The study focuses on sand grain properties in different parts of a beach-dune system built entirely of heavy mineral particles. These properties are related to: (1) resistance of particular minerals to weathering and abrasion, (2) hydraulic sorting in the swash zone, and (3) aeolian sorting during grain transport inland from the upper beach. The main waterlain and windlain sand properties depend on settling velocity which results from grain density (reflecting grain mineralogy), size, shape and roundness. The study was performed on the beach and dunes at Patea on the west coast of the North Island of New Zealand, which are comprised of heavy minerals assemblage containing a ferromagnetic (dominated by titanomagnetite) and non-ferromagnetic (mainly pyroxene and amphibole) fractions. The result demonstrates that three zones of different sand properties can be distinguished: (1) a lower swash zone dominated by non-ferromagnetic, larger and more angular particles which are carried back from the upper swash zone down the foreshore by the backwash; (2) an uppermost swash zone and beach with almost 100% of ferromagnetic, smaller and more rounded particles deposited at the back of the beach by the uprush, which during high tide and storms can reach the cliff toe, and can be reworked by wind; and (3) a climbing dune composed of a more poorly sorted mixture of non- and ferromagnetic particles. In terms of both mineralogy and grain size and shape, the dune sand is less uniform than the beach sand. Aeolian segregation resulted here in sand textural features opposite to those found in dune sands composed of light minerals. The results highlight the density-dependent variability of grain size and shape of beach-dune deposits consisting of only heavy minerals, and broaden our understanding of mechanisms of sedimentary processes which is particularly important when reconstructing older sedimentary successions.

该研究侧重于完全由重矿物颗粒构成的沙滩-沙丘系统不同部分的沙粒特性。这些特性与：(1) 特定矿物对风化和磨损的抵抗力，(2) 冲刷区的水力分选，以及 (3) 谷物从上海滩向内陆运输过程中的风沙分选。主要的滑水和风沙特性取决于由颗粒密度（反映颗粒矿物学）、大小、形状和圆度产生的沉降速度。该研究是在新西兰北岛西海岸帕特亚的海滩和沙丘上进行的，这些沙丘由重矿物组合组成，其中包含铁磁性（以钛磁铁矿为主）和非铁磁性（主要是辉石和角闪石）部分。结果表明，可以区分出三个不同砂质的区域：（1）下斜带主要是非铁磁性的、更大、更有棱角的颗粒，这些颗粒被反冲从上斜带带回前滩；(2) 最上面的冲刷带和海滩，几乎 100% 的铁磁、更小、更圆的颗粒被上升浪沉积在海滩的后面，在涨潮和风暴期间可以到达悬崖脚趾，并且可以被风重新加工; (3) 由非磁性颗粒和铁磁性颗粒的分类较差的混合物组成的攀爬沙丘。在矿物学和颗粒大小和形状方面，沙丘沙不如沙滩均匀。风成分离导致这里的沙质结构特征与在由轻矿物组成的沙丘沙中发现的特征相反。