Horita J, Friedman T J, Lazar B, Holland H D
Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138.
Geochim Cosmochim Acta. 1991;55:417-32. doi: 10.1016/0016-7037(91)90001-l.
Forty-nine brine inclusions in marine halite from the Ochoan Salado Formation in the Delaware Basin and fifteen inclusions in halite from the Leonardian Wellington Formation in the Kansas Basin were extracted, and their chemical compositions were determined. The brines are of the Na-K-Mg-Cl-SO4 type; their compositions resemble those of evaporated modern seawater. The values of (mCl(-) - mNa+)/mBr- and (mMg(2+) + mCa(2+) - mSO4(2-) - 1/2mHCO3-)/mBr- of the inclusion brine from the two formations are equal to or slightly higher than those of modern seawater. The original mNa+/mBr- and mCl-/mBr- ratios of the inclusion brines were probably equal to or slightly larger than those of modern seawater. The values of mMg2+/mBr- of the inclusion brines from the Salado Formation are very close to that of modern seawater; the ratios of inclusion brines from the Wellington Formation are slightly lower, probably due to the formation of dolomite/magnesite. The mMg2+/mBr- ratio in the initial seawater was probably close to the parent seawater of the Salado brines. The values of (mSO4(2-) - mCa(2+) + 1/2mHCO3-)/mBr- of the inclusion brines appear to be reduced by the formation of dolomite/magnesite, and the value of this ratio in Permian seawater was probably similar to that of modern seawater. The mK+/mBr- ratios of the inclusion brines are variable, but the original ratios are probably close to or slightly larger than that of modern seawater. If the Br- concentration of Permian seawater was equal to that of modern seawater, the composition of Permian seawater can be narrowly constrained; in mmol/kg H2O, 460 < or = mNa+ < 630, 550 < or = mCl- < 730, mMg2+ = 54 +/- 6, mK+ approximately equal to 11, (mSO4(2-) - mCa(2+) + 1/2mHCO3-) > or = 17, 20 < mSO4(2-) < 45, 5 < mCa2+ < 20, and 0.15 < mHCO3- < 5. The composition of Permian seawater was therefore quite similar to that of modern seawater.
从特拉华盆地奥乔安盐沼组的海相石盐中提取了49个卤水包裹体，并从堪萨斯盆地莱纳德阶惠灵顿组的石盐中提取了15个包裹体，测定了它们的化学成分。这些卤水属于Na-K-Mg-Cl-SO4类型；其成分与现代蒸发海水的成分相似。两个地层的包裹体卤水的(mCl(-) - mNa+)/mBr-和(mMg(2+) + mCa(2+) - mSO4(2-) - 1/2mHCO3-)/mBr-值等于或略高于现代海水。包裹体卤水的原始mNa+/mBr-和mCl-/mBr-比值可能等于或略大于现代海水。盐沼组包裹体卤水的mMg2+/mBr-值与现代海水非常接近；惠灵顿组包裹体卤水的比值略低，可能是由于白云石/菱镁矿的形成。初始海水中的mMg2+/mBr-比值可能接近盐沼卤水的母海水。包裹体卤水的(mSO4(2-) - mCa(2+) + 1/2mHCO3-)/mBr-值似乎因白云石/菱镁矿的形成而降低，二叠纪海水中该比值的值可能与现代海水相似。包裹体卤水的mK+/mBr-比值是可变的，但原始比值可能接近或略大于现代海水。如果二叠纪海水的Br-浓度与现代海水相等，则二叠纪海水成分可被严格限制；以mmol/kg H2O计，460≤mNa+＜630，550≤mCl-＜730，mMg2+ = 54±6，mK+≈11，(mSO4(2-) - mCa(2+) + 1/2mHCO3-)≥17，20＜mSO4(2-)＜45，5＜mCa2+＜20，且0.15＜mHCO3-＜5。因此，二叠纪海水的成分与现代海水非常相似。
