from Mid dle Or do vi cian ha lite in China to give the ex act com po si tion of Or do vi cian sea wa ter. The ba sic ion com po si tion (K + , Mg 2+ , Ca 2+ , and SO 4 2-) of in clu sion brines was es tab lished with the use of ultramicrochemical anal y sis. The data on the chem ical com po si tion of the brines in the pri mary in clu sions in di cated that the brines were of Na-K-Mg-Ca-Cl (Ca-rich) type, and cover a huge gap in the evo lu tion of sea wa ter chem is try. The chem i cal com po si tion of the pri mary in clu sion brine in ha lite con firmed the ear lier re sults for the Cam brian and Si lu rian ha lite orig i nat ing from other salt bas ins and the pre vi ous spec u lation of "cal cite sea" dur ing the Or do vi cian, in di cat ing a higher po tas sium con tent in the Lower Pa leo zoic sea wa ter than in the sea wa ter of other pe ri ods of the Phanerozoic.

Calculation of salt basin depth using fluid inclusions in halite from the Ordovician Ordos Basin in China

“…The in ter nal pres sure of the in clu sions is slightly higher than the nor mal at mo spheric pres sure which was recorded at the time of col lec tion. Brines are pres ent un til the middle stage of ha lite de po si tion, and they char ac ter ize the sea water as a Na-K-Mg-Ca-Cl (Ca-rich) type (Meng et al, 2018). In our study three groups of sec ond ary in clu sions were dis tin guished:…”

“…Iso tro pic sylvite daugh ter crys tals were found in the in clu sions. The pres ence of K salt min er als in di cated a high con cen tra tion of brines dur ing po tas sium salt pre cip i ta tion (Meng et al, 2018). The in clu sions were ar ranged non-sys tem at i cally in the chev ron ha lite and on the pe riph ery of the chev rons ( Fig.…”

“…The most im por tant petroliferous bas ins are shown on the map (Bao et al, 2004;Meng et al, 2018Meng et al, , 2019. Car bon ate iso tope stra tig ra phy has in dicated that the Majiagou For ma tion formed dur ing the Mid dle Or do vi cian (Meng et al, 2019).…”

Design Optimization of a Disc Brake Based on a Multi-Objective Optimization Algorithm and Analytic Hierarchy Process Method

“…Scheme parameters are given in Table 5. Based on formulae (17,18), the standard weight of various indexes can be calculated as follows:…”

“…Multi-objective optimization of a disc brake system of a heavy truck by using the evolutionary multi-objective optimization and radial basis function networks (RBFNs) was presented for three conflicting objectives [12]. The studies [16][17][18] conducted related research on the disc brake by utilizing the finite element method for the structural optimization. An efficient approach to simulate thermal stresses due to temperature variations in disc brakes was also presented [19].…”