Normal Puerperium

Puerperium is the time following delivery during which pregnancy-induced maternal anatomical and physiological changes return to the nonpregnant state. Puerperium period of 6 weeks can be divided into: (a) immediate – within 24 hours (b) early – up to 7 days (c) remote – up to 6 weeks. The puerperal effects are seen in all organs and particularly in reproductive organs. Infection and haemorrhage are the common postpartum complications. Post partum care is very important. Advice on exclusive breast feeding and contraception is also mandatory after every childbirth

Reactive Infiltration of MORB-Eclogite-Derived Carbonated Silicate Melt into Fertile Peridotite at 3GPa and Genesis of Alkalic Magmas

We performed experiments between two different carbonated eclogite-derived melts and lherzolite at 1375°C and 3 GPa by varying the reacting melt fraction from 8 to 50 wt %. The two starting melt compositions were (1) alkalic basalt with 11·7 wt % dissolved CO2 (ABC), (2) basaltic andesite with 2·6 wt % dissolved CO2 (BAC). The starting melts were mixed homogeneously with peridotite to simulate porous reactive infiltration of melt in the Earth’s mantle. All the experiments produced an assemblage of melt + orthopyroxene + clinopyroxene + garnet ± olivine; olivine was absent for a reacting melt fraction of 50 wt % for ABC and 40 wt % for BAC. Basanitic ABC evolved to melilitites (on a CO2-free basis, SiO2 ∼27–39 wt %, TiO2 ∼2·8–6·3 wt %, Al2O3 ∼4·1–9·1 wt %, FeO* ∼11–16 wt %, MgO ∼17–21 wt %, CaO ∼13–21 wt %, Na2O ∼4–7 wt %, CO2 ∼10–25 wt %) upon melt–rock reaction and the degree of alkalinity of the reacted melts is positively correlated with melt–rock ratio. On the other hand, reacted melts derived from BAC (on a CO2-free basis SiO2 ∼42–53 wt %, TiO2 ∼6·4–8·7 wt %, Al2O3 ∼10·5–12·3 wt %, FeO* ∼6·5–10·5 wt %, MgO ∼7·9–15·4 wt %, CaO ∼7·3–10·3 wt %, Na2O ∼3·4–4 wt %, CO2 ∼6·2–11·7 wt %) increase in alkalinity with decreasing melt–rock ratio. We demonstrate that owing to the presence of only 0·65 wt % of CO2 in the bulk melt–rock mixture (corresponding to 25 wt % BAC + lherzolite mixture), nephelinitic-basanite melts can be generated by partial reactive crystallization of basaltic andesite as opposed to basanites produced in volatile-free conditions. Post 20% olivine fractionation, the reacted melts derived from ABC at low to intermediate melt–rock ratios match with 20–40% of the population of natural nephelinites and melilitites in terms of SiO2 and CaO/Al2O3, 60–80% in terms of TiO2, Al2O3 and FeO, and <20% in terms of CaO and Na2O. The reacted melts from BAC, at intermediate melt–rock ratios, are excellent matches for some of the Mg-rich (MgO >15 wt %) natural nephelinites in terms of SiO2, Al2O3, FeO*, CaO, Na2O and CaO/Al2O3. Not only can these reacted melts erupt by themselves, they can also act as metasomatizing agents in the Earth’s mantle. Our study suggests that a combination of subducted, silica-saturated crust–peridotite interaction and the presence of CO2 in the mantle source region are sufficient to produce a large range of primitive alkalic basalts. Also, mantle potential temperatures of 1330–1350°C appear sufficient to produce high-MgO, primitive basanite–nephelinite if carbonated eclogite melt and peridotite interaction is taken into account

Experimental investigation of crust-mantle hybridization in the Earth’s shallow upper mantle

Chemical heterogeneities in the Earth’s mantle, such as subducted sediments and oceanic crust, along with volatiles such as H2O and CO2 affect melting processes, hence, chemical differentiation of the Earth and their presence in the source of erupted magma has been unequivocally established through isotope and trace element geochemistry. Yet, the nature of major element contribution of recycled crustal lithologies to the erupted basalts on the Earth’s surface is poorly understood because direct partial melting of crustal lithologies at mantle depths produces siliceous melts that are unlike surface basalts or their estimated parental melts. In case of oceanic crust and sediments, partial melting initiates at lower temperatures and at deeper depths than the surrounding mantle, hence, an andesitic partial melt (±CO2) from recycled oceanic crust and a rhyolitic partial melt (±H2O) from subducted sediments, being out of equilibrium with the surrounding peridotitic mantle with a hotter solidus temperature, must undergo reactive crystallization. However, the impact of crustal melt impregnation into mantle peridotite on the potential formation of hybrid melts and lithologies remained largely uninvestigated. The phase equilibria of reaction of siliceous partial melts (derived from crustal heterogeneities) with the mantle has been investigated in this thesis with the aid of high pressure-temperature laboratory experiments that simulated conditions at depths of 80 – 100 km inside the Earth. Andesite evolves to a basanite upon partial reactive crystallization in a peridotite matrix (Chapter 2), and with increasing amount of CO2 in the system, the residual melt evolves even to a nephelinite (Chapter 3 and 4). This is the effect of reaction of the silica component in the melt with olivine in the peridotite to crystallize orthopyroxene, with the orthopyroxene stability field being enhanced under the influence of CO2, therefore, drawing down the SiO2 content of the reacted melt even further. Major element characteristics of alkalic ocean island basalts can be reproduced by the reacted melts from these studies by a two-stage hybridization process: Firstly, partial melt from recycled oceanic crust reacts with surrounding sub-solidus peridotite and undergoes partial reactive crystallization and secondly, the reacted, residual melt from the first step subsequently mixes with peridotite-derived partial melt. An empirical model has been proposed to estimate the source characteristics of alkalic ocean island basalts. The model predicts that 15 – 45 wt.% oceanic-crust derived melt and 0.2 – 2 wt.% CO2 are required, followed by mixing with 25 – 55 wt.% peridotite partial melt to reproduce major element characteristics of alkalic lavas from Canary Islands, Cape Verde and Cook Australs (Chapter 4). The results from the studies obviate the need for the presence of silica-undersaturated exotic lithologies in the source of alkalic ocean island basalts. Also, the studies demonstrate that high MgO (>15 wt.%) alkalic basalts from the mantle can be produced by a potential temperature of 1350 °C and do not require potential temperatures exceeding 1430 °C, as predicted by current thermometers. This is owing to the effect of CO2 dissolution in the melt in the form of MgCO3 complexes, which enhances the MgO content of melts at a given pressure and temperature. Flux of hydrous rhyolitic, sediment-derived melts, to the mantle wedge fertile peridotite leads rhyolites to evolve to ultrapotassic nepheline normative basalts similar in composition to ultrapotassic lavas from active and inactive arcs (Chapter 5). This evolution in melt composition from a highly siliceous rhyolite to a nepheline-normative ultrapotassic basalt is due to the formation of orthopyroxene at the expense of olivine as well as the dominance of phlogopite in the melting systematics, buffering the K2O content of the melt to produce ultrapotassic compositions. Thermal stability of phlogopite to the core of hot mantle wedge is established in conjunction with previous studies, which suggests that recycling of phlogopite to the deeper mantle may be important in deep flux of large ion lithophile elements and volatile elements such as fluorine and nitrogen. Potential long-term survival of phlogopite can potentially create Sr-isotopically enriched zones in the mantle, as evident in the source of several arc and intraplate lavas

Nitrogen evolution within the Earth's atmosphere-mantle system assessed by recycling in subduction zones

Understanding the evolution of nitrogen (N) across Earth's history requires a comprehensive understanding of N's behaviour in the Earth's mantle - a massive reservoir of this volatile element. Investigation of terrestrial N systematics also requires assessment of its evolution in the Earth's atmosphere, especially to constrain the N content of the Archaean atmosphere, which potentially impacted water retention on the post-accretion Earth, potentially causing enough warming of surface temperatures for liquid water to exist. We estimated the proportion of recycled N in the Earth's mantle today, the isotopic composition of the primitive mantle, and the N content of the Archaean atmosphere based on the recycling rates of N in modern-day subduction zones. We have constrained recycling rates in modern-day subduction zones by focusing on the mechanism and efficiency of N transfer from the subducting slab to the sub-arc mantle by both aqueous fluids and slab partial melts. We also address the transfer of N by aqueous fluids as per the model of Li and Keppler (2014). For slab partial melts, we constrained the transfer of N in two ways - firstly, by an experimental study of the solubility limit of N in melt (which provides an upper estimate of N uptake by slab partial melts) and, secondly, by the partitioning of N between the slab and its partial melt. Globally, 45-74% of N introduced into the mantle by subduction enters the deep mantle past the arc magmatism filter, after taking into account the loss of N from the mantle by degassing at mid-ocean ridges, ocean islands and back-arcs. Although the majority of the N in the present-day mantle remains of primordial origin, our results point to a significant, albeit minor proportion of mantle N that is of recycled origin (17 +/- 8% or 12 +/- 5% of N in the present-day mantle has undergone recycling assuming that modern-style subduction was initiated 4 or 3 billion years ago, respectively). This proportion of recycled N is enough to cause a departure of N isotopic composition of the primitive mantle from today's delta N-15 of 5-parts per thousand to -6.8 +/- 0.9 parts per thousand or -6.3 +/- 1.2 parts per thousand. Future studies of Earth's parent bodies based on the bulk Earth N isotopic signature should take into account these revised values for the delta N-15 composition of the primitive mantle. Also, the Archaean atmosphere had a N partial pressure of 1.4-1.6 times higher than today, which may have warmed the Earth's surface above freezing despite a faint young Sun. (C) 2017 Elsevier B.V. All rights reserved

Controls of Hydrogen Partitioning on the Formation of Wet Reservoirs During Lunar Magma Ocean Crystallization

Recent studies indicate the presence of hydrogen (H) in lunar samples. H inherited from the proto-Earth and impactors, as well as added during the phase of accretion (contemporaneous to lunar magma ocean (LMO) crystallization) have been retained in spite of losses during the Moon-forming impact and magma ocean degassing [1]. The bulk H in the LMO or the Bulk Silicate Moon (BSM) is an important constraint to understand the dynamics of the Moon-forming impact as well as determine the origin of volatiles in the Earth-Moon system [2]. Recent analysis of Apollo samples indicates that the Moon has heterogeneous H reservoirs [3], which may be explained by the partitioning of H between nominally anhydrous cumulates and liquid as well as the entrapment of residual liquid during progressive crystallization of the LMO. The recent estimates of H2O in the BSM (5 to 1650 μg/g; [4]) rely heavily on the partition coefficients of H (DH) between minerals and melt used in the models (where DH = H concentration in mineral/ H concentration in the melt). Here we demonstrate the effect of DH between nominally anhydrous minerals (NAMs) and melt on mantle and crustal H contents by modeling the fractional crystallization of a 600 km deep LMO. We follow published crystallization sequences as well as use a combination of the codes SPICES and alphaMELTS. We use lower and upper limits of DH for each mineral-melt pair as published in the literature and vary the initial bulk H assuming 1% residual melt in the crystal mush after compaction. Using joint H2-H2O solubility, we further evaluate the extent of degassing in the LMO. We demonstrate that H in plagioclase may be explained by either DHmin or DHmax, if the initial H content of the LMO was 100 μg/g. However, with higher initial H content, i.e. 1000 μg/g, only DHmin would explain plagioclase chemistry. This demonstrates that the current range of published values of DH are not sufficient to fully capture the dynamics of LMO crystallization, and highlight the necessity in future studies to experimentally constrain the DH values between the NAMs and melt compositions, specific to LMO crystallization conditions. [1] Barnes et al., 2016. Nat. Comm. [2] Desch and Robinson, 2019. Geochem [3] Robinson et al., 2016. GCA [4] McCubbin et al., 2015. Am Min

Controls on determining the bulk water content of the Moon

The Moon is much wetter than previously thought. The estimated bulk H2O concentrations based on the analyses of H2O in lunar materials show a wide range from 5 to 1650 ppm. To better constrain bulk H2O in the lunar magma ocean (LMO), we model LMO crystallization and vary DH (concentration of H2O in LMO mineral/concentration of H2O in melt), interstitial melt fraction, and initial LMO depth. We take the highest and lowest values of DH reported in the literature for the LMO minerals. We assess the bulk H2O content required in the initial magma ocean to satisfy two observational constraints: (1) H2O measured in plagioclase grains from ferroan anorthosites and (2) crustal mass from GRAIL. We find that the initial bulk LMO H2O that best explains the H2O content in crustal plagioclase is strongly dependent on DH rather than interstitial melt fractions or initial LMO depths, with a drier magma ocean (10 ppm H2O) being favored with higher DH and a wetter magma ocean (100-1000 ppm H2O) with lower DH. This underscores the importance of constraining DH specific to lunar conditions in future studies. We also demonstrate that crustal mass is not an effective hygrometer

Replication Data for: Controls on determining the bulk water content of the Moon.

The Moon is much wetter than previously thought. The estimated bulk H2O concentrations based on the analyses of H2O in lunar materials show a wide range from 5 to 1650 ppm. To better constrain bulk H2O in the lunar magma ocean (LMO), we model LMO crystallization and vary DH (concentration of H2O in LMO mineral/concentration of H2O in melt), interstitial melt fraction, and initial LMO depth. We take the highest and lowest values of DH reported in the literature for the LMO minerals. We assess the bulk H2O content required in the initial magma ocean to satisfy two observational constraints: (1) H2O measured in plagioclase grains from ferroan anorthosites and (2) crustal mass from GRAIL. We find that the initial bulk LMO H2O that best explains the H2O content in crustal plagioclase is strongly dependent on DH rather than interstitial melt fractions or initial LMO depths, with a drier magma ocean (10 ppm H2O) being favored with higher DH and a wetter magma ocean (100–1000 ppm H2O) with lower DH. This underscores the importance of constraining DH specific to lunar conditions in future studies. We also demonstrate that crustal mass is not an effective hygrometer