『Abstract
　Mineralogical observations, chemical and oxygen-isotope compositions, absolute ²⁰⁷Pb-²⁰⁶Pb ages and short-lived isotope systematics (⁷Be-⁷Li, ¹⁰Be-¹⁰B, ²⁶Al-²⁶Mg, ³⁶Cl-³⁶S, ⁴¹Ca-⁴¹K, ⁵³Mn-⁵³Cr, ⁶⁰Fe-⁶⁰Ni, ¹⁸²Hf-¹⁸²W) of refractory inclusions [Ca,Al-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs)], chondrules and matrices from primitive (unmetamorphosed) chondrites are reviewed in an attempt to test (i) the x-wind model vs. the shock-wave model of the origin of chondritic components and (ii) irradiation vs. stellar origin of short-lived radionuclides. The data reviewed are consistent with an external, stellar origin for most short-lived radionuclides (⁷Be, ¹⁰Be, and ³⁶Cl are important exceptions) and a shock-wave model for chondrule formation, and provide a sound basis for early Solar System chronology. They are inconsistent with the x-wind model for the origin of chondritic components and a local, irradiation origin of ²⁶Al, ⁴¹Ca, and ⁵³Mn. ¹⁰Be is heterogeneously distributed among CAIs, indicating its formation by local irradiation and precluding its use for the early solar system chronology. ⁴¹Ca-⁴¹K, and ⁶⁰Fe-⁶⁰Ni systematics are important for understanding the astrophysical setting of Solar System formation and origin of short-lived radionuclides, but so far have limited implications for the chronology of chondritic components. The chronological significance of oxygen-isotope compositions of chondritic components is limited. The following general picture of formation of chondritic components is inferred. CAIs and AOAs were the first solids formed in the solar nebula 〜4567-4568 Myr ago, possibly within a period of ＜0.1 Myr, when the Sun was an infalling (class 0) and evolved (class I) protostar. They formed during multiple transient heating events in nebular region(s) with high ambient temperature (at or above condensation temperature of forsterite), either throughout the inner protoplanetary disk (1-4 AU) or in a localized region near the proto-Sun (＜0.1 AU), and were subsequently dispersed throughout the disk. Most CAIs and AOAs formed in the presence of an ¹⁶O-rich (Δ¹⁷O 〜-24±2‰) nebular gas. The ²⁶Al-poor [(²⁶Al/²⁷Al)0＜1×10^-5], ¹⁶O-rich (Δ¹⁷O 〜-24±2‰) CAIs - FUN (fractionation and unidentified nuclear effects) CAIs in CV chondrites, platy hibonite crystals (PLACs) in CM chondrites, pyroxene-hibonite spherules in CM and CO chondrites, and the majority of grossite- and hibonite-rich CAIs in CH chondrites - may have formed prior to injection and/or homogenization of ²⁶Al in the early Solar System. A small number of igneous CAIs in ordinary, enstatite and carbonaceous chondrites, and virtually all CAIs in CB chondrites a ¹⁶O-depleted (Δ¹⁷O＞-10‰) and have (²⁶Al/²⁷Al)0 similar to those in chondrules (＜1×10^-5). These CAIs probably experienced melting during chondrule formation. Chondrules and most of the fine-grained matrix materials in primitive chondrites formed 1-4 Myr after CAIs, when the Sun was a classical (class II) and weak-lined T Tauri star (class III). These chondritic components formed during multiple transient heating events in regions with low ambient temperature (＜1000 K) throughout the inner protoplanetary disk in the presence of ¹⁶O-poor (Δ¹⁷O＞-5‰) nebular gas. The majority of chondrules within a chondrite group may have formed over a much shorter period of time (＜0.5-1 Myr). Mineralogical and isotopic observations indicate that CAIs were present in the regions where chondrules formed and accreted (1-4 AU), indicating that CAIs were present in the disk as free-floating objects for at least 4 Myr. Many CAIs, however, were largely unaffected by chondrule melting, suggesting that chondrule-forming events experienced by a nebular region could have been small in scale and limited in number. Chondrules and metal grains in CB chondrites formed during a single-stage, highly-energetic event 〜4563 Myr ago, possibly from a gas-melt plume produced by collision between planetary embryos.』

1. Introduction
2. major constraints on the origin of chondritic components
　2.1. Refractory inclusions
　2.2. Chondrules
　2.3. Matrices
　2.4. Chondrite groups
3. Absolute and relative chronologies of CAI and chondrule formation
　3.1. Absolute (²⁰⁷Pb-²⁰⁶Pb) chronology of CAI and chondrule formation
　3.2. Relative chronology of CAI and chondrule formation
　　3.2.1. Constraints from mineralogical observations and bulk chemical compositions of CAIs and chondrules
　　3.2.2. ²⁶Al-²⁶Mg systematics of refractory inclusions and chondrules
　　　3.2.2.1. ²⁶Al-²⁶Mg systematics of CAIs and AOAs
　　　3.2.2.2. Chronology of ²⁶Al-poor CAIs
　　　3.2.2.3. ²⁶Al-²⁶Mg systematics of primitive chondrite chondrules
　　3.2.3. ⁵³Mn-⁵³Cr systematics of CAIs and chondrules
　　3.2.4. ⁶⁰Fe-⁶⁰Ni systematics of CAIs and chondrules
　　3.2.5. ¹⁸²Hf-¹⁸²W systematics of CAIs
　　3.2.6. ⁴¹Ca-⁴¹K systematics of CAIs
　　3.2.7. ³⁶Cl-³⁶S systematics of CAIs and chondrules
　　3.2.8. ¹⁰Be-¹⁰B and ⁷Be-⁷Li systematics of CAIs and chondrules
　3.3. Chronological significance of oxygen isotopes
　3.4. On the nature of age gap between CAIs and chondrules
　3.5. Preservation of CAIs in the protoplanetary disk
　3.6. Presence of asteroidal material among chondrule precursors
　3.7. Metal-rich carbonaceous (CB and CH) chondrites and their chronological significance
4. Conclusions
Acknowledgments
Appendix A. Supplementary data
References